Biology Final Exam Review Part 2 Mrs. Depasse. Chapter 9 Cell Reproduction – The hereditary...

Biology Final Exam Review Part 2 Mrs. Depasse

Chapter 9 Cell Reproduction The hereditary information in all cells is deoxyribonucleic acid (DNA) Most of the time, the DNA in each chromosome is wound around proteins called histones These DNA-histone spools are further folded into coils Each DNA molecule consists of a long chain composed of smaller subunits called nucleotides Each nucleotide consists of a phosphate, a sugar (deoxyribose), and one of four basesadenine (A), thymine (T), guanine (G), or cytosine (C)

Figure 9-1 The structure of DNA nucleotide phosphate base sugar A single strand of DNAThe double helix

Types of Cells 1.Stem cells 2.Other cells capable of dividing 3. Permanently differentiated cells Stem cells have two important characteristics: self- renewal, and the ability to differentiate into a variety of cell types Stem cells self-renew because they retain the ability to divide, perhaps for the entire life of the organism Stem cells include most of the daughter cells formed by the first few cell divisions of a fertilized egg, as well as a few adult cells

Types of cells Other cells capable of dividing Many cells of the bodies of embryos, juveniles, and adults can divide Each type of cell typically differentiates into only one or two types of cells Dividing liver cells, for example, can only become more liver cells Permanently differentiated cells differentiate and never divide again

Sexual Reproduction Sexual reproduction in eukaryotic organisms occurs when offspring are produced by the fusion of gametes (sperm and eggs) from two adults Cells in the adults reproductive system undergo a specialized type of cell division called meiotic cell division Products of meiotic cell division, such as gametes, have exactly half the genetic information of their parent cells and reestablish the full genetic complement when they fuse

Asexual Reproduction Reproduction in which offspring are formed from a single parent, without having a sperm fertilize an egg, is called asexual reproduction Clones are offspring genetically identical to the parent and to each other, produced through asexual reproduction Bacteria and single-celled eukaryotic organisms reproduce asexually

Figure 9-3 The prokaryotic cell cycle cell division by prokaryotic fission cell growth and DNA replication The prokaryotic cell cycleProkaryotic fission The parent cell divides into two daughter cells. The plasma membrane grows inward at the middle of the cell. New plasma membrane is added between the attachment points, pushing the two chromosomes farther apart. The DNA replicates and the resulting two chromosomes attach to the plasma membrane at nearby points. The prokaryotic chromosome, a circular DNA double helix, is attached to the plasma membrane at one point. attachment site of chromosome cell wall plasma membrane chromosome

Eukaryotic chromosomes Eukaryotic chromosomes usually occur in pairs with similar genetic information A typical human cell has 23 pairs of chromosomes, for a total of 46 Twenty-two out of 23 pairs are called autosomes Autosomes have similar appearance and similar DNA sequences, and are paired in diploid cells of both sexes The twenty-third pair is called sex chromosomes and is different in the male and the female

Misc. The female has two X chromosomes that usually look similar The male has an X and a Y chromosome that appear very different Enduring mutations, inherited generation after generation, are called alleles Cells in the ovaries and testes undergo meiotic cell division and produce gametes (eggs and sperm) that only have one member of each chromosome pair These kinds of cells are called haploid

Haploid vs. Diploid In biological shorthand, the haploid chromosome number is designated n, whereas the diploid number is 2n In humans n = 23; 2n = 46

Meiosis Most eukaryotic cells spend the majority of their time in interphase Interphase is divided into three phases 1. G 1 (growth phase 1) is a time for acquisition of nutrients and growth to proper size 2. S (synthesis phase) is characterized by DNA synthesis, during which every chromosome is replicated 3. G 2 (growth phase 2) includes completion of cell growth and preparation for division of the cell into daughter cells

Figure 9-8 The eukaryotic cell cycle G 1 : cell growth and differentiation telophase and cytokinesis anaphase metaphase prophase S: synthesis of DNA; duplication of chromosomes G 2 : cell growth and preparation for cell division

Mitotic Cell Division Mitotic cell division is the division of one parental cell into two daughter cells; it consists of two processes: mitosis and cytokinesis Mitosis is the division of the nucleus During mitosis (nuclear division), the nucleus of the cell and the chromosomes divide Each daughter nucleus receives one copy of each of the replicated chromosomes of the parent cell During cytokinesis (cytoplasmic division), the cytoplasm is divided roughly equally between the two daughter cells, and one daughter nucleus enters each of the daughter cells

Mitosis Mitosis has four main phases based on appearance and behavior of the chromosomes 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase

Prophase The first phase of mitosis is prophase (the stage before in Greek) Five major events occur during prophase 1.Duplicated chromosomes condense 2.Spindle microtubules form -Two types of spindle microtubules form: polar microtubules and kinetochore, a protein-containing structure located at the centromere 3.Nuclear envelope breaks down 4.Chromosome condensation causes nucleolus to dissipate 5.Chromosomes are captured by the spindle microtubules

Figure 9-9-1 Mitotic cell division in an animal cell INTERPHASEMITOSIS nuclear envelope chromatin nucleolus centriole pairs condensing chromosomes beginning of spindle formation spindle pole kinetochore microtubules spindle microtubules spindle pole Late Interphase Duplicated chromosomes are in the relaxed uncondensed state; duplicated centrioles remain clustered. Early Prophase Chromosomes condense and shorten; spindle microtubules begin to form between separating centriole pairs. Late Prophase (also called Prometaphase) The nucleolus disappears; the nuclear envelope breaks down; some spindle microtubules attach to the kinetochore (blue) located at the centromere of each sister chromatid. Metaphase Kinetochore microtubules line up the chromosomes at the cells equator.

Figure 9-9-2 Mitotic cell division in an animal cell MITOSIS Anaphase Sister chromatids separate and move to opposite poles of the cell; polar microtubules push the poles apart. INTERPHASE Telophase One set of chromosomes reaches each pole and begins to decondense; nuclear envelopes start to form; nucleoli begin to reappear; spindle microtubules begin to disappear; microfilaments form rings around the equator. Cytokinesis The ring of microfilaments contracts, dividing the cell in two; each daughter cell receives one nucleus and about half of the cytoplasm. Interphase of daughter cells Spindles disappear, intact nuclear envelopes form, and the chromosomes extend completely. polar microtubules chromosomes extending nuclear envelope re-forming microfilamentsnucleolus reappearing

Figure 9-10 Cytokinesis in a plant cell cell plate forming a new cell wall Golgi apparatus cell wall plasma membrane carbohydrate- filled vesicles Carbohydrate-filled vesicles bud off the Golgi apparatus and move to the equator of the cell. The vesicles fuse to form a new cell wall (red) and plasma membrane (yellow) between the daughter cells. Complete separation of the daughter cells.

CDKs The cell cycle is driven by proteins called cyclin- dependent kinases, or CDKs Kinases are enzymes that phosphorylate (add a phosphate group to) other proteins, stimulating or inhibiting the proteins activity

Figure 9-11 Growth factors stimulate cell division (interstitial fluid) cyclin- dependent kinase (Cdk) Cyclin binds to Cdk cyclin Cyclin activates Cdk; active Cdk stimulates DNA replication plasma membrane Cyclins are synthesized growth factor receptor Growth factor binds to its receptor (cytosol) growth factor

Meiosis Meiosis is a specialized cell division process that produces haploid gametes Each gamete receives one member of each pair of homologous chromosomes The first nuclear division, meiosis I, separates the pairs of homologues, with each daughter nucleus receiving one The second nuclear division, meiosis II, separates the chromatids and parcels one chromatid into each of two more daughter nuclei

Crossing over During prophase I, homologous chromosomes pair up and exchange DNA Crossing over is a mutual exchange of corresponding chromatid sections (and, therefore, DNA) between maternal and paternal homologues The binding proteins and enzymes then depart, leaving crosses or chiasmata (singular, chiasma), where the maternal and paternal chromosomes have exchanged parts If the exchanged segments carry different alleles, genetic recombination has occurred

Table 9-1

Chapter 10 Inheritance Inheritance is the process by which the traits of organisms are passed to their offspring A gene is a unit of heredity that encodes information needed to produce proteins, cells, and entire organisms The location of a gene on a chromosome is called its locus (plural, loci) Alternative versions of genes found at the same gene locus are called alleles

Alleles Each cell carries two alleles per characteristic, one on each of the two homologous chromosomes If both homologous chromosomes carry the same allele (gene form) at a given gene locus, the organism is homozygous at that locus If two homologous chromosomes carry different alleles at a given locus, the organism is heterozygous at that locus (a hybrid)

Gregor Mendel Gregor Mendel, an Austrian monk, discovered the common patterns of inheritance and many essential facts about genes, alleles, and the distribution of alleles in gametes and zygotes during sexual reproduction True-breeding organisms possess traits that remain inherited unchanged by all offspring produced by self-fertilization The pairs of alleles on homologous chromosomes separate, or segregate, from each other during meiosis, which is known as Mendels law of segregation

Genotype and Phenotype The particular combination of the two alleles carried by an individual is called the genotype For example, PP (homozygous) or Pp (heterozygous) The physical expression of the genotype is known as the phenotype (for example, purple or white flowers) A test cross is used to deduce whether an organism with a dominant phenotype is homozygous for the dominant allele or heterozygous

When the heterozygous phenotype is intermediate between the two homozygous phenotypes, the pattern of inheritance is called incomplete dominance A species may have multiple alleles for a given characteristic The human blood types are an example of multiple alleles of a single gene

Table 10-1

Polygenic Inheritance These traits are influenced by interactions among two or more genes through a process called polygenic inheritance Examples of this include height, skin color, and body build in humans, and grain color in wheat According to research, human height is controlled by at least 180 genes Human skin color is controlled by at least three genes, each with pairs of incompletely dominant alleles

Gene Linkage Genes on the same chromosome tend to be inherited together, a phenomenon called gene linkage Crossing over creates new combinations of linked alleles The farther apart two linked gene loci are on a chromosome, the more likely crossing over is to occur between them Crossing over, or genetic recombination, in prophase I of meiosis creates new gene combinations

Sex-linked genes Genes carried on one sex chromosome, but not on the other, are sex-linked In humans, the X chromosome is much larger than the Y and carries over 1,000 genes In contrast, the human Y chromosome is smaller and carries only 78 genes Color blindness is caused by recessive alleles of either of two genes located on the X chromosome

Genetic disorders An allele known as TYR (for tyrosinase) encodes a defective tyrosinase protein in skin cells, producing no melanin and a condition called albinism (recessive) Sickle-cell anemia is caused by a defective allele for hemoglobin synthesis (recessive) Huntington disease is a dominant disorder that causes a slow, progressive deterioration of parts of the brain Several defective alleles for characteristics encoded on the X chromosome are known, including red-green color blindness and hemophilia

Non-disjunction The incorrect separation of chromosomes or chromatids in meiosis is known as nondisjunction Nondisjunction causes gametes to have too many and too few chromosomes Turners syndrome (XO) occurs in females with only one X chromosome Trisomy X (XXX) results in a fertile normal woman with an extra X chromosome Men with Klinefelter syndrome (XXY) have an extra X chromosome

Non-disjunction Embryos with three copies of an autosome (trisomy) also usually spontaneously abort; however, a small fraction of embryos with three copies of chromosomes 13, 18, or 21 survive to birth The frequency of nondisjunction increases with the age of the parents In trisomy 21 (Down syndrome), afflicted individuals have three copies of chromosome 21 Occurs in about 1 out of every 800 births

Chapter 11 -DNA Heritable information is carried in discrete units called genes DNA is composed of four nucleotides DNA is made of chains of small subunits called nucleotides Each nucleotide has three components 1. A phosphate group 2. A deoxyribose sugar 3. One of four nitrogen-containing bases 1. Thymine (T) 2. Cytosine (C) 3. Adenine (A) 4. Guanine (G)

Chargaffs Rule In the 1940s Erwin Chargaff, a biochemist at Columbia University, analyzed the amounts of the four bases in DNA from diverse organisms He discovered a consistency in the equal amounts of adenine and thymine, and equal amounts of guanine and cytosine for a given species, although there was a difference in proportion of the bases

Figure 11-5 The Watson-Crick model of DNA structure Hydrogen bonds hold complementary base pairs together in DNA Two DNA strands form a double helix Four turns of a DNA double helix nucleotide free phosphate base (cytosine) sugar hydrogen bonds free sugar free phosphate free sugar

Watson & Crick In 1953, James Watson and Francis Crick consolidated all the historical data about DNA into an accurate model of its structure Genetic information is encoded in the sequence of nucleotides The key lies in the sequence, not the number, of subunits

DNA replication Duplication of the parent cell DNA is called DNA replication DNA replication produces two DNA double helices, each with one original strand and one new strand The ingredients for DNA replication are threefold The parental DNA strands Free nucleotides A variety of enzymes that unwind the parental DNA double helix and synthesize new DNA strands DNA Helicases, DNA polymerases

DNA replication The two resulting DNA molecules have one old parental strand and one new strand (semiconservative replication)

Mutations Infrequent changes in the sequence of bases in DNA result in defective genes called mutations Mutations may have varying effects on function Mutations are often harmful, and an organism inheriting them may quickly die Some mutations may have no functional effect Some mutations may be beneficial and provide an advantage to the organism in certain environments Point (Substitution), deletion, insertion, translocation, inversion

Chapter 12 Gene expression DNA contains the molecular blueprint of every cell Proteins are the construction workers of the cell Proteins control cell shape, function, reproduction, and synthesis of biomolecules DNA information must be carried by an intermediary, ribonucleic acid (RNA), from the nucleus to the cytoplasm DNA in eukaryotes is kept in the nucleus Protein synthesis occurs at ribosomes in the cytoplasm

RNA RNA differs structurally from DNA in three ways 1. RNA is usually single-stranded 2. RNA has the sugar ribose rather than deoxyribose in its backbone 3. RNA contains the nitrogenous base uracil (U) instead of thymine (T)

Types of RNA There are three types of RNA involved in protein synthesis Messenger RNA (mRNA) carries DNA gene information to the ribosome Transfer RNA (tRNA) brings amino acids to the ribosome Ribosomal RNA (rRNA) is part of the structure of ribosomes

Figure 12-1 Cells synthesize three major types of RNA that are required for protein synthesis codons Messenger RNA (mRNA) catalytic site large subunit small subunit tRNA/amino acid binding sites Ribosome: contains ribosomal RNA (rRNA) 12 tyr tRNA attached amino acid Transfer RNA (tRNA) anticodon Each tRNA carries a specific amino acid (in this example, tyrosine [tyr]) to a ribosome during protein synthesis; the anticodon of tRNA pairs with a codon of mRNA, ensuring that the correct amino acid is incorporated into the protein rRNA combines with proteins to form ribosomes; the small subunit binds mRNA; the large subunit binds tRNA and catalyzes peptide bond formation between amino acids during protein synthesis The base sequence of mRNA carries the information for the amino acid sequence of a protein; groups of these bases, called codons, specify the amino acids

Definitions Messenger RNA carries the code for protein synthesis from DNA to the ribosomes Codons, groups of three bases in mRNA, specify which amino acids will be incorporated into a protein Ribosomes, the structures that carry out translation, are composed of rRNA and many different proteins A group of three bases, called an anticodon, protrudes from each tRNA

Transcription - Translation DNA directs protein synthesis in a two-step process 1.Information in a DNA gene is copied into RNA in the process of transcription Occurs in the nucleus of eukaryotic cells 2.Messenger RNA, together with tRNA, amino acids, and a ribosome, synthesizes a protein in the process of translation of the genetic information contained in the mRNA Occurs in the cytoplasm of eukaryotic cells

Genetic code The genetic code translates the sequence of bases in nucleic acids into the sequence of amino acids in proteins DNA and RNA contain four different bases adenine (A); thymine (T; uracil {U} in RNA); guanine (G); and cytosine (C). Given that there are 20 amino acids but only four bases, statistically, the smallest number of bases that could combine to yield a different sequence for each of the 20 amino acids is three A two-base code could produce only 16 combinations The three-base code has the potential to create 64 combinations

Transcription The three steps of transcription correspond to the three major parts of most genes in eukaryotes and prokaryotes 1. A promoter region at the beginning of the gene marks where transcription is to be initiated 2. The body of the gene corresponds with where elongation of the RNA strand occurs 3. A termination signal at the end of the gene marks where RNA synthesis is to terminate

Introns and Exons Each gene consists of two or more segments of DNA that encode for protein, called exons, that are interrupted by other segments that are not translated, called introns Functions of intron-exon gene structure Through alternative splicing of the exons in a gene, a cell can make multiple proteins from a single gene Alternative splicing represents an exception to Beadle and Tatums one geneone protein relationship

Translation During translation, mRNA, tRNA, and ribosomes cooperate to synthesize proteins Like transcription, translation has three steps 1. Initiation 2. Elongation 3. Termination

Mutations affect protein synthesis The effects of mutations depend on how they alter the codons of mRNA Mutations take many forms and can affect protein function in many ways (ex. Sickle cell anemia) Mutations fall into five categories 1. Inversions 2. Translocations 3. Deletions 4. Insertions 5. Substitutions

Figure 12-10 An overview of information flow in a eukaryotic cell Cells can control the frequency of transcription Different mRNAs may be produced from a single gene Cells can control the stability and rate of translation of particular mRNAs Cells can regulate a proteins activity by modifying it Cells can regulate a proteins activity by degrading it Degradation Modification Translation mRNA tRNA amino acids inactive protein active protein amino acids product substrate If the active protein is an enzyme, it will catalyze a chemical reaction in the cell ribosomes (cytosol) (nucleus) mRNA processing tRNApre-mRNArRNA proteins Transcription DNA

Chapter 13 - Biotechnology Biotechnology is the use, and especially the alteration, of organisms, cells, or biological molecules to produce food, drugs, or other goods

Transformation Transformation may combine DNA from different bacterial species In transformation, bacteria pick up pieces of DNA from the environment This DNA could be part of a chromosome from another bacterium or tiny circular DNA molecules called plasmids Passing plasmids from bacteria to yeast may also occur, a process that moves genes from prokaryotes to eukaryotes

PCR Developed by Kary Mullis of the Cetus Corporation, the polymerase chain reaction (PCR) produces virtually unlimited copies of a very small DNA sample PCR involves two major steps 1.Marking the DNA segment to be copied 2.Running repetitive reactions to make multiple copies

Figure 13-3 PCR copies a specific DNA sequence DNA segment to be amplified original double- stranded DNA segment 194 F (90 C)122 F (50 C)158 F (70 C) primers DNA polymerase Heating separates DNA strands Cooling allows primers and DNA polymerase to bind New DNA strands are synthesized new DNA strands One PCR cycleEach PCR cycle doubles the number of copies of the DNA PCR cycles DNA copies 12 21 4 4 etc. 16 etc. 8 3

STRs Forensic scientists have found that small, repeating segments of DNA, called short tandem repeats (STRs), can be used with astonishing accuracy to identify people STRs vary greatly between different human individuals, like genetic fingerprints The U.S. Department of Justice established a standard set of 13 STRs, each four nucleotides long, to identify individuals by DNA samples

Gel electrophoresis Gel electrophoresis separates DNA segments Mixtures of DNA fragments can be separated on the basis of size Gel electrophoresis is a technique used to spread out DNA fragments of varying lengths in a mixture Because of its phosphates, the negatively charged DNA moves toward the positive electrode, with smaller fragments moving through the gel meshwork more quickly than larger ones DNA probes are short, single-stranded DNA fragments used to identify DNA in a gel pattern

GMOs Biotechnology can be used to identify, isolate, and modify genes Combine genes from different organisms Move genes from one species to another Using restriction enzymes, genes are inserted into plasmids Each of the restriction enzymes cut DNA at a specified nucleotide sequence

Transgenic Organisms Transfecting, which is inserting the gene into the host organism and having it be expressed in the appropriate cells, at the appropriate times, and at the desired level, is difficult Transgenic animals can be engineered by incorporating genes into chromosomes of a fertilized egg, which is allowed to grow to term

DNA Technology DNA technology can be used to diagnose inherited disorders Two methods are commonly used to find out if a person carries a normal allele or a malfunctioning allele Restriction enzymes may cut different alleles of a gene at different locations, yielding distinctive fragments characteristic of one allele or the other (sickle cell anemia) PCR can be used to isolate and amplify disease-specific genes for various types of diagnostic procedures DNA probing is especially useful where there are many different alleles at a single gene locus

Chpt. 28 Energy flow in Ecosystems All ecosystems consist of two components The biotic component of an ecosystem is the community of living organismsbacteria, fungi, protists, plants, and animalsin a given area The abiotic component of an ecosystem consists of all nonliving physical or chemical aspects of the environment, such as the climate, light, temperature, availability of water, and minerals in the soil

Energy Energy, in contrast, takes a one-way journey through ecosystems Solar energy is captured by photosynthetic bacteria, algae, and plants, and then flows from organism to organism Eventually, all of lifes energy is converted to heat that is given off to the environment and cannot be used to drive the chemical reactions of living organisms Life requires a continuous input of energy

Trophic levels Each category of organisms is called a trophic level Producers (or autotrophs) make their own food using inorganic nutrients and solar energy from the environment Organisms that cannot photosynthesize are called consumers (or heterotrophs) Primary consumers feed directly and exclusively on producers These herbivores include animals such as grasshoppers, mice, and zebras, and form the second trophic level

Consumers Carnivores (meat eaters), such as spiders, hawks, and salmon, make up the higher-level consumers Carnivores act as secondary consumers when they prey on herbivores Some carnivores eat other carnivores and are called tertiary consumers

Net Primary Production The energy that photosynthetic organisms store and make available to other members of the community over a given period is called net primary production Biomass, or dry biological material, is usually a good measure of the energy stored in organisms bodies

Food Web A food web shows many interconnected food chains, and actual feeding relationships in a community Some animals, such as raccoons, bears, rats, and humans, are omnivores (everything eaters) and act as primary, secondary, and tertiary consumers Among the most important strands in a food web are the detritivores (debris eaters) and decomposers (fungi and bacteria)

Figure 28-5 An energy pyramid for a grassland ecosystem tertiary consumer (1 calorie) secondary consumer (10 calories) primary consumer (100 calories) producers (1,000 calories)

Biological Magnification If the food contains certain types of toxic substances, they may be stored and become more concentrated This biological magnification can lead to harmful and even fatal effects Example DDT

Macronutrients Some of the chemical building blocks of life, called macronutrients, are required by organisms in large quantities Water Carbon Hydrogen Oxygen Nitrogen Phosphorous Sulfur Calcium

Carbon cycle The carbon cycle is the pathway that carbon takes from its major short-term reservoirs in the atmosphere and oceans, through producers and into the bodies of consumers, detritivores, and decomposers, and then back again to its reservoirs

Figure 28-7 The carbon cycle reservoirs processes trophic levels CO 2 dissolved in the ocean CO 2 in the atmosphere burning fossil fuels respirationfire consumers producers photosynthesis fossil fuels (coal, oil, natural gas) detritivores and decomposers decomposition

The Nitrogen Cycle The nitrogen cycle is the pathway taken by nitrogen from its primary reservoirnitrogen gas (N 2 ) in the atmosphereto much smaller reservoirs of ammonia and nitrate in soil and water, through producers, consumers, detritivores and decomposers, and back to its reservoirs

Figure 28-8 The nitrogen cycle reservoirs processes trophic levels burning fossil fuels N 2 in the atmosphere lightning application of manufactured fertilizer producers consumers decomposition ammonia and nitrates in water denitrifying bacteria detritivores and decomposers uptake by producers ammonia and nitrates in soil nitrogen-fixing bacteria in soil and legume roots

The phosphorus Cycle The phosphorus cycle is the pathway taken by phosphorus from its primary reservoir in rocks to much smaller reservoirs and back

Figure 28-9 The phosphorus cycle phosphate in rock reservoirs processes trophic levels geological uplift application of manufactured fertilizer runoff from rivers runoff from fertilized fields phosphate in water uptake by producers producers consumers detritivores and decomposers decomposition phosphate in soil phosphate in sediment formation of phosphate-containing rock

Acid rain Burning of sulfur-containing fossil fuels, primarily coal, accounts for about 75% of all sulfur dioxide emissions worldwide These two substances combine with atmospheric water and form nitric and sulfuric acids Acid deposition (acid rain) damages forests, can render lakes lifeless, and even eats away at buildings and statues. Since 1990, government regulations have resulted in substantial reductions in emissions of both sulfur dioxide and nitrogen oxides from U.S. power plants

Chapter 31 - Homeostasis Walter Cannon coined the term homeostasis to describe the ability of an organism to maintain its internal environment within narrow limits that allow optimal cell functioning Although homeostasis (meaning to stay the same) implies a static, unchanging state, the internal environment actually seethes with activity as the body continuously adjusts to varying internal and external conditions

Homeostasis The internal environment is maintained in a state of dynamic constancy Homeostatic mechanisms regulate various conditions Temperature Water and salt concentrations in body fluids Glucose concentrations pH (acid-base balance) Hormone secretion Oxygen and carbon dioxide concentrations

Feedback Systems Feedback systems regulate internal conditions There are two types of feedback systems 1.Negative feedback systems, which counteract the effects of changes in the internal environment and are principally responsible for maintaining homeostasis 2.Positive feedback systems, which drive rapid, self- limiting changes, such as those that occur when a mother gives birth

Negative Feedback The most important mechanism governing homeostasis is negative feedback, in which a change causes responses that counteract the change The overall result of negative feedback is a return of the system to its original condition Endothermic animals use negative feedback systems to maintain their internal temperature despite fluctuations in the temperature around them In humans and mammals, the temperature control center is located in a part of the brain called the hypothalamus

Positive Feedback Positive feedback enhances the effects of changes In positive feedback, a change produces a response that intensifies the initial change Positive feedback is relatively rare in biological systems, but occurs during childbirth The early contractions of labor push the babys head against the cervix to stretch and open The hypothalamus responds by triggering the release of a hormone called oxytocin

Body Organization This coordination of complex body systems is based on a simple hierarchy of structures cells tissues organs organ systems Cells are the fundamental units of all living organisms

Body Organization Animal tissues are composed of similar cells that perform a specific function Organs are structures that perform complex functions and include two or more interacting tissue types Organ systems consist of two or more interacting organs that function in a coordinated manner

Tissues There are four major categories of animal tissues 1. Epithelial tissue - covers the body, lines its cavities, and forms glands 2. Connective tissue - There are three main categories of connective tissue 1. Loose connective tissue - consisting of a thick fluid containing scattered cells that secrete protein 2. Dense connective tissue- packed with collagen fibers - tendons and cartilage 3. Specialized connective tissue cartilage, bone, adipose, blood and lymph

Figure 31-4c Skin epidermis (stratified epithelium) dead cells flattened dying cells differentiating cells dividing cells basement membrane Skin epidermis (stratified epithelium)

Tissues 3. Muscle tissue has the ability to contract, smooth, skeletal, and cardiac. Smooth and cardiac muscle contractions are involuntary 4. Nerve tissue - makes up the brain, spinal cord, and nerves in all body parts Nerve tissue is composed of two types of cells 1. Nerve cells, also called neurons 2. Glial cells

Chapter 33 - Respiration Requirements for Gas Exchange 1.Respiratory surfaces remain moist, because cell membranes are always moist, and only gases dissolved in water can diffuse into or out of cells 2.Respiratory surfaces are very thin to minimize diffusion distances 3. Respiratory surfaces have a sufficiently large surface area in contact with the environment to allow adequate gas exchange by diffusion to meet the needs of the organism

Adaptations for Gas diffusion Some animals in moist environments lack specialized respiratory structures For O 2 delivery to cells, some animals combine a large skin surface area with a well-developed circulation (earthworm) Most relatively large, active animals have respiratory systems that work as a unit to facilitate gas exchange between the animal and its environment

Lungs and gills Terrestrial vertebrates respire using lungs Lungs are chambers containing moist respiratory surfaces that are protected within the body, where water loss is minimized and the body wall provides support Amphibians use gills for respiration as aquatic larvae, and a simple, sac-like lung when they metamorphose into the adult form

Respiratory system The respiratory system in humans and other mammals can be divided into two parts 1.The conducting portion, which consists of a series of passageways that carry air into and out of the gas-exchange portion of the respiratory system 2.The gas-exchange portion within the lungs, where oxygen and carbon dioxide are exchanged through the blood - alveoli, the tiny air sacs where gas exchange occurs

Breathing Breathing rate is controlled by the respiratory center of the brain Unlike the heart muscle, the diaphragm and rib muscles used in breathing are not self-activating Each contraction causing inhalation is stimulated by impulses from nerve cells These impulses originate in the respiratory center, which is located in the medulla, a portion of the brain just above the spinal cord

Figure 33-10 Gas exchange between alveoli and capillaries to the pulmonary vein from the pulmonary artery capillary walls alveolar wall respiratory membrane surfactant fluid protein fibers Oxygen diffuses into the red blood cells Carbon dioxide diffuses into the alveolus (air)

Chapter 32 Circulatory System All circulatory systems have three major parts 1.A pump, the heart, that keeps the blood circulating 2.A liquid, blood, that serves as a medium of transport for gases, nutrients, and cellular wastes 3.A system of tubes, blood vessels, consisting of arteries that carry blood away from the heart, veins that carry blood toward the heart, and capillaries that link arteries and veins and exchange materials through their walls

Open Circulatory System Open circulatory systems are found in many invertebrates, including arthropods and mollusks These animals have one or more simple hearts, some blood vessels, and a series of interconnected spaces within the body called a hemocoel Tissues and organs in the hemocoel are bathed in a fluid called hemolymph,

Closed Circulatory System Closed circulatory systems confine the blood to the heart and to vessels that carry blood throughout the body Blood pressure and flow rates are higher than is possible in an open system A closed circulatory system is better able to direct blood to specific tissues as needed

Closed circulatory system Closed circulatory systems are present in all vertebrates (such as fishes, reptiles, and mammals) and in a few invertebrates, including very active mollusks (squid and octopuses) and, perhaps surprisingly, earthworms, where five contractile vessels serve as hearts

Heart Structure The vertebrate heart consists of muscular chambers capable of strong contractions Chambers called atria collect blood Atrial contractions send blood into ventricles, chambers whose contractions circulate blood through the lungs and to the rest of the body The four-chambered heartwith its right atrium and right ventricle completely isolated from its left atrium and left ventricleacts like two hearts beating as one

Pulmonary Circuit The right heart deals with oxygen-poor blood The right atrium receives oxygen-depleted blood from the body through the two largest veins, the superior vena cava and the inferior vena cava After filling with blood, the right atrium contracts, forcing blood into the right ventricle Contraction of the right ventricle sends the oxygen- poor blood to the lungs through the pulmonary arteries

The left heart The left heart deals with oxygenated blood Oxygen-rich blood from the lungs enters the left atrium through the pulmonary veins and is then squeezed into the left ventricle A strong contraction of the left ventricle, the hearts most muscular chamber, sends the oxygenated blood coursing out through the largest artery, the aorta, and then to the rest of our body

Blood components Blood, sometimes called the river of life, has two major components 1.A liquid, called plasma, which comprises about 55% to 60% of the blood volume 2.A cell-based portion consisting of red blood cells, white blood cells, and platelets suspended in the plasma

Table 32-1 Blood Components and Their Functions, 2 of 2

Red Blood Cells About 99% of all blood cells, and about 45% of the total blood volume, are oxygen-carrying red blood cells, also called erythrocytes The red color of erythrocytes is caused by the large, iron-containing protein hemoglobin, which transports oxygen in the blood The red blood cell count is maintained by a negative feedback system that involves the hormone erythropoietin. Erythropoietin stimulates the rapid production of new red blood cells by the bone marrow

Capillaries Blood leaving the heart travels from arteries to arterioles to capillaries, then into venules, and finally, to veins, which return it to the heart Capillaries allow individual body cells to exchange nutrients and wastes with the blood by diffusion Capillaries are so narrow that red blood cells pass through them single file

The lymphatic system The lymphatic system includes some organs, as well as an extensive system of lymphatic vessels, which eventually feeds into the circulatory system This organ system performs the following functions: Returns excess extracellular fluid and plasm to the bloodstream Transports fats from the small intestine to the bloodstream Filters aged blood cells and other debris from the blood Defends the body by exposing bacteria and viruses to white blood cells

Chapter 34 Digestion Nutrients are substances obtained from the environment that organisms need for their growth and survival Nutrients fall into six major categories 1. Carbohydrates 2. Lipids 3. Proteins 4. Minerals 5. Vitamins 6. Water

Food sources of energy Nutrients that supply energy are lipids, carbohydrates, and proteins Carbohydrates are a source of quick energy Fats and oils are the most concentrated energy source Fats and oils contain over twice as many Calories per unit weight as do carbohydrates or proteins

Essential Nutrients Our cells can synthesize most of the molecules our bodies require, but they cannot synthesize certain raw materials, called essential nutrients, which must be supplied in the diet Essential nutrients for humans include certain fatty acids and amino acids, a variety of minerals and vitamins, and water

Minerals Minerals are elements required by the body Minerals are elements that play many crucial roles in animal nutrition and can only be obtained in the diet or dissolved in drinking water Calcium, magnesium, and phosphorus are major constituents of bone and teeth Sodium, calcium, and potassium are needed for muscle contraction and the conduction of nerve impulses

Vitamins Vitamins play many roles in metabolism Vitamins are organic molecules that animals require in small amounts for normal cell function, growth, and development Human vitamins are grouped into two categories: water soluble or fat soluble

Table 34-3, 2 of 2

Digestive Systems All digestive systems perform five tasks 1. Ingestion: Food is brought into the digestive tract through an opening, usually called a mouth 2.Mechanical digestion: The food is physically broken down into smaller pieces that have a greater surface area than do larger particles, allowing digestive enzymes to attack them more efficiently 3.Chemical digestion: Digestive chemicals and enzymes break down large food molecules into smaller subunits

Digestive Systems 4. Absorption: The small subunits are transported out of the digestive tract through cells lining the digestive tract to the blood for use by body cells 5.Elimination: Indigestible materials are expelled from body All animals except sponges have evolved a chamber within the body in which chunks of food are broken down by enzymes outside the cells, a process called extracellular digestion.

Figure 34-12 The human digestive tract Large intestine: Absorbs vitamins, minerals, and water; houses bacteria, produces feces Gallbladder: Stores bile from the liver Liver: Secretes bile(also has many non-digestive functions) Esophagus: Transports food to the stomach Pharynx: Shared digestive and respiratory passage Salivary glands: Secrete lubricating fluid and starch-digesting enzymes Oral cavity, tongue,teeth: Grind food, mix with saliva Epiglottis: Directs food down the esophagus Stomach: Breaks down food and begins protein digestion Pancreas: Secretes bicarbonate and several digestive enzymes Small intestine: Food is digested and absorbed Rectum: Stores feces

Chemical Digestion Most chemical digestion and nutrient absorption occurs in the small intestine The small intestine is a long, narrow tube that receives chyme from the stomach, completes digestion of food molecules in the chyme, and absorbs these smaller nutrient molecules into the body

Biology Final Exam Review Part 2 Mrs. Depasse. Chapter 9 Cell Reproduction – The hereditary...

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