A&P I Exam 2 Review SlidesSummer 2013

Lectures 7-11Ch. 3 and Ch. 4

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Some Definitions…

Gene – segment of DNA that codes for a protein or RNA- About 30,000 protein-encoding genes in humans- DNA’s instructions are ultimately responsible for the ability of the cell to make ALL its components

*Chromatin – combination of DNA plus histone proteins used to pack DNA in the cell nucleus

Genome – complete set of genes of an organism- Human Genome Project was complete in 2001- Genomes of other organisms are important also

Genetic Code – method used to translate a sequence of nucleotides of DNA into a sequence of amino acids

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Structure of Nucleic Acids

Figure from: Alberts et al., Essential Cell Biology, Garland Press, 1998

Purines: Adenine and Guanine (double ring)

Pyrimidines: Cytosine, Thymine, and Uracil (single ring)

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Structure of DNA

A double-stranded DNA molecule is created by BASE-PAIRING of the nitrogenous bases via HYDROGEN bonds.

Notice the orientation of the sugars on each stand.

*DNA is an antiparallel, double-stranded polynucleotide helix

5'3'

5' 3'

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Structure of DNA

Base pairing in DNA is VERY specific. - Adenine only pairs with Thymine (A-T) - Guanine only pairs with Cytosine (G-C)

Note that there are:

- THREE hydrogen bonds in G-C pairs

- TWO hydrogen bonds in A-T pairs

- A purine (two rings)base hydrogen bonds with a pyrimidine base (one ring)

Figure from: Martini, “Human Anatomy & Physiology”, Prentice Hall, 2001

Complementary base pairing…

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DNA Replication

Figure from: Martini, “Human Anatomy & Physiology”, Prentice Hall, 2001

THINGS TO NOTE:

1. DNA is replicated in the S phase of the cell cycle

2. New strands are synthesized in a 5’ to 3’ direction

3. DNA polymerase has a proofreading function (1 mistake in 109 nucleotides copied!)

4. Semi-conservative replication describes pairing of post-replication strands of DNA (1 new, 1 old)

5’

5’

5’

5’

3’

3’

5’

3’

3’

3’

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RNA

• RNA is a polynucleotide with important differences from DNA– Uses Uracil (U) rather than Thymine (T)– Uses the pentose sugar, ribose– Usually single-stranded

• There are three important types of RNA– mRNA (carries code for proteins)– tRNA (the adapter for translation)– rRNA (forms ribosomes, for protein synthesis)

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Transciption/Translation

• Transcription – generates mRNA from DNA– Occurs in nucleus of the cell– Uses ribonucleotides to synthesize mRNA

• Translation – generates polypeptides (proteins) from mRNA– Occurs in the cytoplasm of the cell – Uses 3 components: mRNA, tRNA w/aa, and ribosomes

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The Genetic Code

1. Codon – group of three ribonucleotides found in mRNA that specifies an aa

2. Anticodon – group of three ribonucleotides found in tRNA that allows specific hydrogen bonding with mRNA

3. AUG is a start codon and also codes for MET. UAA, UAG, and UGA are stop codons that terminate the translation of the mRNA strand.

Find the AMINO ACID SEQUENCE that corresponds to the following gene region on the DNA:

Template -> C T A A G T A C T

Coding -> G A T T C A T G A

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tRNAs

Transfer RNAs (tRNA) function as ‘adapters’ to allow instructions in the form of nucleic acid to be converted to amino acids.

Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001

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Eukaryotic Genes

Figure from: Alberts et al., Essential Cell Biology, Garland Publishing, 1998

The template strand of DNA is the one that’s transcribed.

The coding strand of DNA is used as the complementary strand for the template strand in DNA and looks like the codons.

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Eukaryotic mRNA Modification

Figure from: Alberts et al., Essential Cell Biology, Garland Publishing, 1998

Newly made eukaryotic mRNA molecules (primary transcripts) undergo modification in the nucleus prior to being exported to the cytoplasm.

1. Introns removed2. 5' guanine cap added3. Poly-A tail added

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The Fate of Proteins in the Cell

• Breakdown of proteins regulates the amount of a given protein that exists at any time.

• Each protein has unique lifetime, but the lifetimes of different proteins varies tremendously.

• Proteins with short life-spans, that are misfolded, or that become oxidized must be destroyed and recycled by the cell.

Enzymes that degrade proteins are called proteases. They are hydrolytic enzymes.

Most large cytosolic proteins in eukaryotes are degraded by enzyme complexes called proteasomes.

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Types/Functions of Epithelial Tissue

• Functions of Epithelial Tissue– Physical protection– Control of permeability

• Secretion, Absorption, Filtration

– Provide sensation– Provide specialized secretions (glands)

• Types of epithelium1. Covering and Lining Epithelium

– External Surfaces, e.g., skin, Internal surfaces

2. Glandular Epithelium

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Characteristics of Epithelial Tissue

• Specialized contacts with other cells

• Polarity (different ends of cell do different things)

• Avascularity (no blood supply)

• Regeneration (can divide to make new cells)

• Cellularity (lots of cells in close contact)

Remember: Epithelial tissues always have a free surface and a basement membrane

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Basal Lamina

Two components:

Lamina Lucida - glycoproteins and fine protein filaments - Barrier for passage of substances from underlying tissue into epithelium

Lamina Densa - bundles of coarse protein fibers - gives basal lamina its strength

Formerly called: Basement membrane

Figure from: Martini, Fundamentals of Anatomy & Physiology, Benjamin Cummings, 2004

Lamina = thin layer

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Classification of Epithelial Tissues

• Shape– Squamous (Thin, flat, irregular in shape)– Cuboidal (Square or cuboidal)– Columnar (Rectangular, tall)

• Type of layering (stratification)– Simple (one layer)– Stratified (two or more layers)– Note that classification of stratified

epithelium is based on the shape of the superficial, not deep, layers

Epithelial tissues are classified according to both their:

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Characteristics of Epithelial TissueSpecialized Contacts

Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Tight junction – forces substances to go through cells, rather than being able to pass between them

Gap junction – allow rapid passage of small molecules/ions between cells

Desmosome – binds cells together firmly so they stay connected

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Review

NAME OF ET DESCRIPTION STRUCTURE

LOCATION FUNCTION

SIMPLESQUAMOUS

a single layer of flattened cells

linings of air sacs, capillaries, lymph vessels, body cavities; covering ventral organs

diffusion, reduction of friction

SIMPLE CUBOIDAL

a single layer of cube-shaped cells with large centrally located nuclei

linings of kidney tubules, ducts of glands

absorption,secretion

SIMPLE COLUMNAR

a single layer of tall cells with basally located nuclei, goblet cells, & mucrovilli

lining of intestine protection,absorption,secretion

PSEUDO-STRATIFIEDCOLUMNAR

a single layer of tall cells with scattered nuclei, cilia, & goblet cells

lining of trachea,lining of fallopian tube

protection, secretion

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Review

NAME OF ET DESCRIPTION STRUCTURE

LOCATION FUNCTION

STRATIFIEDSQUAMOUS

many layers of flattened cells

keratinized = epidermis;non-keratinized = lining of vagina, anus, throat, mouth

protection

TRANSITIONAL several layers of cells that change shape under pressure

lining of urinary bladder and ureters

Distensibility (able to stretch)

GLANDULAR simple cuboidal lining the ducts of glands

secretion

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Review of Epithelial Tissues

• Exocrine glands have several different mechanisms of secretion– Merocrine

• Release of product from vesicles by exocytosis – none of cell is lost

– Holocrine• Entire cell is lost: packed with secretion and then bursts

• Ex: Unicellular = mucous gland; multicelluar = sweat gland, sebaceous gland, mammary gland, etc.

• Glands are specialized epithelium

– Secrete on to a surface (exocrine)

– Secrete into a duct (exocrine)

– Secrete into the blood (endocrine)

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Membranes

Serous• line body cavities that lack openings to outside• reduce friction• inner lining of thorax and abdomen• cover organs of thorax and abdomen• secrete serous fluid

Mucous• line tubes and organs that open to outside world• lining of mouth, nose, throat, digestive tract, etc.• secrete mucus

Cutaneous• covers body• skin

A membrane is a combination of epithelium and connective tissue that covers and protects other structures and tissues. Technically, then, a membrane is an organ.

Synovial• surround joint cavities

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Review of Connective TissuesNAME OF CT DESCRIPTION LOCATION FUNCTION

MESENCHYME Embryo gives rise to all other CT’s

AREOLAR gel-like matrix with fibroblasts, collagen and elastic fibers

beneath ET (serous membranes around organs & lining cavities)

diffusion, cushioning organs

ADIPOSE closely packed adipocytes with nuclei pushed to one side by fats

beneath skin, breasts, around kidneys & eyeballs

insulation, energy store, protection

RETICULAR network of reticular fibers in loose matrix

basement membranes,lymphatic organs

support

DENSEREGULAR

dense matrix of collagen fibers

tendons, ligaments attachment (high tensile strength)

DENSEIRREGULAR

loose matrix of collagen fibers

dermis of skin strength in several directions

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Review of Connective TissuesNAME OF CT DESCRIPTION LOCATION FUNCTION

ELASTIC CT matrix of elastic fibers

lung tissue, wall of aorta

durability with stretch

HYALINECARTILAGE

chondrocytes in lacunae in amorphous matrix

embryonic. skeleton, costal cart, tip of nose, trachea, larynx

support

FIBRO-CARTILAGE

less firm than above intervertebral discs, pubic symphysis

tensile strength, shock absorber

ELASTICCARTILAGE

above plus elastic fibers

external ear, epiglottis

shape maintenance plus flexibility

BONE concentric circles of calcified matrix

Bones support, protection, movement, Ca ++ storage, hematopoiesis

BLOOD red cells, white cells and platelets in liquid plasma

in heart and blood vessels

transport of nutrients, wastes & gases

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Name of CT

Different types of this CT

Main types of cells present

Main types of fibers present

Consistency of matrix Examples of Locations

CT Proper1) Areolar (Loose)2) Dense regular3) Dense irregular4) Adipose5) Reticular6) Elastic

1) Fibroblasts2) Fibroblasts3) Fibroblasts4) Adipocytes5) Fibroblasts6) Fibroblasts

1) Collagen, Elastic2) Collagen3) Collagen4) Reticular5) Reticular6) Elastic

Semi-liquid1) Skin, between muscles2) Tendons, ligaments3) Dermis 4) Body fat areas5) Stroma of liver, spleen6) Lungs, airways, arteries/heart

Cartilage 1) Hyaline2) Fibrocartilage3) Elastic

(All) Chondrocytes1) Collagen (sparse)2) Collagen (dense)3) Elastic

All types: Semi-solid, gelatinous;

rubbery

1) Ribs, ends of bones2) Intervertebral disks3) Pinna of ear, epiglottis

Bone 1) Dense2) Spongy

(All) Osteocytes Collagen Solid (hydroxyapatite)

1) Outer portions of bone2) Inner portions of bone

Blood--

1) RBCs2) WBCs3) Platelets (cell fragments)

Fibrinogen (soluble) Liquid Blood vessels, heart

Lymph -- Lymphocytes Reticular (in stroma of lymphoid organs)

Liquid Lymph vessels

Connective Tissue (CT) Summary Table

Three main components of ALL types of CT: cell, fibers, ground substance

-cyte = fully differentiated; -blast = young, actively synthesizing cell

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Connective Tissue - Major Cell Types

Fibroblasts• fixed cell• most common cell; always in CT proper • large, star-shaped• produce fibers• produce ground substance

Macrophages• wandering cell• phagocytic• important in defense• derived from circulating monocytes

Mast cells are mediators of inflammation – see later…

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Connective Tissue FibersCollagenous fibers

• thick• composed of collagen• great tensile strength • hold structures together• abundant in dense CT• tendons, ligaments

Elastic fibers• bundles of microfibrils embedded in elastin• fibers branch• elasticity• vocal cords, air passages

Reticular fibers• very thin collagenous fibers• highly branched• form supportive networks

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The “Ground Substance” of CT

Figures from: Alberts et al., Essential Cell Biology, Garland Press, 1998

VERY hydrophilic!

**Function: Very active in controlling passage of substances through this portion of the matrix and keeping CT hydrated

GAGs = glycosaminoglycans (negatively charged polysaccharides); a major molecule in ground substance

glucosamine

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Tendons and Ligaments

Tendons: Connect muscle to boneLigaments: Connect bone to boneAponeuroses: Broad, fibrous sheets; usually attach muscle to muscle (or bone)

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CT Framework of the Body

Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Fascia: layers of fibrous connective tissue covering and separating muscle. It connects the organs of the dorsal and ventral cavities with the rest of the body

Provide: - Strength - Stability - Organ position - Conduits

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Muscle – Overview

• General characteristics– Elongated cells with special properties– Muscle cells (myocytes) = muscle fibers– Contractile (major property of all muscle)– Use actin (thin) and myosin (thick) for contraction

• Three types of muscle tissue– Cardiac (involuntary)– Skeletal– Smooth

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Review of Muscle TypesNAME OFMUSCLETISSUE

DESCRIPTION OFSTRUCTURE

TYPE OFCONTROL

LOCATION FUNCTION

SKELETALMUSCLE

long, thin fibers with many nuclei and striations

Voluntary attached to bones to move bones

SMOOTHMUSCLE

spindle shaped cells with one centrally located nucleus, lacking striations

Involuntary walls of visceral hollow organs, irises of eyes, walls of blood vessels

to move substances through passageways (i.e. food, urine, semen),

constrict blood vessels, etc

CARDIAC MUSCLE

a network of striated cells with one centrally located nucleus attached by intercalated discs

- Intercalated disks consist of : 1)gap junctions and 2) desmosomes

Involuntary heart pump blood to lungs and body

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Nervous Tissue• found in brain, spinal cord, and peripheral nerves• conduction of nerve impulses• basic cells are neurons• sensory reception• neuroglial cells are supporting cells

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Introduction to Inflammation

Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Restoration of tissue homeostasis after injury or infections involves two processes, in order: 1) inflammation and 2) repair

Main signs of inflammation: Redness, heat, pain, swelling, and loss of function

(Inflammation = ‘-itis’)

Histamine

HistamineHeparin