Genetics are awesomeeee.

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Structure of DNAEach DNA molecule is made up of two very long

polymers Double helix: is the shape Nucleotides: are the building blocks: each has

deoxyribose ( a 5 carbon sugar) phosphate group nitrogenous base

DNA double helix

Nitrogenous basesThere are four different nitrogenous bases

thymine (T), cytosine (C), adenine (A), and guanine (G)

These four bases are the foundation of the genetic code.

These chemicals act as the cell's memory, instructing it on how to synthesize enzymes and other proteins. These four nucleotides encode everything an organism needs to live and protects this information with incredible accuracy.

In a human beingDNA is broken down onto 46 separate

chromosomesEach chromosome has about 160 million

nucleotide pairs This massive amount of information is stored

and replicated almost flawlessly!

DNA ReplicationINTERPHASE: Before a cell divides, its DNA is

replicated Semi Conservative replication: Two strands

of a DNA molecule are separated, each ONE can be used as a template to produce a complementary strand. 

Each template and its new complement together then form a new DNA double helix, identical to the original.

Before replication can occur, the length of the DNA double helix about to be copied must be unwound. INTERPHASE

The two strands must be separated, much like the two sides of a zippper: helicase   

The enzyme DNA polymerase then moves along the exposed DNA strand, joining newly arrived nucleotides into a new DNA strand that is  complementary to the template.  

Mitosis 1 diploid cell to 2 diploid

daughter cells Interphase: G1 G2 and S

G1 primary checkpt Kinetochore of

centromere Amimal: cleavage furrow Plant: cell plate Prokaryotes: binary

fission

CDK’sThe Cell Cycle regulated by:

cyclin-dependent kinases is regulated by binding to cyclins,

Cyclins: levels vary during the cell cycle. Levels of CDK-molecules(kinases) are const

ant during the cell cycle, their activities vary because of the regulatory function of the cyclins.

CDK’sCell replication of genetic material, followed by:

a) Binary fission in prokaryotes and plastids (mitochondria , chloroplasts). In binary fission: asexual reproduction, a cell divides into two daughter cells after replication.

b) Budding (yeast, spores, Hydra) asexual reproduction in which a new organism buds from a cell protuberance: unequal fission.

c) Mitotic division of somatic cells

c) Meiotic division of germ cells (sexual reproduction)

Cell Cycle ControlsAnchorage dependent: will only grow when

anchored to some tissue (or inside a culture)Density Dependent inhibition: stop growing

when crowded.

Meiosis ISTEP ONE MEIOSIS I: This is basically like the PMATI

of a regular mitosis. Homologous chromosomes split

Meiosis is different because crossing-over. Prophase I

crossing over: an exchange of genes from 1 homologous chromosome to the other (genes from the chromosome you got from mom go onto the chromosome you got from dad.

This is why your children will not look exactly like their Nana or Grandpa….

Recombinant phenotypeLinkage mapsRecombination:

Unlinked genes: independent assortment of chromosomes

Linked genes: crossing overRecombinant phenotype:

Mom: brown hair and brown eyesDad: Blond hair and blue eyesBaby: Brown hair and blue eyes

Meiosis IISTEP TWO MEIOSIS II: In Metaphase II all of the chromosomes line up

along the center of the cell Anaphase II shows the Sister Chromatids splitEach daughter cell will get one-half of the DNAThe cell membrane begins to pinch. When it's all

over, you are left with four haploid cells that are called gametes.

Mendel’s First Law Mendel's First Law is the law of "Segregation”

Humans are Diploid. This means you get two alleles for each trait.

Segregation: you can only get ONE allele from mom. Only ONE from dad.

Mom has 2 alleles…. Which one she passes to you (her egg) is random.

In eye color B Brown is dominant. Blue (b) is recessive.

If mom has Brown eyes she could be BB or Bb. She can only pass ONE allele on in her egg. She passes Either B or b

Basis for Punnett Squares

Segregation - If mom had the genotype AaBb she would make four kinds of

gametes(eggs): they would contain the combinations of either AB, Ab, aB or ab.

A is dominant (big feet): a is recessive (little ft) B is dominant (black hair):b is recessive(blond) So, mom would pass on either: Big feet & black hair (AB), big feet and blonde hair (Ab) Little feet and black hair (aB) Little feet and blonde hair (ab)

Punnett SquareA punnett square is used to predict an expected

outcome ofa particular cross orbreeding experiment.

True breedingTest cross

Independent assortmentMendel's Second Law is the law of "Independent

Assortment". Homologous chromosomes line up randomly Not

all blues to the left and red to the rightOffspring does not get all chromosomes from

maternal nana or grandpa from mom

Independent Assortment

Genetic variation contributes to Evolution

Mutations create different versions of genesMechanisms for variation in Sexual:

Independent Segregation of alleles Independent assortment of chromosomesCrossing over (prophase I)Random fertilization

Non Mendelian GeneticsSome traits are not passed on the way the traits

Mendel studied were. Incomplete dominanceCo dominanceMultiple allelesEpistasis: gene at one site effected by gene at

anotherPleiotropy: gene with multiple phenotypic effectsPolygenic inheritance: mult. Genes involved:

usually phenotype is on a scale: height, skin pigmentation

Incomplete DominanceIncomplete dominance is a form of intermediate

inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a combined phenotype.

Codominance A condition in which both

alleles of a gene pair in a heterozygote are fully expressed, with neither one being dominant or recessive to the other.

Multiple AllelesAny set of three or more

alleles or alternative states of a gene.

Only two of which can be present in an organism at a time.

Responsible for differences in expressions of a given trait. Example: brown eyes v. green eyes.

PleiotropyMost genes have

multiple phenotypic effects. The ability of a gene to affect an organism in many ways is called pleiotropy.

EpistasisEpistasis occurs

when a gene at one locus alters or influences the expression of a gene at a second loci. In this example, C is for color and the dominate allele must be present for pigment (color) to be expressed.

Polygenetic InheritanceQualitative variation usually indicates polygenic inheritance. This occurs when there is an additive effect from two or more genes. Pigmentation in humans is controlled by at least three (3) separately inherited genes.

DiseasesPoint mutation

Point mutation: effect 1 gene

Substitution: change 1 base pair: may still get same amino acid, or 1 different amino acid

Addition/deletion: change whole chain thereafter

Diseases caused by Point Mutation

Cystic Fibrosis: Mutation in gene involved in movement of water and stuff in and

out of cell This causes the build up of thick, sticky mucus

Sickle Cell AnemiaColorblind:

Genetic disease- (X-link): loss of cones in retina

Tay Sachs disease:Genetic Disease – inherited- caused by mutation in gene to

break down fatty substance…. Get lethal accumulation of fatty subst. in brain and spinal cord

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DiseasesGenetic (dominant/recessive)

Dominant Huntingtons Nuerofibromatosis Marfan

Recessive Cystic Fibrosis Tay Sachs Sickle cell anemia phenylketenuria

Sex linked disorders (recessive)

Red green color blindness- malfunction in light sensitive cells in the eye

Hemophilia- lack one or more proteins needed for blood clotting

Duchenne muscular dystrophy- progressive weakening of muscles and loss of coordination

Sex linked recessive

Common Chromosomal Abnormalities

http://anthro.palomar.edu/abnormal/abnormal_4.htm

Two Main CategoriesStructural modification Irregular number

Typically result from nondisjunction during meiosisPolyploidy-complete multiples of sets of

chromosomes (23+23+23)Aneulploidy-addition or loss of chromosomes within

a set (23+22)

Autosomal Defects

http://anthro.palomar.edu/abnormal/abnormal_4.htm

Down’s Syndrome Typically trisomy of

chromosome 21 Some have translocation of

21 to 14 or 15 75-80% of Down syndrome

children are born to women under 35

Monosomy Only one set of

chromosomes remains after fertilization

All fetuses will spontaneously abort

Female Abnormalities Male Abnormalities

http://anthro.palomar.edu/abnormal/abnormal_4.htm

Metafemale(XXX) Unusually tall, low to

normal intelligence Normal sex

characteristics, fertileTurner Syndrome (XO)

Ovaries do not develop, and do not ovulate

Lack secondary sex characteristics

Slight mental retardation

Klinefelter Syndrome (XXY) High-pitched voice Asexual to feminine body

type Low testosterone, sterile 1 in 500

XYY Syndrome Unusually tall, severe acne High testosterone levels,

possibly leading to violence

Sex Chromosome Abnormalities