Bonus 2 due 421 Meiosis and Genetic Diversity

Bonus #2 due 4/21 Meiosis and Genetic Diversity

Asexaul Reproduction extremely low genetic diversity vs. Sexaul Reproduction greater genetic diversity How does sexual reproduction generate genetic diversity?

Gene for growth hormone Gene for brown hair pigment Gene for blue eye pigment Gene for hemoglobin Gene for DNA polymerase Haploid chromosomes

Allele for low express (short) Gene for growth hormone Allele for high express (tall) Allele for black hair Gene for hair color Allele for black hair Allele for sickle cell Hb Gene for hemoglobin Allele for normal Hb Diploid chromosomes

Fig 1. 5 Each pair of chromosomes is comprised of a paternal and maternal chromosome

Fig 1. 11 Diploid meiosis Haploid

Fig 3. 16 Meiosis splits apart the pairs of chromosomes. X 23 in humans

haploid X 23 in humans diploid X 23 in humans Inheritance = The interaction between genes inherited from Mom and Dad.

sister chromatids= replicated DNA (chromosomes) tetrad= pair of sister chromatids Fig 3. 12

Fig 3. 16 Meiosis splits apart the pairs of chromosomes. X 23 in humans

Asexual Reproduction extremely low genetic diversity vs. Sexual Reproduction greater genetic diversity How does sexual reproduction generate genetic diversity?

Fig 3. 10 Crossing-over (aka Recombination) DNA cut and religated

Crossing-over: Proteins in the cell cut and religate the DNA, increasing the genetic diversity in gametes. Fig 3. 10

Crossing-over: Proteins in the cell cut and religate the DNA, increasing the genetic diversity in gametes. Fig 3. 10

Crossing-over: Proteins in the cell cut and religate the DNA, increasing the genetic diversity in gametes. Fig 3. 10

Asexual Reproduction extremely low genetic diversity vs. Sexual Reproduction greater genetic diversity How does sexual reproduction generate genetic diversity?

Fig 3. 17 Independent Assortment (aka Random Assortment)

Fig 3. 17 Independent Assortment 2 possibilities for each pair, for 2 pairs 22 = 4 combinations

Fig 3. 17 Independent Assortment 2 possibilities for each pair, for 23 pairs 223 = 8, 388, 608 combinations

Crossingover Meiosis: In humans, crossing -over and (Ind. Assort. ) independent assortment lead to over 1 trillion possible unique gametes. (1, 000, 000) Meiosis II 4 Haploid cells, each unique

Fig 3. 12

Fig 3. 12 4 haploid cells

{Producing gametes} Sexual reproduction creates genetic diversity by combining DNA from 2 individuals, but also by creating genetically unique gametes. {Producing more cells}

haploid X 23 in humans diploid X 23 in humans Inheritance = The interaction between genes inherited from Mom and Dad.

Do parents’ genes/traits blend together in offspring?

Fig 2. 6 In many instances there is a unique pattern of inheritance. Traits disappear and reappear in new ratios.

Fig 1. 6 from DNA to Protein: from gene to trait

Fig 1. 7 from DNA to Protein: from gene to trait Molecular Cellular Organism Population

Genotype Phenotype

Human blood types Fig 4. 11

Fig 4. 11 One gene with three alleles controls carbohydrates that are found on Red Blood Cell membranes A A A RBC A A Allele A = A carbs B B B RBC B B B Allele B = B carbs Allele O = no carbs

Human blood types Fig 4. 11

We each have two versions of each gene… A So A A RBC A A Genotype could be A and A OR A and O

Recessive alleles do not show their phenotype when a dominant allele is present. A A A RBC A A A See Fig 4. 2 A Genotype could be A and A OR A and O

What about… RBC Genotype = ? ?

What about… RBC Genotype = OO

What about… B A A B A RBC B A B B A

What about… B A A B A RBC B A B Genotype = AB B A

Human blood types AA or AO BB or BO AB OO Fig 4. 11

If Frank has B blood type, his Dad has A blood type, And his Mom has B blood type… Should Frank be worried?

Mom=B blood possible BB or BO genotypes Dad=A blood AA or AO

possible genotypes Mom=B blood Dad=A blood BB or BO AA or AO Gametes all B / 50% B and all A / 50% A and 50% O

Mom=B blood Possible genotypes BB or BO Dad=A blood AA or AO Gametes all B / 50% B and all A / 50% A and 50% O Frank can be BO = B blood …no worries

Grandparents AB and AB Mom=B blood possible BB or BO genotypes Gametes all B / 50% B and 50% O Frank can be BO or BB = B blood Dad=A blood AA all A …Uh-Oh

Pedigree, tracing the genetic past Dom. Rec. Dom.

Fig 2. 11

We can also predict the future Fig 2. 6

Inheritance of blood types Mom = AB Dad = AB

Inheritance of blood types Mom = AB Gametes: A or B Dad = AB A or B

Inheritance of blood types Mom = AB Gametes: A or B Dad A or B A AA Mom or B AB Dad = AB AB BB Chance of each phenotype for each offspring 25% AA 50% AB 25% BB

Single genes controlling a single trait are unusual. Inheritance of most genes/traits is much more complex… Dom. Rec. Dom.

Genotype Phenotype Genes code for proteins (or RNA). These gene products give rise to traits…

Human blood types AA or AO BB or BO AB OO Fig 4. 11

Genotype Phenotype Genes code for proteins (or RNA). These gene products give rise to traits… It is rarely this simple.

Fig 4. 3 Incomplete dominance

Fig 4. 4