Bonus 2 due 421 Inheritance Asexual Reproduction extremely

Bonus #2 due 4/21 Inheritance

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

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

{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

Sickle-cell anemia is caused by a point mutation Fig 4. 7

Sickle and normal red blood cells Fig 4. 7

Sickle-Cell Anemia: S=sickle-cell A dominant or recessive allele? H=normal Mom = HS Dad H or S H HH Mom or S HS HS SS Fig 4. 7 Dad = HS possible offspring 75% Normal 25% Sickle-cell

Coincidence of malaria and sickle-cell anemia Fig 24. 14

Sickle-Cell Anemia: S=sickle-cell A dominant or recessive allele? H=normal Mom = HS Dad H or S H HH Mom or S HS HS SS Fig 4. 7 Dad = HS possible offspring Oxygen transport: 75% Normal 25% Sickle-cell Malaria resistance: 75% resistant 25% susceptible

The relationship between genes and traits is often complex Complexities include: • Complex relationships between alleles

Fig 3. 18 Sex determination is normally inherited by whole chromosomes or by number of chromosomes.

X/Y chromosomes in humans

105 males : 100 females (live births) Why?

105 males : 100 females (live births) Why?

The X chromosome has many genes; the Y chromosome only has genes for maleness.

Sex-linked traits are genes located on the X chromosome

Color Blind Test

Sex-linked traits: Genes on the X chromosome A= normal; a= colorblind normal similar to Fig 4. 13 colorblind No one affected, female carriers

Sex-linked traits: Genes on the X chromosome A= normal; a= colorblind normal 50% of males affected, 0 % females affected similar to Fig 4. 13

Sex-linked traits: Genes on the X chromosome A= normal; a= colorblind normal similar to Fig 4. 13 colorblind 50% males affected, 50% females affected

Sex-linked traits: Genes on the X chromosome A= normal ; a= colorblind No one affected, female carriers similar to Fig 4. 13 50% of males affected, 0 % female affected 50% males affected, 50% females affected

Fig 3. 18 For Th: Males and females may have different numbers of chromosomes. This must be compensated for.