Bonus #2 due 4/21 Inheritance

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

Crossing-over Meiosis: In humans, crossing-over and independent assortment lead to over 1 trillion possible unique gametes. (1,000,000,000,000) Meiosis I (Ind. Assort.) 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 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?

In many instances there is a unique pattern of inheritance. Fig 2.6 In many instances there is a unique pattern of inheritance. Traits disappear and reappear in new ratios.

from DNA to Protein: from gene to trait Fig 1.6 from DNA to Protein: from gene to trait

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 B RBC A B RBC RBC B A B A B A A B B A A B B Allele O = no carbs Allele A = A carbs Allele B = B carbs

Human blood types Fig 4.11

We each have two versions of each gene… RBC A A A So A A 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. RBC A A A A A A A Genotype could be A and A OR A and O See Fig 4.2

What about… RBC Genotype = ??

What about… RBC Genotype = OO

What about… A B RBC B A A B B A A B

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

Human blood types Fig 4.11 AA or AO BB or BO AB OO

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

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

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

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

Pedigree, tracing the genetic past Dom. Rec. 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 Dad = AB Gametes: A or B A or B

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

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

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

Human blood types Fig 4.11 AA or AO BB or BO AB OO

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 and normal red blood cells

Sickle-Cell Anemia: Mom = HS Dad = HS Dad H or S possible offspring Fig 4.7 Sickle-Cell Anemia: A dominant or recessive allele? S=sickle-cell H=normal Mom = HS Dad = HS Dad H or S possible offspring 75% Normal 25% Sickle-cell HH HS H or S Mom HS SS

Coincidence of malaria and sickle-cell anemia Fig 24.14

Sickle-Cell Anemia: Mom = HS Dad = HS possible offspring Fig 4.7 Sickle-Cell Anemia: A dominant or recessive allele? S=sickle-cell H=normal Mom = HS Dad = HS possible offspring Oxygen transport: 75% Normal 25% Sickle-cell Malaria resistance: 75% resistant 25% susceptible Dad H or S HH HS H or S Mom HS SS

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

No one affected, female carriers Sex-linked traits: Genes on the X chromosome A= normal; a= colorblind colorblind normal No one affected, female carriers similar to Fig 4.13

50% of males affected, 0 % females affected Sex-linked traits: Genes on the X chromosome A= normal; a= colorblind normal normal 50% of males affected, 0 % females affected similar to Fig 4.13

50% males affected, 50% females affected Sex-linked traits: Genes on the X chromosome A= normal; a= colorblind colorblind normal 50% males affected, 50% females affected similar to Fig 4.13

Sex-linked traits: Genes on the X chromosome A= normal ; a= colorblind No one affected, female carriers 50% of males affected, 0 % female affected 50% males affected, 50% females affected similar to Fig 4.13

Fig 3.18 For Th: Males and females may have different numbers of chromosomes. This must be compensated for.