Homework #3 is due 11/15 Bonus #2 is posted Today: Meiosis, producing genetically diverse offspring, and inheritance

For life to exist, the information (genes) must be passed on. {Meiosis: producing gametes} For life to exist, the information (genes) must be passed on. {Mitosis: producing more cells}

Gene for growth hormone Gene for brown hair pigment Gene for similar to Fig 2.18 Gene for hemoglobin Gene for DNA polymerase Gene for blue eye pigment Haploid chromosomes

Gene for growth hormone Gene for hair color Gene for hemoglobin similar to Fig 2.18 Allele for low express (short) Allele for black hair Allele for sickle cell Hb Gene for growth hormone Gene for hair color Gene for hemoglobin Diploid chromosomes Allele for high express (tall) Allele for black hair Allele for normal Hb

Each pair of chromosomes is comprised of a paternal and maternal chromosome

Meiosis splits apart the pairs of chromosomes. X 23 in humans Meiosis splits apart the pairs of chromosomes. Fig 2.19

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

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

sister chromatids= replicated DNA (chromosomes) tetrad= pair of sister chromatids Fig 2.41

Meiosis splits apart the pairs of chromosomes. X 23 in humans Meiosis splits apart the pairs of chromosomes. Fig 2.19

Crossing-over (aka Recombination) Fig 4.3 DNA cut and religated

Crossing-over: Proteins in the cell cut and religate the DNA, increasing the genetic diversity in gametes. Fig 4.5

Crossing-over: Proteins in the cell cut and religate the DNA, increasing the genetic diversity in gametes. Fig 4.4

Crossing-over: Proteins in the cell cut and religate the DNA, increasing the genetic diversity in gametes. Fig 4.5

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

Independent Assortment (aka Random Assortment) Fig 3.8

2 possibilities for each pair, for 2 pairs Independent Assortment 2 possibilities for each pair, for 2 pairs 22 = 4 combinations Fig 3.8

2 possibilities for each pair, for 23 pairs Independent Assortment 2 possibilities for each pair, for 23 pairs 223 = 8,388,608 combinations Fig 3.8

Box 2.2 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

Box 2.2

4 haploid cells Box 2.2

{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? Fig 6.4

In many instances there is a unique pattern of inheritance. Traits disappear and reappear in new ratios. Fig 2.12

Genotype Phenotype Pg 23

Human blood types Pg 225

One gene with three alleles controls carbohydrates that are found on Red Blood Cell membranes 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

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

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 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 Gametes all B / 50% B and possible genotypes Gametes all B / 50% B and 50% O all A / 50% A and 50% O Frank can be BO = B blood …no worries

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

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

We can also predict the future Fig 2.12

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 AA or AO BB or BO AB OO

It is rarely this simple. Genotype Phenotype Genes code for proteins (or RNA). These gene products give rise to traits… It is rarely this simple. Figs 1.15-17

Homework #3 is due 11/15 Bonus #2 is posted Today: Meiosis, producing genetically diverse offspring, and inheritance