Bonus #2 due 11/25 Meiosis and Genetic Diversity.

Bonus #2 due 11/25

Meiosis and Genetic Diversity

Is this the best I can do?Maybe I can find someone

with better genes or more genetic diversity.

Am I the only one? Am Ibetter off helping with these

kids or should I matewith someone else?

extremely lowgenetic diversity

greater geneticdiversity

vs.Asexaul Reproduction

SexaulReproduction

How does sexual reproduction generate genetic diversity?

Gene forblue eye pigment

Gene forbrown hair pigment

Gene forgrowth hormone

Haploidchromosomes

Gene forhemoglobin

Gene forDNA polymerase

Gene forhemoglobin

Gene forhair color

Gene forgrowth hormone

Allele forblack hair

Allele forblack hair

Allele forlow express(short)

Allele forhigh express(tall)

Allele for normal Hb

Allele forsickle cell Hb

Diploidchromosomes

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

Fig 1.5

meiosisDiploid Haploid

Fig 1.11

Fig 3.16

Meiosis splits apart the pairs of chromosomes.

X 23in humans

haploid

diploid

X 23in humans X 23

in humans

X 23in humans

Inheritance = The interaction between genes inherited from Mom and Dad.

Fig 3.12

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

Fig 3.16

Meiosis splits apart the pairs of chromosomes.

X 23in humans



vs.Asexual Reproduction

SexualReproduction


Fig 3.10

DNA cut and religated

DNA cut and religated

Crossing-over(aka Recombination)

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

Fig 3.10

Fig 3.10Crossing-over:Proteins in the cell cut and religate the DNA, increasing the genetic diversity in gametes.

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

Fig 3.10



vs.Asexual Reproduction

SexualReproduction


Fig 3.17 Independent Assortment(aka Random Assortment)

Independent Assortment

2 possibilities for each pair,

for 2 pairs22 = 4

combinations

Fig 3.17

Independent Assortment

2 possibilities for each pair, for 23 pairs

223 = 8,388,608

combinations

Fig 3.17

Crossing-Crossing-overover

Meiosis I

Meiosis II

4 Haploid cells, each unique

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

(Ind. Assort.)(Ind. Assort.)

Fig 3.12

4 haploid cells

Fig 3.12

Sexual reproduction creates genetic diversity by combining DNA from 2 individuals, but also by creating genetically unique gametes.

{Producing more cells}

{Producing gametes}

haploid

diploid

X 23in humans X 23

in humans

X 23in 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.

Traits disappear and reappear in new ratios.

Fig 2.6

from DNA to Protein:from gene to trait

Fig 1.6

Cellular

Organism

Population

Molecular

from DNA to Protein:from gene to trait

Fig 1.7

Genotype Phenotype

Human blood types Fig 4.11

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

RBC

A A

A

A

AA

AA

A

RBCRBC

B B

B

B

BB

BB

B

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

Fig 4.11

Human blood types Fig 4.11

RBC

A A

A

A

AA

AA

A

We each have two versions of each gene…

So

Genotype could be A and AORA and O

RBC

A A

A

A

AA

AA

A

Recessive alleles do not show their phenotype when a dominant allele is present.

Genotype could be A and AORA and OSee Fig 4.2

What about…

Genotype = ??

RBC

What about…

Genotype = OO

RBC

RBC

AA

A

B

A A

B

B

B

What about…

B

RBC

AA

A

B

A A

B

B

B

What about…

B

Genotype = AB

Human blood types

AA orAO

AB

BB orBO

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?

possible

genotypes

Mom=B blood

BB or BO

Dad=A blood

AA or AO

Gametes all B / 50% B and50% O

all A / 50% A and50% O

possible

genotypes

Mom=B blood

BB or BO

Dad=A blood

AA or AO

Mom=B blood

BB or BO

Dad=A blood

AA or AO


all A / 50% A and50% O

Possiblegenotypes

Frank can be BO= B blood …no worries

Mom=B bloodBB or BO

Dad=A bloodAA


all A

possible

genotypes

Frank can be BO or BB= B blood …Uh-Oh

GrandparentsAB and AB

Pedigree, tracing the genetic past

Dom. Rec. Rec. Dom.

Fig 2.11

We can also predict the future

Fig 2.6

Mom = AB Dad = AB

Inheritance of blood types

Mom = AB Dad = AB

Gametes: A or B A or B


Mom = AB Dad = AB

Gametes: A or B A or B

A or B

A or B

AA

AB BB

AB

Chance of each phenotype for each offspring25% AA50% AB25% BB

Mom

Dad


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

Dom. Rec. Rec. Dom.

PhenotypeGenotype

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

Human blood types

AA orAO

AB

BB orBO

OO

Fig 4.11

PhenotypeGenotype

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

It is rarely this simple.

Incomplete dominance

Fig 4.3

Fig 4.4

Bonus #2 due 11/25

Bonus #2 due 11/25 Meiosis and Genetic Diversity.

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