Meiosis and Genetics

Meiosis and Genetics

Genetics is all about InheritanceMeiosis -- The process in which cells divide in order to pass on its chromosomes to off spring.

Produces 4 daughter cells from 1 parent cell

Each daughter cell is called a haploids (half the DNA)

We call these Daughter cells gametes

Each gamete is genetically different

Both Mom and Dad undergo MeiosisMomDadSpermEggZygoteFertilization

Male (Dad)Female (Mom)Fertilization4

Genetics is all about chances.MomDadSpermEggZygoteFertilizationWhat are the chances of this sperm and egg will come together?Come questions in GeneticsWhat are the chances our baby will have a disease?

What genes will our baby have?

What will our baby look like?

How does our baby have blue eyes, when we both have brown eyes?Miracle of LifeLets review Chromosomes

Chromosomes are made of DNA.

Chromosomes have bands on them that we call genes.

Each Gene codes for the production of Proteins.

Proteins are the features that we see.Lets look at a Karyotype

Remember Karyotypes?

How many chromosomes in a human cell?

How many homologous pairs?Remember you get one set of chromosomes from Mom and the other from DadLets look at Chromosome 18 further

Each band represents a gene.

Remember a gene is a segment of DNA that codes for a particular protein.

The proteins are the things we see.Lets assign letter to a gene on chromosome 18

Remember a Chromosome is made up of 2 strands of DNA

So lets assign the letter B to a gene on the chromosome from Dad

And lets assign the letter b to a gene on the chromosome from MomBBbbDuring Meiosis what happens to these genes?

Lets talk some Genetic Terminology

Terms to know:

Allele a single gene on a DNA strand. Here we got 4 alleles!

Hetero- = Different

- zygous = individual; diploid cell

Dominant = B is the expressed allele

Recessive = b an allele whose gene in sometimes not expressed.

Genotype is the combination of allelesBBbbBbWe would consider this cell a Heterozygous cell.True definitions:Gene v. AlleleA gene is a locatable region of DNA, corresponding to a unit of inheritance.Allele: alternative form of a gene Ex. Gene that codes for eye colorEx. Allele that codes for blue eyes + an allele that codes for brown eyes

This homologous pairs have the same genesBut different allelesLets talk Some Genetic TerminologyWhat is a Gene?

What is SNPs?

Where do Genes come from?Bellringer: Using TerminologyHh ZZ aa - bb Nn- VV Cc ee Dd PP Heterozygous or Homozygous dominant or recessive?16Well if Genes (or Genotypes) refer to DNA, what about the proteins?Phenotypes - an organism's observable characteristics or traits

http://www.youtube.com/watch?v=jHWJqzlHl3w&feature=related17Bellringer 2: Using TerminologyBlonde hair Heterozygous dominant XY ee Tongue curling Hitchhikers thumb Aa Large Nostrils MM webbed toes

Genotypes v. PhenotypesWhat causes Diversity in living organisms?

Mutations a change in DNA which may or may not get passed on.Gene Mutations Affect NucleotidesChromosomal Mutations Affect Genes

If chromosomal Mutations are sever enough, serious problems can result.20

2) Crossing Over Homologous pair of Chromosomes swap genes.

Why is Crossing-Over Not Considered a Mutation?21

3) Mendels Law of Independent Assortment22

How do we determine probability?Punnett Squares - a diagram that is used to predict an outcome of a particular cross or breeding experiment.

http://www.youtube.com/watch?v=prkHKjfUmMs&feature=related

24Monohybrid Crosses Complete DominancebbBbBbbbBbbbGenotypic Ratio:Phenotypic Ratio:1 Bb : 1 bbAlleles

Brown eye= B

Blue eye = b 1 Brown Eyes : 1 Blue EyesCross a Heterozygous Brown eyed Male with Homozygous recessive FemaleBell RingerQ: In dogs, wire hair (S) is dominant to smooth (s). In a cross of a homozygous wire-haired dog with a smooth-haired dog, what will be the phenotype of the F1 generation?

A:Genotypic Ratio:

Phenotypic Ratio:

Monohybrid Crosses Incomplete DominanceIncomplete Dominance VideoMonohybrid Crosses Incomplete DominanceWWRRRWRWRWRWGenotypic Ratio:Phenotypic Ratio:1 RWAlleles

Red = R

White = W 1 Pink FlowersCross a Red Plant with a White PlantComplete Dominance v. Incomplete DominanceComplete DominanceIncomplete DominanceThe recessive trait of a heterozygous individual is completely masked in the phenotype.

A heterozygous individual is commonly called a Carrier. One can carry the recessive allele that causes a disease, but does not show the effects in the phenotype.

In the case of a heterozygous individual, there is a blending seen in the phenotype.

Ex. A cross between a red and white equal a pink.Monohybrid Crosses Co-dominance Co-dominance VideoMonohybrid Crosses Co-dominanceWWRRRWRWRWRWGenotypic Ratio:Phenotypic Ratio:1 RWAlleles

Red = R

White = W 1 Red and White Spotted FlowersCross a Red Plant with a White PlantComplete Dominance v. Incomplete Dominance v. Co-dominanceComplete DominanceIncomplete DominanceCo-dominanceThe recessive trait of a heterozygous individual is completely masked in the phenotype.

A heterozygous individual is commonly called a Carrier. Ex. One can carry the recessive allele that causes a disease, but does not show the effects in the phenotype.

In the case of a heterozygous individual, there is a blending seen in the phenotype.

Ex. A cross between a red and white equal a pink. In the case of a heterozygous individual, each cell has to pick as some point in their life whether to produce the one allele over the other.

Ex. A cross between a red and white equal a red and white spots

Dihybrid CrossesDihybrid CrossesMultiple Alleles and Blood TypesMultiple Alleles and Blood Types