Classical Genetics - Objectives Identify and label parts of chromosomes Describe Mendels discoveries...

Classical Genetics - Objectives

• Identify and label parts of chromosomes• Describe Mendel’s discoveries• Perform genetic crosses• Identify and perform a karyotype• Analyze probabilities• Distinguish genotype and phenotype• Use Punnett Squares• Predict genetic outcomes• Use a Pedigree Chart

A. The Chromosome

Chromosome

_______________ Thread-like strand made of DNA and proteins that transmits hereditary information.

Chromosome

Histones (proteins)

DNA

This is what we had to break down in the onion

There are _____ pairs of chromosomes in humans giving ______ Total chromosomes.

2346

A. The Chromosome

This picture shows two copies of the chromosomes. Both sides are a single _____________.chromosome

____________ Single Strands of a chromosome____________ Center of two identical chromosomes________ A specific place on chromosome that is a genetic trait (the color coded parts)

Chromatids

Centromere

Gene

B. Karyotype___________ An orderly arrangement of the chromosomes in an organism

Karyotype

Arrangement: Largest to Smallest

First 22 pairs are called: Autosomes

Last pair: ____________________ but may not match

Sex Chromosomes

XX = ________ XY = ______X is __________ than the Y chromosome

Female MaleLarger

B. KaryotypeKaryotypes detect:

__________________Genetic diseases

Find the mistakes?1.2.3.

Partial deletion (2)Total deletion (16)Trisomy (21) ?1.A _____copy of a gene2.Trisomy 21 is ___________________

3rd

Down’s Syndrome

__________ Type of organism with one copy of chromosomes. Some plants, algae, fungi.

C. InheritanceChromosomes are __________fromparents

inherited___ from mother___ from father11

__________ Type of organism with two copies of chromosomesHaploid

Diploid

_________ Cells that contain one-half the genetic information; sperm and egg in humans

Gamete

D. Genes and DominanceLet us say we are studying freckles.The blue gene is the gene for freckles.

But the two genes are different!One gene codes for Freckles andis labeled ___.

F

The other codes for NO Freckles and is labeled ___.f F f_________ are different forms of the same gene.Alleles

D. Genes and Dominance

F f

____________What the genes both are.

Genotype

____________What the organism LOOKS like.Phenotype

So the GENOTYPE IS ______

But what does the person LOOK LIKE?1. Lots of freckles?2. A few freckles?3. No freckles?

Ff

D. Genes and Dominance

F f

___________ genes always override____________ genes.DOMINANTRECESSIVE

Dominant = ___________________1. Are not the most ___________

Like polydactylism2. Most common are __________

Recessive = ___________________1. Act like they are ____________

CAPITAL LETTERS

lowercase lettersTurned off

common

wild type

D. Genes and Dominance

F f

Genotype PhenotypeFFFfff

FRECKLESFRECKLES

NO FRECKLES

Therefore our person has:

This is called _____________________.Complete Dominance

C. Inheritance

E. Other Types of Dominance

_________________________ The dominant and recessive blend together making a new phenotype.

Incomplete Dominance

RR rrRr

________________ Both phenotypes are displayed. Neither is dominant

Codominance

F. Punnett Squares

E eEePupil size in guinea pigsE = ____________ e = ___________

Mother and father are both ___Mother can give __ OR __Father can give __ OR __

EeEE

ee

Large pupil Small pupil

________________ shows all genetic possibilities of the offspring.Punnett Square

F. Punnett Squares

E

e

E eEE Ee

Ee ee

What % have genotype EE? ___________What % have genotype Ee?___________What % have genotype ee? ___________What % have PHENOTYPE Small pupils?______________What % have PHENOTYPE Large pupils?______________

¼ or 25%

¼ or 25%½ or 50%

¼ or 25%¾ or 75%

_________________________ Genotype EE; both dominant

_________________________ Genotype ee; both recessive

_________________________ Genotype Ee; mixed dom/rec

Homozygous Dominant

Homozygous Recessive

Heterozygous

F. Punnett Squares

In orchids, Purple flower (P) is dominant to White (p). If a Pp flower is crossed with a pp flower, show the Punnett square

What percent are Purple? ____________What percent are White? _____________

F. Punnett Squares - Dihybrid_____________________ using a Punnett square to track ONE genetic trait.Monohybrid crosses

_____________________ using a Punnett square to track TWO genetic traits.

Dihybrid crosses

Test cross of peas Y =y =W =w =

YellowGreenWrinkledSmooth

Parent peas’ genotypes:YyWw x YyWw

F. Punnett Squares - Dihybrid

YyWw x YyWw

F. Punnett Squares - DihybridYW Yw yW yw

YWYwyWyw

YYWWYYwwYYWw

YYWwYyWW

YyWW

yywwYyWw

YyWw

YyWwYyww

YywwYyWwyyWWyyWw

yyWw

% Yellow/Wrinkled: _______

% Yellow/Smooth:________

% Green/Wrinkled: _______

% Green/Smooth:________

G. Gregor MendelGregor Mendel is called _____________________

1. Was a _______2. Studied ____________3. Discovered the ______ laws of genetics

The father of geneticsMonk

Pea Plants2

Law 1: Law of Segregation: Alleles __________ during formation of gametes (sperm and egg cells)

Law 2: Independent Assortment: Each Trait is ______________ of one another

separate

Independent

H. Pedigree Chart• Male =

• Female =

• Sexual union =

• Offspring =

H. Pedigree ChartRecessive gene on X chromosome; affects males more than females.

H. Pedigree and X-linkage

Males with trait are: XrY

Females with trait are: XrXr

Males without the trait are XRY

I. Meiosis

___________ Cells with two copies of chromosomes

Diploid

___________ Cells with one copy of chromosomesHaploid

What cells need to be haploid?

GAMETES: The egg and sperm cellsGametes need to be haploid so you get 1 copy of chromosomes from each parent:

1 chromosome from mother1 chromosome from father= 2 copies!

I. Meiosis

Just like Mitosis!

I. Meiosis

NO interphase,This meansNO DNAREPLICATION

1 copy of eachChromosome!

I. Meiosis – Mr. Anderson 8:25

I. Meiosis ________________ Exchange of genetic material between identical chromosomes.

Crossing Over

McClintock &Creighton - discovery

Increases genetic diversity

I. Meiosis

______________ - Genes on the same chromosome are usuallyInherited together.

Mendel’s Independent assortment does not apply during meiosis

Gene Linkage

_____________ - The closer together genes are, the more likely to be linked. A map of the chromosome can be developed.

Gene Map