Which statements about cell Which statements about cell division are CORRECT?division are CORRECT?

A.A. statements 1 and 3statements 1 and 3

B.B. statements 1 and 4statements 1 and 4

C.C. statements 2 and 3statements 2 and 3

D.D. statements 2 and 4statements 2 and 4

Today we will learn:Today we will learn:

Who is the father of Genetics?Who is the father of Genetics? What is heredity?What is heredity? What are traits?What are traits? Phenotypes vs GenotypesPhenotypes vs Genotypes Homozygous vs heterozygous Homozygous vs heterozygous

Mendel’s Laws of Mendel’s Laws of ______GeneticsGenetics

Why we look the way Why we look the way we look...we look...http://learn.genetics.utah.edu/content/begin/traits/

What is What is heredityheredity??

The The passing passing on of on of characteristics characteristics (traits)(traits) from parents to offspringfrom parents to offspring

__GeneticsGenetics____ is the study is the study of of heredityheredity

5

Gregor Gregor MendelMendel

•Austrian monkAustrian monk•Considered the “Considered the “father of father of

geneticsgenetics””•The first person to succeed in The first person to succeed in

predicting how traits would be predicting how traits would be transferred from one generation transferred from one generation to anotherto another–using the using the garden pea garden pea plantplant

Mendel used Mendel used peas...peas...

They reproduce They reproduce sexuallysexuallyThey have two distinct, They have two distinct,

malemale and and femalefemale, sex cells , sex cells called called __gametesgametes_._.

Their Their traitstraits are easy to are easy to isolateisolate

Mendel Mendel crossedcrossed them them

__fertilizationfertilization__ - the - the uniting of male and uniting of male and female gametesfemale gametes

CrossCross - combining - combining gametes from parents gametes from parents with different traitswith different traits

8

Types of Types of pollination/fertilizatiopollination/fertilizationn

Cross-pollination

self-pollinationself-pollination

QuestionsQuestions

What did Mendel cross?What did Mendel cross?What are What are traitstraits??What are What are gametesgametes??What is What is fertilizationfertilization??What is What is heredityheredity??What is What is geneticsgenetics??

What Did Mendel What Did Mendel Find?Find?

He discovered different He discovered different lawslaws and and __rulesrules__ that that explain factors affecting explain factors affecting heredityheredity..

Rule of Unit FactorsRule of Unit Factors

Each organism has two Each organism has two __genesgenes_ _ for each for each traittrait

–Alleles Alleles - different forms of - different forms of the same the same genegene

–Genes Genes - located on - located on chromosomes, they control chromosomes, they control how an organism developshow an organism develops

Rule of DominanceRule of Dominance

The trait that The trait that is observedis observed in the offspring is the in the offspring is the dominantdominant trait trait (uppercase)(uppercase)

The trait that The trait that disappears disappears in the offspring is the in the offspring is the recessive trait recessive trait (lowercase)(lowercase)

Law of SegregationLaw of Segregation

The two alleles for a trait The two alleles for a trait must separatemust separate when when gametes are formed.gametes are formed.

A parent randomly passesA parent randomly passes only oneonly one allele for each allele for each trait to each offspring.trait to each offspring.

Law of Independent Law of Independent AssortmentAssortmentThe genes for different The genes for different

traits are traits are inherited inherited independentlyindependently of each of each other.other.

Genes and Genes and DominanceDominance

Mendel came to two conclusions:Mendel came to two conclusions:

1.1. Factors that are Factors that are passed/inheritedpassed/inherited from one from one generation to the next generation to the next determine inheritance. determine inheritance.

2.2. The Principle of Dominance - The Principle of Dominance - states that some alleles are states that some alleles are dominant and some are dominant and some are recessive.recessive.

Questions...Questions...

How many How many allelesalleles are are there for each trait?there for each trait?

What is an What is an alleleallele??How many How many allelesalleles does a does a

parent pass on to parent pass on to eacheach offspring for offspring for eacheach trait trait

Questions...Questions...What do we call the trait that is What do we call the trait that is

observedobserved? ? What What casecase (upper or lower)(upper or lower) is it is it

written in?written in?What about the one that What about the one that

disappearsdisappears? ? What What casecase is it written in? is it written in?

Phenotype & Phenotype & GenotypeGenotype

phenotypephenotype - the way an - the way an organism organism lookslooks

–red hair or brown hairred hair or brown hair

genotypegenotype - the - the gene gene combinationcombination of an organism of an organism

–AAAA or or Aa Aa oror aa aa

Heterozygous & Heterozygous & HomozygousHomozygous

HeterozygousHeterozygous - if the two - if the two alleles for a trait are alleles for a trait are different different ((AaAa))

__Homozygous Homozygous - if the two - if the two alleles for a trait are the alleles for a trait are the same same ((AAAA or or aaaa))

Dihybrid vs Dihybrid vs MonohybridMonohybrid

Dihybrid CrossDihybrid Cross - crossing - crossing parents who differ in parents who differ in two two traits traits ((AAEEAAEE with with aaeeaaee))

Monohybrid CrossMonohybrid Cross - crossing - crossing parents who differ in only parents who differ in only one trait one trait ((AAAA with with aaaa))

Questions...Questions...

What is the What is the phenotypephenotype??What is the What is the genotypegenotype??What is What is homozygoushomozygous??What is What is heterozygousheterozygous??What is What is monohybrid monohybrid

crossingcrossing??

Which genotype is heterozygous Which genotype is heterozygous for two traits?for two traits?

A.A. ggTtggTt

B.B. GgTtGgTt

C.C. GgTTGgTT

D.D. GGTTGGTT

Punnett SquarePunnett Square

Developed by Developed by Reginald Reginald _Punnett_._Punnett_.

A diagram used to A diagram used to show the probability show the probability or chances of a or chances of a certain trait being certain trait being passed from one passed from one generation to generation to another.another.

ProbabilityProbability

The likelihood of a The likelihood of a particular event particular event occurring. occurring.

ProbabilityProbability

Can be expressed Can be expressed as a fraction or a as a fraction or a percent.percent.

Example: coin flip.Example: coin flip.

What is a What is a PUNNETT PUNNETT SQUARESQUARE??

A tool to predict the probability of A tool to predict the probability of certain traits in offspring that shows certain traits in offspring that shows the different ways alleles can combinethe different ways alleles can combine

A way to show A way to show phenotypephenotype & genotype & genotype

A chart that shows all the possible A chart that shows all the possible combinations of alleles that can result combinations of alleles that can result when genes are crossedwhen genes are crossed

Using a Using a PUNNETT SQUAREPUNNETT SQUARE

To set up a To set up a PunnettPunnett square, draw a square, draw a large square, and then divide it into large square, and then divide it into 4 equal sections (also squares). It 4 equal sections (also squares). It should look something like this:should look something like this:

Using a Using a PUNNETT SQUAREPUNNETT SQUARE

Letters stand for Letters stand for dominantdominant and and recessive allelesrecessive alleles

An uppercase letter stands for a An uppercase letter stands for a dominant allele dominant allele

Lowercase letters stand for recessive Lowercase letters stand for recessive allelesalleles

Using a Using a PUNNETT PUNNETT SQUARESQUARE

Finally, take each Finally, take each letterletter in each column and in each column and combine it with each letter from each row combine it with each letter from each row in the corresponding square. You should in the corresponding square. You should now have a picture close to this:now have a picture close to this:

Using a Using a PUNNETT SQUAREPUNNETT SQUARE

The two-letter combinations are the The two-letter combinations are the possible genotypes of possible genotypes of offspring.offspring.

They are: Rr, Rr, rr, and rr genotypesThey are: Rr, Rr, rr, and rr genotypes

From this it is possible to determine the From this it is possible to determine the probability (chance) that a flower will probability (chance) that a flower will have a red phenotype (2/4 or 50%) or a have a red phenotype (2/4 or 50%) or a white phenotype (2/4 or 50%)white phenotype (2/4 or 50%)

Reading Punnett squaresReading Punnett squares

Allele letters Allele letters are placed above and are placed above and to the left of the squareto the left of the square

Offspring are placed in the square.Offspring are placed in the square. Capital letters (Y) represent Capital letters (Y) represent

dominant alleles.dominant alleles. Lower case letters (y) represent Lower case letters (y) represent

recessive alleles.recessive alleles.

What can you tell me from What can you tell me from this punnet square?this punnet square?

Punnett square review:Punnett square review:

What is independent What is independent assortment?assortment?Chromosomes/Chromosomes/

genesgenes separate separate independently independently

during the during the formation of formation of gametes.gametes.

The dihybrid crossThe dihybrid cross

Punnett square on board:Punnett square on board:

Putting it all together!Putting it all together!T = Tall Plants Mom and Dad are both heterozygous t = short plant

Male gametesT t

Fem

ale

Gam

etes

T

t

TT Tt

tT tt

Genotypic ratio: Phenotypic ratio:

Let’s Practice!Let’s Practice!

http://www.nature.ca/genome/04/041/0414_e.cfm

http://glencoe.mcgraw-hill.com/sites/0078778066/student_view0/chapter5/math_practice.html

http://www.zerobio.com/drag_gr11/mono.htm

How well did you do today?How well did you do today?

Which parts of this Punnett square would Which parts of this Punnett square would contain the genotype that results in the contain the genotype that results in the expression of only the recessive phenotype?expression of only the recessive phenotype?

A. parts 1 and 2B. parts 1 and 4C. parts 2 and 3D. parts 3 and 4