     

Do Now:

1. Certain acquired characteristics, such as mechanical or mathematical skill may be inherited.

2. Certain thoughts or experiences of a mother mark or alter the hereditary makeup of an unborn child.

3. Color blindness is more common in males than in females.

4. A person may transmit characteristics to offspring which he/she does not show.

5. Certain inherited traits may be altered by the stars, planets or moon early in development.

6. The total number of male births exceeds female births each year.

Objectives:

  

To distinguish between heredity and inheritance To describe Mendel’s experiments in heredity To compare heterozygous vs. homozygous and dominant vs. recessive.

Genetics

Chapter 4

Basic Genetics

The Father of Genetics

Gregor Mendel

1866- Gregor Mendel

•Austrian Monk •Worked with Pea Plants •Pure breeds •Self-fertilization •Discovered how traits were inherited in a

population

Heredity

– transmission of

traits from parents to their offspring Inheritance passing of traits by heredity

Mendel’s experiments

used pea plants

Pollination

– transfer of pollen from anthers to stigma in flowers

1) self pollination

occurs within the same flower same plant or 2) cross pollination occurs between different plants

Mendel’s Crosses with Pea Plants P 1 parental generation Pure tall plants

X

Pure short plants Cross Pollination F 1 first filial generation All Tall plants Self Pollination F 2 second filial generation 787 tall plants, 277 short plants 3 to 1 ratio

Definitions

Genetics

– study of heredity

Gene

– segment of DNA on a chromosome that

codes for a particular protein

 genes occur in pairs

Allele

– alternative form of a gene

T = tall

Dominant

capital letter (shields recessive trait) t = short G = green pods

Recessive

Lowercase letter (usually hidden) g = yellow pods

Phenotype – physical characteristics of an organism (

Ex: Blue eyes or Brown Eyes

)

Genotype

– genetic makeup

of an organism (

genes

)

( internal

information Ex: BB, Bb, bb)

Where do Phenotypes come from?

Example of Genotype and Phenotype TT genotype Tall phenotype

DO NOW A man with a widow’s peak marries a woman with no widow’s peak. Widow’s peak is a dominant trait. Identify the following: 1. Man’s geneotype: 2. Woman’s genotype: 3. Man’s phenotype: 4. Woman’s phenotype: Use the letter W or w.

Homozygous

–

when both alleles of a pair are the same homozygous dominant TT homozygous recessive tt

Heterozygous

–

when both of a pair are the same alleles not heterozygous (tall) Tt

In rabbits,

black

fur color is

dominant over brown

fur color

B = black fur b = brown fur bb BB or Bb

Think – Pair - Share

  If Fred Flintstone is heterozygous for black hair. (B=Black, b=blonde)  What is Fred’s genotype?

 What is Fred’s phenotype?  Tweety bird is YY. (Y= yellow feathers, y=brown feathers)  1. What is his genotype?

 2. What is his phenotype?

 3. Is he heterozygous or homozygous? Explain.

Think – Pair - Share

 Worksheet on homozygous/heterozygous and dominant and recessive.

 Due Tomorrow (or next time I see you!)



Homework

Create flashcards with the definition and an example          Heterozygous Homozygous Genotype Phenotype Dominant Recessive Allele Gene Genetics

Do Now

  Sponge Bob Square pants is heterozygous for brown eyes. Sandy is also heterozygous for brown eyes. Create a punnett square to determine the possible outcomes of their children.

Show phenotype and genotype ratios.

Objective:



To describe Mendel’s 3 laws of inheritance



Complete a Monohybrid cross **Take Out your Homework!!!

1) Law of Dominance  Each trait is controlled by 2 factors, one factor (

dominant

)

may

mask the other factor (

recessive

) preventing it from having an effect.

P 1 F 1 F 2

2) Law of Segregation   Each allele a person has separates into different gametes Ex. Ww – one W goes in one sperm and the other w goes into another sperm http://highered.mcgraw hill.com/sites/0072495855/student_view0/ chapter28/animation__random_orientation _of_chromosomes_during_meiosis.html

w w W W

Sperm

3) Law of Independent

Assortment

 Gene pairs (homologous) will separate randomly into gametes (metaphase I of meiosis)

Monohybrid Cross

  R= Can roll your tongue r= Can’t roll your tongue R r  Genotype Ratio: R  Phenotype Ratio: r

Genotypic vs. Phenotypic Ratios



Phenotype Ratio:

  Ratio of different physical traits Ex) Brown eyes ¼ or 25% 

Genotype Ratio:

  Ratio of the different possible alleles Ex) Tt = ¼ or 25%

Lets Try a Monohybrid together!

1) Daffy Duck is heterozygous for black feathers. Daisy Duck is homozygous for yellow feathers. Set up a punnett square and determine probabilities of their potential offspring. (Both genotype and phenotype ratios!) 2) B = Black b = yellow

Practice!

 Get with a partner and work on the sample problems!

DO NOW:

Sleeping Beauty has freckles. Her prince charming is heterozygous for no freckles. What are the chances of her children having freckles? Please show your work.

Do Now

   Being able to roll your tongue is a dominant trait. 1. Write down your phenotype and genotype.

2. Are you positive that’s your genotype?

Test cross

– an individual with

unknown genotype with

a is

crossed homozygous recessive

individual  used to determine the genotype of any individual whose

phenotype is dominant

Lets Try a Test Cross

 Spongebob squarepants doesn’t know whether or not he is Homozygous Dominant or Heterozygous for his yellow color. The recessive trait is a white sponge. Let’s say that we perform a “test cross” on spongebob (spongebob + a white female sponge) and all of the baby sponges are yellow. What would spongebob’s genotype be?

Objectives:



To set up and complete a dihybrid cross.

What is a dihybrid Cross?

 A dihybrid cross allows us to predict possible outcomes of offspring that will have 2 traits simultaneously.

 Ex: what would you get if you crossed a Brown-haired brown-eyed male with a blonde haired blue-eyed female? How many of the children would have brown hair and brown eyes? Brown hair and blue eyes? Blonde hair and brown eyes? Blonde hair and blue eyes?

Example

Setting up Dihybrid Crosses

    1. Determine parent genotypes 2. Determine alleles to be passed down 3. Set up punnet square 4. Determine outcome  Phenotype Ratio  Genotype Ratio

More Practice

 Mickey Mouse is heterozygous for Round ears and homozygous for Black eyes. Minnie Mouse also is homozygous for Floppy ears and heterozygous for Black eyes. Determine genotype and phenotype ratios. (B=black, b=brown, R=round, r= floppy.)



Dihybrid Crosses

Looking at two different traits  Ex. Hair color and eye color   B=brown eyes b=blue eyes   R=Brown hair r=blonde hair   Mother is heterozygous for both traits Father is heterozygous for eye color and homozygous dominant for hair color

What could the phenotypes and genotypes be of their children?

Objectives:



To define gene linkage and polypoidy.



To understand pedigrees and figure out how to use one.

Pedigree

  Shows history of a trait in a family Allows researchers to analyze traits within a family

Symbols for Pedigree

Lets try to figure out their genotypes!

Dominant or Recessive

 Pedigrees can depict both dominant and recessive traits…

Homework

 Pedigree Lab! Due next lab day!

Do Now

   Fill in the genotypes for the following pedigree B=brown eyes b = blue eyes

Objectives

  To be able to solve for the genotypes of pedigrees.

To be able to practice monohybrid and dihybrid crosses.

Practice!

 It’s Harry Potter time!! Get with a partner and work on the sample problems involving some of my favorite fictional characters!

Do Now Dominant or Recessive Trait?

Objectives

  To understand incomplete dominance and be able to do incomplete dominance monohybrid crosses.

To explain codominance, multiple alleles, sex-linked traits, and polygenic inheritence.

   

11.2 Incomplete Dominance:

Heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes.

Two alleles are blended Ex) Four O’clock Flowers

Red

+ White =

Pink

Incomplete Dominance

Codominance

   Neither trait is dominant instead, both traits are shown (No Blending) Ex) Roan Cows

Red

+ White =

R E D A N D W H I T E

Roan Coat



Sickle Cell Disease

Affects red blood cells and ability to transport oxygen.

 Homozygous recessive alleles=  Heterozygous=  Homozygous dominant alleles=

Sickle Cell and Malaria

 People who are heterozygous for sickle cell, have a higher resistance to malaria.



Do Now

A man who is a breeder of roan cows wants to cross two roan cows to produce more roan cows. After the two cows mate, the offspring are one red cow and one white cow. He is very disappointed. Explain why this happened. Provide a punnet square.

Multiple alleles

–

3 or more alleles that control a trait

 Example – blood type (I A ,I B ,i o ) GENOTYPES I A I A I A i o I B I B I B i o I A I B i o i o RESULTING PHENOTYPES Type A Type A Type B Type B Type AB Type O

Universal Donor?

Sample Problem

 Determine the possible offspring of the following crosses    1. AB and O 2. AA and BO 3. AB and AB

Coat Color of Rabbits

   Rabbits have a hierarchy of coat color 4 alleles ( C , Dominant C c ch , > c h , and c ch > c h c > ) c Recessive     C Full color c ch Chinchilla c h Himalayan c albino

Full Color

Coat Color of Rabbits

Chinchilla Albino Himalayan

Let’s try a sample problem

 cc x Cc ch  Genotype and phenotype ratios

What do you see?

What do you see?

Sex Linked Traits

   Traits located on the sex chromosomes (X or Y)

X linked:

gene is located on the X chromosomes

Y linked:

gene is located on the Y chromosome

What are the chances of having a girl?

 How would you go about solving it?

Sex-Linked Traits

 A woman who is color blind marries a man that does NOT have color blindness. What is the chance of having a color blind boy?

Polygenic Traits  Polygenic traits arise from the interaction of multiple pairs of genes.

Objectives:



To define test cross



To define incomplete dominance



To define codominance

Objectives:



To predict the results of dihybrid crosses by using a Punnett square

Do Now: Matching

Quiz Review Question 1  A man that is a carrier for albinism marries a woman what is also a carrier. Set up a punnet square to determine the chance of having a child with albinism.

Quiz Review Question 2  A heterozygous man with achondroplasia marries a woman that is the normal. Set up a punnet square to determine the chance of having a child with achondroplasia.

Quiz Review Question 3 **CHALLENGE**  A man who has hemophilia marries a woman who is normal and not a carrier. What is the chance of having a child with hemophilia?