ap biology discussion notes wednesday 3/25/2015. goals for the day be able to predict the outcomes...

AP Biology Discussion Notes

Wednesday 3/25/2015

Goals for the day• Be able to predict the outcomes of crosses with

intermediate inheritance, co-dominance, or multiple alleles

• Be able to define and perform dihybrid crosses and use multiple strategies to predict the outcomes

• Be able to use probabilities to simplify & complete complex problems.

Question of the day 3/25

• Fill out the 3 questions at the top of your note sheet -

Intermediate Inheritance & Co-Dominance

Answer the 3 questions at the top of your page.


1. Based on the problems you have done previously, predict the PHENOTYPE(s) of the offspring from a cross between a Red flower and a white flower where red is dominant to white.


2. How many phenotypes were possible in the problems we have done so far (look at the legend or the phenotypic ratio)?

Intermediate Inheritance or Incomplete Dominance

3. What does intermediate mean?

What does incomplete mean?

Intermediate Inheritance

Intermediate Inheritance/Incomplete Dominance - is when two alleles BLEND together.

Example: When you cross a Red (FRFR) flower with a White flower (FWFW) you get all pink flowers (FRFW) in the

offspring. (Red x White = 100% Pink)

Legend

Parents Cross it Genotypic Ratio

Phenotypic Ratio

Intermediate Inheritance or Incomplete Dominance

Note in the cross that the Genotype & Phenotype ratios are now the same!

Co-Dominance

What does Dominance mean?

What does “CO” mean? (As in cooperate or Coauthors)

Co-Dominance = Dominant together

Co-Dominance means: BOTH alleles are represented that is they both SHOW UP!

(They are dominant together)

Intermediate inheritance & Co-Dominance

* The difference between Intermediate Inheritance & Co-dominance is in the PHENOTYPE. In Intermediate Inheritance (aka Incomplete Dominance) the alleles _________ together.In Codominance both alleles _____ _______, are EXPERESSED (Both traits are seen in the phenotype)

Cross a homozygous black dog with a homozygous white dog

Legend


Phenotypic Ratio

Intermediate inheritance & Co-Dominance

Questions?

Multiple allelesSome traits may be expressed by more than two possible alleles. This is multiple allele expression. One very important trait expressed through multiple alleles is human blood type.

Multiple allelesThere are four possible types of human blood:

– A, B, AB, and O

•These are expressed by immunoglobulin proteins, so the three possible alleles are written in this way:

IA & IB are both CO-DOMINANT (they both _______ ___) and i is recessive to them.

Multiple allelesMultiple alleles – Traits are controlled by more than 2 possible alleles.

Multiple allelesEven with multiple alleles each individual still only gets _______ alleles for each trait!

One allele from _______ and one allele from ______

Multiple allelesBlood types in humans are a good example of a multiple allele trait. - They are also an example of CO-Dominance – dominant together – Both alleles/traits _________ _____.

Blood Type

(________type)

Alleles

(_______type)

IAIA or IAi

IBIB or IBi

IAIB

ii

Multiple alleles

Very Important in Blood Transfusions!

Multiple alleles1. One parent is homozygous type A and the other is heterozygous type A

Legend


Phenotypic Ratio

Mendel’s Law of Segregation

• Each individual has a pair of factors (alleles) for each trait

• The alleles segregate (separate) during gamete (sperm & egg) formation

• Each gamete contains only one factor (allele) for each trait

• Fertilization gives the offspring two factors (alleles) for each trait

Dihybrid CrossesUp until now we have been looking at Monohybrid crosses. Mono means _______.

This is to say that we have been looking at one ________, or characteristic, at a time. Often times we want to look at two traits at once. If we are looking at the outcomes of two traits in one cross we will call it a __________ ___________. •Di = _______ Mono = _________

Dihybrid CrossesOften times we want to look at two traits at once. If we are looking at the outcomes of two traits in one cross we will call it a Dihybrid Cross

Di = _______ Mono = ______

Dihybrid Crosses

Dihybrid cross – two trait cross

In monohybrid crosses each parent was represented with ___ alleles and there were ____ possible allele combinations.

(Ex. A parent could be AA, Aa, or aa)

Dihybrid Crosses

Dihybrid cross – two trait cross

In Dihybrid crosses there are ___ alleles/parent and ____ possible Allele Combinations.

Mendel tested Two-Trait Inheritance

• Dihybrid cross Mendel used true-breeding (__________/____________) plants differing in two traits

– Observed phenotypes among F2 plants

– Formulated Law of Independent Assortment

Mendel’s Law of Independent Assortment

The Alleles for one trait segregate (separate) independently of the alleles for other traits

All possible combinations of alleles can occur in the gametes(________/_______)*These are ____________ cells ( __ n) and made through the process of ____________

Meiosis Review Let’s refresh our Memory!

OrganismCell type & chromosome # Haploid # Diploid #

Mountain Goat Horn cell = 50

Leopard Seal Tongue cell = 10

Amaryllis Bulb Egg cell = 15

Emperor Penguin Sperm cell = 20

Bald Eagle Heart cell = 100



Mountain Goat Horn cell = 50 25 50Leopard Seal Tongue cell = 10

Amaryllis Bulb Egg cell = 15





Mountain Goat Horn cell = 50 25 50Leopard Seal Tongue cell = 10 5 10Amaryllis Bulb Egg cell = 15





Mountain Goat Horn cell = 50 25 50Leopard Seal Tongue cell = 10 5 10Amaryllis Bulb Egg cell = 15 15 30Emperor Penguin Sperm cell = 20





20 40





20 40

Bald Eagle Heart cell = 100 50 100

Mendel’s Law of Independent Assortment

Round is _______________ to wrinkled.

Yellow is ________________ to green.

In honor of Mendel we will do an example of a dihybrid cross with pea plants.

R – Round

r – wrinkled

Y – Yellow

y - green

Dihybrid Cross

F1 gen. all (100%) RrYy

Parental Generation (P1): RRYY x rryy

Possible Gamete(s) from RRYY:

Possible Gamete(s) from rryy:

Dihybrid Cross – F.O.I.L

F1 generation: RrYy

F – first

O – Outside

I – Inside

L - Last

Possible Gametes from RrYy: ______ , ______ , ______ , _______

RrYy

RY Ry rY ry

RY

Ry

rY

ry

R=Round r =wrinkledY= Yellow g= green RrYy

RY Ry rY ry

RY RRYY RRYy RrYY RrYy

Ry RRYy RRyy RrYy Rryy

rY RrYY RrYy rrYY rrYy

ry RrYy Rryy rrYy rryy


Phenotype (Phenotypic Ratio)

Round & Yellow: ___/16 Round & ________: ___/16 _________ & Yellow: ___/16 __________ & __________ : ___/16

RY Ry rY ry

RY RRYY RRYy RrYY RrYy

Ry RRYy RRyy RrYy Rryy

rY RrYY RrYy rrYY rrYy

ry RrYy Rryy rrYy rryy


Dihybrid Crosses

Phenotypic Ratio: ___: ___: ___: ___ - This will always be the phenotypic ratio for a Heterozygote cross in normal patterns of inheritance. *This will also be a test question!

Typically for Dihybrid Crosses we will only ask you to find the Phenotypic Ratio, and not the Genotypic Ratios

Dihybrid Crosses REVIEWThere are now __ possible allele combinations that could be passed on in the gametes of these parents.

Remember that Crossing over, which happens during Prophase 1 of Meiosis, is a source of _______________.

*This Variation is in part why we might be able to have __ different allele combinations.

Dihybrid Crosses REVIEW*This Variation is in part why we might be able to have 4 different allele combinations.

If I had a heterozygote AaBb I might have AB on one chromosome and ab on another. The possible gametes then would only be AB and ab. The ONLY WAY to get the other possible gametes ___ ___ & ___ ___ are through crossing over which allows the gametes to inherit the alleles in a different way to have (VARIATION)!!!

Wednesday PM

• I will be unavailable – talk to me if you plan to work on corrections after school.

Species of the Day 3/25Common Grackle- Quiscalus quiscula

Species of the Day 3/25Common Grackle- Quiscalus quiscula

European Starling- Sternus vulgaris

ap biology discussion notes wednesday 3/25/2015. goals for the day be able to predict the outcomes...

Documents

possible alleles

intermediate mean

coauthors codominance

dominance dominant

multiple strategies

multiple allelesthere

multiple alleleseven

multiple alleles1