DIHYBRID CROSSES(2 traits)

http://mac122.icu.ac.jp/BIOBK/BioBookgenintro.html

Mendel also asked the question?

Does the gene that determines if a seedis round or wrinkled have anything todo with the gene for seed shape?

Must a seed that is yellow also be round?

MAKING A CROSS with ___________________=____________________

A Punnett square for a DIHYBRID CROSS looks like this:

DIHYBRID CROSSTWO gene traits

Go to Section:

Section 11-3

Figure 11-10 Independent Assortment in Peas

1. ___________ what _________________ are2. ________correct__________ square __________3. ______ possible_______________________4. ______ boxes with _____________________5. Determine ____________of_____________& ____________

LET’S MAKE A DIHYBRID CROSSHOMOZYGOUS

YELLOW ROUND

rryy

HOMOZYGOUSGREEN WRINKLED

Figure out parent allelesChoose Punnett sizePut in parent gametesFill in offspring combinations probabilities phenotypes

genotypes

RRYY

LAW OF __________________________

the factors are distributed to gametes independently of other factors

INDEPENDENT ASSORTMENT

Image modified from: http://anthro.palomar.edu/mendel/mendel_1.htm

R R Y Y

HOMOZYGOUS ROUND YELLOW

PRACTICE MAKING GAMETESWHAT ARE THE POSSIBLE GAMETES THIS PARENT CAN MAKE?

Each gamete shouldget one of each kindof gene

___________ ____________ _____________ _____________R Y R Y R Y R Y

r r y y

HOMOZYGOUS WRINKLED GREEN

PRACTICE MAKING GAMETESWHAT ARE THE POSSIBLE GAMETES THIS PARENT CAN MAKE?

Each gamete shouldget one of each kindof gene

___________ ____________ _____________ _____________r y r y r y r y

R r Y y

HETEROZYGOUSROUND YELLOW

PRACTICE MAKING GAMETESWHAT ARE THE POSSIBLE GAMETES THIS PARENT CAN MAKE?

Each gamete shouldget one of each kindof gene

___________ ____________ _____________ _____________R Y r y r Y R y

ry ry ry ry

RY

RY

RY

RY

100% of offspring = _______ genotype _______________________ phenotype

RrYyROUND YELLOW

RrYy RrYy RrYy RrYy

RrYy RrYy RrYy RrYy

RrYy RrYy RrYy RrYy

RrYy RrYy RrYy RrYy

R r Y y R r Y y

HETEROZYGOUSROUND YELLOW

HETEROZYGOUSROUND YELLOW

MAKE ANOTHER CROSS

X

POSSIBLE PARENT GAMETES?

RY ry RyrY

RY Ry rY ry

RY

Ry

rY

ry

Sign of a ______________________ cross is a_____________ ratio in offspring.9:3:3:1

____ Round & Yellow

____ Round & green

____ Wrinkled & yellow

____ wrinkled & green

9

3

3

1

RRYY RRYy RrYY RrYy

RRYy RRyy RrYy Rryy

RrYY RrYy rrYY rrYy

RrYy Rryy rrYy rryy

heterozygous dihybrid

__________ratio is a clue that it’s a ____________________________cross

____ ____________ TRAIT 1 ; ____________ TRAIT 2 ____ ____________ TRAIT 1; _____________ TRAIT 2

____ ____________ TRAIT 1; _____________ TRAIT 2

____ ____________ TRAIT 1; _____________ TRAIT 2

9

3

3

1

9:3:3:1

HETEROZYGOUS TWO gene

dominant dominant

dominant recessive

recessive dominant

recessive recessive

PRACTICE MAKING GAMETESfor DIHYBRID CROSSES

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookTOC.html

pure round & pure tall = __________

____ ____ _____ ______

What gametes can it produce?

What are the possible gametes?

R R T T

R T R T

R T R T

Heterozygous Tall = __________

& pure round

____ ____ _____ ______

What gametes can it produce?

What are the possible gametes?

T t R R

T R T R

t R t R

Hybrid tall = __________

& pure wrinkled

____ ____ _____ ______

What gametes can it produce?

What are the possible gametes?

T t r r

T r T r

t r t r

Heterozygous tall = __________

& hybrid round

____ ____ _____ ______

What gametes can it produce?

What are the possible gametes?

T t R r

T R T r

t r t R