PROBABILITY & PUNNETT SQUARES

11-2

It can be written as a:

Fraction ____

Percent ____

____________________is the __________ that a

particular _________________

PROBABILITY

1/4

25%

1:4

likelihoodevent will occur

COIN FLIPThere are 2 possible

outcomes:

HEADS TAILS

capital

http://www.arborsci.com/CoolStuff/CoinFlip.jpg

The chance the coin will land on either one is:

____ ____ Alleles segregate randomly just like a coin flip. . . So can use probability to predict outcomes of genetic crosses.

1/2 50% 1:1

PROBABILITIES_____ outcomes ______ affect _________ones

_____________works ______ in ___________ a ________ number of events.

If last coin flip was heads… there is still a 50/50 chance the next flip will be heads too.

The more flips. . . The closer results will be to

the expected 50:50 average.

PAST DON’T FUTURE

Probability best predictinglarge

DOMINANT/RECESSIVE_____________ allele is represented by a

____________ letter.(usually the first letter of the trait)

____________ allele is represented by the SAME_________________ letter.

EX: Tall = ______

Short =______

capital

lower-case

T

t NOT S for short

Dominant

Recessive

HOMOZYGOUSHETEROZYGOUS

When both alleles in the pair are the _______, the organism is _______________ or __________

EX: ____ or ___

When both alleles in the pair are _____________, the organism is

_________________ or _____________

Ex: ____

HETEROZYGOUS HYBRID

HOMOZYGOUS PURESAME

TT tt

DIFFERENT

Tt

PHENOTYPE/GENOTYPE

The ________________ of an organism is its _____________

The ____________of an organism is

its _____________

GENOTYPE

PHENOTYPE

genetic makeup

appearance

MAKING A CROSS for only a __________ trait =____________________

A Punnett square for a MONOHYBRID CROSS looks like this:

MONOHYBRID CROSSONE GENE

PUNNETT SQUARESare used to show possible offspring

from a cross between 2 parents

_______________ go at top and on left side

Boxes show _______________________________

T T

T

t

possible offspring combinations

Parent alleles

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

STEPS FOR MAKING CROSSES

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

genotypes

IN PEA PLANTS

Tall is dominant over short

TALL = ____

SHORT = ____T

tLET’S MAKE A CROSS!

PURE TALL PURE SHORTX

PURE TALL parentWhat are the parent alleles?

T T _________

T T

HOMOZYGOUS

What gametes can it make?

PURE SHORT parent What are the parent alleles?

t t _________

t t

HOMOZYGOUS

What gametes can it make?

GENOTYPE _____ PHENOTYPE _______

_____ of the offspring

____ %

___/4

will be

T T

t

t

T t T t

T t T t

Tt TALL

ALL

100

4

HYBRID TALL parent What are the parent alleles?

T t _________

T t

HETEROZYGOUS

What gametes can it make?

GENOTYPES

¼ = _____

½ = _____

¼ = _____

T t

T

t

T T T t

T t t t

PHENOTYPES ____ or ____% _________ ____ or ____% _________

TT

75

Tt

tt

3/41/4 SHORT

TALL

25

PRACTICE MAKING GAMETES for a MONOHYBRID CROSS

Tall = ____ Round seeds = ___

Short = ____ Wrinkled seeds = ___

T

tR

r

Homozygous Tall parent =

What gametes can it produce?

What are the possible gametes?

T T

T T

PURE wrinkled parent =

What gametes can it produce?

What are the possible gametes?

rr

r r

Heterozygous Round parent =

What gametes can it produce?

What are the possible gametes?

R r

R r

Hybrid Tall parent =

What gametes can it produce?

What are the possible gametes?

Tt

T t