Warm ups – March 2nd, 2012

• What is a Punnett square used for?• What are the parental generation, first filial, and

second filial generations symbolized by?• If fluorescent red eye color was dominant, and

white was recessive,and you crossed a red-eyed rat with a white-eyed rat, IN WHAT GENERATION would you first see the white-eyed trait appear?

O T T F F S S E __

What comes next?

O T T F F S S E __

It’s EASY if you know the PATTERN!(Just like Punnett Squares)

NE

WO

1 2 3 4 5 6 7 8

HREE

OUR

IVE

IX

EVEN

IGHT

9NINE

PROBABILITY & PUNNETT SQUARES

11-2

Go to Section:

Tossing CoinsIf you toss a coin, what is the probability of getting heads? Tails? If you toss a coin 10 times, how many heads and how many tails would you expect to get? Working with a partner, have one person toss a coin 50 times while the other person tallies the results on a sheet of paper. Then, switch tasks to produce a separate tally of the second set of 50 tosses. Add your results together to get a percentage heads or tails.

Section 11-2

Interest Grabber

It can be written as a:Fraction ____

Percent ____Ratio ____

____________________is the __________ that a

particular _________________

PROBABILITY

1/425%

1:3

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

Tt 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/GENOTYPEThe ________________ of an organism

is its _____________

The ____________of an organism isits _____________

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

tpossible 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 PLANTSTall 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 tTt TALL

ALL

1004

HYBRID TALL parent What are the parent alleles?

T t _________

T t

HETEROZYGOUS

What gametes can it make?

GENOTYPES¼ = _____½ = _____¼ = _____

T t

T

t

T T T t

T t t t

PHENOTYPES ____ or ____% _________ ____ or ____% _________

TT

75

Tttt

3/41/4 SHORT

TALL25

PRACTICE MAKING GAMETES for a MONOHYBRID CROSS

Tall = ____ Round seeds = ___ Short = ____ Wrinkled seeds = ___

Tt

Rr

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