PROBABILITY & PUNNETT SQUARES 11-2

It can be written as a: Fraction ____ Percent ____ ____________________ is the __________ that a particular _________________ PROBABILITY 1/4 25% 1:4 likelihood event will occur

COIN FLIP There are 2 possible outcomes: HEADS TAILS capital 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. 1/250%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. PASTDON’T FUTURE Probability best predicting large

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

HOMOZYGOUS HETEROZYGOUS 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 PURE SAME 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 CROSS ONE GENE

PUNNETT SQUARES are used to show possible offspring from a cross between 2 parents _______________ go at top and on left side Boxes show ____________ ___________________ T TtTt possible offspring combinations Parent alleles

1. ___________ what _________________ are 2. ________correct__________ square __________ 3. ______ possible_______________________ 4. ______ boxes with _____________________ 5. Determine ____________of_____________& ____________ STEPS FOR MAKING CROSSES Figure out parent alleles Choose Punnett size Put in parent gametes Fill in offspring combinations probabilities phenotypes genotypes

IN PEA PLANTS Tall is dominant over short TALL = ____ SHORT = ____ T t LET’S MAKE A CROSS! PURE TALL PURE SHORT X

PURE TALL parent What 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 TT t t T tT tT t T tT t T tT t 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 = _____ Tt T t T TT T T t T tT t t tt t PHENOTYPES ____ or ____% _________ ____ or ____% _________ TT 75 Tt tt 3/4 1/4 SHORT TALL 25

PRACTICE MAKING GAMETES for a MONOHYBRID CROSS Tall = ____ Round seeds = ___ Short = ____ Wrinkled seeds = ___ T t R r

Homozygous Tall parent = What gametes can it produce? What are the possible gametes?   T TT

PURE wrinkled parent = What gametes can it produce? What are the possible gametes?   rr rr

Heterozygous Round parent = What gametes can it produce? What are the possible gametes?   R r Rr

Hybrid Tall parent = What gametes can it produce? What are the possible gametes?   Tt T t