Today you need pencil and science notebook Learning target – I will be able to define words related to DNA and genetics. Question – What is mitosis? Cell division that ensures each daughter cell gets exact copies of parent cell DNA.

Using a Punnett Square

What is a PUNNETT SQUARE? A tool to predict the probability of certain traits in offspring that shows the different ways alleles can combine A way to show phenotype & genotype A chart that shows all the possible combinations of alleles that can result when genes are crossed

Trait – physical characteristics of an organism Examples? Blue eyes, brown hair, tall plants Offspring – the next generation of the parents

More PUNNETT SQUARE Vocabulary? Punnett Square – a tool to predict the probability of a trait Alleles –various form of a gene, ex…. Genotype – genetic code, represented by letters. Ex. BB, Bb, bb Phenotype – visible genetic trait. Ex. tall Gene – unit of heredity with a specific location on the DNA Heredity – passing of gene from parent to offspring

Letters stand for dominant and recessive alleles An uppercase letter stands for a dominant allele. ex. B Lowercase letters stand for recessive alleles. Ex. b

What is a PUNNETT SQUARE Vocabulary? Recessive – only expressed in phenotype when two identical copies of alleles are present. Ex. bb or cc Dominate – always expressed in phenotype, even when alleles do not match. Ex. BB, Bb, or CC, Cc

Question – What does recessive mean? Trait is masked by a dominant allele What does dominant mean? Trait always shows up in the organism

Hybrid – a mixture of genes. Ex. Bb Purebred – pure genes. Ex. BB, bb Homozygous – purebred, pure genes, both alleles match. Ex. BB, bb Heterozygous – hybrid, mixture of genes, alleles do not match. Ex. Bb

Learning target – I will be able to use a Punnett square to predict the results of a simple genetic cross. Questions – What is a genotype? genetic code, represented by letters What is a phenotype? The visible genetic (physical) trait

Using a PUNNETT SQUARE To set up a Punnett square, draw a large square, and then divide it into 4 equal sections (also squares). It should look something like this:

Rr x rr Using a PUNNETT SQUARE Now you need to know the genotypes of two parents. Red flowers are dominant to white flowers. For example, a red flower (genotype Rr) and a white flower (genotype rr). Rr x rr

Using a PUNNETT SQUARE Place one of the genotypes on top, and one on the left. You should get a something similar to this:

Using a PUNNETT SQUARE Rr rr Rr rr Take each letter in each column and combine it with each letter from each row in the corresponding square. Rr rr Rr rr

Using a PUNNETT SQUARE You should now have a picture close to this: The 2 letter combinations are the genotypes of the offspring.

genotypes For this cross, they are: Rr, Rr, rr, and rr genotypes. What are the possible phenotypes? Red and white

Percentages and ratios For this cross, they are: Rr, Rr, rr, and rr genotypes So it is possible for us to determine the probability (chance) that a flower will have a red phenotype (2/4 or 50%) or a white phenotype (2/4 or 50%)

Let’s do another Punnett Square Draw another large square, and then divide it into 4 equal sections (also squares).

Let’s do another Punnett Square Parent’s genotpyes: Tt x Tt Tall is dominant to short Genotypes of offspring: TT = Tt = tt = T t TT Tt T Tt tt Phenotype of offspring: Tall = Short = t

Let’s do another Punnett Square Parent’s genotpyes: Tt x Tt Tall is dominant to short Genotypes of offspring: TT = 25% Tt = 50 % tt = 25% T t TT Tt T Tt tt Phenotype of offspring: Tall = 75% Short = 25% t

PP x pp Using a PUNNETT SQUARE Now you need to know the genotypes of two parents. Purple is dominant to white. For example, a purple flower (genotype PP) and a white flower (genotype pp). PP x pp

Using a PUNNETT SQUARE P P p p Place one of the parents on top, and one on the left. You should get a something similar to this: P P p p

Using a PUNNETT SQUARE P P p Pp Pp p Pp Pp Take each letter in each column and combine it with each letter from each row in the corresponding square. P P p Pp Pp p Pp Pp

Using a PUNNETT SQUARE The two-letter combinations are the possible genotypes of offspring They are: Pp, Pp, Pp, Pp genotypes From this it is possible to determine the probability (chance) that a flower will have a purple phenotype (4/4 or 100%) or a white phenotype (0/4 or 0%)

Homozygous/Heterozygous Ho / He Cross a homozygous dominant tall plant with a homozygous recessive short plant. Dominant trait = tall Recessive trait = short T = tall What letters would you use to represent this cross? t = short

What is the genotype of a homozygous dominant tall plant? TT What is the genotype of a homozygous recessive short plant? tt TT x tt Genotype % TT % Tt % tt t t 100 Tt Tt T T Phenotype % tall % short 100 Tt Tt

2. Cross a heterozygous brown haired rabbit with a homozygous recessive white haired rabbit. What letters would you use to represent this cross? Dominant trait = brown hair Recessive trait = white hair B = brown b = white

What is the genotype of a heterozygous brown haired rabbit? Bb What is the genotype of a homozygous recessive white haired rabbit? bb Bb x bb Genotype % BB % Bb % bb b b 50 Bb Bb B b 50 Phenotype % brown % white 50 bb bb 50

3.. Cross a homozygous dominant long haired guinea pig with a heterozygous long haired guinea pig. What letters would you use to represent this cross? Dominant trait = long hair Recessive trait = short hair L = long l = short

What is the genotype of a homozygous dominant long haired guinea pig? LL What is the genotype of a heterozygous long haired guinea pig? Ll LL x Ll Genotype % LL % Ll % ll 50 L l 50 LL Ll L Phenotype % long % short 100 LL Ll

Learning target – I will be able to use a Punnett square to predict the results of a simple genetic cross. Rate yourself again, 1, 2, 3, or 4. Hold up your whiteboard.

4. Cross a heterozygous wrinkly elephant with another heterozygous wrinkly elephant. What letters would you use to represent this cross? Dominant trait = wrinkly skin Recessive trait = smooth skin W = wrinkly w = smooth

What is the genotype of a heterozygous wrinkly-skinned elephant? Ww Ww x Ww Genotype % WW % Ww % ww 25 W w 50 W w WW Ww 25 Phenotype % wrinkly % smooth 75 Ww ww 25

Today you need packet, pencil and notebook Learning target – I will be able to identify some of my own traits. Questions- What is a Punnett square? a tool to predict the probability of a trait showing up in offspring

Using a PUNNETT SQUARE Rr rr Rr rr Parent genotypes -Rr x rr Take each letter in each column and combine it with each letter from each row in the corresponding square. RR = 0% Rr = 50% rr = 50% Dominant = 50% Recessive = 50% Rr rr Rr rr

Volunteer for some examples from the packet Brain pop first Read pages 101 – 103 silently, Discuss – what are acquired traits and what are inherited traits? WS – complete the chart.

A plant that is homozygous dominant for round seeds is crossed with a heterozygous plant. What is the probability that the offspring will have wrinkled seeds? R = round r = wrinkled RR x Rr Genotype % RR % Rr % rr 50 R r 50 R RR Rr Phenotype % round % wrinkled 100 RR Rr

Today you need pencil, notebook. Learning target – I will be able to design a model of an offspring using genotypes of the parents. Question – What are alleles? Different forms of the same gene, ex. Tall and short plants Agenda – Turn in homework Get quiz back Start lab on page 108. Clean up

Parent genotypes: Rr x rr. Round seeds (dominant) and wrinkled seeds. What is the probability that the offspring seeds will be round? 50% What is the ratio of round seeds to wrinkled seeds? 2 to 2, 2:2

Parent genotypes: Rr x rr. Round seeds (dominant) and wrinkled seeds. What is the probability that the offspring seeds will be round? 50% What is the ratio of round seeds to wrinkled seeds? 2 to 2, 2:2