Genetics

Mutations quizWhich is worse and why?

1. Germ or somatic mutation2. Gene or chromosome mutation3. Point or frame shift4. Duplication or translocation

5. An error in which phase would cause nondisjunction?

Mendel studied pea plants - 7 pairs of traits:1. Height –Tall, short2. Seed shape – Round, wrinkled3. Seed color – Yellow, green4. Flower position – Axial, terminal5. Pod color - Green, yellow6. Flower color – Purple, white7. Pod shape – Inflated, constricted

Mendel’s Laws of Genetics

1. Traits are controlled by factors (genes) that occur in pairs

2. Principle of dominance and recessiveness – the dominant gene will be expressed , it will cover the recessive gene

T = tall (dominant) t = short (recessive)

TT = tall (pure dominant)tt = short (pure recessive)Tt = tall (hybrid)

3. Law of segregation – genes are separated during the formation of gametes(homologous chromosomes are separated during meiosis, gametes are haploid)

4. Law of independent assortment – manytraits are inherited independent of other traits(they are on different chromosomes)

Vocabulary:

P1 = parent generation

f1 = first generation of offspring

f2 = second generation of offspring

Genotype= actual genesTT = homozygous dominanttt = homozygous recessiveTt = hybrid, heterozygous

Phenotype = appearance (tall, short, etc.)

Allele = genes for the same trait,T and t are alleles for the trait of height

Punnett Square – chart used to predict the traits of offspring

Punnett square problems have 4 parts:

P1 statementPunnett squareGenotypePhenotype

Ex: P1 = Aa x Aa

Dad is written first, his alleles go on the side of the Punnett square

Mom is written next, her alleles go on the top of the Punnett square

f1 genotype f1 phenotype1 dominant 3 axial2 hybrid 1 terminal1 recessive

Two factor crosses - follow the same rules but you compare 2 traits at the same time

Ex: P1 = RrTt x RrTt• Dad is written first and on the side.• Mom is written next and on the top.• Use foil to determine the alleles: (first, outer, inner, last)

RT, Rt, rT, rt

Ex: P1 = RrTt x RrTt

• Follow dad’s pattern. Whichever letter is first for dad is first for the entire problem.

• The first genotype word describes the first pair of alleles, the next word describes the second pair.

Ex: P1 = RrTt x RrTt

F1 genotype1 dominant, dominant2 dominant, hybrid2 hybrid, dominant4 hybrid, hybrid1 dominant, recessive2 hybrid, recessive1 recessive, dominant2 recessive, hybrid1 recessive, recessive

F1 phenotype9 Round, Tall3 Round, short3 wrinkled, Tall1 wrinkled, short

P1 = Aa x Aa P1 = RrTt x RrTt

Monohybrid cross:Both parents are hybrid for one trait

Genotype ratio = 1:2:1Phenotype ratio = 3:1

Dihybrid cross:Both parents are hybrid for both traits

Phenotype ratio = 9:3:3:1