Chapter 14 Gen BIO

True-breeding

produce offspring of the same variety when they self pollinate.

Example of true distinct alternative form

Purple flowers vs. White flowers

Monohybrid cross

A cross to study only two variations of a single trait

hybridization

mating two contrasting, true breeding varieties

P generation

True-breeding parents

F1 Generation

hybrid offspring of P Generation

F2 Generation

product of self-pollination or cross-pollination of F1 Generation.

What did Mendel find in the F1 Generation

They only resembled one parent reflecting a purple color.

What did Mendel find in the F2 Generation

Most reflected a purple color but some were white.

Dominant trait

phenotypic trait when presented.

Recessive trait

a genetic characteristic that appears in an individual's physical appearance or phenotype only when they inherit two copies of the recessive allele.

What trait did F1 Generation express

Dominant trait

What trait did F2 Generation express

Dominant and Recessive trait

Carriers

Reflect a dominant phenotype but carry a recessive genotype.

Gene

Information for a trait passed from parent to offspring

Alleles

Alternate forms of a gene

Homozgyous

Having two of the same allele

Heterozygous

Having two different alleles

Genotype

Total set of alleles of an individual

Phenotype

Outward appearance of an individual

Behavior of chromosomes during meiosis is…?

physical basis for allele segregation.

allele segregation (Mendel's Law of Segregation)

diploid organisms inherit two alleles for each gene which randomly separate during meiosis making each sperm/egg carry only a single allele for each trait.

Testcross

A cross used to determine the genotype of an individual with dominant phenotype.

Homozygous recessive

an organism thats inherited two identical recessive genes for a specific gene. (pp)

Dihybrid cross

Examination of 2 separate traits in a single cross

Dihybrid cross ratio

9:3:3:1

Law of independent assortment

Each pair of alleles segregate independently of any other pair of alleles during gamete formation (meiosis).

true-breeding strains

carry two identical alleles for those traits and consistently pass down the same appearance to every generation of offspring.

When to use Rule of Addition?

During OR questions.

When to use Rule of Multiplication?

During AND questions

Incomplete dominance

heterozygote is intermediate in phenotype between the two homozygotes

Intermediate

A pattern of genetic inheritance where neither allele is completely dominant over the other.

Codominance

Heterozygote shows some aspect of the phenotype of both homozygotes.

Multiple alleles

Most genes exist in populations in more than two allelic forms

allelic

A specific alternative form of a gene at a particular location (locus) on a chromosome.

Multiple alleles in the human ABO blood system

3 alleles of the I gene (I^a, I^b, i)

Codominance in the human ABO blood system

I^a and I^b are dominant to i but codominant to eachother

pleiotropy

An allele which has more then one phenotypic effect.

polygenic inheritance

occurs when multiple genes are involved in controlling the phenotype of a trait.

Continuous variation

a trait that has a full spectrum of intermediate phenotypes between two extremes rather than distinct categories

Quantitive traits

measurable phenotypic characteristics that vary along a continuous or numeric scale

what primary reason did mendel choose the pea plants for his studies

For their capability to self-fertilize and cross-fertilize

Mendels expirments

tracked two distinct alternative forms of varieties that true-breed

What does the 9 refer to in a 9:3:3:1 ratio

9 showing both dominant traits (R_Y_)

What does the first 3 refer to in a 9:3:3:1 ratio

3 dominant for R only

What does the second 3 refer to in a 9:3:3:1 ratio

3 showing dominant Y only

What does the 1 refer to in a 9:3:3:1 ratio

1 showing both recessive traits (rryy)

1:2:1 ratio

1 BB, 2 Bb,1 bb

Probability of homozygous recessive in a monohybrid cross

¼ (rr)

Probability of homozygous dominant in a monohybrid cross

¼ (BB)

Probability of heterozygous in a monohybrid cross

2/4 (Bb)

How to determine the genotype of a plant?

Cross test with recessive plant

epistasis

Expression of a gene at one locus alters the phenotype expression of a gene at a second locus

pedigree

A family that describes the inheritance of a trait across generations

polydactyl

individual is born with extra extremities

amniocentesis

Test where liquid that bathes the fetus is removed

Chorionic villus sampling

Sample of placenta is removed and tested

complete dominant of one allele

Heterozygous phenotype same as that of homozygous dominant

incomplete dominant of either allele

Heterozygous phenotype intermediate between the two homozygous phenotype.

codminance

both phenotype expressed in heterozygous

Multiple alleles

in the population some genes have more than two alleles