Ch 1 Mendel

If there are homozygous parents (AA and aa) but the F1 offspring are a mixture, what is the F2 ratio?

1:2:1 (AA, Aa (incomplete dominance), aa)

What will F2 generation be from F1's Rr (roundness) 1- geno/phenotype

1:2:1 RR, Rr ,Rr, rr. 3 Round, 1 Wrinkled (INDEPENDENT SEGREGATION)

F2 Generation Ratio (Aa & Aa)

3:1 Dominant to Recessive

5 Map Units

5% frequency of recombination

What will the F2 phenotype be of F1 generation with 2 alleles: RrYy

9:3:3:1. 9 round yellow, 3 wrinkled and yellow, 3 round and green, 1 wrinkled and green. (INDEPENDENT ASSORTMENT)

Mutations

A change in the nucleotide sequence of an organism's DNA, ultimately creating genetic diversity. Mutations also can occur in the DNA or RNA of a virus.

50:50 Chance of a gene

A given gamete contains only one (allele) of the two copies of the genes present in the organism it came from. R or r - never both

Gene

A segment of DNA on a chromosome that codes for a specific trait

Which of the following parental genotypes would yield a 1:1:1:1 phenotypic ratio in the offspring?

AaBb, aabb

What will F1 generation be with parental RR and rr for roundness. 1- Geno/Phenotype

All Rr. All Round

What is the difference between heterozygous and homozygous individuals?

All of the gametes from a homozygote carry the same version of the gene while those of a heterozygote will differ.

Which of the following statements most accurately describes the process of independent assortment?

Alleles of different genes segregate from one another in a random manner.

Genotype

An organism's genetic makeup, or allele combinations.

Phenotype

An organism's physical appearance, or visible traits.

Synapsis

Bring together 4 chromatid which coil around each other Pairing of homologous chromosomes along their long axis

Alleles

Different forms of a gene. (Different colors, shape)

True or false? The principle of independent assortment is best illustrated by events that take place during metaphase II, during which sister chromatids segregate independently of each other.

FALSE; The principle of independent assortment is best illustrated by events that take place during metaphase I, during which nonhomologous chromosomes segregate independently of each other.

How do cells acquire homologous chromosome pairs that carry the alleles that are independently assorted?

Fusion of gametes

Linked Genes

Genes located close enough together on a chromosome that they tend to be inherited together.

Homozygous

Maternal and Paternal genes are identical. PP or pp. Having two identical alleles for a particular gene

Heterozygous

Maternal and Paternal genes differ. Pp. Describes an organism with two different alleles for a trait.

What process is responsible for the independent assortment of alleles?

Meiosis

Three factor crosses: Least frequent gene pair

Must occur from double crossover

Of the methods listed below, which would be the best way to determine which of two alleles of a gene is dominant to the other?

Observe the relevant phenotype in the progeny that result from a cross between individuals from two different pure-breeding lines. All progeny will be heterozygous for the trait in question and will display the phenotype that corresponds with the dominant allele.

Incomplete Dominance

PP (Red flower) pp (white flower) has F1 generation that makes pink flower (Pp). F2 generation: (1) PP: (2) Pp (Pink) : (1) pp (white)

Crossing Over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

Genetic map

Relative positions of genes on chromosomes

What will F1 geno/pheno be with two alleles: RRYY and rryy

RrYy, All round and Yellow.

Wild-type gene

The form of a gene (allele) normally found in nature.

The 3:1 phenotypic ratio observed among progeny of an F1 X F1 cross requires random union of gametes

True; The 1:2:1 genotypic ratio represents relative probabilities of gamete combinations based on the assumption that gamete union is random.

Principal of Independent Segregation (Mendels 1st Law)

Two alleles for a particular gene segregate (or separate) from each other during gamete formation and end up in different gametes. The law of segregation says that when I make gametes (sperm or eggs), the alleles for my eye color genes will separate. An egg may get the blue eye gene or the brown eye gene, but not both. Same for hair. Exactly one allele from each pair of alleles is found in each gamete (assuming there are no mistakes).

How many genetically unique types of gametes could be produced by an individual with the genotype RrYY

Two; The gametes would be either RY or rY

Genes will end up together if

an even number of cross overs occur between them

Recombinants

an offspring whose phenotype differs from that of the true-breeding P generation parents

Principal of Independent Assortment (Mendels 2nd Law)

each pair of alleles segregates independently of other pairs of alleles during gamete formation. In other words, traits are transmitted to offspring independently of one another The law of independent assortment says that whether an egg gets the blue eyes gene or brown eyes gene does not depend on whether it gets the brown hair gene or blonde hair gene. Therefore, brown hair + blue eyes, brown hair + brown eyes, blonde hair + blue eyes, and blonde hair + brown eyes are all possible. They are randomly assorted, not linked together in patterns

Various traits are controlled by

factors (genes)

Which of the following would be true of a plant heterozygous for a single gene controlling flower color? (Assume complete dominance).

if crossed with another heterozygous plant, the majority of progeny will have the dominant flower color. There will be roughly three times as many plants with the dominant flower color as plants with the recessive flower color.

First Filial (F1)

the ____ generation is the offspring of the P, or parental, generation

Genes will be separated if

there is an odd number of cross overs between them