Mendelian Inheritance and Meiosis - Practice Flashcards

Flashcards covering key concepts from the lecture notes on Mendelian genetics, meiosis, and related terms.

If a gene has five different alleles, how many alleles for that gene could be found in a diploid cell?

At most two alleles (one on each homologous chromosome).

Starting with a diploid cell with 2n = 4 (n = 2), how many haploid gametes are produced by meiosis?

Four haploid gametes.

Define homozygous and heterozygous genotypes.

Homozygous: two identical alleles. Heterozygous: two different alleles.

What are alleles?

Different versions of the same gene.

Differentiate dominant and recessive alleles in terms of phenotype expression.

Dominant allele is expressed in the phenotype when present (in homozygous or heterozygous); recessive allele is expressed only when homozygous recessive.

Purple flower genotype is PP or Pp; White flower is pp. A plant with genotype Pp is what genotype and what phenotype?

Genotype: heterozygous; Phenotype: purple (dominant).

What hypothesis did Mendel's experiments test and what did he conclude?

Tested the blending inheritance hypothesis; concluded that inheritance is particulate rather than blending.

Two features of garden peas that aided Mendel's experiments.

Controlled matings and easily recognizable traits.

What is a pure-breeding line?

Homozygous for the gene of interest; offspring identical to the parent for that trait.

Monohybrid cross between two heterozygotes (Aa x Aa): what are the F1 and F2 outcomes?

F1: all heterozygous; F2: genotype 1:2:1 (AA:Aa:aa); phenotype 3:1 (dominant:recessive).

What is a Punnett square used for?

To visualize allele flow during crosses and predict offspring genotypes and phenotypes.

Name the four key mechanisms Mendel's results are based on.

1) Segregation of alleles into gametes; 2) Dominant and recessive alleles; 3) Random fertilization; 4) Equal contribution of genetic material from males and females.

What does the law of segregation state?

During meiosis, the two alleles of a gene segregate into different gametes.

What does the law of independent assortment state?

Alleles of different genes assort independently into gametes.

How does meiosis explain Mendel's two principles?

Meiosis creates gametes with one allele per gene (segregation) and mixes maternal and paternal chromosomes, allowing independent assortment.

Mendel's experiments with two traits (dihybrid cross) begin with RRYY x rryy. What is the F1 genotype and the F2 phenotype ratio under independent assortment?

F1 genotype: RrYy; F2 phenotype ratio: 9:3:3:1 (Round Yellow : Round Green : Wrinkled Yellow : Wrinkled Green).

What is crossing over and when does it occur?

Crossing over is the exchange of genetic material between homologous chromosomes during meiosis; creates new combinations of alleles within a chromosome.

What does 'random fertilization' mean?

Any sperm may fertilize any egg, creating genetic variety.

What organism did Mendel study for his genetics experiments?

Garden peas, Pisum sativum.

What is the difference between a haploid gamete and a diploid zygote?

A haploid gamete contains one set of chromosomes; a diploid zygote contains two sets after fertilization.