Chapter 10: Sexual Reproduction & Genetics

What are homologous chromosomes?

Chromosomes that have the same genes at the same loci but may have different alleles.

What does diploid mean?

A cell that has two complete sets of chromosomes, one from each parent, represented as 2n. (Double)

What does haploid mean?

A cell that has one complete set of chromosomes, represented as n. (Half)

Which kind of cell can be represented by 2n?

Diploid cells.

Which kind of cell can be represented by n?

Haploid cells.

What is meiosis?

A type of cell division that reduces the chromosome number by half, creating four haploid cells.

What kind of cells undergo meiosis?

gametes

What is the purpose of meiosis?

To produce gametes for sexual reproduction.

How are mitosis and meiosis different?

Mitosis produces two identical diploid cells, while meiosis produces four genetically unidentical haploid cells.

What is crossing over?

The exchange of genetic material between homologous chromosomes during Prophase I of meiosis.

What happens during interphase of meiosis?

Chromosomes are replicated, resulting in two sister chromatids for each chromosome.

What happens during Prophase I of meiosis?

Homologous chromosomes pair up and crossing over occurs.

What happens during Metaphase I of meiosis?

Homologous chromosome pairs line up along the metaphase plate.

What happens during Anaphase I of meiosis?

Homologous chromosomes are pulled apart to opposite poles.

What happens during Telophase I of meiosis?

The nuclear membrane may reappear, and the cell divides through cytokinesis.

What happens during Prophase II of meiosis?

Chromosomes condense again, and the nuclear envelope breaks down if it had reformed.

What happens during Metaphase II of meiosis?

Chromosomes line up along the metaphase plate without homologous pairs.

What happens during Anaphase II of meiosis?

Sister chromatids are pulled apart to opposite poles.

What happens during Telophase II of meiosis?

Nuclear membranes reform around each set of chromosomes, and the cell divides.

What is cytokinesis in meiosis?

The division of the cytoplasm to form separate daughter cells after telophase.

What is the end result of meiosis?

Four genetically diverse haploid cells, each with half the number of chromosomes of the parent cell.

How do the cells produced by meiosis compare to each other and the parent cell?

The cells are haploid and genetically diverse, in contrast to the diploid parent cell.

How does meiosis increase genetic variation?

Through independent assortment and crossing over during gamete formation.

Who was Gregor Mendel?

A scientist known as the father of genetics for his work on pea plants and inheritance.

What was Mendel's famous pea plant experiment?

He crossbred pea plants and observed traits, leading to the formulation of the laws of inheritance.

What is a gene?

A segment of DNA that codes for a specific trait.

What is an allele?

Different versions or variants of a gene.

What does homozygous mean?

Having two identical alleles for a particular gene.

What does heterozygous mean?

Having two different alleles for a particular gene.

What is a phenotype?

The physical expression or characteristics of a trait.

What is a genotype?

The genetic makeup of an organism, consisting of alleles.

What is the principle of dominance?

The principle that states that some alleles are dominant and others are recessive.

What is segregation in genetics?

The separation of alleles during gamete formation.

What is an example of a homozygous dominant genotype?

TT for tall plants.

What is an example of a homozygous recessive genotype?

tt for short plants.

What is an example of a heterozygous genotype?

Tt for a plant with one tall and one short allele.

What are the genotypes and phenotypes of offspring from a TT and Tt cross?

Genotypes: TT, Tt; Phenotypes: all tall plants.

What are the genotypes and phenotypes of offspring from two heterozygous red flower plants?

Genotypes: 25% RR, 50% Rr, 25% rr; Phenotypes: 75% red, 25% white.

What is the probability the child will have hitchhiker's thumb if one parent is heterozygous?

50% chance of having hitchhiker's thumb.

What is the difference between a monohybrid cross and a dihybrid cross?

A monohybrid cross involves one trait, while a dihybrid cross involves two traits.

What are the genotypes and phenotypes of children from a heterozygous brown hair and homozygous brown hair with attached earlobes marriage?

Genotypes: BB, Bb, bb, and earlobe types; phenotypes: brown hair with free and attached earlobes.

What are the genotypes and phenotypes of children from a blond hair and heterozygous trait marriage?

Genotypes: combinations of alleles for hair and earlobes; phenotypes reflect respective traits.

What is genetic recombination?

The process of forming new allelic combinations in offspring.

What is gene linkage?

The tendency of genes located close together on a chromosome to be inherited together.

How is gene linkage related to crossing over and genetic variation?

Linkage affects the probability of crossing over, thus influencing genetic variation.

What does it mean for an organism to be polyploid?

An organism with more than two complete sets of chromosomes.

Give examples of organisms with polyploid cells?

Many plants like wheat and strawberries are polyploid.

How does agriculture utilize polyploidy?

Agriculture uses polyploid varieties for traits like increased size and yield.