Chapter 25: Sexual Reproduction, Meiosis & Genetic Recombination

These flashcards cover the key concepts from Chapter 25, focusing on sexual reproduction, meiosis, and genetic recombination.

What is sexual reproduction?

The production of genetically unique offspring through the fusion of two haploid gametes to form a diploid zygote.

What are homologous chromosomes?

Chromosome pairs, one maternal and one paternal, that have the same gene loci but potentially different alleles.

What are alleles?

Alternative versions of a gene at the same locus that produce variations in a trait.

What does it mean for an allele to be dominant?

An allele that is expressed in the phenotype even when only one copy is present.

What is a recessive allele?

An allele that is masked by a dominant allele and is expressed only when both copies are present.

Define homozygous.

Having two identical alleles for a gene.

Define heterozygous.

Having two different alleles for a gene.

What is meant by genotype?

The genetic makeup of an organism, specifically the allele combinations present.

Define phenotype.

The observable traits or characteristics resulting from the genotype and environment.

What is a diploid cell?

A cell containing two sets of chromosomes, one from each parent.

What is a haploid cell?

A cell containing one set of chromosomes, such as gametes like sperm and egg.

What is alternation of generations?

A life cycle in plants where multicellular diploid and multicellular haploid stages alternate.

What are gametes?

Haploid reproductive cells produced by meiosis.

Describe meiosis.

A specialized form of cell division that reduces chromosome number from diploid to haploid to produce gametes.

What happens during prophase I of meiosis?

Homologous chromosomes condense and pair up, leading to crossing over and genetic recombination.

What is crossing over?

The physical exchange of DNA between non-sister, homologous chromatids at corresponding locations.

What are the consequences of nondisjunction during meiosis?

Improper separation of chromosomes that leads to gametes or daughter cells with an abnormal number of chromosomes.

What can result from aneuploidy?

Conditions like monosomy (missing a chromosome) or trisomy (having an extra chromosome).

What is transformation in prokaryotes?

The absorption of DNA molecules from the environment.

What is transduction?

The incorporation of DNA introduced by a virus.

What is conjugation in bacteria?

The transfer of DNA from one cell to another through a tube called a pilus.