Meiosis and Sexual Reproduction

This set of flashcards covers vocabulary and key concepts related to meiosis, sexual reproduction, and genetic variation as discussed in the lecture notes.

Haploid

A cell that contains one complete set of chromosomes (n).

Diploid

A cell that contains two complete sets of chromosomes (2n).

Asexual reproduction

A mode of reproduction that does not involve the fusion of gametes and produces genetically identical offspring.

Sexual reproduction

A process that involves the fusion of gametes, resulting in offspring with genetic variation.

Gamete

A reproductive cell that is involved in sexual reproduction, containing half the number of chromosomes of a somatic cell.

Mitosis

A type of cell division that produces two identical diploid daughter cells.

Meiosis

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

Crossing over

The exchange of genetic material between homologous chromosomes during meiosis, contributing to genetic diversity.

Homologous chromosomes

Pairs of chromosomes that have the same length, shape, and carry genes for the same traits.

Genetic diversity

Variability in the genetic makeup among individuals within a population.

Cell division stages

The three stages of the sexual life cycle: mitosis, meiosis, and fertilization.

Fertilization

The process where two gametes fuse to form a zygote.

Sister chromatids

Identical copies of a chromosome connected by a centromere.

Chromatid

A single thread of a duplicated chromosome.

Karyotype

A photograph or diagram of the chromosomes in a cell used for analysis.

Reduction division

The division that halves the number of chromosomes, characteristic of meiosis.

Independent assortment

The random distribution of homologous chromosomes during meiosis.

Nondisjunction

An error in meiosis when chromosomes fail to separate properly.

Autosomal trisomy

A genetic condition where an individual has three copies of a chromosome instead of two.

XXY Syndrome

Also known as Klinefelter's syndrome, a condition in males caused by an extra X chromosome.

XO Syndrome

Also known as Turner syndrome, a condition in females caused by a missing X chromosome.

Meiosis I

The first division of meiosis that separates homologous chromosomes.

Meiosis II

The second division of meiosis that separates sister chromatids.

Zygote

The fertilized egg that results from the fusion of gametes.

Somatic cells

Non-reproductive cells that contain the diploid number of chromosomes.

Centromere

The region of a chromosome where sister chromatids are joined.

Bivalents

Paired homologous chromosomes that form during meiosis I.

Tetrad

A group of four chromatids formed during meiosis by the pairing of two homologous chromosomes.

Synapsis

The pairing of homologous chromosomes during meiosis.

Metaphase I

The stage of meiosis I where homologous chromosomes align at the equatorial plane.

Anaphase I

The stage of meiosis I where homologous chromosomes are pulled apart to opposite poles.

Telophase I

The stage of meiosis I where the cell divides into two haploid cells.

Prophase II

The stage of meiosis II where chromosomes condense and spindle fibers form.

Metaphase II

The stage of meiosis II where chromosomes align at the equatorial plane.

Anaphase II

The stage of meiosis II where sister chromatids separate.

Telophase II

The final stage of meiosis II characterized by the formation of four haploid cells.

Parental chromosomes

The original chromosomes contributed by the parents in sexual reproduction.

Chromosome duplication

The process by which a cell creates an identical copy of its chromosomes.

Genetic recombination

The process by which genetic material is mixed and shuffled during sexual reproduction.

Clonal organisms

Organisms that reproduce asexually and are genetically identical to the parent.

Novel genetic combinations

New genetic variations formed through sexual reproduction.

Sister chromatid separation

The process that occurs during anaphase of meiosis II, where sister chromatids split apart.

Haploid cells

Cells that contain half the number of chromosomes, represented as n.

Diploid cells

Cells that contain two complete sets of chromosomes, represented as 2n.

Gamete fusion

The process of two gametes coming together to form a zygote.

Meiotic non-disjunction

Occurs when chromosomes fail to separate properly during meiosis.

Fertilization variations

Different genetic combinations that arise from the fusion of gametes from two parents.

Genetic variation mechanisms

Methods through which genetic diversity is generated, including crossing over, independent assortment, and random fertilization.

Human somatic cells

Cells of the human body that are not involved in reproduction, having 46 chromosomes.

Alleles

Different versions of the same gene that can produce varying traits.

Parental generation

The original generation that contributes to the offspring in genetic studies.

Offspring generation

The next generation produced from parental organisms.

Meiosis significance

Crucial for producing genetic variation and maintaining chromosome numbers across generations.

Sperm cell

The male gamete involved in sexual reproduction.

Egg cell

The female gamete involved in sexual reproduction.

Diploid number

The total number of chromosomes in diploid cells, e.g., 46 in humans.

Fertilization process

The union of male and female gametes to form a zygote.

Microtubule spindle apparatus

Structure that helps separate chromosomes during cell division.

Chiasma

The point of crossing over between homologous chromosomes.

Reproductive strategies

Different methods organisms use to reproduce, either sexually or asexually.

Mitosis outcome

Results in two identical daughter cells with the same diploid number.

Meiosis outcome

Results in four genetically diverse haploid cells.

DNA replication

The process of duplicating the cell's DNA before division.

Genetic disorder

A disease caused by an abnormality in an individual’s genetic makeup.

Chromosomal abnormalities

Alterations in chromosome number or structure, leading to genetic disorders.

Mutation's role in variation

Changes in DNA that can lead to variation in offspring, especially in asexual reproduction.

Life cycle stages

The series of developmental stages that organisms go through, including growth, reproduction, and death.

Homologs

Refers to the homologous chromosomes that pair during meiosis.

Meiotic error consequences

Can lead to genetic disorders in offspring, such as Down syndrome.

Ploidy levels

The number of sets of chromosomes in a cell; haploid (n), diploid (2n), etc.

Unique gametes

Gametes that differ genetically due to meiosis, contributing to diversity.

Meiosis and genetic diversity

Meiosis introduces genetic variation through independent assortment and crossing over.

Species survival

A function of genetic diversity, ensuring adaptability to environmental changes.

Environmental stability and asexuality

In stable environments, asexual reproduction may be advantageous due to consistency in successful traits.

Genetic trait inheritance

The transmission of genetic characteristics from parent to offspring.

Non-crossover chromatids

Sister chromatids that remain identical due to lack of crossover.

Allelic combinations

The various ways alleles can combine during gamete formation.

Gamete production site

Occurs in reproductive organs, such as ovaries and testes.