Biology: Karyotypes, Reproduction, and DNA Replication

These flashcards cover key concepts related to karyotypes, reproduction, and DNA replication.

Karyotype

A picture of an individual's chromosomes.

Nondisjunction

An event in which chromosomes fail to separate properly during cell division, resulting in missing or extra chromosomes.

Chromosome

A tightly coiled strand of DNA that carries genes.

Sex Chromosome

Chromosomes that determine the sex of an individual (X,Y).

Autosome

Any chromosome not involved in determining sex.

Chromatin

DNA found in the nucleus when the cell is not dividing.

Chromatid

One of two identical copies of a duplicated chromosome joined at the centromere.

Tetrad formation (synapsis)

When homologous chromosomes pair up during prophase I of meiosis, forming a group of four chromatids.

Homologous Chromosomes

Matching pairs of chromosomes, one from each parent.

Gamete

A sex cell (sperm or egg) that contains half the usual number of chromosomes (haploid).

Gonad

An organ that makes gametes (testes in males, ovaries in females).

Somatic Cell

Any body cell that is not a gamete, contains a full set of chromosomes (diploid).

Zygote

A fertilized egg cell formed when a sperm and egg unite, has both sets of chromosomes (diploid).

Asexual Reproduction

Reproduction involving only one parent, offspring are identical to each other and to the parent.

Sexual Reproduction

Reproduction involving two parents, resulting in offspring that inherit DNA from both parents.

Mitosis

A type of cell division that produces identical cells for growth and repair.

Meiosis

A type of cell division that reduces the number of chromosomes by half in preparation for sexual reproduction.

DNA Replication

The process of making a copy of DNA prior to cell division.

DNA Polymerase

The enzyme that synthesizes new DNA strands by adding nucleotides in the 5' to 3' direction.

Leading Strand

The DNA strand that is synthesized continuously during DNA replication.

Lagging Strand

The DNA strand that is synthesized in short fragments during DNA replication, forming Okazaki fragments.

Semiconservative Replication

A method of DNA replication in which each new DNA molecule contains one old strand and one new strand.

RNase H

An enzyme that removes RNA primers during DNA replication, which are replaced with DNA.

DNA Ligase

An enzyme that joins Okazaki fragments together on the lagging strand during DNA replication.