Chapter 3 Cell Division, Meiosis, and Development Flashcards

Vocabulary practice flashcards covering chromatin structure, cell division, mitosis, meiosis, gametogenesis, and early embryonic development.

Chromatin Structure

The organized complex of DNA and proteins that packages the genome inside the eukaryotic nucleus.

Nucleotides

Nitrogenous bases (A, T, C, G) paired together that make the rungs of the DNA double helix.

DNA Packaging

Process in which DNA wraps around histone proteins to form a relaxed or unwound chromatin state.

Unduplicated Chromosome State

State before S phase consisting of $1$ single chromatid.

Duplicated Chromosome State

X-shaped structure consisting of $2$ identical sister chromatids attached at the centromere.

S-phase (Synthesis)

Stage of interphase during which DNA replication and cell growth occur.

Autosomes

The $22$ pairs of chromosomes in humans responsible for body functions.

Zygote

Fertilized egg containing one set of chromosomes inherited from the mother (egg; $23$) and one set from the father (sperm; $23$).

Mitosis

Cell division used for growth, tissue repair, and asexual reproduction, where $1$ diploid ($2n$) parent cell produces $2$ genetically identical diploid daughter cells ($2N \rightarrow 2N$).

Gametogenesis

The production of sex cells with half the chromosomal number in reproductive organs via meiosis.

Crossing Over

Physical mixing and exchange of genetic material between paired homologous chromosomes during Prophase I that results in genetic variation.

Prophase I

Stage of meiosis where homologous pairs line up next to each other and crossing over occurs.

Anaphase I

Stage of meiosis where homologous pairs separate and move toward opposite poles.

Anaphase II

Stage of meiosis II where sister chromatids separate at the centromeres.

Telophase

Stage where a cleavage furrow forms (cytokinesis), cells start to divide, and new nuclear envelopes form.

Oogenesis

The process of egg making.

Oogonia

Cells located in the ovaries that enter prophase I during fetal development.

Primary Oocytes

Oogonia entering prophase I during fetal development that stop at prophase I and resume maturing at puberty under LH influence.

Secondary Oocytes

Oocytes that stop in meiosis II at ovulation and only complete meiosis II if fertilized.

Corona Radita

Surrounding structure of the ovum composed of several layers of cuboidal cells.

Zona Pellucida

A clear layer of proteins below the corona radita that sperm must penetrate to fertilize the ovum.

Spermatogenesis

The process of sperm making, located in the seminiferous tubules.

Acrosome

Structure on sperm containing digestive enzymes released upon contact with corona radita cells to penetrate the zona pellucida.

Cleavage

A series of mitotic divisions following zygote formation where the number of cells increases while the overall size remains the same.

Morula

The $16$-cell stage of embryonic development.

Blastocyst

Structure formed when cells in the morula develop a fluid-filled cavity in the center within the uterine cavity, consisting of two regions: trophoblast and embryoblast.

Trophoblast

Outer ring of blastocyst cells that develops into the chorion and helps form the placenta.

Embryoblast

Cluster of tightly packed cells inside one portion of the trophoblast whose inner cell mass cells are pluripotent.

Pluripotent

Refers to inner cell mass cells that are able to differentiate into any cell type in the body.

Endometrium

Cells lining the inside of the uterus to form a layer with which the trophoblast makes direct contact.