Lesson 3.1: Cell Cycle and Cell Divisions - Vocabulary Flashcards

Vocabulary flashcards covering key terms and definitions from Lesson 3.1: Cell Cycle and Cell Divisions.

Cell Cycle

The series of events by which a cell grows, replicates its DNA, and divides to form two daughter cells.

Interphase

Cell cycle phase during which the cell grows, carries out normal functions, and duplicates DNA; includes G1, S, and G2.

G1 phase

First subphase of interphase; cell growth, production of proteins/energy, doubling of organelles, and movement of centrioles toward centrosomes.

S phase

DNA replication; synthesis of a copy of the DNA, resulting in identical sister chromatids (semi-conservative replication).

G2 phase

Second subphase of interphase; continued growth and preparation for division; protein synthesis continues.

M phase

Mitosis or meiosis; division of the nucleus (followed by cytokinesis in most cases).

Cytokinesis

Division of the cytoplasm; cleavage furrow forms in animal cells, cell plate forms in plant cells.

Mitosis

Nuclear division in somatic (non-sex) cells producing two genetically identical daughter nuclei.

Meiosis

Nuclear division in sex cells (gametes) that reduces chromosome number to produce haploid cells.

Cleavage furrow

Indentation that forms during cytokinesis in animal cells to split the cell membrane.

Cell plate

Structure formed during cytokinesis in plant cells that develops into a separating cell wall.

DNA

Deoxyribonucleic acid; genetic material of living cells; stores information in nucleotide sequences.

Nucleotide

Building block of DNA (and RNA); includes a sugar, a phosphate group, and a nitrogenous base.

Histone

Positively charged proteins that help package DNA into chromatin.

Histone octamer

Eight histone proteins around which DNA winds to form nucleosomes.

Chromatin

DNA wrapped around histones; dispersed in the nucleus during interphase.

Chromosome

Highly condensed form of chromatin; visible structure of DNA during cell division.

Chromatid

One of the two identical halves of a replicated chromosome; sister chromatids separate during anaphase.

Centrioles

Organelles that organize the spindle apparatus and move toward the poles during cell division.

Mitotic spindle

Microtubule-based structure that separates chromosomes during mitosis/meiosis.

Autosomes

Human chromosome pairs that are not sex chromosomes (22 pairs in total).

Sex chromosomes

Chromosomes that determine sex (X and Y); humans have XX (female) or XY (male).

Blastula

Early multicellular embryonic stage formed after initial cell divisions.

DNA replication

Process of copying DNA to produce two identical molecules; semi-conservative mechanism.

DNA polymerase

Enzyme that adds complementary nucleotides to synthesize new DNA strands during replication.

Semi-conservative replication

Each new DNA molecule contains one original strand and one new strand.

Checkpoint

Control point in the cell cycle (G1-to-S, G2-to-M, M) that verifies conditions before progression.

G1-to-S checkpoint

Assesses cell size/energy, DNA integrity, and readiness for DNA replication.

G2-to-M checkpoint

Assesses DNA replication completion, environmental conditions, and DNA integrity before mitosis/meiosis.

M checkpoint

Ensures proper spindle attachment and alignment before chromosome separation.