Unit 2 Section 3: Chromosomes, cell cycle & Mitosis

Vocabulary flashcards reviewing chromosome structure, cell cycle phases (G1, S, G2, M), the stages of mitosis, and DNA strand composition.

Unreplicated chromosome

A chromosome before S phase that consists of 1 chromosome, 1 DNA molecule, and 2 DNA strands.

Replicated chromosome

A chromosome after S phase that consists of 1 chromosome, 2 sister chromatids attached at a centromere, 2 DNA molecules, and 4 DNA strands.

Centromere

The structure where two sister chromatids remain attached to form a replicated chromosome.

G1 phase

The cell growth stage of the cell cycle where the cell grows, organelles, ribosomes, and proteins are duplicated, and DNA remains unreplicated.

S phase

The stage of the cell cycle where DNA replication occurs, forming 2 sister chromatids per chromosome and doubling the DNA amount while keeping chromosome count the same.

G2 phase

The cell cycle phase of preparation for mitosis where proteins necessary for mitosis (such as centrosomes) are prepared, DNA is checked for errors at a checkpoint, and chromosomes remain replicated.

M phase

The phase of the cell cycle that includes mitosis and cytokinesis, during which replicated chromosomes are separated into 2 nuclei.

Prophase

The first stage of mitosis during which chromosomes condense, the nuclear membrane disappears, and spindle fibers appear.

Metaphase

The stage of mitosis where chromosomes align in the middle of the cell and spindle fibers attach to the centromeres.

Anaphase

The stage of mitosis where spindle fibers pull sister chromatids apart at the centromere toward opposite poles, doubling the chromosome number in the single cell once separated.

Telophase

The stage of mitosis where new nuclei form, giving each nucleus the original number of chromosomes.

Cytokinesis

The process following mitosis where the cell membrane pinches in to produce 2 new cells, each with its own DNA and organelles.

Mitosis Stage Order

The sequential order of stages during cell division: Prophase, Metaphase, Anaphase, Telophase, followed by Cytokinesis.

Sister Chromatid DNA Strand Composition

After DNA replication, each sister chromatid contains 1 original (old) strand and 1 new strand of DNA.

Centrosome

An organelle prepared during the G2 phase that helps organize spindle fibers during mitosis.

Spindle Fibers

Protein structures that appear in prophase, attach to centromeres during metaphase, and pull sister chromatids apart during anaphase.