Ch 3; Phases of the Cell Cycle

Cell Cycle

The series of events that take place in a cell leading to its division and duplication.

Interphase

The phase of the cell cycle where the cell prepares for division, consisting of G1, S, and G2 subphases.

M phase

The phase of the cell cycle characterized by cell division, which includes mitosis and cytokinesis.

G1 phase

The first subphase of interphase where the cell grows and synthesizes proteins necessary for DNA replication.

S phase

The subphase of interphase where DNA synthesis occurs, resulting in the duplication of the genetic material.

G2 phase

The second subphase of interphase where the cell continues to grow and prepares for mitosis.

DNA Synthesis Steps

1. The DNA strands are separated by the enzyme helicase. 2. The enzyme primase builds an RNA primer on the exposed DNA strands. 3. The enzyme DNA polymerase adds nucleotides to the RNA primer. 4. DNA polymerase proceeds in opposite directions along each strand as helicase separates them. 5. The end result is two identical double helices.

Mitosis

The process during M phase where newly replicated genetic material is divided between two daughter cells.

Cytokinesis

The process during M phase where the cell's proteins, organelles, and cytosol are divided between the two daughter cells.

Prophase

The first stage of mitosis where chromatin is compacted into chromosomes, each with two sister chromatids joined at the centromere.

Metaphase

The second and longest stage of mitosis where spindle fibers pull sister chromatids into a line along the equator of the cell.

Anaphase

The third stage of mitosis where sister chromatids are pulled apart toward opposite poles, becoming daughter chromosomes.

Telophase

The fourth and final stage of mitosis where the nuclear envelope is reassembled, nucleoli reappear, and chromosomes return to chromatin.

Daughter Chromosomes

The individual chromosomes that result from the separation of sister chromatids during anaphase.

Centromere

The region of a chromosome where the two sister chromatids are joined.

Spindle Fibers

Structures that pull sister chromatids apart during mitosis.

Chromatin

The material that makes up chromosomes, consisting of DNA and proteins.

Nuclear Envelope

The double membrane that surrounds the nucleus in a cell.

Nucleoli

The small, dense structures in the nucleus where ribosomal RNA is produced.

46 Chromosomes

The total number of chromosomes in a human somatic cell, consisting of 23 pairs.

23 Pairs

The number of chromosome pairs in a human cell, resulting from one chromosome from each parent.

prophase, metaphase, anaphase, and telophase

Mitosis in order