Cell Cycle Overview

Study Notes

Cell Cycle

The cell cycle describes how eukaryotic cells divide.
Eukaryotes have a nucleus containing multiple linear chromosomes, while prokaryotes have a single looped chromosome outside of a nucleus.
Humans have 46 chromosomes in most cells, with half coming from each parent.
The cell cycle is divided into two main phases: interphase and mitosis.

Interphase

Interphase is the longest phase of the cell cycle, when the cell grows and prepares for division.
Interphase consists of three subphases: G1, S, and G2.
G1 (Gap 1) is the initial growth phase where organelles are produced.
S (Synthesis) is the phase where DNA replicates, doubling the number of chromosomes.
G2 (Gap 2) is the phase where errors in the newly synthesized DNA are repaired.

Mitosis

Mitosis is the division of the nucleus, ensuring each daughter cell receives a complete set of chromosomes.
Mitosis begins with a diploid (2N) number of chromosomes and ends with two identical diploid cells.
Mitosis is not the entire cell cycle, it's just a part of it.
Mitosis involves four main phases: prophase, metaphase, anaphase, and telophase.
Prophase: Chromosomes condense and move towards the center of the cell.
Metaphase: The chromosomes align randomly along the middle of the cell, and spindle fibers form.
Anaphase: Spindle fibers attach to the centromere of the chromosomes, pulling them apart to opposite sides of the cell.
Telophase: The cell begins to pinch in, the nucleus reforms, and in plant cells, a cell plate forms to separate the daughter cells.

Terms & Definitions

Cytokinesis: The division of the cytoplasm following nuclear division.
Homologous Chromosomes: Identical chromosomes, one from each parent, with the same size and genes.
Centromere: The central part of a chromosome where sister chromatids are joined.
Sister Chromatids: The original chromosome and its copy made during the S phase of interphase.

Meiosis

Meiosis is a type of cell division that produces four haploid (N) daughter cells from a diploid (2N) parent cell.
It involves two rounds of division, resulting in gametes (sex cells).
Prophase I is unique to meiosis and involves crossing over, which creates genetic diversity.
The random alignment of chromosomes during meiosis also contributes to genetic diversity.

Stem Cells

Stem cells are undifferentiated cells that can develop into various cell types.
Embryonic stem cells are more responsive to programming than adult stem cells.
Stem cell research is controversial because some people believe it involves aborted fetal tissue, however, this is not true.

Cancer

Uncontrolled cell division can lead to cancer.
Tumors are abnormal growths of cells.
Malignant tumors are cancerous and can metastasize (spread to other tissues).
Benign tumors are not cancerous and do not spread.

Description

This quiz covers the structure and phases of the cell cycle in eukaryotic cells. It discusses interphase, its subphases, and the process of mitosis. Test your understanding of how cells grow, replicate DNA, and divide to maintain genetic continuity.