Cell Division and Mitosis

Cells: All living things are composed of cells.
Replication: Cells must replicate via cell division.
Information Storage: Organisms must store and pass on information about their structure and function during replication.
Energy Usage: All living things acquire and utilize energy.
Evolution: Traits of living organisms evolve over time.

Binary Fission: Prokaryotic cells replicate through a process called binary fission, which consists of four key processes:
1. DNA Replication: The chromosome is duplicated, resulting in two complete copies of its DNA.
2. Chromosome Segregation: The two copies of chromosomes are separated to opposite ends of the cell.
3. Cytokinesis: The cell membrane pinches in the middle to separate the two cells.
4. Cell Separation: The pinched membrane combines itself, creating two separate cells.

Complexity: Eukaryotic cells are more complex than prokaryotic cells and their replication occurs in defined phases: the cell cycle.
Mitosis: The actual process of cell division is called mitosis.
Interphase: Periods between rounds of mitosis classified into three phases: G1, S, G2.

G1 Phase:
- Phase of growth; cells become larger and increase organelles and proteins.
- Cells perform specialized functions.
- Most of a cell's life is spent in G1.
S Phase:
- Chromosomes of the cell are copied to prepare for division.
- Eukaryotic chromosomes are more complex than prokaryotic ones.
G2 Phase:
- Cells prepare for mitosis, checking for DNA errors and producing necessary proteins and enzymes.

Prokaryotic Chromosomes:
- Typically possess one circular chromosome.
- Located in a nucleoid, not in a nucleus.
- Undergo supercoiling to fit within the cell.
Eukaryotic Chromosomes:
- Possess multiple linear chromosomes stored in a nucleus.
- Chromosomes are X-shaped, with two chromosomes attached at the centromere.
- DNA is wrapped around histones, forming nucleosomes which further coil into chromosomes.

Chromatin: Loosely packed form of DNA called chromatin is spread throughout the nucleus during interphase.
Condensation: During mitosis, chromatin condenses into distinct mitotic chromosomes.

Chromosome Count: Different species have varied chromosome counts; humans have 46 chromosomes in 23 pairs.
Homologous Chromosomes: Pairs consist of one chromosome from each parent; not always identical in the case of sex chromosomes.
Sister Chromatids: After replication in S phase, each homologous chromosome has two identical copies called sister chromatids, held together at the centromere by cohesins.

Prophase: Chromatin condenses into mitotic chromosomes; mitotic spindle forms.
Prometaphase: Nuclear envelope breaks down and spindle attaches to kinetochores on chromosomes.
Metaphase: Homologous chromosomes align in the cell's center.
Anaphase: Cohesins are destroyed; sister chromatids pulled to opposite ends.
Telophase: Nuclear envelope reforms; chromosomes decondense back to chromatin.
Cytokinesis: In animal cells, a protein ring pinches the cell; in plant cells, a cell plate forms to create two new cells.

Understand binary fission and its four stages.
Review interphase and the three phases with their respective functions.
Compare prokaryotic and eukaryotic chromosomes.
Know the structures: homologous chromosomes, sister chromatids, centromeres, cohesins, and kinetochores.
Memorize the stages of mitosis and their order, along with their functions.
Understand how cytokinesis differs between animal and plant cells.

Read Chapter 13, pages 278-280, focusing on:
- Definition of autosome, gene, allele.
- Concept of ploidy, haploid, and diploid.
- Understanding "haploid number" and the meaning of n, 2n, 3n in terms of ploidy.