2. Cell Cycle and Mitosis/Meiosis

Flashcards covering key terms and definitions related to the cell cycle, mitosis, and meiosis.

Cell Cycle

The sequence of events between one cell division and the next in eukaryotic cells.

Mitosis

A division process that results in two daughter cells that are completely identical to the mother cell.

Meiosis

A reduction division process that ultimately results in four daughter cells with half the genetic material of the original cell.

Interphase

The phase of the cell cycle where the cell prepares for division; includes G1, S, and G2 phases.

G1 Phase

Cell growth and organelle duplication characterise in this phase in the cell cycle. The Golgi apparatus and ER organelles break into small pieces, which are then subsequently scattered between daughter cells. Mitochondria replicate once each cycle

S Phase

The synthesis phase in the cell cycle where DNA is replicated.

G2 Phase

The second gap phase in the cell cycle where the cell prepares for mitosis.

Chromosome compression

• The purpose is to allow for thier equal distrubution between daughter cells compression occurs during the mitosis phase

• The chromosomes can only be seen after they have been unfolded and are in the middle right before cell devision

• During interphase, gene activity is necessary, therefore they are refolded in the new daughter cells.

Karyotype

A visual representation of an individual's set of chromosomes, organized by size, shape, and number.

Prophase

The first stage is where chromosomes condense and the nuclear membrane begins to disintegrate.

Anaphase

The stage where sister chromatids are pulled apart to opposite poles of the cell.

Telophase

The final stage of mitosis where the nuclear membrane re-forms around each set of chromosomes.

Cytokinesis

The process where the cytoplasm divides, resulting in two daughter cells.

Homologous Chromosomes

Chromosomes that have the same sequence of genes and the same structure.

Kinetochore

A protein complex assembled on the centromere that connects chromosomes to the spindle fibers.

Crossing Over

A process during prophase I of meiosis where homologous chromosomes exchange genetic material.

Independent Assortment

The random distribution of maternal and paternal chromosomes during meiosis.

Prophase I

The first meiosis phase involves several key processes: homologous chromosomes pair up in synapsis, forming tetrads. This phase also involves crossing over, where segments of genetic material are exchanged between homologous chromosomes, increasing genetic diversity.

Metaphase I

2nd meiosis phase. The tetrads line up along the cell's equatorial plane. Spindle fibres attach to the centromeres of each homologous pair.

Anaphase I

Third meiosis phase. The spindle fibres shorten, pulling the homologous chromosomes apart towards the cell's opposite poles. Unlike mitosis, the sister chromatids remain attached at this stage.

Telephase I

The fourth stage of meiosis where the cytoplasm divides, forming two daughter cells.

Meiosis I outcome

Two haploid cells, each containing half the original number of chromosomes but with duplicated DNA. Each chromosome still consists of two sister chromatids.

Meiosis II

Separates the sister chromatids of each chromosome. Does not involve another round of DNA replication.

Prophase II

Fifth meiosis phase. The chromosomes, each still consisting of two sister chromatids, condense again. If the nuclear envelope has formed, it breaks down, and the spindle apparatus begins forming in the two haploid cells.

Metaphase II

Sixth meiosis phase. The sister chromatids align at the equatorial plane of each haploid cell. Spindle fibres attach to the centromeres of the sister chromatids.

Anaphase II

Seventh meiosis phase. The spindle fibres shorten, and the sister chromatids are pulled apart toward opposite poles of the cell, separating them into individual chromosomes.

Telephase II

Final stage of Meiosis. The cytoplasm divides resulting in the formation of four haploid daughter cells, each with half the number of chromosomes as the original cell.

What is the final outcome of meiosis?

The final outcome of meiosis is four genetically unique haploid cells, each with a complete set of chromosomes but half the original number. This process is crucial for sexual reproduction and contributes to genetic variation.

Meiosis Vs. Mitosis

Mitosis:

• Daughter cells genotypes identical to parental genotypes

Meiosis:

• Promotes variation among the product of meosis (crossing over and reassortment)

• Allows for the change in creation of the products o