BIOL 1951 W6-Mitosis, Meiosis, and the Cell Cycle

Chromatin

The complex of DNA and proteins that makes up eukaryotic chromosomes.

Nucleosome

A structural unit of eukaryotic chromosomes composed of an octamer of histones (eight histone proteins) wrapped with DNA.

Histones

A group of proteins involved in the formation of nucleosomes, which aid in the compaction of eukaryotic DNA.

somatic cells

The type of cell that constitutes all cells of an animal or plant body except those that give rise to gametes.

germline cells

Cells that give rise to gametes, such as egg and sperm cells.

sister chromatids

The two duplicated chromatids that are still joined to each other after eukaryotic DNA replication.

homologous chromosomes

Pair of chromosomes that are the same size, same appearance and same genes.

Centromere

The region where the two sister chromatids are tightly associated; the centromere is an attachment site for kinetochore proteins.

Mitosis

In eukaryotes, the process in which nuclear division results in two nuclei, each of which receives the same complement of chromosomes.

Meiosis

The process by which haploid cells are produced from a cell that was originally diploid.

Prophase

The phase of mitosis during which the chromosomes condense and the nuclear membrane begins to vesiculate (dissociate into small vesicles).

Metaphase

the phase of mitosis during which the chromosomes are aligned along the metaphase plate.

Telophase

The phase of mitosis during which the chromosomes decondense and the nuclear envelope re-forms.

Anaphase

The phase of mitosis during which the sister chromatids separate from each other and move to opposite poles; the poles themselves also move farther apart.

Interphase

The portion of the eukaryotic cell cycle consisting of the G1, S, and G2 phases, during which the chromosomes are decondensed and found in the nucleus.

Cyclin

A protein responsible for advancing a cell through the phases of the cell cycle by binding to a cyclin-dependent kinase.

checkpoint

One of three critical regulatory points found in the cell cycle of eukaryotic cells. At these checkpoints, a variety of proteins act as sensors to determine if a cell is in the proper condition to divide.

Carcinogen

An agent that increases the likelihood of developing cancer, usually a mutagen

Proto-oncogene

A normal gene that, if mutated, can become an oncogene

Oncogene

A type of mutant gene derived from a proto-oncogene. An oncogene is overactive, thus contributing to uncontrolled cell growth and promoting cancer.

tumor suppressor gene

A gene that when normal (that is, not mutant) codes a protein that prevents cancer; however, when a mutation eliminates its function, cancer may occur.

tumor

An abnormal overgrowth of cells

benign tumor

A precancerous mass of abnormal cells.

malignant tumor

A growth of cells that has progressed to the cancerous stage.

Metastasis

The process by which cancer cells spread from their original location to distant parts of the body.

Fission

The process of cell division in bacteria and archaea in which one cell divides into two cells. It is also the process by which mitochondria and chloroplasts divide.

Identify the main phases of the eukaryotic cell cycle and describe what happens in each phase.

Interphase (G1, S phase, and G2) and the Mitotic (M) phase (Mitosis(Prophase, Metaphase, Anaphase, and Telophase), and Cytokinesis)

Identify the main checkpoints of the eukaryotic cell cycle and predict what will happen to the cell at these checkpoints based on data.

The G1/S Checkpoint (Restriction Point): checks the Cell size, nutrient availability, growth factors, and DNA integrity

The G2/M Checkpoint: Checks Complete and accurate DNA replication (checking for unreplicated or damaged DNA) and overall cell growth

The Spindle Assembly Checkpoint (M Checkpoint / Metaphase Checkpoint): Checks the Proper attachment of every sister chromatid (kinetochore) to spindle microtubules at the metaphase plate and bipolar tension.

Compare and contrast the processes of mitosis and meiosis.

Mitosis: is a type of cell division in eukaryotic cells where a single cell divides to produce two genetically identical daughter cells

Meiosis: a specialized type of cell division that reduces the chromosome number by half, turning one diploid cell into four haploid gametes

Use the model of DNA replication to characterize the relationship between chromosomes and sister chromatids.

A chromosome before DNA replication consists of a single DNA molecule, and DNA replication during the S phase produces two identical DNA molecules called sister chromatids that remain joined together as a single duplicated chromosome

Explain the relationship between mutation and cancer.

Mutations are permanent alterations in a cell's DNA sequence. When these errors change the function of proteins that control the cell cycle, a cell can begin to multiply uncontrollably; causing cancer.

explain why cancer is a rare event

Cancer is a rare event at the cellular level because your body has multiple layers of strict defense mechanisms that require a rare "perfect storm" of mutations to fail.