Cell Cycle: Interphase & Mitosis

Vocabulary flashcards covering key terms and concepts related to the cell cycle, interphase, and mitosis, designed to aid in reviewing cell biology lecture notes.

Cell Cycle

Series of phases and steps a cell goes through to replicate itself, turning one cell into two; also important to control cell growth.

Cell Cycle Regulation

Controlled by proto-oncogenes, tumor suppressor genes, and DNA repair enzymes.

Cell

The basic unit of all living things.

Eukaryotic Cells

Classified by the cell membrane, nucleus, and cytoplasm.

Interphase

Consists of the G1 phase, G1/S checkpoint, S phase, and G2 phase, preparing the cell for division.

G1 Phase (GAP 1)

The first phase in the cell cycle where the cell prepares for replication, making more organelles and synthesizing proteins/enzymes.

Diploid (2n)

Cells containing a total of two sets of chromosomes; in humans, this means 46 chromosomes (23 paternal + 23 maternal).

Thymine Dimer

DNA damage caused by exposure to ultraviolet light, considered a bulky and destabilizing lesion.

Labile/Proliferative Cells

Cells that are constantly going through the cell cycle, such as epithelial cells of the skin and hematopoietic stem cells.

Stable Cells

Cells that do NOT go through constant replication, only replicating when there is a strong stimulus (e.g., hepatocytes).

Permanent Cells (Amitotic Cells)

Cells that do not undergo replication, such as neurons, skeletal muscles, and cardiac muscles.

S Phase (Synthetic Phase)

The phase in interphase where DNA replication occurs, changing the chromosome count from 2n to 4n (46 to 92 in humans).

Semi-conservative Replication Model

During DNA replication, the two original DNA strands separate, each serving as a template for a new strand, resulting in a new double helix made of one original and one new strand.

DNA Polymerase I and III

Enzymes responsible for quickly and faithfully replicating DNA.

G1/S Checkpoint

A control point that ensures the cell has enough proteins and organelles and no DNA damage before entering the S phase.

G2 Phase

The phase where the cell (now with 92 chromosomes) continues to grow by increasing its cytoplasm and other components, preparing for mitosis.

Mitosis (M Phase)

The process of cell division that results in two identical daughter cells, consisting of prophase, metaphase, anaphase, and telophase (PMAT).

Prophase

The first phase of mitosis where chromatin condenses, the nuclear envelope dissolves, and the microtubule organization center (MTOC) forms.

Chromatin

The complex of DNA and histone proteins found in the nucleus of eukaryotic cells.

Microtubule Organization Center (MTOC)

Structures from which microtubules emerge, with centrioles serving as markers for their formation.

Metaphase

The phase in mitosis where chromosomes are perfectly lined up in the middle of the cell at the metaphase plate, preparing for separation.

Centromere

The constricted region of a chromosome that determines the chromosome number and to which the kinetochore attaches.

Sister Chromatids

The two identical copies of a chromosome produced by DNA replication, joined together by cohesin.

Kinetochore

A 'hook'-like structure on the centromere of a chromosome where polar microtubules connect.

Anaphase

The phase in mitosis where sister chromatids separate and are transported to opposite poles of the cell by motor proteins.

Cohesin

A protein complex that 'glues' sister chromatids together.

Motor Proteins (Dynein & Kinesin)

Proteins that 'walk' the chromatids along the microtubules during anaphase, with dynein typically moving towards the minus end and kinesin towards the plus end.

Telophase

The final phase of mitosis where the cleavage furrow forms, the nuclear envelope reforms, and chromatin and organelles are evenly distributed into two nascent cells.

Cleavage Furrow

A constriction ring formed by actin and myosin contractile proteins that pinches the cell into two.

Cytokinesis

The equal separation of cytoplasm that occurs during telophase, completing cell division.

G0 Phase (Quiescent Phase)

A dormant state where cells remain when they are not actively dividing; stable cells enter this phase, while permanent cells stay here indefinitely.

Telomeres

Protective caps found at the ends of chromosomes; their shortening due to aging contributes to cell senescence.

Cell Senescence

A state where cells are irreversibly out of the cell cycle, often due to aging and telomere shortening.

G2/M Checkpoint

A control point that ensures there are no mistakes in DNA replication before the cell enters mitosis, often involving ATM genes.

M Checkpoint

A control point positioned after metaphase and before anaphase, which ensures that chromosomes are aligned perfectly at the metaphase plate via proteins like APC and securins.