Cell Signaling, Cell Cycle, and Meiosis

Flashcards about Cell Signaling, Cell Cycle and Meiosis

How is cell division is related to information flow?

Cells respond to signals that tell them when to divide.

What is the mitotic index?

The rate of cell division.

How does the mitotic index change in the skin?

Low during normal conditions, higher during wound healing, and very high and uncontrolled in cancer.

What does PDGF stand for?

Platelet-derived growth factor.

What is PDGF?

A protein that acts like a message sent from one cell to another.

What happens when PDGF binds to its receptor?

It activates the receptor’s enzyme activity, specifically a type called a kinase.

What is phosphorylation?

Adding phosphate groups to other proteins, which turns those proteins on or off like a light switch.

What is signal transduction?

A chain of reactions inside the cell.

Name three different types of receptors.

Receptor Kinases, G-Protein Coupled Receptors, and Ion Channel Receptors.

What are the two important roles of platelets when you get a cut?

They form clots to stop bleeding, and they release PDGF (platelet-derived growth factor).

What do platelets carry?

They carry vesicles full of PDGF.

What are the two parts of a PDGF receptor?

Outside part binds PDGF, and the inside part activates a kinase enzyme.

What does the PDGF receptor signaling do to the cell cycle?

It pushes skin cells past the G1-to-S checkpoint in the cell cycle, making them divide faster.

What mutation causes skin cancer?

A translocation between chromosome 17 and chromosome 22, which swaps part of the PDGF gene with part of a collagen gene.

Why is swapping part of the PDGF gene with part of a collagen gene dangerous?

The collagen gene’s promoter tells cells to make the gene in the skin.

What is the positive feedback loop that leads to uncontrolled cell growth?

PDGF made → binds a receptor on the same cell → tells the cell to divide → more PDGF made.

What is the cell cycle?

The series of steps cells undergo to grow and divide.

What are the key events for each phase of mitosis?

Chromosome condensation (prophase), alignment (metaphase), separation (anaphase), nucleus reformation (telophase), and cell division (cytokinesis).

What is a genome?

All DNA for a species.

What does diploid (2n) mean?

Cells in G1 with two genome copies.

What does haploid (1n) mean?

Sperm and egg cells with one genome copy.

What does tetraploid (4n) mean?

Cells in G2 after DNA replication, with four copies of each chromosome.

What are sister chromatids?

Identical DNA copies after replication in S phase.

What are homologous chromosomes?

Non-identical chromosome pairs with the same genes but potentially different versions.

What happens in Meiosis I?

Homologous chromosomes separate, reducing from 4n to 2n; sister chromatids stay together.

What happens in Meiosis II?

Sister chromatids separate, reducing from 2n to 1n, producing four haploid cells.

What are the three key facts about Meiosis?

No S phase between Meiosis I and II, homologous chromosomes separate, and recombination (crossing over) occurs.