chp 24 Flashcards
(15 cards)
What are the primary functions of cell division in unicellular and multicellular organisms?
In unicellular organisms, cell division is for reproduction. In multicellular organisms, it enables growth, tissue repair, and development.
What are the phases of interphase in the eukaryotic cell cycle?
Interphase consists of G1 (cell growth), S (DNA replication), and G2 (final preparations for division).
What occurs during the G1 phase of interphase?
The cell grows, performs normal functions, and prepares for DNA replication. Some cells may enter G0, a non-dividing state.
What happens during the S phase of interphase?
DNA is replicated, resulting in two identical sister chromatids for each chromosome. Centrosomes are also duplicated.
What occurs during the G2 phase of interphase?
The cell continues to grow, makes final preparations for division, and checks for DNA damage.
How do sister chromatids differ from homologous chromosomes?
Sister chromatids are identical copies of a chromosome joined at the centromere, formed after DNA replication. Homologous chromosomes are a pair of similar but not identical chromosomes (one from each parent).
What are the stages of mitosis and a key event in each?
Prophase: Chromosomes condense, spindle fibers begin to form.
Prometaphase: Nuclear envelope breaks down, spindle fibers attach to kinetochores.
Metaphase: Chromosomes align at the cell’s equator.
Anaphase: Sister chromatids separate and move to opposite poles.
Telophase: Chromosomes decondense, nuclear envelopes reform.
What roles do kinetochores and microtubules play during metaphase and anaphase?
Kinetochores attach chromosomes to spindle microtubules, which align chromosomes at the metaphase plate and then pull sister chromatids apart during anaphase.
How does cytokinesis differ in animal and plant cells?
Animal cells use a contractile ring (cleavage furrow) to divide, while plant cells form a cell plate that develops into a new cell wall.
What are the major cell cycle checkpoints and what do they monitor?
G1/S (Restriction Point): Checks cell size, nutrients, DNA damage.
G2/M: Checks DNA replication completeness and damage.
M (Spindle): Ensures all chromosomes are properly attached to spindle fibers before separation.
What influences cell cycle checkpoints?
Internal factors (DNA integrity, cell size) and external signals (growth factors).
What can result from failure at cell cycle checkpoints?
Unregulated cell division, which may lead to cancer.
What happens to a cell that fails the G1 checkpoint?
The cell may enter G0 (a non-dividing state) or undergo apoptosis (programmed cell death).
What is metastasis and how does cancer spread through the body?
Metastasis is the process by which cancer cells spread from the original tumor to other parts of the body via the bloodstream or lymphatic system.
How do chemotherapy and radiation therapy affect healthy versus cancerous cells?
Both treatments target rapidly dividing cells, damaging DNA or cell structures. Cancer cells are more affected, but healthy dividing cells can also be harmed, causing side effects.
