Mitosis
What is the first visible phase of mitosis when chromosomes begin to condense?
Prophase
What separates during Meiosis 1
Homologous chromosomes
What separates in metaphase II?
Sister chromatids
What phase are most non-dividing cells in?
G0 phase
What is checked at the G1 checkpoint?
For the correct growing environment
How many divisions occur in mitosis? In meiosis?
One in mitosis; two in meiosis
What is ploidy (n)?
The number of sets of chromosomes in a cell.
During which phase do chromosomes line up along the center of the cell?
Metaphase
What process occurs during Prophase 1 that increases genetic diversity?
Crossing over
How many cells result from Meiosis II?
Four haploid daughter cells
What is the main cause of cancer at the cell cycle level?
Loss of cell cycle control (ignoring checkpoints)
What happens if a cell fails the G1 checkpoint?
How many daughter cells are produced in mitosis vs. meiosis?
Meiosis: four
What is binary fission?
Reproduction in prokaryotes where one cell splits into two identical cells.
During which phase are sister chromatids pulled apart to opposite poles of the cell?
Anaphase
What happens during Metaphase 1 that increases genetic variation?
Independent assortment - homologous pairs line up randomly at the metaphase plate.
Are the cells identical or different after meiosis II?
Genetically different
What happens when cancer cells lose adhesion?
They can break away and spread (metastasis)
What does the S checkpoint prevent?
Cells with damaged DNA from replicating further.
Whaat kind of cells does mitosis and meiosis produce?
Mitosis: identical somatic cells (2n)
Meiosis: unique gametes (n)
What are histones and what do they do?
Proteins that DNA wraps around to form chromatin; they help condense and organize DNA.
What are the three stages of interphase, and what happens in each?
G1: Cell grows and carries out normal functions
S: DNA is replicated
G2: Organelles and proteins are prepared for mitosis
After Meiosis 1, how many cells are produced, and are they haploid or diploid?
Two haploid cells (each with duplicated chromosomes)
Why are the cells genetically different after meiosis II?
Because of crossing over and independent assortment in Meiosis I.
What is the name of the immortal human cancer cell line?
HeLa cells
What is checked at the G2 checkpoint?
Proper DNA replication and cell growth.
How many times is DNA replicated in mitosis and meiosis?
Once - during the S phase before division begins
What does tetraploid (4n) mean?
A cell or organism with four complete sets of chromosomes
Why is DNA replication not part of mitosis itself?
Because replication occurs during the S phase of interphase before mitosis begins. Mitosis only divides the already replicated DNA.
What is the main purpose of Meiosis 1?
To separate homologous chromosomes and reduce the chromosome number from diploid to halploid.
If no crossing over occurred in Meiosis I, what would be true about the daughter cells after Meiosis II?
They would still be haploid but genetically identical to each other, since no genetic variation was introduced.
What changes allow a tumor to become metastatic?
Loss of anchorage dependence, loss of density inhibition, and secretion of signals for blood vessel growth (angiogenesis).
What does the M checkpoint ensure?
If a diploid cell with 46 chromosomes undergoes mitosis and meiosis, how many chromosomes will each daughter cell have in each process?
Mitosis: 46 chromosomes (diploid, identical to parent)
Meiosis: 23 chromosomes (haploid, half the original number)
What are gametes, and how do they differ from somatic cells in chromosome number?