Chapter 3 Flashcards
What are the types of cell division?
2 types, mitosis and meiosis
Mitosis :
It produces :
The growth and repair of body cells
-2 genetically identical daughter cells w/ the same chromosome number as the parent cell
(mitosis) Each daughter cell is
Diploid (2n), just like its parent cell
Meiosis
Each resulting cell:
- Occurs on in sexually reproducing organisms
- it produces gametes (sperm and ova) w/ ½ the chromosome number of the parent cell
- Is haploid (n)
Chromosome consists of
A highly coiled and condensed strand of DNA
A replicated chromosome consists of
2 sister chromatids, where 1 is an exact copy of the other
Centromere
A specialized region that holds the 2 sister chromatids together
Spindle fibers connect the
Centromere to the centrosome during cell division
Each chromosome contains
2 identical chromatids connected at a centromere
Cell cycle
When living and dividing cells pass through a regular sequence of growth and division
Stem cells (from human embryos)
- Retain the ability to divide indefinitely
2. to differentiate into any cell type
Cell cycle is strictly regulated by many
Proteins including some called cyclins
Some proteins are internal regulators making sure
That the cell does not undergo mitosis until certain conditions are met
Other proteins such as growth factors are
External regulators of the cell cyle: speeding up, slowing it down, or even stopping it
Cell cycle consists of
To move from one phase to the next
5 stages: G1 , S, G2, mitosis, cytokinesis
The cell must pass through 3 checkpoints
G1
Newly divided cell enters this phase right after completing mitosis
During G1, the cell
- Increases in size
2. prepares to replicate it’s DNA
G-1 checkpoint
If the cell is: - healthy - contains adequate resources - DNA is undamaged, growth factors stimulate the cell to proceed to DNA synthesis of S phase
If the cell doesn’t pass G1-checkpoint, the cell
Dies or enters a resting state, G0 phase
S-phase
DNA is synthesized through the process of replication
S-checkpoint
DNA synthesis is monitored for any replication errors
S-phase checkpoint: If the synthesis progresses without errors
Growth signals will stimulate the cell to proceed to G2