CH 9 Mitosis and Cytokinesis Flashcards
Why do cells divide?
Reproduction
Development
Repair
What is mitosis?
Division of chromosomes (Nuclear material)
what is cytokinesis?
Physical splitting of single cells into 2
-Division of cytoplasm
What does the Eukaryotic cell cycle consist of?
G1 S phase G2 Mitosis Cytokinesis
What happens in the G1 step of the cell cycle? (1st step) (Gap 1)
Cell is growing/Normal functions
Gap 1 no physical difference
What happens in S Phase? (2nd step)
DNA polymerase copies DNA
What happens in the G2 step of the cell cycle? (3rd step) (Gap 2)
DNA replication is done and is carrying out functions to prepare for mitosis
What happens in Mitosis (4th step of the cell cycle)?
2 copies of DNA move to opposite sides of cell
What happens in cytokinesis (5th step)?
Cell physically splits into 2 then are back in G1 phase
What are the 4 bases of DNA
Adenine
Thymine
Cytosine
Guanine
If you take all DNA in one cell and extend it, how long would it be?
6 Ft
When is a chromosome in the “X” structure?
During mitosis (4th step)
Why is it necessary to supercoil DNA?
Easier to move around during mitosis
DNA would get snagged and break
Daughter cells wouldn’t have all DNA
What does chromatin consist of?
DNA and Histone protein
Where is a centromere located?
(Structural) In the center; It is the part of a chromosome that links sister chromatids
-Where chromatids are pinched together
What is the difference between chromatin and chromosomes?
Chromatin is unwound DNA that looks like a bowl of spaghetti; Chromosomes are tightly wound DNA in an “X” shape
What is a chromatid?
Half of the chromosome
1 of the 2 sides
What is a kinetochore?
(Protein) associated with the centromere of a chromosome during cell division
What is a telomere?
(Structural) Repetitive nucleotide sequences at each end of a chromosome –Protects the end of the chromosome from deterioration
At the end of G2 what does chromatin do?
Condenses into chromosomes
What is a nucleosome?
DNA coiled around a core of histones.
What are homologous chromosomes?
Set or pair of chromosomes
Same chromosome but different pair
What does diploid mean?
2 copies of every chromosome
*How do you determine diploid number?
Count number of centromeres
What are the phases of mitosis?
Prophase
Metaphase
Anaphase
Telophase
1st step of Mitosis is? What happens?
Prophase:
- Early phase: Where duplicated chromosomes condense (visually condensed)
- Nucleus starts to deteriorate
- Late phase: New microtubules assembled; centrioles move to opposite ends
2nd step of Mitosis is? What happens?
Metaphase: Middle
- Spindle forms and microtubules attach to chromatids
- Chromosomes line up at spindle midline
3rd step of Mitosis?
Anaphase: Apart
- Sister chromatids pulled apart
- Once chromatids are separated they are called chromosomes
4th step of Mitosis?
Telophase: Two
- Cell separates
- Chromosomes de-condense (Chromosomes back to chromatin)
- Nuclear membranes form
- Cell is pinched to prepare for division
How do animal and plant cells differ in cytokinesis?
Plants form a cell plate; Animal cells DO NOT
Do bacteria and archaea perform mitosis?
No; They participate in prokaryotic fusion
What does the ring of microfilaments (in animal cells) do to aid cell division?
From the spindle equator the microfilaments contract and pinch the cells center to split the cell into 2
What is G0?
Resting phase of certain cells (i.e) cardiac cells
-Really long 10+ yr G1 Phase
Do all Eukaryotic cells perform the cell cycle at the same rate?
No; Skin cells can take 12 hours where cardiac cells cant take 10 yrs
What is Interphase?
G1 and G2 different from Mitosis
When is DNA in the chromatin phase
G1, S and most of G2
In what phase is DNA copied?
S phase
When does chromatin condense into chromosomes?
End of G2
What is a cell considered when individual chromosomes are visible?
Prophase
What is a nucleosome?
DNA wrapped around a histone in a chain that makes of chromatin
What are centrosomes/Centrioles?
Look like little cans that form spindles (Protein)
