Cell Division Flashcards
Define the cell cycle:
What a cell is doing in it’s lifetime.
*consists of 2 stages which alternate with each other
- Interphase:
- Normal metabolic functions of cell : Metabolism
- (skin –> sweating, shivering etc)
- Cell division:
- MITOSIS (most cells)
- MEIOSIS (ovary & testes cell)
Cell structure : Interphase
- chromosomes not visible as separate (entangled : CHROMATIN network (DNA)
- Chromatin Network: UNREPLICATED chromosomes
- Each UNREPLICATED chromosome =
(carries) 1 set DNA
End of Interphase:
DNA replication occurs
(process where DNA of chromosome makes an exact copy of itself to form:
2 identical DNA molecules
End of DNA replication:
- Replicated chromosome is formed.
(carries 2 sets DNA) - 1 set DNA per Chromatid
- two chromatids joined by: CENTROMERE
Why is DNA replication a significant process?
Ensures that each new daughter cell formed will receive the correct amount of DNA at the end of mitosis
1.2 Cell Division (structure)
Mitosis / Meiosis (NEVER BOTH)
why do somatic cells divide by Mitosis?
To form identical daughter cells in body for:
- Growth
- Repair & Replacement
- Reproduction (asexual & vegetative)
why do somatic cells divide by meiosis?
To form GAMETES (sex cells) for sexual reproduction
Define: Chromosome
The DNA- containing structure that is made up of genes
(found in cells during cell division)
Gene:
segment of DNA
Define:
Centrosome
Structure that is responsible for the formation of spindle fibres during cell division in animal cells
(made up of 2 centrioles)
Define:
Centromere
Structure that holds two Chromatids together in a replicated chromosome and which also attaches the chromosome to the spindle fibres during cell division.
Define:
Centriole
Two structures arranged at right angles to each other and together make up the centrosome.
Define:
Chromatin Network
The DNA-containing network found in cells in interphase (non-dividing)
Define:
Chromatid
A replicated chromosome is made up of two chromatids held together by a centromere
Cell division occurs in 2 parts:
- KARYOKINESIS
Division of Nucleus
(making new nucleus for each
daughter cell) - CYTOKINESIS
Division of cytoplasm (cytosol &
organelles)
Sharing btw daughter cells.
similarities :
PROCESS: mitosis / meiosis
SOMATIC Cell = Mother cell
Mother Cell is DIPLOID:
full set chromosomes in pairs
Diploid = 2n
Mitosis (properties) / stats
- 2 daughter cells formed
- Both: identical to mother cell
- Diploids
- Same chromosome no. (as mother)