The Cell Cycle Flashcards
1
Q
Why is mitosis important?
A
- Growth, replacement and repair of tissues in multicellular organisms.
- Also necessary for asexual reproduction, which is the production of genetically identical offspring from one parent in multicellular organisms.
2
Q
What is mitosis?
A
The prices of nuclear division by which two genetically identical daughter nuclei are produced and also genetically identical to parent cell.
3
Q
What happens in prophase in mitosis?
A
- Chromosomes condense and now visible when stained.
- The two centrosomes move towards opposite poles.
- Spindle fibres begin to emerge from the centrosomes.
- Nuclear envelope breaks down into small vesicles.
- Nucleolus disappears.
4
Q
metaphase in mitosis
A
- each centrosome reaches a pole
- centrosomes organise spindle fibres -chromosomes line up on equator attached by spindles to centromere
5
Q
Anaphase in mitosis.
A
-chromosomes split at centromere
- chromatids move to opposite poles centromere first
- chromatids are pulled apart.
6
Q
Telophase of mitosis.
A
- nucleolus reforms
- nuclear envelope reforms
- spindle breaks down
-chromatids decondense - cytokinesis (division of cytoplasm py constriction)
7
Q
Prophase 1 in meiosis.
A
- DNA condenses.
- nucleolus breaks down
- nuclear membrane breaks down
- centrioles move to poles
- Crossing over may occur at chiasmata, as sister chromatids are close to each other. This causes alleles to swap places, which causes genetic variation.
8
Q
How are chromosomes arranged in prophase 1 in meiosis and what is this called?
A
- Chromosomes are arranged side by side in homologous pairs.
- Pair of homologous chromosomes is called bivalent.
9
Q
What happens in metaphase 1 in meiosis?
A
- Bivalents line up along equator of the spindle.
- Maternal and paternal chromosomes in each pair position themselves independently of the others; this is independent assortment.
10
Q
What happens in anaphase 1 in meiosis?
A
- Homologous pairs are separated, spindle fibres contract.
- Microtubules pull chromosomes to opposite ends.
- Centromeres do not divide.
11
Q
Telophase 1 in meiosis.
A
- Chromosomes arrive at opposite poles.
- Spindle fibres start to break down.
- Nuclear envelope forms around two groups of chromosomes and nucleoli reforms.
12
Q
prophase 2 is meiosis
A
- Nuclear membrane breaks down.
- Chromosomes condense.
13
Q
Metaphase 2 in meiosis.
A
- Chromosomes line up in a single line along equator of spindle.
14
Q
Anaphase 2 in meiosis.
A
- Centromeres divide.
- Chromatids pulled to opposite poles.
- 4 groups of chromosomes created that have half n. of chromosomes compared to original parent cell.
15
Q
What happens after anaphase 2 in meiosis?
A
Cytokinesis creates 4 haploid cells.
