MITOSIS AND MEIOSIS Flashcards
1
Q
what is mitosis?
A
- division that maintains same number of chromosomes producing two new identical cells
2
Q
what is meiosis?
A
- division that halves the number of chromosomes, producing 4 haploid cells.
- genetically different
3
Q
what is a ploidy?
A
- how many complete sets of chromosomes a cell has
4
Q
what is a nucleus?
A
- membrane bound region of cell that contains chromatin.
- and in which transcription to mRNA ocurs.
5
Q
what is a nucleolus?
A
- region within nucleus (not membrane bound) in which ribosomes are made
6
Q
what is interphase?
A
- stage where cell spends most of life.
- cell actively consumes nutrients.
7
Q
what is gap 1 of interphase?
A
- cell grows and metaboizes normally.
- grows to double size
- makes more organelles and cytoplasm
8
Q
what is synthesis of interphase?
A
- more DNA is synthesised
9
Q
what is gap 2 of interphase?
A
- mitochondria divides by binary fission
- cell keeps growing
10
Q
what is prophase?
A
- chromosomes condenses out of chromatin.
- nucleoli breaks down
- centrosomes move apart
- microtubules reorganise
- Microtubules have formed short asters on centrosomes and beginning of mitotic spindle.
11
Q
what is prometaphase?
A
- nuclear envelope breaks down into vesicles
- membrane vesicles visible
- mitotic spindle is formed
kietochores form
12
Q
what is metaphase?
A
- chromosomes align along equator of cell
- chromosomes are aligned along the equator of the cell.
13
Q
what is anaphase?
A
- protein securin blocks anaphase from starting till everything is ready.
- anaphase promoting complex destroys it.
14
Q
ANAPHASE A?
A
- ANAPHASE A = kinetochore microtubules pull on the chromatids pulling them apart and moves towards poles.
15
Q
ANAPHASE B?
A
- microtubules move towards the middle of the cell and pushes against one another.
- pushes chromatids nearer to the poles
16
Q
what is telophase?
A
- one nuclear envelope re- forms
- chromatids condense into chromatin and nucleoli reform
- mitotic spindle in disassembled.
- cytokinesis occurs - myosin and actin around equator of cell contracts and splits cell into two daughter cells.
17
Q
interphase in meiosis?
A
- G1 AND S PHASE ONLY OCCURS
18
Q
meiosis 1 = prophase 1?
A
crossing over events but otherwise same as mitosis
1. leptonene pahse
2. zygotene phase
3. pachytene phase
4. diplotene phase
19
Q
what is the leptonene phase?
A
- pairs of sister chromatids are copied and becomes tightly associated.
- some elements of synaptonemal complex assemble between each pair of chromatids.
20
Q
what is zygotene phase?
A
- homologous chromosomes line up next to each other.
21
Q
what is pachytene phase?
A
- homologous recombination occurs by crossing- over.
- chiasmata form at contact points.
- chromatids exchnage info
22
Q
what is diplotene phase?
A
- synaptonemal complex degrades.
- chiasmata not degraded
23
Q
meiosis 1 = metaphase 1 and anaphase 1
A
- happens much like mitosis but with chromosomes at poles of cell
24
Q
what is interkinesis?
A
two daughter cells
produced will have a little rest before
proceeding after telophase I
25
what happens in meiosis 2?
- happens like mitosis but for each of two daughter cells made in meisois 1
