cell division Flashcards
(15 cards)
1
Q
why does cell division occur?
A
- growth
- repairing damaged cells
- replacement of old cells
- asexual reproduction
2
Q
what is interphase?
A
time of high metabolic activity for the cell
3
Q
what occurs during interphase?
A
- replication of organelles such as mitochondria and chloroplasts which have their own DNA
- new organelles are made
- synthesis of ATP and proteins
- increase in cell size
4
Q
what occurs in prophase?
A
- chromosomes condense and become visible
- centrioles move to opposite sides of cell in animal cells
- spindle forms from microtubles
- nuclear envelope disintegrates
5
Q
what occurs in metaphase?
A
- centromeres of chromosomes attach to spindle and line up on the equator
6
Q
what occurs in anaphase?
A
- spindle fibres shorten
- centromere seperates
- individual chromatids are pulled to the polls, centromere first
7
Q
what occurs in telophase?
A
- spindle breaks down
- chromosomes uncoil
- nuclear envelope reforms
8
Q
what is cytokinesis?
A
the division of the cytoplasm to create the 2 new genetically identical cells
9
Q
what are the differences in plant cells?
A
- there are no centrioles
- in cytokinesis, a cell plate develops from the centre out instead of cleavage from the outside in
10
Q
what are genes that cause cancer?
A
oncogenes
11
Q
what is meiosis? where does it take place?
A
- produces cells which are haploid for sexual reproduction
- takes place in the gonads
12
Q
what occurs in metaphase I?
A
- homo chromosomes arrange themselves in pairs along the equator
- independent assortment occurs
- homo chromosomes from parent 1 and 2 arrange themselves randomly along the spindle facing each pole
12
Q
what occurs in prophase I?
A
- chromosomes form bivalents
-arms of chromatids may cross over forming chiasmata - genetic material is exchanged between homo chromosomes
- variation in inherited genomes increases
13
Q
what occurs in anaphase I?
A
- the chromosome bivalents separate as each chromosome is pulled by its centromere towards the opposite pole
13
Q
what occurs in telophase I?
A
- nuclear envelopes reform around the chromosomes at the poles
- chromosomes are no longer in pairs and the cells are haploid
