6 Mitosis and the cell cycle Flashcards
Why do cells need to divide?
repair of damaged tissues, growth, asexual reproduction
Why does the cell cycle need to be controlled?
so that growth is regulated and controlled, otherwise tumours may form
What is the name given to cell division in prokaryotes?
binary fission
What are the 2 types of nuclear division that take place in eukaryotic cells?
mitosis and meiosis
What are the products of mitosis?
2 daughter cells that carry same number of chromosomes as parent cell and identical copies of their DNA
What are the products of meiosis?
4 daughter cells that each contain half number of chromosomes of parent cell
List the 4 stages of mitosis in the correct order
prophase, metaphase, anaphase, telophase and cytokinesis
Acronym for the stages of mitosis
IPMAT (interphase, prophase, metaphase, anaphase, telophase)
Describe the structure of a chromosome
2 genetically identical sister chromatids joined by a centromere
Describe the structural changes that occur during prophase
chromosomes thicken and shorten by supercoiling; nuclear envelope disappears; centrioles form spindle fibres, separate and move opposite poles of cell
Describe the structural changes that occur during metaphase
chromosomes align at equator of cell; spindle fibres attach to centromeres
Describe the structural changes that occur during anaphase
spindle fibres contract, seperating sister chromatids; each chromatid pulled towards poles (now chromosomes)
Describe the structural changes that occur during telophase and cytokinesis
nuclear envelope appears around each set of chromatids to form 2 new nuclei; chromosomes uncoil and no longer visible and spindle fibres disintegrate; cell division of cytoplasm
List and describe the 3 stages of the cell cycle
Interphase (G1- Gap phase 1: proteins required for organelles synthesised; S- Synthesis phase: DNA replicated; G2- Gap phase 2: organelles grow, ATP levels increase)
Nuclear division
Cell division- cytokinesis
Why is a cell in interphase not ‘resting’?
cell is actively synthesising organelles, increasing ATP levels, and growing
During which phases of mitosis does the nuclear envelope (a) disintegrate, and (b) reappear?
(a) prophase
(b) telophase
Describe what happens to (a) the spindle fibres, and (b) the chromosomes during anaphase
(a) spindle fibres contract
(b) chromatids of each chromosome pulled to opposite poles of cell
Describe the appearance of a cell during telophase
cell contain 2 distinct nuclei
In a cell undergoing mitosis, what happens during cytokinesis?
parent cell divides to form 2 daughter cells that are genetically identical (chromosome number and DNA) to parent cell
List the 3 stages of interphase in order
G1- Gap phase 1, S- Synthesis phase, G2- Gap phase 2
During which phase in interphase does DNA replication take place?
Synthsis (S) phase
During which stage in interphase does the formation of organelles and an increase in ATP levels take place?
Growth phase 2 (G2)
Why does DNA replication have to take place?
so each daughter cell formed has an identical copy of DNA to the parent cell
What is a mitotic index?
the proportion of cells in a population undergoing mitosis
