3.2.2 Cell Cycle Flashcards
Do all cells retain the ability to divide?
No
What is interphase stage of mitosis?
Gap 1 = cell growth, normal function
DNA synthesis = DNA is copied
Gap 2 = additional growth, chromatids become replicated chromosomes, centriole replicates
What is the prophase stage of mitosis?
Chromosomes condense and become visible as they stain more intensely
Nuclear envelope breaks up into small vesicles
Nucleolus forms part of several chromosomes
Centrioles separate and take positions on opposite poles of the cell
Single fibres form and radiate towards the centre of the cell
What is metaphase in mitosis?
Shortest phase
Chromosomes line up in the middle of the cell
Spindle fibres connect to the centromere of each sister chromatid
What is anaphase in mitosis?
Spindle fibres start to contract
Centromeres that join the sister chromatid split
Sister chromatids are pulled apart
Separated chromatids move to opposite poles of the cell
Centromeres move first
What is telophase in mitosis?
Chromosomes each consisting of a chromatid uncoil
A nuclear envelope forms around the chromosomes at each pole of the cell
Spindle fibres break down and dissolve
Cytokinesis begins
What is cytokinesis?
The division of the cytoplasm that creates two separate cells
Made by constriction from the edge of the cell
Process differs in plant and animals
Animal cytokinesis: cell membrane forms a cleavage furrow that eventually pinches the cell into two clearly equal parts, each part containing its own nucleus
Does mitosis occur if the cell is damaged?
No
An uncontrollable process can lead to tumours or cancer
What is cancer?
An uncontrollable tumour
Many cancer treatments are directed at controlling the rate of division
What is binary fission?
Occurs in prokaryotic cells
The circular DNA and plasmids replicate
The cytoplasm then divides to produce two daughter cells
Each daughter cell has a single copy of the circular DNA and a variable number of copies of plasmids
Do viruses undergo cell division?
They don’t
They inject nucleic acid into the host cell so that the host will replicate the virus particles
What do the stages of mitosis look like?
See card
What is a somatic cell?
A typical body cell with twice the number of chromosomes as the gamete
What are the factors that regulate the cell cycle?
Before a cell divides, the DNA is checked to make sure it has replicated correctly
A gene mutation occurs if DNA doesn’t copy directly
Chemical signals tell a cell when to stop or start dividing
Neighbouring cells communicate with dividing cells to regulate growth
Cancer is a disease of the cell cycle, some of the body’s cells divide uncontrollably and tumours form
Cancer can be caused by smoking, radiation, pollution and other chemicals. It can also occur naturally
What are the quantities of DNA throughout the mitosis?
G1: n
Synthesis - Anaphase: 2n
Telophase and cell division: n
