Cell Cycle Flashcards
What are the two types of nuclear division?
Mitosis, meiosis
What is chromatin?
More spread out form of DNA
What is a chromosome?
A more condensed form of DNA
What is a centromere?
Attaches to genetically identical molecules made from DNA replication
What is a centriole?
Small hollow cylinders which form centrozones
What are centrosomes?
2 hollow cylinders orientated at right angles to one another and for a network of microtubules/ filaments (spindle fibres)
What are the three main stages of the cell cycle?
Interphase
Mitosis
Cytokinesis
What are the 3 stages of interphase?
G1, S G2
What happens during the G1 phase of interphase?
- Growth of cell
- duplication of organelles
- Protein synthesis
What happens during the S phase of interphase
DNA replication
What happens during the G2 phase of interphase?
- more growth
- checking for errors in replicated DNA
What are the 4 stages of mitosis
Prophase
Metaphase
Anaphase
Telophase
What happens during prophase of mitosis
The nuclear envelope disintergrates
The nucleolus disappears
Chromatin condenses (shortens/thickens) to form chromosomes
Centrioles move to opposite poles of the cell
Spindle fibres (microtubules) start to develop
What happens during the metaphase stage of mitosis?
Chromosomes line up along the equator (in the middle of the cell)
Attached to the spindle fibres by their centromeres
What happens during the Anaphase stage of mitosis?
Spindle fibres contract and shorten pulling sister chromatids apart and to opposite sides of the cell.
Centromeres divide in two separating each pair of sister chromatids
This appears v shaped
What happens during the Telophase stage of mitosis?
Chromatids reach opposite poles on spindle fibres - called chromosomes
Chromosomes decondeses to reform chromatin
Spindle fibres disintegrate
Nuclear envelope reforms around each group of chromosomes
Nucleolus reappears
Cleavage furrows form to begin cytokinesis
What is a clevage furrow
When a cell pinches together to perform cytokinesis
What is cytokinesis?
The cytoplasm splits / divides to form 2 genetically identical daughter cells
How do prokaryotic cells divide
Binary fission
Describe the process of binary fission
- cell replicates it’s circular DNA and plasmids
- the cell elongates and grows separating the DNA loops to opposite ends of the cell
- cross walls from so membrane invaginate (fold in) and the cytoplasm divides
- forms 2 daughter cells
Why do we use logs when working out bacteria cell growth?
It helps us to compare data with a large range of values more accurately
What type of process is mitosis?
It’s a gene controlled process
What are the two types of genes which control mitosis?
Oncogenes
Tumour suppressor genes
What do proto-oncogenes do when switched on?
Cause cell to divide
If the proto-oncogene mutates to an oncogene what happen?
The oncogene becomes permanently switched on leading to uncontrolled cell division
What is a TS gene
Tumour suppressor gene
What will happen if a mutation of the TS gene occurs?
Leads to uncontrolled cell division and and tumour growth
What is the function of a TS gene?
Slows down cell division ( helps maintain normal rates of cell division)
What are cancer treatments directed at?
Controlling the rate of cell division by killing rapidly dividing cells through blocking parts of the cell cycle
How does chemotherapy control rapidly dividing cells?
Prevents DNA replication,
Inhibits metaphase by preventing spindle fibres forming
Inhibits nucleotide synthesis
What is the problem with cancer treatment like chemotherapy?
It can interfere with the cell cycle of normal cells which divide rapidly (causing damage)
For example hair producing cells = hair loss
