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 mor condensed form of DNA
What’s a centromere?
Attaches two genetically identical molecules made from DNA replication
What is a centriole?
Small hollow cylinders which form centrosomes
What are centrosomes?
2 hollow cylinders orientated at right angles to one another and form a network of microtubules/filaments (spindle fibres)
What are the three main stages of the cell cycle?
Interphase
Mitosis
Cytokinesis
What are the three stages of interphase?
G1
S
G2
What happens during the G1 stage of interphase?
- Growth of cell
- Duplication of organelles
- Protein Synthesis
What happens during the S stage of interphase?
DNA replication
What happens during the G2 stage 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 poles 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 decondenses to reform chromatin
- Spindle fibres disintegrate
- Nuclear envelope reforms around each group of chromosomes
- Nucleolus reappears
- Clevage furrows form to begin cytokinesis
What is a clevage furrow?
When the cell pinches together to perform cytokinesis
What is cytokinesis?
The cytoplasm splits/divides to form 2 genetically identical daughter cells
Why is only the root tip used when calculating a mitotic index?
- They have meristem cells at the root tip which are actively undergoing mitosis
- Cells further up from the root tip are elongating but not dividing
How do prokaryotic cells divide?
Binary Fiisoon
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 form so membrane invaginate (fold in) and the cytoplasm divides
- Forms two 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
