The cell cycle and mitosis Flashcards
In order, what are the 3 phases of the cell cycle?
- Interphase
- Mitosis
- Cytokinesis
- Interphase not apart of mitosis
What happens during interphase?
Cell grows, new organelles made, DNA replicates
- No active division
In order, what are the three stages of interphase?
G1 - first gap
S - synthesis of new DNA
G2 - second gap
What is the longest phase of the cell cycle?
Interphase
What happens during G1 in interphase?
- Cell grows
- New organelles made
- Proteins are made
What happens during S phase in interphase?
DNA replicates
What happens during G2 in interphase?
- Cell keeps growing
- Proteins needed for cell division are made
- ATP produced
In order, what are the four stages of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
What happens during prophase in mitosis?
- Chromosomes condense and become visible under a microscope
- Nuclear envelope disintegrates and the nucleolus disappears, leaving chromosomes free in the cytoplasm
- Centrioles (bundles of protein) move to opposite ends of cell and form spindle fibres
What happens during metaphase in mitosis?
- Chromosomes line up at the equator of the cell
- Each chromosome attaches to spindle fibres by their centromere
What happens during anaphase in mitosis?
- The centromeres divide to separate each pair of sister chromatids
- Spidle fibres contract, pulling the chromatids by their centromere to opposite poles of the cell
What happens during telophase in mitosis?
- Chromatids reach opposite poles of the cell
- Chromatids uncoil and become chromatin again
- A nuclear envelope forms around each set of chromosomes and nucleolus reforms
- Spindle disintegrates
- Two new nuclei produced
What happens after mitosis?
Cytokinesis
What happens during cytokinesis?
The cytoplasm divides and produces two daughter cells that are genetically identical to one another
What is the purpose of chromosomes condensing during prophase?
- Ensures that large amounts of DNA can fit in small space
- Ensures that DNA is organised when daughter cells split
What is mitosis important for?
- Growth
- Repair
- Asexual reproduction
- Production of stem cells
How do we calculate the mitotic index (MI)?
MI = Number of cells with condensed chromosomes / total number of cells
Why is it important that mitosis is a controlled process?
Uncontrolled mitosis can lead to cancer
What is meant by a ‘mutation’?
A change to the base sequence of DNA
What factors can increase the risk of mutations?
- UV light
- Smoking
- X-rays
- Genetics
Do all mutations lead to cancer?
No
- Mutations are common
What are the two types of tumor?
- Begnin
- Malignant
What are the characteristics of begnin tumors?
- Non cancerous
- Surrounded by membrane
- Slow growing
What are the characteristics of malignant tumors?
- Cancerous
- Large nucleus
- Can grow projections
- Faster growing
