Th cell cycle Flashcards
State the stages of the cell cycle in order
- Interphase
- Mitosis
- Cytokinesis
What’s the longest stage called
Interphase
Describe what happens during interphase
To prepare for division:
- The cell grows as the volume of the cytoplasm increases
- The cell replicates it’s DNA
- The cell replicates the organelles and increases ATP synthesis
Describe the process of mitosis
- During Prophase, the nuclear envelope breaks down, chromosome condense, centrioles move to opposite poles and produce spindle fibres
- During Metaphase, Chromosomes move to the middle of the cell and spindle fibres attach to the centromere of each chromosome
- During anaphase, Chromosomes move to opposite sides of the cell, when the centromeres divide and the spindle fibres contract, with the energy provided by ATP
- During Telophase, Spindle fibres break down, and the nuclear envelope reforms.
Describe the process of cytokinesis
The cytoplasm divides, and the cell membrane reforms to produce 2 identical daughter cells
In which stage do new cell membranes form
Interphase
In which stages can you see the nucleus
Interphase and Cytokinesis
Why can’t you see the nucleus in mitosis
The nucleus breaks down in prophase
In which stages can you see the Chromosomes. Explain why
- Mitosis
- They condense
In which stage do DNA helicase and DNA polymerase act. Explain why
- Interphase
- They catalyse DNA replication, which happens during interphase
Describe what is meant by cancer and how it is caused
- Cancer is uncontrollable cell division
- Caused by DNA mutations, which affect the genes that regulate the cell cycle, causing the cell cycle to occur more quickly, and so cells divide uncontrollably
Define tumour
Masses of rapidly dividing cells
Describe how tumours cause harm
They exert pressure on organs, and create blockages
What are the 2 types of tumours, and describe the difference between them
- Malignant and benign
- Malignant can spread, whereas benign cannot
What are the 2 genes that regulate the cell cycle called
- Protooncogenes
- Tumour suppressor genes
Describe the difference between the 2 genes that regulate the cell cycle
Protooncogenes stimulate the cell cycle, whereas tumour suppressors prevent the continuation of the cell cycle
Describe how Protooncogenes stimulate cell division
When a growth factor binds to a receptor on the cell membrane, the protooncogene is switched on, and the cell divides
What do we call a protooncogene when it mutates
Oncogene
Describe the properties and function of Oncogenes
- Oncogenes are permanently switched on
- The rate of cell division increases uncontrollably as the cell divides even when growth factors are absent
Describe the function of tumour suppressor genes
- Tumour suppressor genes produce proteins, which either repair damaged DNA, or cause cells with damaged DNA to self destruct (apoptosis)
Describe what happens when the tumour suppressor genes mutate
- They no longer function correctly
- Cells with damaged DNA continue to divide, which can lead to cancer
What do cancer drugs aim to do
- Prevent DNA replication
- Prevent spindle fibre formation
Why is it difficult to treat cancer
- It’s difficult to treat cancer without harming healthy cells, and so cancer treatments often have many side effects
- This is why quickly replicating cells, such as hair cells and immune cells are particularly affected
What are the 3 stages of interphase
G1 (growth)
S (synthesis)
G3 (growth)
