Topic 2: Cell Division and Stem Cells Flashcards
A* LFG
What is a chromosome?
The structure made of DNA that codes for all the characteristics of an organism.
Where is a chromosome found?
Found in pairs in the nucleus of the cell.
What does a chromosome do?
Carry genetic information in a molecule called DNA.
What is DNA?
Carries information about how an organism looks and functions.
Is everyone’s DNA different?
Everyone’s is different but identical twins who share the same DNA.
How many chromosomes do human’s have?
46 (23 pairs)
What is a gene?
A short length of DNA.
What is an allele?
Alleles are different versions of the same gene.
(for example:
gene= eye colour
allele=blue eye colour)
What do genes code for?
They code for a specific protein.
What is mitosis?
A type of cell division that creates cells with identical genetic information.
When does mitosis occur?
When an organism grows, needs to replace worn-out cells or needs to repair damaged tissue.
How many cells does mitosis produce?
2 (daughter) cells.
How many divisions occur in mitosis?
1
What is the process of mitosis?
The cell begins its divide
DNA replicates to form two copies of each chromosome
The nuclear membrane breaks down and the chromosomes line up across the centre of the cells
One set of chromosomes is pulled to each end of the cell and the nucleus divides
The cytoplasm and cell membranes divide to form two identical cells.
What happens when a cell becomes cancerous?
It begins to grow and divide uncontrollably.
What is cancer?
A disease caused by normal cells changing so that they grow and divide in an uncontrollable way.
What is a group of cancerous cells that causes a lump called?
A tumour.
What causes cancer?
Carcinogens
Mutations
Genetic factors
Lifestyle factors
What is a carcinogen?
A chemical or other agent that causes cancer.
What do carcinogens do?
Damage DNA which can cause mutations to occur (a random change in the structure of a gene, chromosome or number of chromosome).