B2 Flashcards
What does the nucleus carry?
The chromosomes
What do the chromosomes carry?
Genes
What do the genes contain?
Instructions for making new cells
What is a gene?
Small packet of information that controls the characteristics of your body. Unique molecule that makes up chromosomes.
How many genes do chromosomes carry?
Could carry several hundred or even thousand genes.
How many chromosomes per cell?
- 46 chromosomes, 23 pairs
- 1 from father
- 1 from mother
What is mitosis?
Stage in cell cycle that divides the nucleus to create identicla daughter cells.
Why identical cells are necessary ?
Same genetic material is needed in every cell.
How do asexual production produce offspring?
Mitosis
How long is the cell cycle?
Tim varies can be less than 24 hours or could take several years.
When is the cell cycle the fastest?
Embryonic stage.
Is the cell cycle fast during childhood?
Yes remain fairly rapid during childhood , as they are growing.
What happens to the cell cycle when puberty is over?
Slows down
What happens to the cell cycle when you are an adult ?
Only for repair and replacement , rather than growth.
What cells can get replaced?
Hair follicles , skin , blood , lining of digestive system.
STAGE 1 of the cell cycle , what is it?
Interphase: cell grows in size , DNA and organelles replicate (ribosomes and mitochondria), forms two copies of each chromosome.
STAGE 2 of the cell cycle , what is it ?
Mitosis: replicated chromosomes line up along the centre and get pulled to opposite poles. The nucleus divides.
STAGE 3 of the cell cycle, what is it ?
Cytokinesis: cell membrane and cytoplasm divide to form 2 new identical daughter cells.
Why is the cell cycle important?
For the growth and development of multicellular organisms
How many cells in the body?
37.2 trillion
What is the state of all cells in early development of both animal and plant embryos?
Unspecialised