Topic 1 Chromosomes And Mitosis % Flashcards
What is a chromosome
Coiled up lengths of dna
What does each Chromosome carry
 A large number of genes
What do genes control,
Development of different characteristics
How,many chromosomes do body cells usually have
2 Copies of each chromosome one from the mother one from the father
What happens in stages called the cell cycle
Body cells in multicellular organisms divide to produce new cells
What is the stage of the cell cycle called when a cell divides
Mitosis
What is mitosis used for
To grow or replace cells that have been damaged
What is made at the end of mitosis
Two new cells identical to the original cell with the same number of chromosomes 46
What happens in the first stage of the cell cycle
Growth and DNA replication
What does a cell have to do before it divides by mitosis
Has to grow and increase the amount of sub cellular structures such as mitochondria and ribosomes
What happens to DNA in the first stage of the cell cycle
DNA duplicates so there is one copy for each new cell
copied DNA forms X shape chromosomes, each arm an exact duplicate of each other
What is stage two of the cell cycle called
Mitosis
What happens to the chromosomes during mitosis
The chromosomes line up at the centre of the cell and cell fibres pull them apart
the two arms of each chromosome go to opposite ends of the cell
What happens after the chromosomes have been pulled apart in mitosis
Membranes form round each of the new sets of chromosomes
These become the nuclei of the two new cells, nucleus has divided
What is the last step of mitosis
The cytoplasm and cell membrane divide
