Section 2 - Cells and control - Mitosis and stem cells Flashcards
Why do multicellular cells use mitosis?
To grow or replace cells that have been damaged
Main stages of the cells cycle in order?
Interphase => Prophase => Metaphase => Anaphase => Telophase
What happens in interphase of the cell cycle?
DNA spread out in long strings
Before it divides, cell has to grow and increase amount of subcellular structures
DNA duplicated and forms X-shaped chromosomes with each ‘arm’ of the chromosome an exact duplicate of other
What happens in prophase of the cell cycle?
Chromosomes condense, getting shorter and fatter. Membrane around nucleus breaks down and chromosomes lie free in cytoplasm
What happens in metaphase of the cell cycle?
Chromosomes line up at centre of cell
What happens in anaphase of the cell cycle?
Cell fibres pull chromosomes apart. 2 arms of each chromosome go to opposite ends of cell.
What happens in telophase of the cell cycle?
Membranes form around each of sets of chromosomes. These become nuclei of 2 new cells - nucleus has divided
When does cytokinesis happen and what happens during it?
Before telophase ends, cytoplasm and cell membrane divide to form 2 separate cells
In mitosis, how many daughter cells are produced, are they diploid or haploid, and are they identical? Where does it happen?
2 new, identical daughter cells, identical to parents and diploid. Happens throughout body
2 ways plants and animals grow and develop? 1 other way plants grow and develop?
P + A: Cell differentiation and cell division
P: and cell elongation
What is cell differentiation?
Process by which a cell changes to become specialised for its job. Having specialised cells allows multicellular organisms to work more efficiently
How is cancer caused?
Change in one of genes that controls cell division causes uncontrolled cell division. This results in a tumour which invades and destroys surrounding tissue
What are stem cells and what can they do?
Undifferentiated cells and divide by mitosis to become new cells, which then can differentiate into different types of cells
2 places stems cells are found in?
In early human embryos and bone marrow
Where are meristem tissues found in plants?
In the areas of a plant that are growing
