B2.1.4- B2.1.6 supplying the cell Flashcards
What is mitosis?
It is the process by which body cells divide to replace worn out cells, to repair damaged tissue and to enable the organism to increase in size.
What happens during mitosis?
Each cell divides to produce two genetically identical daughter cells. They are genetically identical to the parent cell so They are clones.
What affect does mitosis have on the number of cells in a multicellular organism
It increases the number of cells in a multicellular organism
What is the cell cycle.
It is the process of cell growth and division
How is DNA replicated?
First the DNA molecule ‘unzips’ forming 2 separate strands
The DNA bases on each strand are exposed
Free nucleotides in the nucleus line up against each of the strands following the rule of complementary base pairing
This forms DNA base pairs
When the whole strand is complete there are 2 identical molecules of DNA
How do the chromosomes move?
- Chromosomes condense -prophase
- The chromosomes line up across the centre of the cell (metaphase)
- Chromosomes break at centromeres and sister chromatids move to the opposite ends of the cell. (Anaphase )
- Nuclear membranes form and the cell begins to split in two
- The cell membrane pinches inwards to separate and enclose the two new nuclei and then splits the original cell into two new genetically identical daughter cells.
What does is differentiation
Conversion of cell from unspecialised to specialised
What is a specialised cell?
A cell that is adapted to perform a particular function
What happens when a cell becomes specialised
It’s structure changes so that it is better adapted to perform its function
Why do cells become specialised
As It makes the entire organism more efficient as life processes are carried out more effectively
What are some examples of specialised cells?
Sperm cell
Fat cell
Red blood cell
Ciliated cells
Palisade cells
How are sperm cells specialised?
They are specialised to transfer genetic material from the male to the ovum (egg).
It’s adaptions include:
- flagellum (tail) whips from side to side to propel the sperm to the ovum
- lots of mitochondria - respiration occurs in the mitochondria and the reactions of respiration transfer energy from chemical stores so the flagellum can move.
- acrosome- stores digestive enzymes which breaks down the outer layers of the ovum to allow the sperm to transfer genetic material
How are fat cells adapted to perform its function ?
Fat cells are specialised to store fat .
Fat cells are adapted by :
having a small layer of cytoplasm surrounding a fat reservoir.
They can expand up to 1000 times their original size as they fill with fat.
How are red blood cells specialised for their function?
Red blood cells are specialised to transport oxygen around the body.
They are adapted by having:
- biconcave discs - they are pushed in on both sides to form a biconcave shape. This increases the surface area to volume ratio speeding up the diffusion of oxygen into the cell and carbon dioxide out of the cell.
- lots of haemoglobin - this protein binds to oxygen to form oxyhemoglobin which is bright red
- no nucleus - this means there is more space to contain haemoglobin molecules
How are ciliated cells adapted to perform their function?
You have ciliated cells in your airways
In between these cells are goblet cells which produce sticky mucus to trap dirt and bacteria.
The cilia on top of the cells sweep the mucus away from the lungs and to the back of your throat.
