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Cell structure, transport and division. - Coggle Diagram
Cell structure, transport and division.
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Cell transport
Diffusion
If there is a situation where particles of a substance are in a higher concentration, they will move from this region to where they are in a lower concentration. This is called diffusion.
Active transport
Substances are transported passively down concentration gradients. Often, substances have to be moved from a low to a high concentration - against a concentration gradient.
Active transport is a process that is required to move molecules against a concentration gradient. This process requires energy.
Osmosis
Osmosis is the diffusion of water molecules, from a region where the water molecules are in higher concentration, to a region where they are in lower concentration, through a partially permeable membrane.
Cell Division
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DNA exists in a cell's nucleus within structures called chromosomes. Each section of a chromosome that contains the code for the production of a particular protein is called a gene.
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Mitosis
- The cell begins to divide. 2.The DNA replicates to form two copies of each chromosome. 3. The nucleus breaks down. 4. One set of chromosomes is pulled to each end of the cell and the nucleus divides. 5.The cytoplasm and cell membranes divide to form two identical cells.
Meiosis
Meiosis only occurs in the testes and ovaries, producing gametes (sperm and egg cells). Human sex cells contain one chromosome from each of the 23 pairs. Meiosis is the process of human reproduction. The four gametes produced in meiosis are genetically different. Independent assortment and the random nature of fertilisation lead to variation in living organisms – no two organisms are the same (apart from identical twins).