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Biology - Coggle Diagram
Biology
Cell structure
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Cell wall- strengthens the cell, made of cellulose.
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Stem Cells
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Embryonic stem cells are found in the early stages of an embryo (zygote) and can differentiate into any cell.
Adult stem cells can be found in bone marrow and can only specialise into some cells such as red blood cells.
There are ethical and moral issues with using embryonic stem cells for treatments as the embryo has a very low chance of surviving.
Adult stem cells can be used to treat diseases such leukaemia, heart disease, diabetes and multiple sclerosis.
In plants, stem cells are called meristems and are found in the tips of the roots of the plant.
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Diffusion and Osmosis
Diffusion is the spreading out of particles from an area of higher concentration to an area of lower concentration.
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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 formation
Cell cycle- Growth, dna synthesis, cell division (mitosis)
Mitosis
- DNA replicates to from 2 copies of each chromosome.
- The cell begins to divide.
- The nuclear membrane breaks down and all the chromosomes line up across the centre of the cell.
- One set of chromosomes is pulled to each end of the cell.
- The cytoplasm and cell membranes divide to form two identical cells that are also identical to the parent cell.
Specialised cells
Animal
Sperms cells: function is to fertilise egg cell. They have a flagellum to swim to the egg, acrosomes (which contain enzymes) in the head to digest the egg cell membrane and lots of mitochondria in the midsection to release energy for movement.
Nerve cells: function is to carry electrical signals. They're long to carry signals long distances, have branched connections to connect to other nerve cells and create a network around the body and an insulating sheath to enhance transmission of electrical signals.
Muscle cells: function is to connect joints and allow movement. They are long so that they have enough space to contract and contain lots of mitochondria to release energy from respiration for movement.
Plant
Root hair cells: function is to absorb water and minerals from the soil. They have hair like projections to increase the surface area.
Xylem cells: function is to carry water and minerals in plants. They form hollow xylem tubes full of dead tissue, they are long and water and minerals flow in one direction through them from the roots to the leaves (transpiration).
Phloem cells: function is to carry glucose around the plan. They form phloem tubes made of living tissue, have end plates with holes in them and glucose in solution moves from the leaves to growth and storage tissues (translocation).
As the cell differentiates, it forms different sub-cellular structures.