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biology unit 1: cell biology - Coggle Diagram
biology unit 1: cell biology
animal cells
sub cellular structures: nucleus - control of the cell and contains genetic material
cytoplasm - where chemical reactions take place.
cell membrane - controls the passage of substances in and out of cell
mitochondria - where aerobic respiration takes place and releases energy.
ribosomes - where proteins are synthesized (made).
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subcellular structures: - all animal components.
cell wall is made of cellulose to strengthen cells.
permanent vacuole - filled with cell sap to support the plant.
chloroplasts - absorb light for photosynthesis.
these are both eukaryotic meaning they have a nucleus
differences between prokaryotic and eukaryotic: - prokaryote's genetic material is not stored in a nucleus and instead in plasmids.
prokaryotes don't contain mitochondria or chloroplasts.
microscopes
light microscope vs electron microscope:
light: can be stained to see the structure more clearly. see plant animal and bacterial cells. inexpensive to buy and can be used by all. fairly low magnification and resolution so some sub-cellular structures cant be seen.
electron microscope: species have to be dead for viewing. black and white. expensive. high magnification and can see most sub-cellular structures.
magnification = size of image/size of real object.
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required practical
tissue sample on a microscope slide. 2. add a few drops of suitable stain. 3. lower a coverslip on tissue. 4. place a slide on the microscope stage and focus on the cells using low power. 5. change to high power and refocus.
cell cycle
before mitosis, a cell grows and increases its number of ribosomes and mitochondria.
dna then replicates itself to form two copies of each chromosome. parent and daughter chromosomes.
mitosis: one set of chromosomes are pulled to each end of the cell. the nucleus divides, the cytoplasm and cell membranes divide to form two identical cells.
stem cells.
found in human embryos, in the umbilical cord of a new baby or in some organs and tissues. stem cells from human embryos are called embryonic stem cells and can differenciate to form any cell.
adult stem cells - e.g bone barrow to form red blood cells, only make certain types of cells.
useful in replacing damaged tissue or treat disease like diabetes or paralysis. A cloned embryo of a patient can be a source of cells - theraputic cloning. - these will not be rejected from the patient.
cloned embroyo issue - risks in transfer of viral infection. ethical or religious issues as it is exploiting an unborn baby for science.
plant stem cells = meristems. useful to - clone rare plants to protect from extinction. mass identical crop plants with special features such as disease resistance.
diffusion
net movement of particles from an area of higher concentration to an area of lower concentration until in equilibrium.
factors affecting: concentration gradient. temperature, the surface area of the membrane.
adaptations of small intestine and lungs, gills, and roots and leaves
large surface area
surface is thin often one cell thick so diffusion is a short distance.
usually kept moist for quickness.
rich blood supply maintains concentration gradient - in mammals.
ventillation occurs to speed up gas exchange - in mammals.
osmosis.
movement of water from a dilute solution to a concentrated solution through a partially permeable membrane.
active transport
movement of substances against a concentration gradient, from an area of low concentration to high concentration.
it requires energy from respiration
allows for mineral ions to be absorbed into plant root hairs from dilute solutions in the soil.
allows sugar molecules to be absorbed from lower concentrations in the gun into the blood of higher concentration
required practical
potatos measure the effect of sugar solutions on plant tissue.
cut cylinders of potato and measure mass. 2. place in different concentrations of sugar solutions. 3. after 30 minutes remove cylinders and measure mass. If cylinders have a change in mass they have gained or lost water by osmosis.
variables: independant: concentration of sugar solution. dependant variable: the change in the mass of the potato. control variable: temperature, time in solution, volume of solution.
