Cell Structure
- Created by: grace.goodyer
- Created on: 11-12-17 16:31
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- Cell Biology
- Cell Structure
- Plant and Animal Cells
- Plant Cells
- Nucleus- controls the activities of the cell and contains DNA
- Cytoplasm- in which most of the chemical reactions take place
- Cell Membrane- controls what enters and leaves the cell
- Ribosomes- where proteins are made
- Mitrochondria- where aerobic respiration takes place
- Cell Wall- Made of cellulose to strengthen the cell
- Animal Cells
- Cell Membrane- controls what enters and leaves the cell
- Cytoplasm- in which most of the chemical reactions take place
- Mitrochondria- where aerobic respiration takes place
- Nucleus- controls the activities of the cell and contains DNA
- Ribosomes- where proteins are made
- Vacuole- filled with cell sap to support the plant
- Chloroplasts- absorb light to make food through photosynthesis
- Animal Cells
- Plant Cells
- Eukaryotic & Prokaryotic Cells
- Eukaryotic
- Plant, animal and fungal cells are all eukarotic
- Has a nucleus and organelles with membranes e,g, mitrochondria, chloroplasts
- Prokaryotic
- The cell wall is made from peptidoglycan (protein and sugar)
- They have no nucleus or any organelles with membranes
- Has a tail/ flagellum to help with its movement
- Bacteria is an example of a prokaryotic cell
- Plasmid- ring of DNA
- Bacteria is an example of a prokaryotic cell
- Mesosome- a folded membrane that has a high surface area where respiration occurs
- Plasmid- ring of DNA
- Eukaryotic
- Plant and Animal Cells
- Investigating Cells
- Size of cells
- Animal cells about 0.2mn in diameter
- Plant cells are about 0.1mn in diameter
- Prokaryotic cells are smaller often around 0.002mn long
- Microscopes
- TransmissionElectron Microscope
- The limit of resolution is less than one. You can see how pathogens work
- Black and white images. Large and expensive. To use, a vacuum needs to be created. Resolution isn't great
- Light Microscope
- Not too expensive and they show colour when used with a stain
- High magnifications aren't possible. The resolving power is limited
- Can see as small as 400nm e.g blood cells, sperm cells or chloroplasts
- TransmissionElectron Microscope
- Size of cells
- Cell Division
- Chromosomes
- The nucleus contains chromosomes made of DNA
- Each chromosome contains hundreds to thousands of genes
- Different genes contain the code to make different proteins so controls the development of characteristics
- Chromosome are found in pairs and there are 23 pairs found in humans
- Mitosis and the Cell Cycle
- Cells go through the cell cycle in order for changes like growth and division
- Before a cell can divide it needs to increase the number of organelles inside. DNA is also replicated to form two copies of each chromosome
- Mitosis
- 1. One set of chromosomes replicates itself
- 2.Chromosomes line up along the centre of the cell, divide then copies move to opposite sides of the cell
- 3. The cytoplasm and cell membrane divides to form two daughter cells
- 2.Chromosomes line up along the centre of the cell, divide then copies move to opposite sides of the cell
- 1. One set of chromosomes replicates itself
- Stem Cells
- Cells that are undifferentiated can divide into different cells are stem cells
- Stem cells are found in embryos, umbilical cords and some organs and tissues
- Adult stem cells are found in some organs and tissues e.g. bone marrow and can only make certain types of cells
- Uses of Stem Cells
- A cloned embryo of the patient may be made and used as a source of stem cells. This is called therapeutic cloning
- Stem cells from the cloned embryo will not be rejected by the patients body so are very useful in treatment
- A cloned embryo of the patient may be made and used as a source of stem cells. This is called therapeutic cloning
- Chromosomes
- Transport in and out of Cells
- Diffusion
- Diffusion is the movement of particles from an area of high concentration to a lower concentration until evenly spread out
- Examples in living organisms are:
- Oxygen and carbon dioxide diffusing in gaseous exchange in lungs, gills and plant leaves
- Digested food molecules from the small intestine diffuse into the blood
- Urea diffuses from cells into the blood plasma for excretion by the kidney
- Factors affecting diffusion
- Concentration gradient
- Temperature
- Surface area to ration volume
- A larger surface area means more molecules can diffuse across a membrane.
- Osmosis
- The diffusion of water through a semi-permeable membrane into a solution with a lower concentration of water
- Potato in distilled water
- Water diffuses into the vacuoles of the cells as there is a lower concentration of water inside the cell
- The cytoplasm is pushed against the cell wall and the cell becomes turgid
- Water diffuses into the vacuoles of the cells as there is a lower concentration of water inside the cell
- Potato cell in sugar solution
- Water diffuses into the cell so there is a low concentration of water inside compared to outside the cell
- The cell becomes plasmolysed as water diffuses out of the sell and the cytoplasm shrinks away from the cell wall
- Water diffuses into the cell so there is a low concentration of water inside compared to outside the cell
- Active Transport
- It allows mineral ions to be absorbed from the soil into the roots of plants
- Diffusion
- Cell Structure
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