Animal and Plant cells
Most cells have some structures in common. They have:
A nucleus to control the cell’s activities
Cytoplasm where many chemical reactions take place
A cell membrane that controls the movement of materials in and out of the cell
Mitochondria where energy is released during aerobic respiration
Ribosome’s are present where protein synthesis takes place
Plant and algal cells also have:
A rigid cell wall made of cellulose for support
Chloroplasts that contain chlorophyll for photosynthesis; the chloroplasts absorb light energy to make food
A permanent vacuole containing cell sap
Bacteria and Yeast
Bacterial cells have a cell membrane and a cell wall which is surrounded by cytoplasm
They do not have a nucleus so the genetic material is in the cytoplasm
When bacteria multiply they form a colony
Bacteria have the 3 c’s!!
Yeast is a single-celled organism
Yeast cells have a nucleus, cytoplasm and a membrane surrounded by a cell wall
Specialised cells
If a cell has many mitochondria, it must need a lot of energy e.g. muscle cell, sperm cell
If a cell has many ribosomes, it is making a lot of protein e.g. gland cells which produce enzymes
Diffusion
Diffusion is the spreading out of the particles of a gas, or of any substance in solution
The net movement into or out of cells depends on the concentration of the particles on each side of the cell membrane
Because the particles move randomly, there will be a net (overall) movement from an area of high concentration to an area of lower concentration
The difference in concentration between two areas is called the concentration gradient
The larger the difference in concentration, the faster the rate of diffusion
Examples are:
The diffusion of oxygen into the cells of the body from the bloodstream as the cells are respiring
The diffusion of carbon dioxide into actively photosynthesising plant cells
The diffusion of simple sugars and amino acids form the gut through the membranes
Photosynthesis
Carbon dioxide + water + (light and energy) = glucose + oxygen
Oxygen is released as a by-product of photosynthesis
Limiting Factors
Lack of light
Cold
Too little carbon dioxide
Temperature
How plants use glucose
Glucose produced from photosynthesis may be:
Converted into insoluble starch for storage
Used for respiration
Converted into fats or oils
Used to produce cellulose which strengths cell wall
Used to produce proteins
Plant and algae cells also need a supply of mineral ions such as nitrate ions in order to produce protein. Both absorb minerals from their surrounding environment
2 Converted and 3 used!!!
Organisms in their environment
Things that affect the distribution of organisms
Temperature
Availability of nutrients
Amount of light
Availability of water
Availability of oxygen
Availability of carbon dioxide
Enzymes
Proteins are made up of amino acids
The long chains are folded to produce specific shapes
The shape of a protein depends on its function
Proteins can be:
Muscles
Hormones Most Hormones Are Camp!
Antibodies
Catalysts
Chemical reactions in the body are controlled by enzymes
Enzymes are biological catalysts
The shape of an enzyme has an area where other molecules can fit (active site)
Enzymes can:
Build large molecules from many smaller ones
Change one molecule into another
Break down larger molecules into smaller ones
Reactions take place faster when it is warmer
The warmer the temperature, the faster the molecules move around and the more they collide with each other and with more energy
If the temperature gets too hot, the active site changes shape
The enzyme becomes denatured
Each enzyme works best at a particular pH
If the pH is too acidic or alkaline for