bio - key concepts (1)

• bio - key concepts (1) What are the components of an animal cell? Nucleus Cell membrane Mitochondria Ribosomes Cytoplasm
• bio - key concepts (1) What is the nucleus? It holds DNA and controls cell activities
• bio - key concepts (1) What is the cell membrane? It controls what enters + exists the cell
• bio - key concepts (1) What is the mitochondria? It is where aerobic respiration takes place and energy is produced
• bio - key concepts (1) What are ribosomes? They create vital proteins for the cell
• bio - key concepts (1) What is the cytoplasm? It is where the chemical reactions take place
• bio - key concepts (1) What are the components of a plant cell (additional) ? Cell wall Chloroplast Permanent large vacuole
• bio - key concepts (1) What is the cell wall? Provides the cell with structure and strength
• bio - key concepts (1) What is a chloroplast? Has chlorophyll - photosynthesis - how the cell makes energy (food) from sunlight
• bio - key concepts (1) What is a permanent large vacuole? It holds cell sap and gives the cell structure
• bio - key concepts (1) What does a bacterial cell have? Has ribosomes, cell membrane, cytoplasm But - DNA floats loosely in the cytoplasm - Has flagellum (moves the bacterium) - Has plasmid loops (also carries DNA)
• bio - key concepts (1) What are the differences between prokaryotic and eukaryotic cells? Prokaryotic cells – smaller + simpler + have no nucleus - bacteria Eukaryotic cells – bigger + more complex + have a nucleus – plant + animal
• bio - key concepts (1) What is the process of diffrentiation? Process cells go through where they turn on/off certain genes to develop characteristics and become specialised to adapt to their specific functions
• bio - key concepts (1) What are the 3 different specialised cells in animals? Egg cell Sperm cell Ciliated epithelial cell
• bio - key concepts (1) How are egg cells specialised? Has lots of nutrients in its cytoplasm - can feed the zygote when it is formed The membrane can change structure - after fertilization sperm is prevented from entering.
• bio - key concepts (1) How are sperm cells specialised? At the top - acrosome - filled with enzymes that are released to help break down the egg Underneath the head - lots of mitochondria - lots of energy to reach the egg cell Tail - for movement
• bio - key concepts (1) How are ciliated epithelial cells specialised? Has cilia (these cells typically lines organs) cilia sways to help move substances along
• bio - key concepts (1) What are the components of a light microscope? Eyepiece lens – the part you look through Stage clips – holds down the slide The course and fine focus wheels – makes the image clearer The objective lenses – magnifies image The stage – where the slide is placed
• bio - key concepts (1) What is the history of the light microscope? The light microscope was invented in the 1500s they work by passing beams of light through the specimen. They have a relatively low resolution, they can also view living cells
• bio - key concepts (1) What is the history of the electron microscope? The electron microscope invented in the 1930s they work by passing beams of electrons through the specimen so they have a much higher magnification and resolution They cannot view living cells this is because they work in a vacuum, so the cells don't survive.
• bio - key concepts (1) What must you know about electron microscopes? Electrons are used rather than light waves – higher magnification + resolution Living cells can’t be examined
• bio - key concepts (1) What are enzymes? Biological catalysts - made by living things They also speed up reactions Also enzymes aren’t living they are just molecules
• bio - key concepts (1) How do enzymes work? We have the substrate which is the thing the enzyme is reacting with and the active site on the enzyme which is the place the substrate fits into - the active site and substrate have complimentary shapes Also enzymes are highly specific this means they can only catalyse one reaction Only one type of substrate can fit into the enzyme Enzymes can either be broken down or synthesised (when they join smaller molecules together to form larger ones) - enzymes need specific conditions to work If temp is too low - doesn’t have enough energy to work properly...
• bio - key concepts (1) How is substrate conc. relate to enzyme activity? We can increase enzyme activity by increasing substrate conc. This influences the activity until all the active sites become full after that increasing the substrate concentration has no effect on the activity
• bio - key concepts (1) How do you test for reducing sugars? Benedict’s reagent test Add reagent to the sample, then heat gently with a water bath If the test is positive, it will form a coloured precipitate The solution will go from aqua blue to yellow to orange then to brick red. The warmer the colour, the higher the reducing sugar concentration.
• bio - key concepts (1) How do you test for proteins? Biuret test Add some potassium hydroxide and then some copper sulphate If the test is positive, it will go purple (Blue to purple)
• bio - key concepts (1) How do you test for lipids? Emulsion test Add ethanol Shake it until it’s fully dissolved Pour the solution into the water If the test is positive, the water will go milky
• bio - key concepts (1) How do you test for starch? Iodine test Add iodine to the sample If the test is positive the sample will be blue/black
• bio - key concepts (1) What is calorimetry? Process used to find how much energy food has
• bio - key concepts (1) How do you carry out the calorimetry experiment? 1. Take a tube of 50ml cold water 2. Record the starting temperature of the water 3. Place the test tube at 45 degrees and hold a burning food sample just beneath it 4. When the food is burned up, record the final temperature of the water We can work out the energy transferred to the water using the equation: Energy transferred = mass of water x 4.2 x temperature increase
• bio - key concepts (1) What is diffusion? The movement of molecules from an area of high concentration to an area of low concentration until a plateau An example of this would be spraying air freshener as it diffuses into surroundings This is a passive process meaning it requires no energy
• bio - key concepts (1) What is active transport? The opposite of diffusion It’s the movement of particles from low concentration to high concentration This process does require energy
• bio - key concepts (1) What is osmosis? The movement of water molecules from a high to low concentration It’s a specific type of diffusion, it’s also through a partially permeable membrane which is just a barrier which allows some particles through and block others This is to balance the concentration of water