Membranes and transport PROMPT ANSWERS
- Created by: Pudgee
- Created on: 29-10-17 19:17
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- Roles of membranes at surface and within cells
- separates the cell contents from the external environment
- regulates transport
- enzymes for specific metabolic pathways
- antigens
- signalling
- a site of chemical reactions
- cristae in mitochondria allow a large surface area for aerobic respiration
- thylakoid membranes house chlorophyll and allow space for photosynthesis
- digestive enzymes on the epithelial cells that line the small intestine catalyse final stages in the breakdown of sugars
- Fluid mosaic model structure
- phospholipid bilayer- hydrophilic phosphate heads and hydrophobic lipid tails
- pores- water-filled channel proteins for transport. lines with hydrophilic amino acids
- glycolipids and glycoproteins are carbohydrate chains attached to lipids or proteins
- glycocalyx - all carbohydrate molecules that are outside of the membrane, hydrophilic so attract solutes
- channel and carrier proteins that span the whole bilayer.
- cholesterol gives mechanical stability and flexibility
- protein receptors
- enzymes
- Different cell composition
- neurons have protein channels and carriers in the axon membrane to allow movement of ions to bring about the conduction of electricity
- the myelin sheath is made of flattened cells with membranes about 76% lipid and 20% protein
- white blood cells have receptors to recognise the antigens of foreign cells
- root hair cells have many carrier proteins to transport nitrate ions
- inner mitochondria are 76% protein and 24% lipid as they have many ion carriers for aerobic respiration.
- Simple diffusion
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- molecules move down a concentration gradient. doesn't require energy
- how
- molecules have kinetic energy. at high concentrations, they bump into each other more causing them to spread out
- what
- small molecules
- lipid soluble molecules
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- Factors that affect diffusion
- temperature
- distance
- size of…
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