b1 definitions (cell level systems) Flashcards
active site
the part of the enzyme which is specific to the substrate and has a complementary shape to it.
aerobic respiration
a form of respiration that uses a plentiful supply of oxygen to release energy from glucose. it is shown by the following equation:
glucose + oxygen > carbon dioxide + water
amino acids
small molecules that make up a protein
amylase
an enzyme that breaks down carbohydrates into simple sugars. it is produced in the pancreas and salivary glands.
anaerobic respiration
a form of respiration that releases energy from glucose when there is an oxygen debt. anaerobic respiration in animals is shown by the following equation:
glucose > lactic acid
carbohydrate
a large molecule that is synthesised from simple sugars
cell membrane
a selectively permeable barrier which controls the movement of substances into and out of the cell. it also has receptor molecules on the surface for cell to cell signalling
cellular respiration
a continuously occurring chemical process which is universal and occurs in all living cells. it is exothermic and releases energy (in the form of ATP) from the breakdown of organic compounds such as glucose
cell wall
an outer layer made of cellulose fibres. it provides the plant cell with strength and support.
chloroplasts
the organelles that are the site of photosynthesis. they contain chlorophyll (a green pigment) which absorbs light energy and important enzymes that are needed for photosynthesis
chromosome
a long coiled molecule of DNA that carries genetic information in the form of genes
cover slip
a small piece of glass placed on top of the specimen to protect it from the lens
denaturation
the permanent change in the shape of an enzyme’s active site that stops the enzyme functioning normally
DNA
a polymer made up of four nucleotides, each consisting of a phosphate group and a common sugar which has one of four different bases attached: adenine, thymine, cytosine and guanine
enzymes
biological catalysts that increase the rate of chemical reactions
enzyme specificity
enzymes will only act on specific substrates that have a complementary shape to the active site of the enzyme
eukaryotic cell
a type of cell found in plants and animals that has a nucleus and other membrane-bound organelles
exothermic reaction
a reaction that releases energy, usually in the form of light or heat
eyepiece lens
the lens that further magnifies the image produced by the objective lens
fatty acid
a carboxylic acid that has a long carbon chain. fatty acids react with glycerol to make lipids