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
genetic material
the material that stores the genetic information
light microscope
a microscope that uses light to produce an image of a specimen
limiting factor
a factor that when in short or inadequate supply limits the rate of a reaction
lipase
an enzyme that breaks down lipids into fatty acids and glycerol
lipid
a large molecule that is synthesised from three fatty acids and a glycerol molecule
lock and key hypothesis
a theory that describes how substrates must be the correct shape to fit the active site of an enzyme
magnification
how many times larger the image appears relative to the original object
magnification = image size / actual size
mitochondria
the organelle which is the site of aerobic respiration. it contains enzymes required for cellular respiration.
monomer
a small molecule which can be bonded to other identical monomers to form a large polymer. monomers usually contain a carbon-carbon double bond, C=C.
nucleotide
the monomers of DNA that consist of a common sugar, a phosphate group and a base attached to the sugar.
nucleus
an organelle found in most eukaryotic cells that contains the cell’s genetic material and controls the activities of the cell
objective lens
the lens found closest to the specimen that magnifies the image
palisade mesophyll
a specialised plant tissue that carries out photosynthesis
permanent vacuole
an organelle found in plant cells which stores cell sap and helps maintain the cell’s turgidity. a small, temporary vacuole can be found in animal cells that is used for the storage and transportation of substances.
photosynthesis
an endothermic reaction that takes place in the chloroplasts, converting carbon dioxide and water into glucose and oxygen using light energy. it is a two-stage process.
6CO2 + 6H20 > C6H12O6 + 6O2
photosynthetic organisms
organisms that are the main producers of food and therefore biomass for life on earth
plasmid
a circular loop of double-stranded DNA that is found in the cytoplasm of prokaryotic cells. it is free to move unlike chromosomal DNA
polymer
many small molecules (monomers) chemically joined together to make 1 large molecule
prokaryotic cell
a unicellular organism that lacks a nucleus and other membrane-bound organelles etc bacteria
protein
a large molecule synthesised from amino acid monomers
protein synthesis
the formation of proteins from amino acids which takes place in the ribosomes
resolution
the ability to see two cells as two separate entities (measured in dpi)
ribosomes
organelles which are the site of protein synthesis
scanning electron microscope
a microscope that uses reflected electrons to produce an image of a specimen. it creates a 3d image with a lower resolution.
slide
a thin piece of glass on which the specimen is placed
slide
a thin piece of glass on which the specimen is placed
transcription
the unzipping of the DNA molecule around the gene, copying it to mRNA in the nucleus
translation
translating the mRNA sequence to an amino acid sequence during protein synthesis
transmission electron microscope
a microscope that uses transmitted electrons to produce an image of a specimen. it creates a 2d image with a higher resolution so details of organelles can be seen.
xylem
a specialised plant tissue that transports water and dissolved minerals from the roots to the leaves of the plant
