breaks down big molecules to make them smaller and soluble
how does substrate concentration affect the reaction?
the higher the concentration, the faster the reaction
what will happen if the substrate’s shape doesn’t match the active site’s shape?
the reaction won’t be catalysed
what is a substrate?
the molecule that has changed in the reaction
what are the purposes of enzymes?
reduces the need for high temperatures. they speed up useful chemical reactions in the body
what is the equation for total magnification?
eyepiece lens magnification X objective lens magnification
what does Benedict’s reagent test for?
sugars
what does the Biuret test test for?
proteins
what solution is used to test for starch?
iodine
what do lipases convert lipids into?
glycerol and fatty acids
what is an active site?
the part where it joins on its substrate to catalyse the reaction
what is active transport?
movement of particles across a membrane, from low to high concentration using energy transferred from respiration
what is osmosis?
movement of water across a semi permeable membrane from high to low water concentration
what is diffusion?
movement of particles from high to low concentration
what is the difference between prokaryote and eukaryote cells?
prokaryotes: singlecelled organisms
eukaryotes: multicellular organisms
where are the nutrients in the egg cell to feed the embryo?
cytoplasm
why do sperm cells have a lot of mitochondria?
to provide energy (from respiration) to swim the distance
when using a microscope, what is the purpose of stain?
to make transparent/colourless specimens easier to see by highlighting different structures within cells
when were light microscopes invented?
1590s
what do light microscopes allow you to see?
nuclei and chloroplasts, they are used to study living cells
when were electron microscopes invented?
1930s
what do electron microscopes allow you to see?
internal structures of mitochondria and chloroplast, they are used to study how cells work and the role of subcellular structures
what is the ‘lock and key’ mechanism?
for the enzyme to work, the substrate has to fit into the active site, if it doesn’t match, the reaction won’t be catalysed
how many substrates do enzymes usually work with?
one substrate, they are said to have high specifity for their substrate
what happens if an enzyme-catalysed reaction gets too hot?
some of the bonds holding the enzymes together break. This changes the shape of the enzyme’s active site so the substrate won’t fit. The enzyme is denatured.
what other factors affect the nature of enzymes?
pH, if the pH is too high/low it interferes with bonds holding the enzyme together
what does the Emulsion Test test for?
lipids
which liquid is added to the test substance when testing for lipids?
ethanol, shake the test substance with ethanol for about a minute until it dissolves, then pour the solution into water
what will happen in the Emulsion Test if lipids are present?
lipids will precipitate out of the liquid and showup as a milkyemulsion
what is an emulsion?
when oneliquid doesn’t dissolve in another, it just forms little droplets
what do amylase convert starch into?
maltose
when using iodine, what colour does the solution turn when starch is present?
brown/orange to blue/black
what is the equation for the rate of reaction?
rate = 1000 / time
what happens inside plants when they need energy?
plants store energy in the form of starch. Enzymes break down the starch into smaller molecules (sugars), these can be respired to transfer energy to be used by cells
how are carbohydrates synthesised?
byjoining together simple sugars
how are proteins synthesised?
byjoiningtogetheramino acids
how are lipids synthesised?
by joining glycerol and fatty acids
what is glycogen synthase?
an enzyme that joins together lots of chains of glucose molecules to make glycogen