topic 1: key concepts in biology Flashcards
acrosome
an organelle in the tip of a sperm that contains enzymes which digest the egg cell membrane
active site
a specific region on an enzyme where the substrate binds and the reaction takes place
active transport
the movement of substances from a low concentration to a high concentration (against the concentration gradient) across a membrane, with the use of energy from respiration
Benedict’s test
a chemical test used to test for reducing sugars that produces a different colour based on the amount of reducing sugar present
biuret test
a chemical test that produces a purple colour when it is added to a solution containing protein
carbohydrases
enzymes that break down carbohydrates into simple sugars
carbohydrate
a large molecule that is synthesised from simple sugars
cell
the basic building block of all living organisms
cell membrane
a partially permeable barrier that surrounds the cell
cell wall
an outer layer made of cellulose that strengthens plant cells
chloroplast
an organelle that is the site of photosynthesis
chromosome
a long, coiled molecule of DNA that carries genetic information in the form of genes
cilia
hair like structures found on ciliated epithelial cells which waft substances across the surface of the tissue in one direction
ciliated epithelial cell
a type of epithelial cell that lines the surface of structures such as the respiratory tract and uterus
concentration gradient
the difference in concentration between two areas
denaturation
upon exposure to high temperatures or extremes of pH, the permanent change in the shape of an enzymes active site that prevents the binding of the substrate
diffusion
the net spreading out of particles from a high concentration to a lower concentration (down their concentration gradient)
diploid cell
a cell that contains two copies of each chromosome (i.e. a full set of chromosomes)
egg cell
a specialised female sex cell involved in reproduction
electron microscope
a type of microscope that uses a beam of electrons, focused using magnets, to produce an image of a specimen. it has a higher magnification and resolution that a light microscope
enzyme
a biological catalyst that increases the rate of reactions in living organisms
eukaryotic cell
a type of cell found in plants and animals that contains a nucleus
flagella
a long hair like structure found on bacterial cells that is used for cell movement
haploid cell
a cell that contains a single copy of each chromosome (i.e. half the number of chromosomes)
light microscope
a type of microscope that uses a series of lenses to magnify the visible light reflecting off a specimen
lipases
enzymes that break down lipids into fatty acids and glycerol
lipid
a large molecule that is synthesised from fatty acids and glycerol
lock and key hypothesis
a theory that describes how substrates must be the correct shape to fit the active site of an enzyme
magnification
the number of times bigger an image appears compared to the original object
(image size = magnification x real size)
micrometre (μm)
a quantitative unit of length. one micrometer is equal to x10⁻⁶ meter
millimeter (mm)
a quantitative unit of length. one millimetre is equal to x10⁻³ meter
mitochondria
an organelle that is the site of respiration
nanometer (nm)
a quantitative unit of length. one nanometer is equal to x10⁻⁹ meter
nucleus
an organelle found in most eukaryotic cells that contains the genetic material of the cell and controls the activities of the cell.
organelle
a specialised structure found inside a cell
osmosis
the diffusion of water molecules from a region of high water concentration to a region of lower water concentration across a partially permeable membrane
percentage change in mass
the proportion of the mans of a substance that has changed over a set period
picometer (pm)
a quantitative unit of length. one picometer is equal to x10⁻¹² meter
plasmid
loops of DNA found in the cytoplasm of prokaryotic cells
prokaryotic cell
a type of cell found in bacteria that does not contain a nucleus
proteses
enzymes that break down proteins into amino acids
rate of reaction
the speed at which reactants are converted into products
resolution
the smallest distance between two objects that can be distinguished
ribosomes
sub-cellular structures that are the site of protein synthesis
specialised cell
a cell that has a structure which makes it adapted to its function
specificity
describes the ability of an enzyme to catalyse only a particular reaction or set of reactions in which a specific substrate fits the active site of the enzyme
sperm cell
a specialised male sex cell that is involved in reproduction
vacuole
an organelle found in plant cells which stores cell sap and supports the cell
