Studied by 9 people
Looks like no one added any tags here yet for you.
catalyst
a substance that speeds up a reaction without changing the substances produced or being changed itself
enzymes
proteins that act as biological catalysts for a specific reaction or group of reactions
specificity
the characteristic of enzymes that means that each enzyme will catalyse only a specific reaction or group of reactions; this is due to the very specific shapes which come from the tertiary and quaternary structures
anabolic reaction
a reaction that builds up (synthesises) new molecules in a cell
catabolic reaction
a reaction which breaks down substances within a cell
metabolism
the sum of the anabolic and catabolic processes in a cell
metabolic chain (metabolic pathway)
a series of linked reactions in the metabolism of a cell
intracellular enzymes
enzymes that catalyse reactions within the cell
extracellular enzymes
enzymes that catalyse reactions outside of the cell in which they were made
activation energy
the energy needed for a chemical reaction to get started
substrate
the molecule or molecules on which an enzyme acts
lock-and-key hypothesis
a model that explains enzyme action by an active site in the protein structure that has a very specific shape; the enzyme and substrate slot together to form a complex in the same way as a key fits in a lock
active site
the area of an enzyme that has a specific shape into which the substrate(s) of a reaction fit
induced-fit hypothesis
a modified version of the lock and-key model of enzyme action where the active site is considered to have a more flexible shape; after the substrate enters the active site, the shape of that site changes around it to form the active complex; after the products have left the complex, the enzyme returns to its inactive, relaxed form
molecular activity (turnover number)
the number of substrate molecules transformed per minute by a single enzyme molecule
temperature coefficient (Q10)
the measure of the effect of temperature on the rate of a reaction
denaturation
the loss of the three-dimensional shape of a protein (e.g. caused by changes in temperature or pH)
initial rate of reaction
the measure taken to compare the rates of enzyme-controlled reactions under different conditions
mononucleotides
molecules with three parts - a 5-carbon pentose sugar, a nitrogen-containing base and a phosphate group - joined by condensation reactions
adenosine triphosphate (ATP)
a molecule that acts as the universal energy supply molecule in cells; it is made up of the base adenine, the pentose sugar ribose and three phosphate groups
deoxyribonucleic acid (DNA)
a nucleic acid that is the genetic material in many organisms
ribonucleic acid (RNA)
a nucleic acid which is the genetic material in some organisms and is involved in protein synthesis
ribose
a pentose sugar that is part of the structure of RNA
deoxyribose
a pentose sugar that is part of the structure of DNA
purine base
a base found in nucleotides that has two nitrogen-containing rings
pyrimidine base
a base found in nucleotides that has one nitrogen-containing ring
adenine
a purine base found in DNA and RNA
guanine
a purine base found in DNA and RNA
cytosine
a pyrimidine base found in DNA and RNA
thymine
a pyrimidine base found in DNA
uracil
a pyrimidine base found in RNA
nucleic acids
polynucleotides /polymers made up of many nucleotide monomer units that carry all the information needed to form new cells
phosphodiester bond
bond formed between the phosphate group of one nucleotide and the sugar of the next nucleotide in a condensation reaction
complementary base pairs
complementary purine and pyrimidine bases which align in a DNA helix, with hydrogen bonds holding them together (C-G, A-T)
genome
the entire genetic material of an organism
conservative replication
a model of DNA replication which suggests that the original double helix remains intact and in some way instructs the formation of a new, identical double helix made up entirely of new material
semiconservative replication
the accepted model of DNA replication in which the DNA 'unzips' and new nucleotides align along each strand; each new double helix contains one strand of the original DNA and one strand made up of new material
isotopes
different atoms of the same element, with the same number of protons but a different number of neutrons; isotopes have the same chemical properties
DNA helicase
an enzyme involved in DNA replication that 'unzips' the two strands of the DNA molecules
DNA polymerase
an enzyme involved in DNA replication that lines up the new nucleotides along the DNA template strands
DNA ligase
an enzyme involved in DNA replication that catalyses the formation of phosphodiester bonds between the nucleotides
translation
the process by which proteins are produced, via RNA, using the genetic code found in the DNA; it takes place on the ribosomes
ribosomes
the site of protein synthesis in the cell
triplet code
the code of three bases that is the basis of the genetic information in the DNA
gene
a sequence of bases on a DNA molecule; it contains coding for a sequence of amino acids in a polypeptide chain that affects a characteristic in the phenotype of the organism
codon
a sequence of three bases in DNA or mRNA
messenger RNA (mRNA)
the RNA formed in the nucleus that carries the genetic code out into the cytoplasm
complementary strand
the strand of RNA formed that complements the DNA acting as the coding strand
non-overlapping code
a code where each codon codes for only one thing with no overlap between codons
degenerate code
a code containing more information than is needed
point mutation
a change in a single base of the DNA code
sense strand
the DNA strand that carries the code for the protein to be produced
antisense strand (template strand)
the DNA strand which acts as a template for an mRNA molecule
start codon
the sequence of bases which indicates the start of an amino acid chain - TAC; this is the code for the amino acid methionine
RNA polymerase
the enzyme that polymerises nucleotide units to form RNA in a sequence determined by the antisense strand of DNA
stop codon
one of three sequences of bases which indicate the end of an amino acid chain
transfer RNA (tRNA)
small units of RNA that pick up specific amino acids from the cytoplasm and transport them to the surface of the ribosome to align with the mRNA
anticodon
a sequence of three bases on tRNA that are complementary to the bases in the mRNA codon
translation
the process by which the DNA code is converted into a protein from the mRNA strand made in the nucleus
transcription
the process by which the DNA sequence is used to make a strand of mRNA in the nucleus
polysomes
groups of ribosomes, joined by a thread of mRNA, that can produce large quantities of a particular protein
