topic 1

anti-sense strand

the strand of DNA which is used as a complementary template and used for complementary mRNA synthesis

coding DNA

the sections of DNA which code for proteins

degenerate

a term used to describe the fact that some amino acids can be coded for by multiple different codons

deletion mutation

a type of mutation where nucleotides are not incorporated into the chain and are lost which results in frameshift mutation

deoxyribonucleic acid

a helical double-stranded polymer made of deoxyribonucleotide monomers joined by phosphodiester bonds which contains genes that code for proteins

DNA helicase

the enzyme which unzips the DNA helix by breaking down the hydrogen bonds between the chains during processes like DNA replication and transcription

DNA polymerase

an enzyme that catalyses the formation of phosphodiester bonds between nucleotides during the synthesis of a new DNA strand

gene

a sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chain

gene mutation

a change to at least one nucleotide base in DNA or the arrangement of bases. gene mutations occur spontaneously and may result in harmful or beneficial changes to the genotype

insertion mutation

a type of mutation where extra nucleotides are incorporated into the growing DNA chain which results in frameshift mutation

ligase

the enzyme which joins okazaki fragments on the lagging strand together by forming phosphodiester bonds between them

mRNA

a type of single-stranded RNA molecule that carries genetic information from the DNA in the nucleus to the ribosomes for translation

non-coding DNA

the sections of DNA which do not code for proteins

non-overlapping

a term used to describe the fact that each base is only part of one codon and that each codon is read one at a time in order

nucelotides

the individual monomers that make up polynucleotides which are composed of a phosphate group, pentose sugar, and a nitrogenous base

purines

a class of nitrogenous base which are made up of two rings that adenine and guanine are members of

pyrimidines

a class of nitrogenous base which are made up of a single ring that cytosine, thymine, and uracil are members of

ribosome

an organelle found either free in the cytoplasm or as a part of the rough endoplasmic reticulum which catalyses protein synthesis

RNA polymerase

an enzyme that catalyses the formation of phosphodiester bonds between nucleotides during the synthesis of a new RNA strand

semi-conservative replication

a type of DNA replication where each new molecule of DNA produced contains one original strand and one newly synthesised strand

sense strand

the strand of DNA which is complementary to the anti-sense strand and is identical to the transcribed mRNA (with the exception of the sense strand containing thymine in the place of uracil)

sickle cell anaemia

a type of genetic disease which produces faulty 'sickle shaped' haemoglobin due to a point mutation that causes a change in a single amino acid in the polypeptide sequence

substitution mutation

a type of mutation where the incorrect nucleotide is incorporated into the growing DNA chain

transcription

the process of synthesising a new mRNA strand from a molecule of DNA which occurs in the nucleus

tRNA

a type of RNA that has three hairpin loops, an anticodon for attachment to the mRNA codon and an amino acid binding site. it is used to carry amino acids to the ribosome for translation

translation

the process of protein synthesis where complementary tRNAs carrying amino acids are brought to each codon in an mRNA molecule as it moves through a ribosome

triplet

a term used to describe the fact that DNA is grouped into three base long codons that are read together and code for an amino acid

alpha glucose

an isomer of glucose which has the hydroxyl group on carbon-1 below the plane of the ring

beta glucose

an isomer of glucose which has the hydroxyl group on carbon-1 above the plane of the ring

cellulose

a structural polysaccharide found in plants that composes the cell wall and is made of beta glucose molecules joined by 1-4 glycosidic bonds

condensation reaction

a type of reaction between two molecules which forms a bond and releases water

disaccharides

molecules formed by the condensation of two monosaccharides

glycogen

a highly branched polysaccharide made of alpha glucose monomers that is used as the main storage of energy in humans and animals

glycosidic linkage

a type of covalent bond formed between two sugars during a condensation reaction in the form C-O-C

hexose sugar

a type of monosaccharide which contains 6 carbon atoms such as glucose

hydrolysis

a type of reaction which breaks a chemical bond using a molecule of water

lactose

a simple disaccharide of alpha glucose and galactose joined by a glycosidic bond

maltose

a simple disaccharide composed of two alpha glucose molecules joined by a glycosidic bond

monosaccharides

the individual sugar monomers from which larger carbohydrates are made

polysaccharide

polymers formed by the condensation of many monosaccharides

ribose

a 5-carbon sugar which is found in the structure of molecules like RNA

starch

a polysaccharide made of amylose and amylopectin that is used as the main storage of energy in plants

sucrose

a simple disaccharide composed of glucose and fructose joined by a glycosidic bond

amphipathic

a molecule which has both hydrophobic parts and hydrophilic parts

ester bond

a type of bond formed in a condensation reaction which joins each of the fatty acids tails to the glycerol molecule in a triglyceride

fatty acids

long carbon chain molecules which have a carboxylic acid head group and may contain C\=C bonds

glycerol

a 3-carbon molecule which contains 3 hydroxyl groups and is a component of triglycerides

phospholipids

a type of amphipathic lipid found in cell membranes which is based on a triglyceride where one of the fatty acid tails is replaced with a negative phosphate group

saturated lipid

a lipid molecule containing only single bonds between the carbon atoms

triglyceride

a lipid macromolecule composed of one molecule of glycerol joined by ester bonds to 3 fatty acid tails

unsaturated lipid

a lipid which contains at least one C\=C double bond

amino acid

the monomers containing an amino group, a carboxyl group, and a variable R group that make up proteins

collagen

a type of fibrous protein that provides strength to many different cell types and makes up connective tissues

disulfide bond

a type of covalent bond between two sulphur containing R-groups which holds together the tertiary and quaternary structures of proteins

fibrous protein

a class of long chain proteins that are generally insoluble in water and typically have structural roles

globular protein

a class of spherical shaped proteins that are generally water soluble and typically have metabolic roles

haemoglobin

a conjugated globular protein that is specialised to transport oxygen around the body and has a quaternary structure which is composed of two alpha chains and two beta chains that contain non-protein haem groups

hydrogen bond

a type of intermolecular bond between a slightly positive hydrogen atom and a slightly negative atom such as oxygen or nitrogen which is used to hold together the secondary, tertiary, and quaternary structures of proteins

ionic bond

a type of bond between two charged R groups which help stabilise the tertiary and quaternary structures of proteins

peptide bond

a type of bond which joins the amino group in one amino acid to the carboxyl group of in another amino acid in a condensation reaction

primary structure

the individual sequence of amino acids in a protein

protein

a polymer made up of amino acid monomers joined by peptide bonds in condensation reactions

quaternary structure

a structure only applicable to proteins with multiple polypeptide chains that describe the interactions of the different chains

secondary structure

the local interactions of the amino acids in the polypeptide chain held together by hydrogen bonds in the form of alpha helices or beta pleated sheets

tertiary structure

the way that the whole protein folds to make a three dimensional structure involving hydrogen bonds, ionic bonds, and disulphide bridges