1.2 proteins

Question 1

alternative RNA splicing

Answer 1

removal of non-coding inions form a primary mRNA transcript to leave only the coding axons; several different mature transcripts can be produced from a single primary trancript

Question 2

ER (endoplasmic reticulum)

Answer 2

a network of membrane tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane

Question 3

exon

Answer 3

section of RNA usually retained during splicing

Question 4

glycoprotein

Answer 4

a protein with a carbohydrate added by post-translational modification

Question 5

Golgi apparatus

Answer 5

a series of flattened membrane discs the package proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination

Question 6

hydrolyses

Answer 6

a class of enzyme that use water to break chemical bonds

Question 7

intron

Answer 7

a section of RNA usually removed during splicing

Question 8

lysosome

Answer 8

a modified Golgi vesicle containing hydrolytic enzymes

Question 9

non-coding RNA gene

Answer 9

a gene that codes for RNA’s other than messenger RNA, so they do not code for a protein

Question 10

phospholipid

Answer 10

component of cell membrane

Question 11

post-translational modification

Answer 11

addition of different chemical groups to, or modification of, a protein to allow for a particular function

Question 12

proteolytic cleavage

Answer 12

a major form of post-translational modification; it occurs when a protein cleaves one or more bonds in a target protein to activate, inhibit or destroy the proteins activity

Question 13

proteome

Answer 13

the entire set of proteins expressed by a genome; it is much larger than the genome

Question 14

RER (rough endoplasmic reticulum)

Answer 14

organelle made up of membrane with ribosomes attached

Question 15

signal sequence

Answer 15

a short stretch of amino acids at one end of the polypeptide that determines its eventual location in a cell

Question 16

SER (smooth endoplasmic reticulum)

Answer 16

a membrane organelle found in most eukaryotic cells; its main function are to synthesis of lipids and steroid hormones

Question 17

vesicles

Answer 17

small membrane bound compartments filled with liquid

Question 18

allosteric enzymes

Answer 18

enzymes that change conformation in response to a modulator

Question 19

alpha helix

Answer 19

polypeptide chain coiled into a helix with hydrogen bonding occurring to maintain the arrangement

Question 20

beta-pleated sheets

Answer 20

polypeptide chain arranged in rows with the chain folding in parallel or anti-parallel arrangements

Question 21

conformation

Answer 21

structural arrangement of the polypeptide chains within a protein; it can be altered by factors such as pH and the binding of ligands and modulators

Question 22

co-operativity

Answer 22

changes in binding of a target molecules to one subunit of a multiunit polypeptide changes the affinity of the other subunits for the target molecule

Question 23

disulphide bridge

Answer 23

a strong covalent bond that stabilises the tertiary and quaternary structures of many proteins

Question 24

hydrogen bonds

Answer 24

attractions between polar molecules in which hydrogen is bound to a larger atom, such as oxygen or nitrogen

Question 25

ionic bonds

Answer 25

a type of chemical bonding that involves the electrostatic attraction between opposites charged ions

Question 26

ligand

Answer 26

a substance that can bind to a protein; the protein has a complementary shape to the ligand to allow binding

Question 27

London dispersion force

Answer 27

a temporary weak attraction between atoms and molecules

Question 28

modulators

Answer 28

these bind to a secondary site on an enzyme to alter its conformation; positive modulators activate enzymes and negative modulators deactivate/inhibit them

Question 29

monomer

Answer 29

a molecule that can bind chemically to other monomers to form a polymer

Question 30

polymer

Answer 30

a macromolecule composed of many repeated subunits

Question 31

prosthetic group

Answer 31

a non-protein unit tightly bound to a protein and necessary for its function

Question 32

protein kinases

Answer 32

catalyse the transfer of a phosphate group from a donor molecule (usually ATP) to an acceptor

Question 33

protein phosphatases

Answer 33

an enzyme that removes a phosphate group from its substrate

Question 34

protein strucure

Answer 34

different levels of arrangement of polypeptides within a protein

Question 35

primary structure

Answer 35

sequence in which amino acids are found within a protein

Question 36

secondary structure

Answer 36

hydrogen bonding occurring within a polypeptide forming alpha helices or beta-pleated sheets

Question 37

tertiary structure

Answer 37

bonding of many types occurring between the R groups of amino acids within a protein

Question 38

quaternary structure

Answer 38

the arrangement of multiple folded polypeptides connected together

Question 39

proteolytic cleavage

Answer 39

a major form of post-translation modification; it occurs when a protease cleaves one or more bonds in a target protein to activate, inhibit or destroy the proteins activity

Question 40

R groups

Answer 40

side groups that allow different bonding between amino acids and give them their wide range of functions

Question 41

hydrophobic group

Answer 41

composed mostly of carbon and hydrogen, and tend to be repelled from water

Question 42

turns

Answer 42

secondary structure that reverses the direction of a polypeptide chain