Definitions Flashcards
Anticodon
A sequence of 3 adjacent nucleotides on a molecule of tRNA that is complementary to a particular codon on a mRNA molecule
Cardiac Muscle
Type of muscle found only in the heart. Fewer striations than skeletal muscle and can contract continuously throughout life without stimulation by nerve impulses.
Clone
A group of genetically identical organisms formed form a single parent as a result of asexual reproduction or by artificial means
Dendrite
Extending from the cell body of a neurone -> conducts impulses towards the cell body
Depolarisation
Temporary reversal of charges on the csm of a neurone that takes place when a nerve impulse is transmitted
Diabetes
A metabolic disorder in which the body is unable to regulate the level of blood glucose
DNA helicase
Enzyme that acts on a specific region of the DNA molecule to break the hydrogen bonds between bases causing 2 strands to separate and expose the nucleotide bases in that region
Ectotherm
An organism that uses the environment to regulate its body temperature
Gene marker
A section of DNA that’s used to indicate the location of a gene or other section of DNA
Gene therapy
A mechanism by which genetic diseases may be cured by masking the effect of the defective gene by inserting a functional gene
Generator potential
Depolarisation of the membrane of a receptor cell as a result of a stimulus
GMO
Organism that has had its DNA altered as a result of recombinant DNA technology
Glucagon
A hormone produced by alpha cells of the islets of Langerhan the pancreas that increases blood glucose levels by initiating the breakdown of glycogen to glucose
Gluconeogensis
The conversion of non-carbohydrate molecules to glucose
Glycogenesis
The conversion of glucose to glycogen
Hypothalamus
A region of the brain adjoining the pituitary gland that acts as the control centre for the autonomic nervous system and regulates body temperature and fluid balance
Insulin
A hormone produced by beta cells of the islets of Langerhans in the pancreas, which decreases blood glucose levels by increasing the rate of conversion of glucose to glycogen
Ligament
A tough fibrous connective tissue, rich in collagen that joins bone to bone
Motor neurone
Neurone that transmits action potential from the CNS to an effector
Mutagen
Any agent that induces a mutation
Mutation
A change in teh sequence of bases in DNA
Myelin
A fatty substance that surrounds axons and dendrites
Negative feedback
A serious of changes that result in a substance being restored to its normal level
Neurotransmitter
One of a number of chemicals that are involved in communication between adjacent neurones or between nerve cells and muscles.
node of Ranvier
Gap in myelin sheath
Normal distribution
Bell shaped curve
Oestrous
The period in the oestrous cycle immediately after ovulation when the female is most fertile
Oncogenes
Mutated proto-oncogenes that result in increased cell division leading to the growth of a tumour
Pentose sugar
In ribose and deoxyribose
Plasmid
Small circular piece of DNA found in bacterial cells
Polygenes
Group of genes that are responsible for controlling a characteristic
PCR
Process of making many copies of a specific sequence of DNA or part of a gene
Positive feedback
Process which results in a substance that departs from its normal level becoming further from its normal
Receptor
A cell adapted to detect changes in the environment
Recognition site
A nucleotide sequence that is recognised by a restriction endonuclease when it attaches
Recombinant DNA Technology
Processes by which genes are manipulated, altered or transferred from organism to organism
Reflex arc
The nerve pathway in the body taken by an action potential that leads to a rapid, involuntary response to a stimulus
Refractory period
Membrane of the axon of a neurone can’t be depolarised so no new action potential can be initiated -> prevents continuous nerve impulses
Repolarisation
Return to resting potential in the axon of a neurone after an action potential
Resting potential
The difference in electrical charge maintained across the membrane of the axon of a neurone when not stimulated
RNA polymerase
Enzyme that joins together nucleotides to form mRNA during transcription
Restriction endonuclease
A group of enzymes that cut DNA molecules at a specific sequence of bases called a recognition site
Saltatory conduction
Propagation of a nerve impulse along a myelinated dendron or axon in which the action potential moves by saltatory conduction through adjacent nodes of Ranvier
Sacromere
A section of myofibril between two adjacent Z lines that form the basic structural unit of skeletal muscle
Schwann cell
Cell around a neurone whose csm wraps around the dendron or axon to form a myelin sheath
Sensory neurone
transmits an a.p. from a sensory receptor to CNS
Skeletal muscle
Makes up the bulk of the body and works under conscious control -> voluntary muscle
SAN
An area of the heart muscle in the right atrium that controls and coordinates the contraction of the heart
Smooth muscle
Involuntary + unstriated found in the alimentary canal and the walls of blood vessels. Its contraction is not under conscious control
Stem cells
Undifferentiated dividing cells
Synapse
A junction between 2 neurones where they do not touch across which a NT can pass
Tendon
Tough, flexible but inelastic connective tissue that joins muscle to bone
Threshold value
The minimum intensity a stimulus must reach in order to trigger an action potential in a neurone
Transducer cells
Cells that convert a non-electrical signal into an electrical nervous signal
Tumour suppressor gene
A gene that maintains normal rates of cell division preventing the development of tumours
Vasoconstriction
Narrowing of the internal diameter of blood vessles
Vasodilation
Widening of the internal diameter of blood vessels
Vector
A carrier e.g. a plasmid which carries DNA into a cell
