bio unit 1 mwhehe

diffusion

diffusion

the movement of the particles in a liquid or a gas down a concentration gradient from an area where they are at a relatively high concentration to an area where they are at a relatively low concentration

mass transport system

an arrangement of structures by which substances are transported in the flow of a fluid with a mechanism for moving it around the bod

concentration gradient

the change in the concentration of solutes present in a solution between two regions; in biology, this typically means across a cell membrane

single circulation system

a circulation in which the heart pumps the blood to the organs of gas exchange and the blood then travels on around the body before returning to the heart

double circulation system

system a circulation that involves two separate circuits, one of deoxygenated blood flowing from the heart to the gas exchange organs to be oxygenated before returning to the heart, and one of oxygenated blood leaving the heart and flowing around the body, returning as deoxygenated blood to the heart

systemic circulation

carries oxygenated blood from the heart to the cells of the body where the oxygen is used, and carries the deoxygenated blood back to the heart

pulmonary circulation

carries deoxygenated blood to the lungs and oxygenated blood back to the heart

cardiovascular system

the mass transport system of the body made up of a series of vessels with a pump (the heart) to move blood through the vessels circulation the passage of blood through the blood vessels

leucocytes

white blood cells; there are several different types which play important roles in defending the body against the entry of pathogens and in the immune system

carbonic anhydrase

the enzyme that controls the rate of the reaction between carbon dioxide and water to produce carbonic acid

Bohr effect

the name given to changes in the oxygen dissociation curve of haemoglobin that occur due to a rise in carbon dioxide levels and a reduction of the affinity of haemoglobin for oxygen

fetal haemoglobin

a form of haemoglobin found only in the developing fetus with a higher affinity for oxygen than adult haemoglobin

serotonin

a chemical that causes the smooth muscle of the blood vessels to contract. narrowing them and cutting off the blood flow to the damaged area

thromboplastin

an enzyme that sets in progress a cascade of events that leads to the formation of a blood clot

prothrombin

a large.soluble protein found in the plasma that is the precursor to an enzyme called thrombin

thrombin

an enzyme that acts on fibrinogen, converting it to fibrin during clot formation

fibrinogen

a soluble plasma protein which is the precursor of the insoluble protein fibrin

fibrin

an insoluble protein formed from fibrinogen by the action of thrombin that forms a mesh of fibres that trap erythrocytes and platelets to form a blood clot

systole

the contraction of the heart atrial systole when the atria of the heart contract

ventricular systole

when the ventricles of the heart contract

diastole

when the heart relaxes and fills with blood

cardiac cycle

the cycle of contraction (systole) and relaxation (diastole) in the heart

cardiovascular diseases

diseases of the heart and circulatory system, many of which are linked to atherosclerosis

atherosclerosis

a condition in which yellow fatty deposits build up (increase in amount) on the lining of the arteries, causing them to be narrowed and resulting in many different health problems

artheroma

plaques yellowish fatty deposits that form on the inside of arteries in atherosclerosis

atheroma

another term for a plaque formed on the arterial lining

aneurysm

a weakened, bulging area of artery wall that results from blood collecting behind a blockage caused by plaques

angina

a condition in which plaques are deposited on the
endothelium of the arteries and reduce the blood flow to the cardiac muscle through the coronary artery; it results in pain during exercise

angina

a condition in which plaques are deposited on the endothelium of the arteries and reduce the blood flow to the cardiac muscle through the coronary artery; it results in pain during exercise

myocardial Infarction (heart attack)

the events which take place when atherosclerosis leads to the formation of a clot that blocks the coronary artery entirely and deprives the heart muscle of oxygen, so it dies; it can stop the heart functioning

stent

a metal or plastic mesh tube that is inserted into an artery affected by atherosclerosis to hold it open and allow blood to pass through freely

thrombosis

a clot that forms in a blood vessel

stroke

an event caused by an interruption to the normal blood supply to an area of the brain which may be due to bleeding from d damaged capillaries or a blockage cutting off the blood supply to the brain, usually caused by a blood clot

anti hypertensive

drug which reduces high blood pressure

diuretics

drugs which increase the volume of urine produced

beta blockers

drugs which block the response of the heart to hormones such as adrenaline

sympathetic nerve inhibitors

drugs which inhibit sympathetic nerves, keeping arteries dilated

ACE inhibtors

drugs which block the production of angiotensin

statins

drugs that lower the level of cholesterol in the blood

placebo

an inactive substance resembling a drug being trialled which is used as an experimental control

plant stanols and sterols

similar in structure to cholesterol, these compounds can help reduce blood cholesterol in those consuming them

anti coagulant

a substance that interferes with the manufacture of prothrombin in the body

platelet inhibitory drug

drugs used to prevent blood clots forming by preventing platelets clumping together

fluid mosaic model

the current model of the structure of the cell membrane including floating proteins forming pores, channels and carrier systems in a lipid bilayer

gated channels

protein channels through the lipid bilayer of a membrane that are opened or closed, depending on conditions in the cell

glycoprotein

conjugated proteins with a carbohydrate prosthetic group

passive transport

transport that takes place as a result of concentration, pressure or electrochemical gradients and involves no energy from a cell

active transport

the movement of substances into or out of the cell using ATP which is produced during cellular respiration

diffusion

the movement of the particles in a liquid or gas down a concentration gradient from an area where they are at a relatively high concentration to an area where they are at a relatively low concentration

facilitated diffusion

diffusion that takes place through carrier proteins or protein channels

osmosis

a specialised form of diffusion that involves the movement of solvent molecules down their water potential gradient

carrier protein

a protein that moves a substance through the membrane in active transport using energy from the breakdown of ATP or in passive transport such as facilitated diffusion down a concentration gradient

endocytosis

the movement of large molecules into cells through vesicle formation

exocytosis

the movement of large molecules out of cells by the fusing of a vesicle containing the molecules with the surface cell membrane; the process requires ATP

water potential

a measure of the potential for water to move out of a solution by osmosis

osmotic concentration

a measure of the concentration of the solutes in a solution that have an osmotic effect

isotonic solution

a solution in which the osmotic concentration of the solutes is the same as that in the cells

hypotonic solution

a solution in which the osmotic concentration of solutes is lower than that in the cell contents

hypertonic solution

a solution in which the osmotic concentration of solutes is higher than that in the cell contents

hydrostatic pressure

the pressure exerted by a fluid in an equilibrium

turgor

the state of a plant cell when the solute potential causing water to be moved into the cell by osmosis is balanced by the force of the cell wall pressing on the protoplasm

incipient plasmolysis

the point at which so much water has moved out of the cell by osmosis that turgor is lost and the cell membrane begins to pull away from the cell wall as the protoplasm shrinks

plasmolysis

the situation when a plant cell is placed in hypertonic solution when so much water leaves the cell by osmosis that the vacuole is reduced and the protoplasm is concentrated and shrinks away from the cell walls

phagocytosis

the active process when a cell engulfs something relatively large such as a bacterium and encloses it in a vesicle

pinocytosis

the active process by which cells take in tiny amounts of extracellular fluid by tiny vesicles

lung surfactant

a special phospholipid that coats the alveoli and prevents them from collapsing

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

a series of linked reactions in the metabolism of a cell

intracelluar 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

molecular activity or turnover number

the number of substrate molecules transformed per minute by a single enzyme molecule

temperature coefficient

the measure of the effect of temperature on the rate of a reaction

denaturation

the loss of the three

intial 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

purine base

a base found in nucleotides that has two nitrogen

pyrimidine base

a base found in nucleotides that has one nitrogen

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

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

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

semi conservative 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

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

triplet code

the code of three bases that is the basis of the genetic information in the DNA

complementary strand

the strand of RNA formed that complements the DNA acting as the coding strand