Higher Biology Unit 2

anabolic pathway brings about the biosynthesis of complex molecules from simpler ones, which requires energy

e.g. protein synthesis

catabolic pathway brings about the breakdown of complex molecules to simpler ones, releasing energy

e.g. aerobic respiration

The cell membrane is composed of proteins and phospholipids which is selectively permeable. this means it allows certain molecules enter or exit the cell through the membrane.

Cell organelles are also bounded by membranes- mitochondria and chloroplast, which take the forms of folds and compartments. This allows meatbolic activity to be localised with particular sites only responsible for specific reactions.

certain metabolites need to be in close and continuous association in order to work in an efficient and integrated manner.

Protein pores transports large molecules across the membrane into or out of the cell. They provide channels for specific substances to diffuse across the membrane.

sodium/ potassium pump act as carrier molecules which they transfer specific ions across the cell membrane. the sodium ions gets actively pumped ot of the cell and the potassium ions into the cell ech against its own concentration gradient.

a pump requires energy therefore factors such as temperature and availability of oxygen and food is directly affects the rate of active transport

glycolysis occurs in the cytoplasm

a molecule of glucose is broken down to form pyruvate.

in the energy investment stage 2 ATPs are used per molecule of glucose

in the energy payoff phase 4 ATPs is produced  per molecule of glucose giving a net gain of 2 ATPs per molecule of glucose

H ions is released from the dehydrogenase enzyme and then passed to the coenzyme molecule- NAD froming NADH

gycolysis does not require oxygen

citric acid cycle takes place in the matrix of the mitochondria

pyruvate is then broken down into CO2 and an acetyl group

each acteyl group combines to  coenzyme A  to from acteyl coenzyme A.

further H ions are released and bounded to NAD to form NADH

acetyle coenzyme A combines with oxaloacetate to form citrate and enter the citric acid cycle

a series of enzyme controlled steps results in the regeneration of oxaloacetate

dehygrogenase enzymes remove H ions from respiratory substrate along with high energy electrons

H ions and high energy electrons are passed to coenzyme Nad to ofrm NADH

FAD coenzyme accepts H ions and electrons which  forms FADH2

ATP is produced, CO2 is released

electron transport chain takes place in the inner membrane of the mitochondria

NADH and FADH2 releases high energy electrons and pass them to electron transport chain

as electrons flow along a chain of electron acceptors, they release energy

this is used to pump H ions across the membrane fron the inner matrix where a high concentration of H ions are

the return flow of H ions to the matrix via molecules of ATP synthase drives this enzyme to synthesise ATP from ADP + Pi

electrons combine with o2, the final acceptor as well as the oxygen combines with a pair of hydrogen ions to form water

starch (plants) + gylcogen (animals)  are composed of chains of glucose. they act as repiratory substrates and can be broken down to release glucose

fat is broken down into glycerol and fatty acids. Gycerol is then converted to to a gycolytic intermediate and the fatty acids are metabolised into molecular fragments that enter metabolic pathway as acetyl coenzyme A for citric acid cycle

present in a fish

described as single because blood passes through the two chambered heart only once for each complete circuit of the body.

a drop in pressure occurs when blood passeds through the capillary bed beacuse its network of narrow tubes which offer resistance to flow of blood

inneficient method

blood is passed through the heart twice for each complete circuit of the body

blood is pumped to the lungs and the bodys cappilary beds at high pressure ensuring a vigourous flow to all parts

more efficient than a single one

amphibians and reptiles

only one ventricle in the heart

some mixing of oygenated blood from the lungs and deoxygenated blood from the body occures

blood returning from the body has been partly oxygenated by gas exchange through animals moist skin

in most reptiles, little mixing occurs because the single venticle is partly divided by a septum

birds and mammals

the heart has 2 venticles completely sparated by a septum. Therefore no mixing of oxygenated and deoxygenated blood occurs.

most advance and efficient

enables endothermic vertebrate to deliver large quatities of oxygen to repiring tissues which release heat during metabolism and keep its body warm

fluctuations in an external abiotic factor such as the salinity and temperature may occur in an organisms environment.

some organisms such as regulators are able to alter their metabolic rate to maintain a steady state by employing physiological machanism

the state of a regulators internal environment is not directly dependant upon the abiotic factors that affect its external environment

regulaters employ physiological means to control their inner state

the animal is able to exploit a wider range of ecological niches

the animal has to expend energy generated bny its metabolism on the physiological mechanisms needed to maintain its inner state

the state of a conformers internal environment is directly dependant upon the abiotic factors that affect its external environment

conformers live in environments that are relatively stable

metabolic costs are low since it does not emply enerfy consuming physiological meachanisms to maintain its inner state

the aninal is restricted to a narrow range of ecological niche s and is less adaptable to environmental change.

many emply behavioral responses to maintain their optimum meatbolic rate

ectothern is an animal which is unable to regulate its body temp by physiological means.

their temperatures normally varies directly with that of the extermal environment

they obtain most heat by absorbing it from the surrounding environment

endothern is an animal which is able to maintain its body temperature at a constant level independant of the temperature of the external environment

lag phase- little or no increase in cell number. the cells adjust to its growth medium

log phase - the cells grow and multiply at the maximum rate, provided that no factor is limited

stationaty phase - nutrients begins to run out and/ or secondary metabolites start to build up- have a toxic effect. the rate of production of new cells equal to the death rate of old ones

death phase - lack of nutrient substrates and/or accumulation of a high concentration of toxic metabolites lead to the death phase.

restriction endonuclease is an enzyme extracted from bacteria which is used to cut up the DNA into fragments and to cleave open the bacterial plasmids that are to recieve it

recognises a specific short sequence of DNA bases called a restriction site.

DNA ligase is an enzyme which seals sticky ends together.

seal a DNA fragment into a bacterial plasmid to from recominant plasmid containing recombinant DNA