Chapter 9 Flashcards
what are the advantages of having membrane bound organelles
creates specialised environments for specific functions. increases the number of activities that can occur at the same time in a limited space + under different conditions. Can concentrate reactants and store products
what is an enzyme
organic substance that increases the speed of chemical changes without being altered in the change
what is a catabolic reaction
where complex molecules break down into simpler ones. eg, Breakdown of glucose in respiration
what is a anabolic reaction
where simple molecules join together to form larger, complex molecules. Eg, when amino acids are joined together to form proteins
what are exergonic reactions
Reactions that release energy (exo=out). Seen in catabolic reactions
what are endergonic reactions
reactions that absorb energy (endo=in). Seen in anabolic reactions
what is activation energy
the energy required to initiate a reaction
what is the lock and key model
a model suggesting that the shape of a substrate molecule is an exact fit to the shape of an enzymes active site.
what is the induced fit model
a model to explain that the shape of an enzyme’s active site undergoes specific changes, induced by the substrate to achieve a high degree of specificity with the substrate
what are the five factors that affect enzyme activity
Temperature, pH, Concentration, Inhibitors, Cofactors and coenzymes
how does a change in temperature effect enzyme activity
as the temperature increases, molecules become more active and collide more often. This increase in collisions increases the opportunity for a substrate to bump into its enzyme. the rate of reactions therefore increases. However, if the temperature gets too high the protein will denature. a lower temperature means a lower rate of reaction
how does a change in pH effect enzyme activity
Each enzyme has an optimum pH at which it works. changes in pH may lead to change in shape, denaturation and change in substrate shape
how can substrate and enzyme concentration affect enzyme activity. Draw graph
increasing substrate results in an increase of products until all enzymes are occupied. increasing enzyme results in exponential increase in products until inhibition of enzyme or substrate is depleted
max activity I
I saturation point Rate of reaction I
I
I
I
I
I
I \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Substrate concentration
what is a competitive inhibitor
substance that competes with a substrate for the enzymes active site
what is a non competitive inhibitor
a molecule that binds to an enzyme at a site other than the active site, this changes shape of the active site so the substrate can no longer bind to it
what are cofactors
some enzymes are inactive until they bind with another molecule that changes their shape and activates active site. Cofactors are small inorganic substances that meed to be present for a reaction to take place (Zinc, magnesium ions)
what are coenzymes
small nonprotein organic substances that meed to be present for a reaction to take place (vitamins)
what is photosynthesis
the process by which plants utilise light energy and use it to break down water and carbon dioxide, and build them back up into oxygen, glucose and water molecules
what is the balanced equation for photosynthesis
6CO2 + 12H20 –> C 6H12O6 + 6O2 + 6H2O
what are the two stages of photosynthensis
Light dependent and independent
what is the light dependent stage
When light energy is absorbed by chlorophyll in the thylakoid membranes resulting in the electrons becoming energised. the energy is used to split water molecules into hydrogen ions and oxygen gas. ATP is also formed
what is the light independent stage
Occurs in the stroma, glucose molecules are produced from carbon dioxide. during the day, chloroplasts convert glucose into sucrose or starch. sucrose is easily transported , starch is most commonly stored
what is the equation for respiration
C6H12O6 + O2 –> CO2 + H2O + 36 ATP
what is glycolysis
takes place in the cytosol, turns glucose into 2 pyruvate and 2 ATP. ATP can be used but is not enough to sustain a large organism
what is aerobic respiration
respiration with oxygen present, 2 pyruvate enter the mitochondria which produces 34 ATP
what is anaerobic respiration
respiration without oxygen. Glycolysis is allowed to continue in the cytosol by utilising other molecules other than oxygen. two forms, alcohol and lactic acid fermentation
what is the equation for alcohol fermentation
Glucose –> Ethanol + co2 + 2ATP
what is alcohol fermentation
a form of anaerobic respiration where glucose is converted to ethanol. used by bacteria and yeast
what is lactic acid fermentation
a form of anaerobic respiration where glucose is converted to lactic acid. used by animals
