Chapter 3 + 4 Flashcards
Cofactors
non-protein additional component that is essential for the normal functioning of some enzymes
Examples of cofactors
calcium, zinc, potassium, magnesium.
Coenzyme
organic compound that acts with an enzyme to alter the rate of a reaction.
Important thing to remember about cofactors
if it is organic e.g. vitamin, then it is a coenzyme
Antioxidant
molecule that prevents the oxidation of other molecules that is synthesised in our body
What do antioxidants prevent
tissue damage due to oxidative reactions
Coenzyme Q10
needed for antioxidant (lipid soluble), used aerobic respiration in mitochondria
Role of Coenzyme Q10
improves energy production, enhances muscle function, reduced lipid oxidation
Enzymes
biological catalyst that increase the rate of a reaction by lowering the activation energy
How enzymes work
reduce the activation energy required through weakening bonds in substrates, which happens when the enzyme puts stress on the chemical bonds
Activation energy
the minimum amount of energy required for a reaction to take place
A chemical reaction can only occur if
there is sufficient energy to begin the reaction
In the absence of enzymes the activation energy is…
high
Enzymes only bind to
substrates with a complementary shape to active site
Term when substrate binds in correct way to enzyme
it binds in the correct orientation
What are enzymes made up of
protein and RNA
Enzymes can be either….
intracellular or extracellular
Enzymes are highly….
specific in their action
Most enzymes have the suffix…
“ase”
Exceptions examples
pepsin, trypsin
Enzymes act best at their…
optimal conditions e.g. temp, pH
What is it called when enzymes combine with substrates
enzyme-substrate complex
Are enzymes used up in the reaction
no, they are available for reuse
Substrate
compound upon which an enzyme acts
Products
the compounds obtained as a result of enzyme action.
Lock and key theory
Lock and key model - the specific shape of the active site fits exactly the shape of the substrate it will act on, hence will only act on that substrate.
Induced fit theory
the specific shape of the active site of the enzyme varies slightly from that of the substrate and the two fit only after contact when the substrate induces a complementary shape at the active site of the enzyme.
Factors that affect rates of enzyme reactions (5)
temperature, pH, enzyme concentration, substrate concentration, inhibition
If temperature is too hot
is (permanently) denatured, active sites are destroyed, enzyme-substrate complexes can no longer form, therefore reaction rates fall
How does temperature denature enzyme
hydrogen bonds break
Denatured
the shape of the active site being changed meaning that the enzyme can no longer bind to its complementary substrate hence the function of the enzyme is lost.
If temperature is too cold
enzymes and substrate molecules lose kinetic energy, so collisions between these molecules occur less often, enzyme-substrate complexes are less likely to form, therefore reaction rates fall. The effects are fully reversible with the addition of heat.
Can some enzymes survive in extremely hot temperatures
yes, an example is thermophilic bacteria in the hot springs
If pH is not optimal
changes the shape of active site so is denatured, enzyme-substrate complexes can no longer form, therefore reaction rates fall
Enzyme concentration
if solution has enough enzymes and enzymes are added then no affect, if not enough enzymes and more are added then rate rapidly increases, if enzymes are taken from too many then no effect, if taken from normal then rate decreases
Substrate concentration
if there is more enzymes than needed and substrate is added then rate increases, if there is not enough enzymes and substrate is added then rate decreases.
Two types of inhibition
competitive, non-competitive
Competitive inhibition
an enzyme inhibitor which binds with the active site of an enzyme and hence prevents normal action of the enzyme. An example of the use if competitive inhibition is alcohol treatment of a person suffering from poisoning by ethylene glycol.
Non-competitive inhibitor
an enzyme inhibitor which binds to a site on an enzyme other than the active site. In so doing, it alters the shape of the active site, preventing the binding by the normal substrate. For example, the action of heavy metals, such as arsenic, mercury and lead, on several enzymes.
Heterotrophic organisms
organisms that cannot make their own food and must ingest or absorb organic material from their environment.
Heterotrophs are also known as
consumers
Autotrophic organisms
organisms that, given a source of energy, can produce its own food from simple inorganic substances. Are generally photosynthetic or chemosynthetic.
Autotrophs are also known as
producers
Why do we need energy in cells
to drive metabolic reactions
E.g. of how energy is used
protein synthesis, protein carriers involved in active transport, contraction of muscle cells
What form of energy is used
ATP
ATP stands for
Adenosine triphosphate
ATP formulas
ATP -> ADP + Pi
ADP + Pi -> ATP
ATP definition
?
Explanation for ATP breakdown producing energy
when organic compounds react to form products with a lower energy, such as inorganic compounds, energy is released either chemically or as heat.
Photoautotrophs
light autotrophs
Chemoautotrophs
chemical autotrophs
Metabolic reactions
chemical reactions that occur in the body
Metabolic reactions are either…
exergonic or endergonic
Endergonic
refers to a chemical reaction that is energy requiring.
Examples of endergonic reactions
photosynthesis, reduction
Exergonic
refers to a chemical reaction that is energy releasing.
Examples of exergonic reactions
cellular respiration, oxidation
Why are there exergonic reactions if all reactions require energy
exergonic is a net production
Energy profile - graph showing energy
Energy profile
graph showing energy
Anabolic reactions
reactions that form larger compounds from smaller units
Catabolic reactions
reactions that break down larger compounds into smaller compounds
Photosynthesis and cellular respiration are
closely related and complementary
Adaptations plants have for photosynthesis (5)
flat shape for SA:V, many stomata to let in water and CO2, thinness allows ready diffusion, xylem transports water to photosynthetic cells, contains chloroplasts to trap
Photosynthesis
process by which plants convert sunlight trapped by chlorophyll along with carbon dioxide and water into chemical energy
Difference between plant and bacteria photosynthesis
bacteria don’t do it in chloroplasts
Most efficient light waves for photosynthesis
blue/violet and red
Two stages of photosynthesis
light dependent stage, light “independent stage”
Where does the light dependent stage occur
grana of chloroplast
Inputs for light dependent stage
light, H2O, NADP+, ADP + Pi,
Outputs for light dependent stage
NADPH, O2, ATP
What happens in the light dependent stage
light energy trapped, this causes H+ electrons to become excited and so are passed down the electron transport chain resulting in ATP formation, the H+ electrons are loaded on to NADP+, H+ replaced and spare O2 from H2O is released
Other names for light independent stage
dark stage, Calvin/Benson cycle, carbon reduction
Where does the light independent stage occur
stroma of chloroplast
Inputs for light independent stage
6CO2, ATP, NADPH,
Outputs for light independent stage
C6H12O6, 6H2O, NADP+, ADP + Pi
What happens in light independent stage
calvin cycle spins around carbon dioxide and H+ ions to form glucose
Cellular respiration
a process of transferring energy present in organic compounds to a form useable by cells, typically ATP
Do all cells undergo cellular respiration
yes, as all cells require energy
Is the process of transferring energy from glucose to ATP 100% efficient
no only 40%, 60% is lost as heat
What happens to heat produced by cellular respiration
trapped by insulating layers of fat as an internal source of heat
Can cells use heat instead of ATP as an energy source
no
Aerobic respiration
breakdown of glucose into simple inorganic compounds in order to produce energy, in the presence of oxygen.
Anaerobic respiration
form of respiration occurring in the absence of oxygen in which glucose is broken down to smaller compounds, with release of energy that is transferred to ATP.
Is aerobic respiration or aerobic respiration more efficient
aerobic as it produces less ATP but anaerobic is more rapid
Differences between aerobic and anaerobic respiration
aerobic requires oxygen, produces more ATP, takes more time,
Stages of aerobic respiration
glycolysis, Krebs’ cycle, electron transport chain
Where does glycolysis occur
cytosol
Inputs of glycolysis
NAD+, glucose, 2ADP + Pi
Outputs of glycolysis
NADH + H+ ions, 2 pyruvate, 2 ATP
What happens in glycolysis
glucose broken down into pyruvate
Where does the Krebs’ cycle occur
matrix of mitochondria
Inputs in Krebs’ cycle
2 pyruvate, NAD+, FAD, 2 ADP + Pi
Outputs in Krebs’ cycle
NADH + H+ ions, FADH2, 6CO2, 2 ATP
What happens in the Krebs’ cycle
?
Where does the electron transport chain occur
cristae of the mitochondria
Inputs in ETC
NADH + H+ ions, FADH2, O2, 32-34 ADP + Pi
Outputs of ETC
NAD+, FAD, H2O, 32-34 ATP
What happens in ETC
?
Anaerobic respiration stages
glycolysis, fermentation
Where does fermentation occur in cells
cytosol
Products in animals
lactic acid, 2ATP
Products in plants and fungi
ethanol, carbon dioxide
Acceptor molecules
NAD, FAD
Electron carriers
NAD, FAD, NADP+
NAD stands for
nicotinamide adenine dinucleotide
FAD stands for
favine adenine dinucleotide
Lactic acid formula
2C3H6O3
Aerobic equation
C6H12O6 + 602 -> 36-38 ATP + 6CO2 + 6H20
ATPase
universal carrier
Rational drug design
construction of a drug to fit the active site of a molecule so that the natural action of the molecule cannot occur.
What does the rational drug design involve
how the infective agent works against a cell and using that information to design a drug that prevents the infective agent from being able to do what it does.
Basis of rational drug design
complementarity
Relationship between rational drug design and proteomics
study structure of proteins in order to find drug so can look at function, and binding sites of proteins
