outcome 2

Question 1

catabolic vs anabolic

Answer 1

catabolic: the enzymatic breakdown of larger molecules into smaller molecules
–DECOMPOSITION+ EXERGONIC (energy releasing )

anabolic: the enzymatic synthesis of more complex molecules from simpler ones
–SYNTHESIS+ ENDERGONIC (energy requiring)

Question 2

autotrophic vs heterotrophic

Answer 2

autographic: create own organic compounds from small inorganic molecules (plants make own food via photosynthesis)

heterotrophic: ingest/ absorb organic compounds from living or dead organisms and their by- products (animals)

Question 3

what are photosynthesis and cellular res. in terms of types of reaction

Answer 3

PHOTOSYN:
-synthesis
-anabolic and endergonic reaction
-energy requiring

CELLLULAR RESP.:
- decomposition
- catabolic and exergonic
- release energy

Question 4

what are enzymes?

Answer 4

they are biological catalysts so substances that speed up the rate of reaction w/o being used up

• they are proteins (most are soluble globular proteins)
• enzyme consist of one or more polypeptide chains
• tertiary structure, exception= monomeric enzyme (single polypeptide shape)

Question 5

components of enzymes and what they do

Answer 5

• every enzyme has an active site ( substrate binding site)
• SUBSTRATE= the molecule that the enzyme acts on = INPUT to an enzyme- catalysed reaction
• PRODUCT= the OUTPUT of an enzyme catalysed reaction

Question 6

group and bond specifity

Answer 6

bond spec. means enzyme only acts on a specific type of chemical bond and group spec. acts on molecules w/ spec. functional group near target bond

Question 7

lock and key model

Answer 7

• simplest model to represent how an enzyme works. the substrate simply fits into the active site to form a reaction

STEPS:
1. substrate binds to enzyme active site
2. bonds in the subsrate are weakened Ae is lowered = substrate enzyme complex
2. substrate is broken products are formed

Question 8

induced fit

Answer 8

• the combining of the enzyme and substrate results in a slight change in the shape of both
• this strained fit acts to break old chem bonds and form new ones
  —> results in the formation of the product from the substrate
  —-> once this occurs the product is released from enzyme and enzyme is free to combine w/ any other substrate molecule

Question 9

activation energy and how enzymes lower it

Answer 9

the energy of the reactants required to initiate a reaction (acts as a barrier to the chem reaction occurring or speed at which it occurs)

HOW THEY LOWER AE:
enzymes carry out their function of lowering activation energy by temporally combining w/ the chemicals involved in the reaction. these chemicals are called the substrate:
…

Question 10

Enzymes involved in PHOTOSYNTHESIS

Answer 10

• WATER OXIDIZING ENZYME: splits water molecules releasing hydrogen ions and electrons that will be built in energy- rich molecules oxygen is released as waste
• THE ATP SYNTHASE generates atp for use in photosyn
• THE RUBISCO ENZYME captures CO2 molecules from air and catalyses their conversion to organic 3 carbon molecules

Question 11

cofactors + co-enzymes

Answer 11

cofactors:
are additional (non-protein) chemical components that are essential for ENZYME FUNCTION adding to stability and activity

CAN BE INORGANIC ex. iron in catalase, zinc in DNA polymerase

CAN BE ORGANIC which are either co enzymes and prosthetic groups

Question 12

how coenzymes work

Answer 12

1. BINDING: a co enzyme temp binds to the enzyme active site or near it
2. TRANFER: during a reaction it transfer something ( like electrons hydrogen atoms, or chemical groups)
3. RELEASE: after the reaction the co-enzyme is released- sometimes unchanged sometimes need to be recharged ( NAD+ –> NADH)

Question 13

common co enzymes and function

Answer 13

ATP →ADP +pi
- energy transfer

NADH→NAD+
- transfer of electrons + proteins in cellular resp.

NADPH→NADP
- transfer of electrons + proteins in photosynthesis

FADH2→FAD
- transfer of electrons + proteins in cellular resp.

Question 14

ATP

Answer 14

• a coenzyme
• ATP is an energy rich compound, formed in mitochondria (site for resp.)
• ATP provides the energy to drive all metabolic process in the cell
• energy is released when ATP is hydrolysed ( release energy and loses one of its phosphates as its unstable bond between last phos) into ADP +pi

Question 15

loaded vs unloaded

Question 16

FACTORS EFFECTING ENZYME ACTIVITY: temperature

Answer 16

• enzymes are proteins and as such can be denatured
• each enzyme has optimal temp depending on the ‘usual’ conditions in which the enzyme function.
  Most enzymes denature above 40°
  → At low temps, not enough energy for enzyme to work
  → At high temps, the enzyme denatures (H-bonds break) due to too much energy, changing its structure
• Some enzymes can reform old shapes when cooled down again

Question 17

FACTORS EFFECTING ENZYME ACTIVITY: PH

Answer 17

Each enzyme Has an optimal pH depending on the “usual” conditions in which the enzyme function

→ This is due to increased levels of H+(acidic) or OH- (alkaline) particles, which interfere wl H-bonding of 2° and 3° structures.

• changes in pH can make and break intra- and intermolecular bonds, changing the shape of (denaturing) the enzyme and, therefore, its effectiveness

Question 18

FACTORS EFFECTING ENZYME ACTIVITY: concentration

Answer 18

enzyme concentration: the more enzyme molecules (high conc.)the faster the reaction will proceed

substrate concentration:
high concentration will increase speed of reaction until all of the active site of the enzymes present are occupied

Question 19

enzyme irreversible inhibitors:

Answer 19

• bind covalently (strong bond) to the enzyme active site
• causes a permant loss/ denaturation of catalytic activity – secondary/ tertiary structure is altered
• such molecules are toxic and poison to the cell

Question 20

enzyme Reversible inhibitors

Answer 20

• bind to the enzyme via weak H-bonds and other intermoleculer bonds and can dissociate from the enzyme
• turn off a reaction but not permanently
• sometimes an end-product molecule used to slow/prevent production of a molecule that is no longer needed
  —> can be competitive or non-competitive

Question 21

competitive and non-competitive

Answer 21

competitive: compete directly w/ the substrate foe the active site
–it binds to active site blocking sub.
– HAVE SIMILAR SHAPE TO USAL SUBSTRATE THATS WHY IT CAN BIND TO ACTIVE SITE

non-competitive:
binds to enzyme not active site. changes conformational shape of enzyme, decreasing likelihood of sub. binding. HOWEVER IF IT DOES BIND NO REACTION WILL OCCUR

• the site it binds to is the allosteric site (side of enzyme)

Question 22

why we regulate biochemical pathways:

Answer 22

precisely coordinated and regulated so that a balance is established between energy production and energy needs of the cell. Controlling enzyme activity is a major means by which regulation of biochem pathway is maintained

• prevents waste, build up in cells of products to potentially harmful lvls and depletion of substrate

Question 23

what is photosynthesises and briefly describe components + stages + chlorophyll info. + equation

Answer 23

→ photosynthesis captures the energy in sunlight storing it as glucose. LOCATION: takes place in the chloroplast of plants and algae

→HAS TWO STAGES:
LIGHT DEPENTANT→ grana on thylakoid membranes
LIGHT INDEPENDANT (Calvin cycle)→ in the stroma

CHLOROPHYLL (green because it cannot pick up that colour)
- enables plants to capture the radient energy of sunlight, bringing it into cells as the starting point of photosyn.
- accessory pigments such as catenoids are also present they can capture sunlight energy and transfer the radiant energy they absorb to chlorophyll

6CO₂ + 12H₂O + (light energy, chlorophyll) → C₆H₁₂O₆ + 6H₂O

Question 24

light dependant stage role + outputs+ inputs

Answer 24

takes place on the thylakoid membranes of the thylakoids and requires chlorophyll and light energy

BY THE END:
- a supply of high energy loaded ATP molecules
- a supply of high energy loaded NADPH co-enzyme
→ oxygen produced plays no further part will be released via leaves

role + outputs+ inputs:

SUNLIGHT→…
- initial input of energy to chlorophyll

NADP+→ NADPH
- NADP+ = unloaded coenzyme and acceptor of H+ and electrons
- NADPH = loaded coenzyme and doner of H+ and electrons
NADP+ +H +2e- → NADPH

ADP+pi → ATP
- ADP+pi = unloaded coenzyme ( waiting to act as a energy supplier
- ATP = loaded coenzyme and energy supplier
ADP+pi→ ATP
- atp synthase

Water→O2
- water = supplier of H+ (for NADP and atp) and electrons and O2
- O2 = (by product) by- product splitting water

coenzymes assist rubisco

Question 25

light independant stage role + outputs+ inputs (C3)

Answer 25

stage in which inorganic carbon dioxide molecules are built into energy-rich reduced organic molecule such as glucose the enzyme required for this stage are in solution in the stroma. the main enzyme for C3 plants is known as Rubisco which is vital for carbon fixation role + outputs+ inputs: NADPH→ NADP+ - NADPH = loaded coenzyme and doner H+ and electrons - NADP+ = unloaded coenzyme acceptor of hydrogen ions and electrons ATP → ADP+pi - ADP+pi = unloaded coenzyme - ATP = loaded coenzyme and energy supplier CO2 → Glucose - CO2 = supplier of carbon and oxygen atoms - Glucose = final product in photosynthesis

Question 26

C3 plant Calvin cycle + condition and why it can accommodate all plants

Answer 26

- cool to temperate conditions THIS DOES NOT ACCOMADATE TO ALL PLANTS: → reason: in dry environments for example cam plants stomata close to reduce water loss which block O2 causing build up in plant and RUBISCO WILL BIND TO O2 INSTEAD OF CO2 CAUSING PHOTORESPIRATION (rubisco will add o2 to RuBP) - as it gets hot it fits o2 better than co2 (competes w/ CO2) carboxylase reaction→ when it binds to carbon hydroxylase→ when it binds to O2

Question 27

C4 photosynthesis

Answer 27

- warm temperate regions + tropical regions 1. CO2 enters the MESOPHYLL CELL(LD) (permeable, chloroplasts w/ no Rubisco in here ) 2. CO2 + PEP(3c) using the enzyme PEP CARBOXYLASE = Malate(4c) 3. malate enters BUNDLE SHEATH(LI) turns into pyruvate CO2 which enters the chloroplast Calvin cycle in stroma. 4. forms glucose which enters vascular tissue

Question 28

CAM plants photosynthesis

Answer 28

→ hot and arid conditions - AT NIGHT they open their stomata to take in CO2, which the store as malic acid (Malate in the cells large vacuole - DURING THE DAY when its hot CAM plants close their stomata to prevent water loss → they are able to supply the calvin cycle with CO2 from the breakdown of malic acid that was stored in the vacuole during the night

Question 29

FACTORS EFFECTING RATE OF PHOTOSYN: light intensity

Answer 29

The photosynthetic rate increases as light intensity increases until it reaches a maximal point → Beyond the optimal light intensity , further increases in light intensity have no effect and the rate of photosynthesis stays constant. This is called light saturation point

Question 30

FACTORS EFFECTING RATE OF PHOTOSYN: water availability

Answer 30

Photosynthesis requires water as an input. If too little available, the rate of photosynthesis will be slowed Too much water can have similar effect on photosyn. ---as waterlogging(when more rain falls than the water can absorb = decrease O2) of soil, the rate of photosyn. will decline due to the lack o2 for cellular respiration in root cells stops wafer uptake. * A lack of water also affects photosynthesis because dehydrated plants lose turgor and their stomata close, preventing gas exchange, including absorption of CO2

Question 31

FACTORS EFFECTING RATE OF PHOTOSYN: temperature

Answer 31

As temperature increases the rate of photosyn, increases due to molecules moving faster → increase collision rate = increase Reaction. In most plants the optimal temperature for photosythetic enzymes 15 20°C * AT higher temp. the rate of photosyn. decreases mainly due to enzyme denaturation (if its too too hot unlikely) . Plus in higher temp. photorespiration is likely to occur because Rubiscos affinity for Oz increases

Question 32

FACTORS EFFECTING RATE OF PHOTOSYN: concentration

Answer 32

higher concentration of CO2 increases photosyn. until it levels off due to limiting factor

Question 33

Limiting factors

Answer 33

The rate of photosynthesis could theoretically always be faster than it is currently. The factor that is holding it back at a point in time is the limiting factor!. Adjusting the limiting factor to a more favourable level will theoretically increase the rate of photosynthesis until its constrained by yet another limiting factor

Question 34

photorespiration when is it likely to occur and how?

Answer 34

→ WHEN TEMP. INCREASES In the cool temperate conditions in which C3 plants thrive, photorespiration is not a problem as Rubisco will preferentially bind carbon dioxide. However as leaves are exposed to higher temperatures, the rate of photo respiration Increases faster than the rate of photosynthesis → At low temps. Rubisco preferentially binds carbon dioxide But, as temperature increases, the ability of the Rubisco enzyme to distinguish between carbon dioxide and oxygen decreases and as a result, Rubisco will bind to O2. In addition at higher temp., the solubility of co2 in the cytosol drops more rapidly than that of O2, so there is more or available in the mesophyll cell. → DRY CONDITIONS Plants close their stomata to prevent water loss ( restrict CO2 entry and O2 exit). This block the entry of carbon dioxide needed as a input to the Calvin cycle and limits the exit of o2 in the light dependant stage . This creates a high oxygen and low co2 enviroment in leaf mesophyll cells, in which the Rubiscos enzyme will bind to o2 rather than co2 . decreasing glucose synthesis.

Question 35

what are the two types of cellular respiration

Answer 35

vital for survival providing us essential energy to grow reproduce and function AEROBIC- oxygen requiring (plants and animals) -lots of ATP, slower ANAEOBIC- non-oxygen requiring (bacteria) - less ATP, faster

Question 36

AEROBIC CELLULAR RESP.

Answer 36

STAGE 1: glycolysis (cytosol) → INPUTS: 2 ADP+pi Glucose 2 NAD+ →OUTPUTS: 2 ATP 2 Pyruvate 2 NADH STAGE 1: kerb cycle (inner mitochondrial matrix ) (load coenzyme so they can be used in ETC) → glycolysis ends with the production of two molecules of pyruvate molecules cannot directly enter the kerb cycle. before entering the kerb cycle a short linking process known as pyruvate oxidation. → INPUTS: 8NAD+ 2FAD 2ADP+pi 2Pyruvate →OUTPUTS: 8NADH 2FADH2 2 ATP 6CO2 STAGE 3: electron transport chain (cristae of mitochondria) → INPUTS: 10 NADH 2FADH2 26/28 ADP+pi 6CO2 →OUTPUTS: 10NAD+ 2FAD 26/28 ATP 6H2O

Question 37

ANEROBIC FERMANTATION

Answer 37

→ ALCOHOL FERMENTATION IN YEAST: Without O2, no more ATP can be produced, but ATP will still be used in the cell. NADH on the other hand will not be used, and the cell may run out of NAD+. For this reason the NADH must be recycled back to NAD+. This is done by oxidising it, resulting in two molecules of ethanol and two CO2. GLUCOSE →(glycolysis)→ PYRUVATE 2NAD+ 2NADH 2ADP+pi 2ATP →(pyruvate decarboxylase)→(alcohol dehydrogenase)→ ETHANOL+CO2 2NAD+ 2ATP → LACTIC ACID FERMENTATION IN ANIMALS : In animals, pyruvate is converted by a different enzyme to lactic acid. While a different end product results, the process takes place for the same reason: to recycle NADH so that glycolysis doesn’t stop due to a lack of NAD+. GLUCOSE →(glycolysis)→ PYRUVATE 2NAD+ 2NADH 2ADP+pi 2ATP →(lactic acid dehydrogenase)→ LACTIC ACID 2NAD+ 2ATP

Question 38

Comparing fermentation and aerobic

Answer 38

→ Oxygen requirement Aerobic requires oxygen * Fermentation doesn't → EffIciency (ATP yield per glucose) Aerobic cellular respiration is much more efficient than fermentation. Fermentation results in two ATP per glucose molecule. Aerobic yields 16 times as much (30/32 net yield) → Rate of ATP production Fermentation Is MUCH FASTER than aerobic. Although it is inefficient , a cell can produce 30 ATP faster by doing Fermentation 13 times, than it can by doing aerobic once. → Sustainability Aerobic cellular respiration can be sustained indefinitely. Fermentation cannot since the product are toxic to the cells that produce them.

Question 39

Factors that effect cellular respiration:

Answer 39

→ Temperature At low temperatures, collisions between substrate and enzyme molecules are less frequent, resulting in low rate of respiration. As the temp. increases further, the respiration rate also increases until the optimal temperature for an organisms cells is reached. At temperatures above optimal, heat denaturation of enzymes begin to occur → Glucose concentration | availability! The higher the concentration of glucose, the greater the rate of cellular respiration. since glucose is the preferred input of cellular respiration. → Oxygen availability : since oxygen is also an input for cellular respiration, If there is a lack of oxygen, the rate of cellular respiration will decrease. AT very low concentrations of O2, the cell may start to use anaerobic fermentation rather than aerobic

Question 40

Agricultural applications of CRISPR-Cas9

Answer 40

Current uses of CRISPR-Cas9 in improving crop yields * Since 2013 CRISPR-Cas9 has been used to: * Reduce stress on tomato crop plants caused by viruses, fungi and insects. * Reduce loss of fruit crop productivity due to heat stress and cold stress. * Reduced the rate of shelf-ripening in tomatoes. * Increased the size of fruit. * Flax seeds with increased omega-3 content. * Drought-tolerant soybeans. In the future CRISPR-Cas9 will continue to be used as a powerful tool to alter crops to meet the needs of a growing population and a changing climate. Two areas are particularly exciting: * Staple crops (wheat, soybeans, corn, rice) that are disease resistant, drought resistant, and produce more nutritious crops. * The modification of RuBisCO and associated enzymes, to improve the efficiency of photosynthesis by reducing the rate of photorespiration.