Bio 107.1.3

Question 1

3 Parts of Cytoskeleton

Answer 1

Microtubules: a and b tubulins form dimers, dimers form protofilaments, protofilaments have a MTOC (- end) made of gamma tubulins, such as centrosomes which have 2 centrioles, and form tubes

Actin Filaments: myosin is a motor protein that interacts with actin

Intermediate: not dynamic, no plus/minus end

Question 2

-ve entropy and -ve enthalpy

-ve entropy and +ve enthalpy

+ve entropy and -ve enthalpy

+ve entropy and +ve enthalpy

Answer 2

spontaneous at low temperatures

not spontaneous

spontaneous

spontaneous at high temp

Question 3

Can Gibbs free energy predict rate?

Answer 3

no

Question 4

What are other names for spontaneous and non-spontaneous?

Answer 4

exergonic and endergonic

Question 5

What is Catalysis?

Answer 5

acceleration of reaction by catalysts

Question 6

Cofactors and Coenzymes

Answer 6

cofactors (inorganic) are non-protein molecules that support chemical reactions (metal ions). Two forms: inorganic ions (zinc, Ca), or organic molecules known as coenzymes.

Coenzymes are non-protein organic molecules that carry chemical groups between enzymes (NAD and FAD)

Coenzymes are required by enzymes to carry their catalytic activities

Question 7

Holoenzyme vs Apoenzyme

Answer 7

coenzyme and enzyme (functional group)

non functional, protein part of the enzyme

Apoenzyme and cofactor (and coenzyme) -> holoenzyme

Question 7

What is allosteric regulation

Answer 7

proteins function at one site is affected by the binding of a molecule at another site (i.e. non-competitive inhibition or feedback inhibition)

Question 8

What are autotrophs? Heterotrophs?

Answer 8

take energy from inorganic sources (plants)

take energy from organic sources (plants and animals)

Question 9

Where is the major location of photosynthesis?

Where is chlorophyll found?

Answer 9

Leaves

Mesophyll

Question 10

What are the two reactions of photosynthesis?

Answer 10

Light-dependent reactions (thylakoid, convert light energy to chemical energy (ATP and NADPH) H2O to O2

Calvin cycle (stroma/cytoplasm, E stored in ATP and NADPH drives fixation of C into carbohydrates) CO2 to carbohydrate

Question 11

What type of process is photosynthesis?

Answer 11

Redox, H2O is oxidized to give O2, CO2 is reduced to produce carbohydrate

Endergonic, light energy needed

Question 12

What is the process of the light-dependent reaction

Answer 12

proton strikes P680 -> P680+, go the pheophytin

H2O split, 2 H+ thylakoid, 2e- reduce P680+, 2 O2 released

photoexcited e- from pheophytin go to Pq cytob6f, Pc
4H+ released from cytob6f

proton strikes P700 -> P700+

P700 accepts ETC e-

primary acceptor to Fd to NADP reductase takes 2 e- 1H+ to make NADPH

ATP is made from 3-4 protons through ATP synthase

Question 13

What happens if there is a build up of NADPH?

Answer 13

high energy electrons have nowhere to go, cyclic photophosphorylation

electrons from Fd go to Pq to cytob6f to Pc to PSI to make ATP from 2H (per electron), no oxygen or NADPH is made

Question 14

What is the Calvin cycle for 3 CO2

Answer 14

carbon fixation
3CO2 + Rubisco enzyme + RuBP -> 3PGA
6ATP -> 6ADP

reduction of 3-PGA by NADPH
6 3-PGA -> 6G3P
6NADPH -> 6NADP+ + 6H+

1G3P leaves calvin cycle (1/2 glucose)

regeneration of RuBP
5G3P -> 3RuBP
3ATP -> 3ADP

per one usable molecule of G3P, 9ATP and 6NADPH used

Question 15

What type of action is photosynthesis and when is it favoured

Answer 15

carboxylase action, favoured when CO2 conc higher than O2

Question 16

What type of action is photorespiration and when is it favoured

Answer 16

oxygenase action, when O2 is higher

Question 17

Process of photorespiration

Answer 17

against C fixation (photorespiration and photosynthesis compete for the active site of RuBP)

under certain conditions, Rubisco combines RuBP with O2 instead of CO2

RuBP + O2 -> 3-C (stay in calvin) + 2-c glycolate (further metabolised, CO2 released

Question 18

Mechanisms to avoiding photosynthesis

Answer 18

CAM and C4