Exam 2

Question 1

Carbohydrate

Answer 1

Aldehydes or ketone with at least two hydroxyl groups or substances that yield such compounds upon hydrolysis
- most abundant biomolecules in nature

Question 2

Stereoisomer

Answer 2

two or more compounds with the same molecular formula different only in spatial arrangement of their atoms.

Question 3

Enantiomer

Answer 3

(optical isomer) stereoisomers that are mirror images

Question 4

Diastereomers

Answer 4

stereoisomers that are not enantiomers (not mirror images)

Question 5

Epimer

Answer 5

one of two stereoisomers that differ in configuration at only one stereocenter. ( an anomer is a type of epimer)

Question 6

Aldose

Answer 6

sugar with the carbonyl group at the end of the carbon chain ( in aldehyde group)

Question 7

Hemiacetal (/hemiketal)

Answer 7

Hemiacetal(ring formations) -
an alcohol and ether attached to the same carbon.

Question 7

Ketose

Answer 7

sugar with the carbonyl group anywhere but the ends

Question 8

acetal (/ketal)

Answer 8

hemiacetals and hemiketals react with alcohols to form the corresponding acetal and ketal

Question 9

Pyranose

Answer 9

six-membered rings

Question 10

Furanose

Answer 10

five-membered rings

Question 11

Anomer (a and b)

Answer 11

two possible diastereomers that form because of cyclization

Question 12

Substrate-level phosphorylation

Answer 12

the direct formation of ATP or GTP by transferring a phosphate group from a high-energy compound to an ADP or GDP molecule (in cytoplast or mitochondria)

Question 13

The Chemiosmotic Theory

Answer 13

1. As electrons pass through the ETC, protons are pumped into the intermembrane space from the matrix, generating an electrical potential and a proton gradient (protonmotive force)
2. Protons move back across the inner membrane to the matrix (down their concentration gradient) through ATP synthase, driving ATP formation

Question 14

According to the Chemiosmotic Theory, ATP synthesis in mitochondria is driven by

Answer 14

Membrane potential and gradient

Question 15

ATP synthesis

Answer 15

Requires translocation of three protons through the ATP synthase
ATP synthase consists of two rotors – F1 unit (the ATP synthase) and F0 unit (transmembrane channel) – linked by a strong flexible stator

Question 16

ATP synthase steps

Answer 16

Steps:
1. ADP and Pi bind to L site; rotation converts it to T conformation
2. ATP synthesized
3. Rotation converts T site to O site, releasing ATP

Question 17

F0 motor role

Answer 17

F0 motor converts the protonmotive force into the rotational force of the central shaft which drives ATP synthesis

Question 18

Oxidative phosphorylation

Answer 18

Activated when ADP (respiratory control) and Pi concentrations are high
 Inhibited when ATP concentrations are high
 Amounts of ATP and ADP in mitochondria are
controlled by the ADP-ATP translocator

Question 19

What type of reactions are NAD and NADP involved in?

Answer 19

Two coenzyme forms: nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP)
 Have oxidized (NAD+ and NADP+) and reduced (NADH and NADPH) forms
 NAD+ is involved in catabolic reactions and NADP+ is involved in biosynthetic reactions

Question 20

Redox reactions - roles of coenzymes

Answer 20

Living organisms utilize redox coenzymes as high-energy electron carriers (e.g., NADH and FADH2) from nicotinic acid and riboflavin vitamin molecules

Question 21

What is FAD and its function?

Answer 21

Riboflavin (vitamin B2) is a component of two coenzymes: flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)
-Function as dehydrogenases, oxidases, and hydroxylases

Question 22

Coenzyme A

Answer 22

Coenzyme A (CoA) is an acyl carrier molecule
- Because the reactive SH group forms a thioester bond with acyl groups, coenzyme A is often abbreviated as CoASH

Question 23

ETC purpose

Answer 23

is a mechanism by which electrons are transferred from NADH and FADH2 to a series of electron carriers, arranged in order of increasing electron affinity, that are sequentially reduced and then oxidized

Question 24

ETC location

Answer 24

Located in the inner mitochondrial membrane
-Aerobic respiration couples electron transfer ultimately to ATP synthesis

Question 25

ETC Complex 1

Answer 25

(NADH dehydrogenase complex) catalyzes the transfer of electrons from NADH to UQ
-The largest protein component in the inner membrane
-UQ is lipid-soluble and shuttles electrons between ETC complexes along the inner
mitochondrial membrane

Question 26

ETC Complex 2

Answer 26

(succinate dehydrogenase complex) transfers electrons from succinate to UQ
 It contains four subunits (ShdA-D), succinate dehydrogenase, and iron-sulfur proteins
-UQ can also get electrons from acyl-CoA and glycerol-3-phosphate dehydrogenases

Question 27

ETC Complex 3

Answer 27

(cytochrome bc1 complex) transfers electrons from reduced
UQ (UQH2) to cytochrome c (cyt c)
-Q cycle is the transfer of electrons through Complex III – four protons are
pumped across the IMM into the intermembrane space

Question 28

ETC Complex 4

Answer 28

(cytochrome c oxidase) catalyzes the four-electron reduction of O2 to H2O
- Contains 14 cytochromes a and a3, and three copper ions

Question 29

ETC four complexes

Answer 29

1. (NADH dehydrogenase complex)
2. (succinate dehydrogenase complex)
3. (cytochrome bc1 complex)
4. (cytochrome c oxidase)