Chapter 8 Intro to Metabolism (Glycolysis 8)

Question 1

Metabolism

1. what are the two major pathways of metabolism ?
2. what is the differnece between catabolism and anabolism ?
3. Another terminology for catabolic and anabolic ?
4. Pathways that REGENRATE a component ?

Answer 1

1. catabolic and anabolic
2. Catabolism:** breaks down molecules into smaller units; **Anabolism builds up smaller units into bigger units.
3. Degradative and Synthetic
4. cycles

Question 2

1. define metabolism based on the book
2. Give one example of anabolism ?

Answer 2

1. metabolism is the sum of all chemical changes occuring in the cell.
2. glycogen from glucose

Question 3

Metabolism Map

keypoints to remember

Answer 3

• easier to understand through pathways
• each pathways are composed of multienzymes

Question 4

Catabolic Pathway

1. how does the catabolic pathway function ?
2. how many stages that the catabolic pathway have ?
3. Define the three stages of catabolism ?

Answer 4

1. capture chemical energy in the form of ATP from the degradation of energy rich fuel molecules
2. Occurs in THREE STAGES
3. Hydrolysis,Conversion and Oxidation

Question 5

Three stages of catabolism

Answer 5

STAGE I.

hydrolysis of complex molecules (polymers to monomers)

Proeteins = amino acids

Carbohydrates = monosaccharides

Fats = Glycerol fatty acids

STAGE II.

Conversion of building blocks to Acetyl CoA

STAGE III.

Oxidation of Acetyl CoA = Oxidative Phosphorylation

Electron Transport Chain (TCA cycle)

Question 6

Answer this questions to either TRUE or FALSE

1. Catabolic pathways are typically reductive and require the reduction of coenzymes such as NAD ⁺
2. Catabolism is a convergent process

Answer 6

1. False ; Oxidative; requires the oxidation of coenzymes like NAD⁺
2. True

Question 7

1. The oxidation of Acetyl CoA generates large amounts of
2. The oxidation of acetyl CoA makes ATP through
3. Define this process: “ the flow of electrons from NADH to FADH2 to Oxygen

Answer 7

1. ATP
2. Oxidative Phosphorylation
3. Oxydation of Acetyl CoA

Question 8

Anabolic Pathways

1. in contrast to catabolism (which is convergent) anabolism is ?
2. What do anabolic pathways require ?
3. requiring energy is called
4. Anabolic reactions involve chemical :

a. reductions
b. oxidations

Answer 8

1. divergent
2. energy
3. endergonic
4. reduction

Question 9

METABOLISM REGULATION

1. important for moment-to-moment regulation and elicit in rapid responses
2. signaling between cells for long range integration (may result as response to gene expression; surface to surface contact

Answer 9

1. intracellular communication
2. intercellular communication

Question 10

Second Messenger Systems

1. name two of the most widely recognized second messenger systems?
2. What second messenger systems are most important in regulating intermediary metabolism
3. what is the role of hormones and neurotransmitters in this subject ?

Answer 10

• Calcium/Phosphatidylinositol system
• Adenylyl cyclase (Adenylate cyclase) system
• Adenylyl Cyclase and Calcium/Phosphatidylinositol
• signal detectors

Question 11

1. Adnylyl cyclase: define in three points
2. what is GPCR define in three points

Answer 11

• membrane bound enzyme
• converts ATP to cAMP
• chemical signals arre mostly hormones and neurotransmitters
• G-Protein Coupled Receptor
• characterized by extra-cellular ligand-binding domain
• GPCRs’ have seven transmembrane alpha helices and an INTRACELLULAR domain (that interacts with G-proteins)

Question 12

GDP and GTP

1. GPCR contains subunits; what are these subunits called ?
2. How are the occupied GPCR mediated ?
3. what causes the trigger of replacement of GDP to GTP?
4. forms a link chain of communication between receptor and AC
5. GTPase activity: results in rapid hydrolysis of GTP to GDP
6. G-alpha _ GTP complex: (true or false) are short lived ?

Answer 12

1. alpha , beta and gamma
2. by specialized trimeric subunits (alpha, beta and gamma)
3. Ligand binding
4. GDP or GTP
5. G-alpha -GTP COMPLEX
6. TRUE

Question 13

p. 95

1. An increase in the activity of adenylyl cyclase is caused by
2. formed by ONE active receptor
3. hydrolysis of GTP to GDP causes inactivation of G-alpha (what is happening in this case) ?

Answer 13

1. the recognition of chemical signals that can INCREASE or DECRREASE the activity of AC
2. molecules of active G-alpha protein
3. dissociation from AC and reassociation with Beta-dimer.

Question 14

Concept: Glucose Phosphorylation

Phosphorylation (addition of a phosphate group)

1. Mammamls have 4 isozymes (I-IV) of the enzyme______________
2. One of the three regulatory enzymes of glycolysis ?
3. Catalysis of the phosphorylation of glucose to _________________
4. Traits of Hexokinase I-III : give three please.
5. Traits of Hexokinase IV isozyme: give three please.

Answer 14

1. hexokinase
2. hexokinase
3. glucose -6 - phosphate

• have a low Michaelis constan K_m
• have high affinity for glucose
• have low maximal velocity (V_max)
• is also known as glucokinase
• liver enzymes (parenchymal cells and pancreatic B-cells)
• responsible for glucose “phosphorylation”

Question 15

Glucokinase vs.Hexokinase I-III

1. How do glucokinase** differ from **hexokinase:
2. what are the three main regulatory enzymes for glycolysis
3. Describe their affinity for glucose

Answer 15

• hexokinase is found in all cellwalls
• Glucokinase is hexokinase IV found in the liver
• Hexokinase: one of the regulatory enzymes of glycolysis

1. hexokinase I-III and hexokinase IV
2. phosphofructokinase
3. pyruvate kinase

Affinit for glucose

1. glucokinase: low affinity for glucose
2. hexokinase high affinity for glucose

Question 16

1. The conversion of glucose to pyruvate occurs in how many stages ?
2. what part of glycolysis corresponds to energy-investment phase ?
3. The next subsequent stages of glycolysis corresponds to
4. The energy-generation phase yeilds how many molecules ATP per each glucose metabolized ?

Answer 16

1. two stages
2. first five stages of glycolysis
3. energy-generation phase
4. two molecules of ATP per glucose metabolized

Question 17

EFFECT OF

1. ACTIVATED GPCR
2. INACTIVE GPCR

Answer 17

ACTIVATED

• mediated by alpha, beta and gamma subunits
• alpha “boy” binds to GDP or GTP

INACTIVE

• Alpha binds to GTP
• GDP to GTP ( transition)
• GTP dissociates from B, Y and moves to Adenylyl Cyclase

Question 18

What is the rate limiting step for glycolysis ?

Answer 18

Phosphofructokinase - 1