Lecture 11 - Cell Respiration II

What is the literal translation of glycolysis?

Splitting sugar

What is glycolysis?

The breakdown of glucose by enzymes, releasing energy and pyruvic acid.

What is the net production of glucose?

2 Pyruvate + 2H20

What is the net production of 2 ADP + 2 Pi?

2 ATP

What is the net production of 2 NAD+?

2 NADH + 2H+

What is produced in the energy investment phase?

2ATP --> 2 ADP

What is produced in the energy payoff phase?

4 ADP --> 4 ATP

2 NAD+ --> 2 NADH

2 X C3H303

What enzymes are used in glycolysis?

1. Hexokinase

2. Phosphoglucose isomerase

3. Phosphofructokinase

4. Fructose-bisphosphate aldolase

5. Triose phosphate isomerase

6. Glyceraldehyde-3-phosphate dehydrogenase

7. Phosphoglycerte kinase

8. Phosphoglycerate mutase

9. Enolase

10. Pyruvate kinase

Hexokinase:

uses ATP to phosphorylate glucose, increasing its potential energy

Phosphoglucose isomerase:

Converts glucose 6-phosphate into fructose 6-phosphate; referred to as an isomer of glucose-6-phosphate

Phosphofructokinase:

Uses ATP to phosphorylate the opposite end of fructose-6-phosphate, increasing its potential energy

Fructose-bisphosphate aldolase:

cleaves fructose-1,6-bisphosphate into two different three-carbon sugars

Triose phosphate isomerase:

converts dihydroxyacetone phosphate (daP) to glyceraldehyde 3-phosphate (G3P). Reaction is fully reversible but the DAP-G3P reaction is favored because G3P is immediately used as a substrate for step 6

Glyceraldehyde-3-phosphate dehydrogenase:

a 2 step reaction that first oxidizes G3P using the NAD+ coenzyme to produce NADH. Energy from this reaction is used to attach a Pi to the oxidized product to form 1,3-bisphosphoglycerarate

Phosphoglycerate kinase:

Transfers a phosphate from 1,3-bisphosphoglycerate to ADP to make 3-phosphoglycerate and ATP

Phosphoglycerate mutase:

rearranges the phosphate in 3-phosphoglycerate to make 2-phosphoglycerate

Enolase:

Removes a water molecule from 2-phosphoglycerate to form a C=C double bond and produce phosphoenolpyruvate.

Pyruvate kinase:

transfers a phosphate from phosphoenolpyruvate to ADP to make pyruvate and ATP

What is the function of kinase?

Phosphorylation

What is the function of isomerase?

Creation of isomers

What is an isomer?

compounds with the same molecular formula but different structural formulas

What is the function of dehydrogenase?

Oxidization (removing H+)

What is the function of mutase?

Rearranging

What steps of glycolysis is part of the energy investment phase?

3-5

Where is the first use of ATP in glycolysis?

In step 1, when hexokinase converts glucose to glucose-6-phosphate

Where is the second use of ATP in glycolysis?

In step 3, when phosphofructokinase converts fructose-6-phosphate to fructose 1,6-bisphosphate

1 glucose is converted in 2 ____

G3P

F-1,6-BP is ___________________________________________________

a high-energy, unstable molecule

What does destabilization prepare the molecule for?

Cleavage into two 3-carbon sugars

What step is irreversible and highly regulated in glycolysis?

The conversion of fructose-6-phosphate to fructose-1,6-bisphosphate.

How much NADH is produced per G3P?

1

What happens when G3P is oxidized?

Hydrogen atoms are released, reducing NAD+ to NADH

What steps of glycolysis is part of the energy payoff phase?

4-10

What is used in glycolysis?

2 ATP

What us produced in glycolysis

4 ATP

2 NADH

2 pyruvate

All 6 carbons of glucose are in ___________________________________

2 molecules of pyruvate

Is carbon lost in glycolysis?

No

True or False: There is a change (decrease) IN potential energy in glycolysis

True

What happens in substrate-level phosphorylation?

Enzyme catalyzes transfer of phosphate from phosphorylated substrate to ADP to form ATP

What is an allosteric inhibitor of PFK?

ATP

What happens in the PFK low affinity state in layman's terms?

ATP binds to the regulatory site, causing reaction rate to slow dramatically

What happens in the PFK low affinity state?

Binding site: Active site only

Effect on PFK: enzyme active

Glycolysis outcome: glycolysis proceeds

What happens in the PFK high affinity state in layman's terms?

Fructose-6-phosphate is at the active site

ATP is at the active site

What happens in the PFK high affinity state?

Binding site: Active and allosteric sites

Effect on PFK: enzyme inhibited

Glycolysis outcome: glycolysis slows down

Energy production difference in sprinting and marathons

Free energy changes in aerobic respiration

What is the mitochondria made up of?

Cristae

Matrix

Inner membrane

Intermembrane space

Outer membrane

What are cristae?

Sacs of inner membrane joined to the rest of the inner membrane by short tubes

Pyruvate oxidation occurs in the

mitochondrial matrix

The electron transport chain occurs in the

inner mitochondrial membrane

ATP synthase occurs in the

inner mitochondrial membrane

The citric acid cycle occurs in the

mitochondrial matrix

[H+] s pumped into the

intermembrane space

ATP is released into the

What is used in pyruvate oxidation?

2 pyruvate is used and converted into 2 acetyl-CoA

What is produced in pyruvate oxidation?

2 NADH (1 per pyruvate conversion)

2 CO2 released (1 per pyruvate conversion)

Which complex catalyzes in pyruvate oxidation?

A pyruate dehydrogenase complex

What are the steps of pyruvate oxidation?

1. CO2 release

2. NADH generation

3. Acetyl-CoA formation

What type of pathway is the Krebs cycle?

Cyclic, meaning it must start and end with the same thing

What starts off, and ends Krebs cycle?

Oxaloacetate, a 4-carbon sugar

What are the steps in Krebs cycle

Glucose --> 2 pyruvate --> 2 acetyl-CoA

What is produced in Krebs cycle?

6 NADH

2 FADH

2 ATP/GTP

When is the first time that Acetyl-CoA is used in the citric cycle?

In step 1, when the acetyl group (2 carbon) is added to oxaloacetate (4 C) to create citrate (6 C)

What is released when Acetyl-CoA is used in the citric cycle?

Coenzyme CoA-SH is released and will be added back later in the cycle

Which enzyme is used in the first step of the citric acid cycle?

Citric acid synthase

When is the second time that Acetyl-CoA is used in the citric cycle?

In step 2, when the citrate (6C) molecule is rearranged into isocitrate (6C)

What enzyme is used in the second step of the citric cycle?

Aconitase (isomerase)

When is NADH produced in the citric cycle?

In steps 3 & 4 where:

2e and H are transferred to NAD+ creating NASH + H+

1 carbon is released and added to O2 to produce CO2

What happens in step 4 of the citric acid cycle?

CoA-SH is added creating a high energy bond

True or False: CoA-SH is cleaved from acetyl CoA

True

What happens in step 5 of the citric acid cycle?

-CoA-SH is released. This release energy is used to transfer a phosphate (Pi) to ADP/GDP creating a high energy ATP/GTP

-Phosphate passed to GDP to create GTP

-Phosphate passed from GTP to ADP to create ATP

What happens in step 6 of the citric acid cycle?

2e and 2H transferred to FAD to produced FADH2

What enzyme is used in step 6 of the citric cycle?

Succinate dehydrogenase

What happens in step 7 of the citric cycle?

H2O is added to fumarate to form malate

What hapens in step 8 of the citric cycle

2e AND H+ transferred to NAD+ to produce NADH + H+

Oxaloacetate recreated

Fill in the following: Electrons are pulled from (1), transferred to electron carrier molecules, (2), and at last moved to (30 at the end of the ECG.

1)Glucose, pyruvate, acetyl-CoA

2)NADH, FADH2

3)O2