Chapter 14 Flashcards
What are the major pathways of glucose?
- Use in the synthesis of polysaccharides
- Stores in cells
- Oxicdized to a 3-carbon compound via glycolysis
- Oxidized via the pentose phosphate
In glycolysis
A molecule of glucose is degraded in a series of enzyme - catalyzed reaction to yield two molecules of the 3 carbon compounds pyruvate
Fermentation
Is the term for anaerobic degradation of glucose or other organic nutrients to obtain energy conserved as ATP
The 1st 5 steps is called the _____________
preparatory phase which is the phosphorylation of glucose & its conversion to glyceraldehyde 3- phosphate
The last 5 steps in glycolysis is called what?
Payoff phase which is the oxidative conversion of glyceraldehyde 3-phosphate to pyruvate & the coupled formation of ATP & NADH
The preparatory phase of glycolysis requires _______
ATP
Phosporylation of glucose is the ______ step of glycolysis where glucose is activated for subsequent reaction by its phosphorylation at C6 to yield glucose 6-phosphate with ATP as the phosphoryl donor
1st
The 1st step is catalyzed by ________
Hexokinase
________ shields the negative charges of the phosphoryl group in ATP making the terminal phosphorous atom an easier target for nucleophilic attack by an -OH of glucose
Mg2+
Induced fit in hexokinase (HK)
Order substrate binding prevents unwanted ATP hydrolysis
HK & glucose leads to a conformation change which leads to the formation of ______ binding site which leads to the HK-glucose- ATP complex which leads to P transfer to given GGP & ADP
ATP
Isozymes
Two or more enzymes that catalyze the same reaction but are encoded by different genes
The _____ step in glycolysis is the conversion of glucose 6-phosphate into fructose 6 - phosphate
2nd
In the 2nd step the enzyme ___________________ catalyzes the reversible isomerization of glucose 6-phosphate which is an aldose to fructose 6-phosphate (which is a ketose)
phosphohexose isomerase
The ____ step of glycolysis is the phosphorylation of fructose 6 - phosphate to fructose 1,6 - Bisphopshate
3rd
_________________ catalyzes the transfer of a phosphoryl group from ATP to fructose 6 - phosphate to make fructose 1,6- bisphosphate (irreversible)
Phosphofructokinase - 1 (PFK-1)
Bisphosphate
Are compounds that contain 2 phosphate or phosphoryl groups attached at different positions in the molecule
_______________ catalyze the 3rd step reaction
PFK-1
Which step in glycolysis is the first committed step in the reaction?
The 3rd step is the first committed step iin the reaction
The _______ step in glycolysis is the cleavage of fructose 1,6-Bisphosphate
4th
The enzyme ___________ catalyzes the 4th step which is a reversible aldol condensation
Aldolase
In the 4th step fructose 1,6-bisphosphate is cleaved to yield two different triose phosphate which are what?
- Glyceraldeehyde 3- phosphate(an aldose)
- Dihydroxyacetone phosphate (a ketose)
The ______ step of glycolysis is the interconversion of the triose phosphate
5th
In the 5th step of glycolysis what happens to the two phosphate groups?
Only glyceraldehyde 3-phosphate is degraded & dihydroxyacetone phosphate is rapidly & reversibly converted to glyceraldehyde 3- phosphate by the 5th enzyme
What enzyme is used to catalyzethe 5th step in glycolysis?
Triose phosphate isomerase
At the end of the first phase of glycolysis what has happened?
The hexose molecule has been phosphorylated at C-1 & C-6 & then cleaved to form two molecules of glyceraldheyde 3- phosphate
The payoff phase of glycolysis (the 2nd phase) yields what?
ATP & NADH
In the first phase of glycolysis, one molecule of glucose yields two molecules of _____________________ & both halves of the glucose molecule follow the same pathway in the second phase of glycolysis
Glyceraldehyde 3-phosphate
The _____ step of glycolysis (which is the 1srt step in the payoff phase) is the oxidation of glyceraldehyde 3-phosphate to 1,3bisphosphoglcerate
6th
What is the enzyme used in the 6th step to catalyze the reaction?
Glyceraldehyde 3- dehydrogenase
The 6th step is the first ______________ reaction of glycolysis
Energy conserving
In the 6th step in the oxidation of the substrate energy is conserved as what?
2 electrons on NADH & acyl phosphate group of product (used to make ATP in the next reaction)
The aldehyde group of glyceraldehyde 3-phosphate is oxidized to a carboxylic acid anhydride with phosphoric acid and its called _______________
Acyl phosphate
The formation of 1,3-BPG can be thought of as occurring in what two steps?
- The highly favorable oxidation of GAP to an acid (∆Go’ = - 50Kcal/mol)
- The highly unfavorable formation of 1,3-BPG from the acid (∆Go’ = 50Kcal/mol)
The two reaction in the formation of 1,3 BPG are linked by the formation of an energy - rich ___________ intermediate in the active site of gluceraldehyde 3- phosphate dehydrogenase
thioester
The ______ step of glycolysis is the phosphoryl transfer from 1,3 bisphosphoglycerate to ADP
7th step (first production of ATP)
What happens in the 7th step?
Its enzyme transfers the high energy phosphoryl group from the carboxy group of 1,3-bisphosphoglycerate to ADP from ATP & 3-phosphoglycerate
What is the enzyme used in the 7th step?
Phosphoglycerate kinase
In the 7th step substrate - level phosphorylation occurs where what happens?
The formation of ATP by phosphoryl group transfer from a substrate such as 1,3-BPG
The formation of ATP by phosphoryl group transfer from a substrate such as 1,3 Bisphosphoglycerate or PEP is referred to as what?
Substrate- level phosphorylation
The ____ step is the conversion of 3-phosphoglycerate to 2-phoshoglycerate
8Th
What is the enzyme used in the 8th step?
Phosphoglycerate mutase
Step ____ is the dehydration of 2-phosphoglycerate to phosphoenolpyruvate (PEP)
9th
What enzyme is used in step 9?
Enolase
The ______ is the transfer of the phosphoryl group from PEP to ADP
10th
What is the enzyme used in the 10th step?
Pyruvate kinase (which requires K+ & either Mg2+ or Mn2+)
At the end of glycolysis how many ATP molecules are there?
2 ATP
Pyruvate Tautomerization drives _____ production
ATP
Even thought glycolysis has two part to it, it can be broken down into ___ stages
3
Stage 1 of glycolysis (step 1,2,&3) it traps _______ in the cell & destabilizes its structure
Glucose
In stage 2 of glycolysis (step 4 & 5) it breaks down the _____________ into smaller components
Glucose
In stage 3 of glycolysis (step 6,7,8,9,& 10) it harvest the energy to form _______ molecule & pyruvates
ATP
G6P happens so it can become more ______ so that it can become trap in the cell
Polar
In stage 3 of glycolysis, it aims to harvest the energy in glyceraldehyde 3 phosphate to form _____, NADH, & pyruvate molecules
ATP
In step 6 the enzyme that is used has a cysteine that is used to form a _____________ intermediate
thioester
In the absence of the enzyme for step 6 the process in step 6 would occur via two reaction pathways, a redox followed by ________________ reaction
Dehydration
The _____________ intermediate for step 6 is used to couple the oxidation redox reaction & dehydration reaction & decrease the activation energy to make the step more favorable
Thioester
Glucose 6 phosphate turns into fructose 6 phosphate so that when its aldolase at the alpha-beta position it forms two separate ________ carbon molecules
3
In step 7 the mutase enzyme moves the phosphoryl group form the ____ carbon into the 2nd carbon
3
When glucose is broken down in glycolysis its overall an ______________ reaction
Exergonic
Step 7 is the 1st production of ______ & step 10 is the 2nd production of ______
ATP
Glycolysis is heavily regulated to ensure the proper use of nutrients & ensure production of _______ only when needed
ATP
