Biochem Exam 2
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Biochem Exam 2
What does the term Carbohydrate mean?
polyhydroxy aldehydes and ketones
Monosaccharide name for an aldehyde
Monosaccharide term for Ketones
3 carbons in a monosaccaride
4 carbons in a monosaccharide
5 carbons in a monosaccharide
6 carbons in a monosaccharide
*has a chiral carbon
In a Fischer projection where is the most oxidized carbon?
Groups that aren't part of the main chain are pointed which way?
They project horizontally towards the viewer
If the sterocenter at the bottom of the chain has an OH to the right, is the sugar D or L
If the sterocenter at the bottom the chain has an OH to the left is the sugar D or L?
Are the most common sugars in D or L form?
There is a change at every chiral carbon
Epimers (special Diasteriomers)
If theres a change at
There is a change at more then 1 chiral carbon
The most simple sugars of four or more carbons exist in what form?
cyclic (hemiacetal/hemiketal) form
What group in the sugar reacts with the carbonyl carbon?
A hydroxy group
For D sugars if the OH on the anomeric carbon is "up" then the carbon is what?
For D sugars if the OH on the anomeric carbon is "down" then the carbon is what?
a 6-membered ring is called?
A 5-membered ring is called?
To form a cyclic sugar the attack of an alcohol on the carbonyl carbon forms what?
What is formed at the anomeric carbon during the formation of cyclic sugars?
In the formation of the hemiacetal, an alpha anomeric carbon has the OH pointing?
In the formation of the hemiacetal, a beta anomeric carbon has the OH pointing?
What is a reducing sugar?
a free aldehyde that can be oxidized
In what function are reducing sugars important?
They are important in the metabolism of polysaccarides
The OH groups of sugars can reach with a phosphorylating agent to give what?
Phosphoesters are common in what kind of pathways?
In metabolic pathways
What can the anomeric carbon react with?
an OH group or an alchohol
when the anomeric carbon reacts with an alchohol on another sugar what does it yeild?
a glucosidic bond
Animals lack what when it comes to cellulose?
The enzymes necessary to hydrolyze cellulose
what are starches
starches are storage forms of glucose found in plants
how do animals store glucose?
Where is the division between the 2 stages of glycolysis?
Right after the second ATP is invested
What is a kinase?
It does phosphorylation with ATP, either using it or producing it.
Step 1 of Glycolysis
1. Hydroxy group attacks the phosphoanhydride on ATP
2. Gives Glucose a charge
3. Makes the Oxygen on C6 of Glucose more reactive
Why is glucose given a charge in step 1 of glycolysis
to keep it in the cell.
What type of intermediate does step 2 of glycolysis go through?
It goes through an enodiol intermediate to isomerize from an aldehyde to a ketone
Why isn't C1 available for phosphorylation on glucose in glycolysis?
It is anomeric, but C1 on Fru can be phosphorylated
Step 1 of Glycolysis
Glucose -> Glucose-6-Phosphate
Step 2 of Glycolysis
Glucose-6-Phosphate -> Fructose-6-Phosphate
Step 3 of Glycolysis
Fructose-6-Phosphate -> Fructose-1.6-biPhosphate
Step 4 of Glycolysis
Fructose-1,6-biPhosphate -> Trioses
Step 5 of Glycolysis
Isomerization of DHAP
What does bis-phosphate mean?
2 separate phosphates
Allosteric regulation is based on what?
the reverse reaction of step 4 of glycolysis is what?
an aldol condensation reaction
Having 2 phosphose on a 6-carbon sugar allows what?
Cleavage into 2 phosphorylated trioses
DHAP and Glyc-3-P are in equilibrium that favors which one?
Even though DHAP is favored over Glyc-3-P, it is rapidly converted. Why?
The loop in Triose Phosphate Isomerase serves as what?
A lid to prevent biologically useless but energtically favorable side reaction.
overall glycolysis yields what?
per glucose molecule
Step 6 of Glycolysis
Glyceraldehyde-3-Phosphate -> 1,3- Bis phosphoglycerate
What does step 6 of Glycolysis produce?
A high energy mixed anhydride bond
In step 6 of glycolysis what preserves energy from the first step to couple it to the second step?
The thiosester intermediated with the enzyme's cys residue
Step 7 of Glycolysis
1,3-Bisphosphoglycerate -> 3-phosphoglycerate
What does step 7 of glycolysis produce?
the first production of ATP from the high energy mixed anhydride.
Step 8 of Glycolysis
3-Phosphoglycerate -> 2-Phosphoglycerate
What do the first 2 steps of step 8 make?
a phosphoend pyruvate
( a molecule with high phosphoryl transfer potential)
What is the function of Mutas phosphoglycerate?
It catalyzes step 8 of glycolysis
Step 9 of Glycolysis
3-Phosphoglycerate -> Phosphoenolpyruvate
Step 9 of glycolysis is catalyzed by what?
What does the phosphate group to in step 9?
It hold the PEP in the enol form, rather then the keto form
Step 10 of Glycolysis
What catalyzes step 10 of glycolysis?
Is step 10 energetically favorable or unfavorable?
It is favorable, pyruvate is very stable compared to the enol from. and PEP has a very high transfer potential
What does step 10 produce?
the second ATP
Glycolysis Produces ATP, but uses what?
In Aerobic conditions what happens to NADH
it is reoxidized in electron transport
In anaerobic conditions what needs to happen to NAD
It needs to be regenerated in order to continue producing ATP through glycolysis
Galactose + Glucose
Glucose - Fructose
Synthesis of glucose from pyruvate instead of carbs
Does gluconeogenesis use the same enzymes as glycolysis?
no, they each use different enzymes gluconeogenesis uses phosphatase, which removes a phosphate group.
In the reaction of Pyruvate to PEP what enzyme cofactor is used?
Biotin, to carry CO
In the reaction of Pyruvate to PEP is ATP consumed or produced?
It consumes 2 ATP
What is the biotin cofactor bound to?
To a Lys residue
What carries the biotin cofactor?
In the reaction of fructose-1,6-bisphosphate to fructose-6-phosphate how is the phosphorus released?
It is released as PO
instead of ATP
What happens to the glucose produced by glucose-6-phosphate?
it is released into the blood
how is the glucose from glucose-6-phosphate stored?
Why is Glycogen metabolism regulated?
So that sufficient glucose is available for the body's energy needs
what controls glycogenesis and glycogenolysis?
insulin, glucagon, and epinephrine
what does insulin do to glycogenesis?
it speeds it up
what does glucagon do to glycogenolysis?
it speeds it up
what is the function of glycogen phosphorylase during glycogenolysis?
it removes glucose unites from non-reducing end of glycogen until 4 are left approaching a branch point.