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178 Cards in this Set

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What are the three main energy producing nutrients?
Carbohydrates
Lipids
Proteins
How are Carbohydrates classified?
mono, di, and poly saccharides.
How are Lipids classified?
Glycerides
Fatty Acids
How are proteins classified?
Polymer
Amino Acids
What is preferred by most cells for nutrient use?
carbohydrate (CHO)
If Carbohydrates are not available (dieting or fasting) cells can undergo what process?
Gluconogenesis. (using proteins)
If a week or so of dieting/fasting goes by what will the body adapt to using?
Lipids
What happens when the lipids are depleted after carbs have been exhausted?
the body will resume the use of protein.
When 1/3 of the bodies available proteins are depleted after lipids/carbs are used up what happens?
death
What is the definition of a carbohydrate?
it is the most abundant class of organic molecules in nature.
What is the definition of a carbohydrate?
the most abundant class of organic molecules in nature.

they are hydrates of carbon (CH2O)n where n>/= 39
Carbs normally constitute what percentage of the human diet in the US?
40-45% of caloric intake.
What are the major functions of Carbohydrates?
Provide energy
Structural components of body.
What is a monosaccharide?
The simplest sugar.

Can be either aldose or ketose
What is the difference in (CH2O)n and just plain CH2O.
It is a huge difference. One is a carbohydrate and the other is just an aldehyde. you must have at least 3 or it's not a sugar and thus, cannot be a carbohydrate.
What is an oligosaccharide?
Usually 2-10 monosaccharides.
How are monosaccharides named?

Count to ten like that yo!
by the number of sugars included and adding -ose.

diose
triose
tetrose
pentose
hexose
heptose
octose
nonose (?)
decose
What is the difference in an aldose and a ketose?
an aldose has the Ch2O group on the end, and a ketose has it somewhere in the middle.
What are the names of the monosaccharide structures you are required to know?

What type of monosaccharide are they?
Aldotrioses
D-Glyceraldehyde
Dihydroxyacetone

Aldopentoses
D-Ribose
D-Ribulose

Aldohexoses
D-Glucose
D-Mannose
D-Galactose
D-Fructose
What is the structure of D-Glyceraldehyde and Dihydroxyacetone?

Why do you put these together on this slide?
They are both aldotrioses and that helps remember the structure.

3 carbons each

D-Glyceraldehyde is
CHO-CH2O-CH2OH

Dihydroxyacetone
CH2OH-CO-CH2OH
What is the structure of D-Dibose and D-Dibulose?

Why put these together?
They are both aldopentoses.

D-Ribose
CHO-CH2O-CH2O-CH2O-CH2OH

D-Ribulose
CH2OH-CO-HCOH-HCOH-CH2OH
What is the structure of D-Glucose, D-Mannose, and D-Galactose?

why put them together?
All three are aldohexoses

D-Glucose
CHO-HCOH-HOCH-HCOH-CH2OH

D-Mannose
CHO-HOCH-HOCH-HCOH-HCOH-CH2OH

D-Galacttose
CHO-CO-HOCH0HCOH-HCOH-CH2OH
What is a tautomer?
Tautomers are isomers of organic compounds that readily interconvert by a chemical reaction called tautomerization.
What is an example of a monosaccharide tautomer?
The very slow interconversion of D-glyceraldehyde to enediol intermediate to dihydroxyacetone.

All three compounds are stable so the conversion is very slow.
What determines whether a monosaccharide is D or L?
The farthest asymmetric carbon from C=O determines it.

D = same side
L = opposite side
Sugars often have multiple chiral centers. If n chiral centers 2^n = stereoisomers.
thats 2 to the power of n stupidass!
What is an epimer?

Some examples? What is important to remember before you call it an epimer?
two sugars that differ only in the configuration of one carbon.

D-glucose and D-Mannose have 1 difference in the #2 carbon.

Make sure it's not just an isomer before you call it an epimer.
What happens to most sugars 5 carbons and bigger when they are in aqueous solutions?
they typically cyclyze at the #1 carbon.
What is the new chiral center called following cyclization?
it is called anomeric carbon.
What are the three ways to represent sugars and which is most popular?
fisher projections - most popular!
haworth
conformational structures
Can a sugar be used as a reducing agent?
sugars with free anomeric carbons will reduce oxidizing agents, (peroxide/ferricyanide, Cu/Ag)
Reducing a sugar leads to a...
redox reaction that converts the sugar to a sugar acid.
Mild reduction of a sugar leads to..
sugar alcohols.
What is a deoxy sugar?
it's the constituent of DNA.. duh.. it's missing the OH group on the #2 carbon.
What is a sugar ester?
A sugar ester is a phosphate ester.. like ATP.
Where is ATP important?
uh.. everywhere but for this class.. it's especially important in metabolism.
What is a Amino Sugar?
it has an amino in place of a hydroxyl.
What are glycosidic linkages?
they are formed by elimination of water between anomeric OH of cyclic monosaccharide and hydroxyl group of another compound.
What are glycosides?
they have no mutarotation in the absence of acid catalyst.
Where will you find glycosidic linkages?
they link sugars in oligosaccharides and polysaccharides.
What are disaccharides?
2 sugar residues joined by glycosidic linkages.
What are common disaccharides?
Sucrose
Lactose
Maltose
Trehalose
What are the two constituents in the common diasaccharides and what type of bonds do they have?

Sucrose, Lactose, Maltose, & Trehalose?
Sucrose - gly/fru/ alpha 1,2
Lactose - gal/glu b-1,4
Maltose - glu/glu a-1,4
Trehalose - glu/glu - a-1,1
What is Trisaccharide? and what are the sugars involved in making it?
Raffinose - glu/gal/fru
What it tetrasaccharide and it's involved sugars?
stachyose - 2gal/glu/fru
What is a pentasaccharide and it's sugars?
verbascose - 3gal/glu/fru
What is a hexasaccharide and it's sugars?
ajugose - 4gal/glu/fru
What are N-, and 0- glycosidic bonds?
like those found in an RNA molecule.

PICTURE IT!

base N - C - sugar

triphosphate - C - sugar
What is a polysaccharide?
a polymer of monosaccharides.
If a polysaccharide is made up entirely of the same monosaccharides what is it called?

Different monosaccharides?
homopolysaccharides have all the same mono's

Heteropolysaccharides have all different
Modified monosaccharides can also be these..
monomeric units.
How can polysaccharides store energy in higher organisms?
as starch - in plants

as glycogen - in animal storage.
What are the two forms of starch and in what percentages do they exist?
amylose - 10-30%
amylopectin - 70-90%
What is amylopectin and how is it linked?
it is made of D-glucose and has a-1,4 links.
Amylopectin branches, how often, and what type of links does it use?
every 12-30 residues and it uses a-1,6 to do so.
What is amylose and how is it linked?
D-Glucose ION and it is linked by a-1,4 and it has one reducing end.
Glycogen differs from starch in what way?
It is still composed of glucose and has a-1,4 links (a1,6 for branches) but it branches more often, every 8-12 residues.
What do Glycogen and Amylopectin have in common?
they both give a red-violet color with iodine.
What percentages of the liver and muscle mass are glycogen?
10% of liver mass

1-2% of muscle mass
What are the two main functions of polysaccharides?
Energy storage in higher organisms

Structural funtions
What are three ways polysaccharides can serve as structural functions?
cellulose, chitin, and collagen.
What are some other misc functions of polysaccharides besides energy storage and structural?
hyaluronic acid - viscosity increasing agent or lubricating agent in the vitreous humor of the eye and synovial fluid of joints.

heparin - inhibits blood clotting

peptidoglycans - cell-cell recognition.
What are structural polysaccharides made up of?
monosaccharides and dervatives.
How are structural polysaccharides linked?
They are linked by glysodic bonds but they are different from normal.
What is the structural arrangement of starch?
It is a-1,4 linked D-glucose and makes a zig/zag pattern.
What is the structural arrangement of Cellulose?
It is B-1,4 linked - D-glucose uniots. It is linear.
What is a stronger structure cellulose or starch and why?
cellulose is stronger because it's links make it a linear shape and it can be stacked on top of each other.
b-1,4 links can make sheets how stabilizes and makes this a stronger structure?
H bonds between the sheets.

Intrachain H bonds, and interchain H bongs also add strength.
How are b-1,4 cellulose sheets arranged?
Typically they are parallel.
What are the two most abundant polysaccharides? What is different about them?
Cellulose and Chitin are the most abundant polysaccharides.

they are both b-1,4 linked.

Cellulose has D-glucose units and chitin is composed of N-acetylglucosamine units it has a Amine group attached to each unit and it is arranged in a trans pattern when they are linked.
Where does the digestion of carbohydrates being?
in the mouth. Salivary amylase begins hydrolysis of the sugars.
What does salivary amylase do?
it cuts the a-1,4 bond found in carbohydrates.
what is, and what is the purpose of endoglycosidase?
It is the cutting of a-1,4 binds and it's purpose is to break down bigger units through the use of amylase.
What happens to carbohydrates in the stomach?
not much carb digestion but acid/pepsin unfold proteins.
What happens to the carbs in the small intestines?
Pancreatic enzymes (a-amylase) further breaks down the carbohydrates.
What are maltose and isomaltose and sucrose broken down with? what do they breakdown to?
Sucrase-isomaltose complex breaks them down into glucose or glucose + fructose.
What breaks down oligosaccharides? what does it break down to?
glucoamylase complex and it breaks them down to glucose.
What breaks down lactose and what it is broken down to?
lactase B-galactosidase complex. it is broken down to glucose and galactose.
What breaks down trehalose and what is it broken down to?
trehalase complex breaks it down to glucose.
What happens to the left over fiber after digestion?
IT IS FOR POOPING!!
How does fructose get across the intestinal epithelium into the blood stream?
Fructose travels across the intestinal epithelium by facilitated glucose transporters
How does glucose get across the intestinal epithelium?
glucose can use either the Na+glucose cotransporters or the facilitated glucose transporters.
How does galactose get across the intestinal epithelium into the blood?
Galactose uses the Na+glucose cotransporter to get into the membrane layer and uses the facilitated glucose transporters.
What do the monosaccharides have to pass to get into the blood stream once they have been broken down?
the microvilli (brush border)
terminal web
tight junction
"NORMAL ORGANELLES in the intercellular space"
then the basolateral cell membrane.
What is an example of carbohydrate malabsorption?
lactose intolerance (hypolactasia)
read p. 508 in book.
What are some signs of lactose hypolactasia?
the lactose is fermented in the body which causes gas and volatile FA, water retention, and diarrhea/bloating.
What populations typically suffer from more incidences of lactose intolerance?
northern european have lower incidences while asian/african americans have higher instances.
What are the causes of LI
first degree LI is due to decline in lactase with age.

Lactase cuts the b-1,4 linkage between galactase and glucose.. when it doesn't work.. well thats LI.

2 degree LI is caused by injury or something along those lines
how can someone be diagnosed with LI?
there is a lactose tolerance test that includes a hydrogen (h2) breath test, and a stool acidity test.
What is the treatment for LI?
lactase enzymes in tablet/liquid form.
consume smaller amounts
low lactose products
calcium and vitamin D supplements
What happens to monosaccharides that are not absorbed in the upper intestines?
They go on to the lower intestines to produce short chain fatty acids.
What happens to the carbs that are absorbed into the blood stream?
they provide immediate energy needs of all cells
What happens to excess CHO's?
some are converted to glycogen and stored in the muscle/liver.

others are converted to fat in liver and stored in adipose cells.
What are normal blood glucose levels? High/Low?
Normal is 70-99 mg/dl (fasting)

below 40mg/dl is low

above 180 mg/dl is considered high.
What can high/low blood glucose levels cause?
low can cause coma, seizure, death, not generating enough energy - Hypoglecemic

high can cause glycosuria, caloric loss, thirst, hunger.
Chronic effects renal, retinal, nerve, blood vessel damage.
This is considered hyperglycemic.
What is the glycemic index?
a quantitative ranking of foods based on their effect on blood glucose compared to a reference food.
What is the reference food for the glycemic index?
white bread (50g of available carbs)
Glucose - 50 g
what is the scale for the Gly index?
>70 is a high GI
56-69 - moderate/med gi
<55 is a low GI.
How/who applies application of glycemic index?
diabetics - low gi foods help in control of blood glucose and insulin responses.

sports - different GI foods more effectively replenish glycogen stores after exercise: high GI foods replenish glycogen better than low GI.

Appetite research 0 low foods produce greater satiety than high GI foods.
What are factors that affect foods GI?
particle size - as particle size goes down GI goes up.

differences in cooking

starch composition: amylose v. amylopectin

fiber content

ripeness

food processing.
What is carb counting?
CHO is the nutrient in food that raises blood glucose the most

amount of CHO eaten determines how high blood glucose will rise after a meal.

takes approx 15 minutes of eating.
how does carb counting help diabetics?
they keep track of amount of CHO eaten at meals and snacks.

helps keep CHO levels consistent

they can match insulin injectiosn to CHO intake (for some patients)
How does insulin (high blood glucose) and glucagon (low blood glucose) regulate blood glucose?
insulin stimulates cells to take up glucose from the blood.

Glucagon stimulates liver cells to break down glycogen to glucose.
insulin/glucagon.. which does what?
insulin lowers blood glucose
glucagon raises it (the glucose is gone man!)
What is catabolism?
the breaking down of molecules to smaller/simpler molecules.

Canabilism!
What is anabolism?
Building up of a molecule from smaller particles.
What are the three major components of ATP?
adenine, a ribose, and three linked phosphates.

Po3(OH)- = a phosphate. It binds where the OH group is after dehydration.
What is an endergonic reaction?
requires energy to be added +deltaG
What is an exergonic reaction?
Releases energy.
-deltaG
What is a coupled reaction?
When the release of energy in an exergonic reaction drives an endergonic reaction.

-working together and has a net gain of energy.
What is oxidative phophorylation?
It transforms the energy from the chemical bonds of fuels into the reduction state of coenzymes (NAD+ and FAD)
Determining oxidation.. how to do it from ox numbers?
A decrease in charge 2+ - 0, or 0 - -2 is oxidized.
Determine reduction.. how to?
An increase in ox number 0 - 2+ or -2 - 0 is reduced
How is ATP generated in the body/regenerated?
The degradration of glucose and glycogen.

Anerobic glycolysis
What is glycolysis?
the central, nearly universal pathway for glucose utilization.
What organ is principally responsible for the maintenance of blood glucose levels?
The liver
What two hormones are primarily responsible for regulating blood glucose levels?
Insulin = too much
Glucagon - not enough
What is the function of glycolysis?
to generate ATP in both aerobic, and anaerobic conditions.

It also serves as an anabolic pathway for precursors for biosynthetic pathway.
Where does glycolysis actually take place?
It occurs in the cytosol.
What are the two phases of glycolysis?
The preparatory phase and the payoff phase (ATP generating phase)
What happens in the preparatory phase?
collection of sugars by the liver
subsequent phosphorylation of these sugars.
Conversion of glucose to glyceraldehyde-3-phosphate.
What happens in the payoff stage?
Conversion of G3P to either pyruvate or lactate
concomitant conservation of energy via formation of 4 ATP
What is the official "end" of the preparatory stage ?
When F-1,6-P is cleaved by Aldolase at the 3/4 carbon.
What is the main reason intermediates are phophorylated during glycolysis?
To retain molecules within the cell (polarity)
they are essential components in enzymatic conservation of metabolic Energy.
It is used to regulate glycolytic enzymes (pyruvase kinase, PFK1)
When does glycolysis actually start?
Why does it stay there?
As soon as the glucose enters the cell.

it is held there by polarity until it's finished.
Which steps in glycolysis are reversible? which are non-reversible?
1,3, and 10 are non-reversible (regulation points)
the rest are readily reversible.
What is the first "commited" step of glycolysis?
F6P - F-1,6-P
What is DHAP?
dihydroxyacetone-3-phosphate
Reaction #4 in glycolysis is non-spontaneous (cleavage by aldolase of F-1,6-P). How does the reaction occur?
The product is used immediately to avoid it going backwards.
Where is the ATP paid into glycolysis get paid back?
Step 7, (1,3biphosg --> 3-phos).

You get 1 ATP for each molecule (2 total) so this evens things out for energy.
Why is PEP to pyruvate irreversible?
enol form of pyruvate tautomerizes to much favored keto form.
What is the 11th step of glycolysis that only happens if the reaction is in a anaerobic condition?
pyruvate to lactate.
What is important about the NAD+ generateed in anaerobic glycolysis?
it is essential for continued anaerobic glycolysis
What happens to the lactate that is produced during anaerobic glycolysis?
it accumulates as lactic acid in the muscles (it's what burns)
What is the net yield of glycolysis in an anaerobic condition?
D-glucose + 2 Pi + 2 ADP ---> 2 lactate + 2H+ + 2 ATP + 2H2O.

NET YIELD!!!
What is the NET yield of glycolysis in an aerobic condition?
D-glucose + 2 Pi + 2 ADP + 2 NAD+ ---> 2H+ + 2 ATP + 2 NADH + 2 H20
What is the fate of NADH in glycolysis?
It must be conitnuously oxidized by ETS.
Where are some examples of anaerobic glycolysis in the body?
Red Blood Cells
Kidney Medulla
Eye tissue
Hypoxia
Why are RBC's anaerobic?
no mitochondira, limited oxidative capacity.
What is hypoxia?
occurs when limited oxygen supply to very active skeletal muscles

and also in cancer cells.
What happens to the pyruvate made in glycolysis?
Mostly it goes to Acetyl CoA + CO2 in aerobic conditions, but if anaerobic it goes to lactate.
What is the total lactate production of the body per day?
roughly 115 g/d
What happens to the lactate that is released?
It is taken up by other tissues (liver, heart, skeletal muscle) and oxidized back to pyruvate and back to synthesized glucose with the glyconeogenesis pathway.
What are the cofactors involved in pyruvate to AcetylCoA? (list by complex)
thiamine pyrophosphate (TPP), Lipoamide, & FAD

NAD+

CoA
What is pyruvate deficiency?
Pyruvate gets shunted to lactate (via lactate dehydrogenase)
Causes congenital lactic acidosis.
What is the pathophysiology of pyruvate dehydrogenase deficiency?
overwhelming lactic acidosis and neonatal death.

psychomotor retardation, damage to cerebral cortex, basal ganglia and brainstem, leads to death.

causes ataxia after a carb rich meal.
What are the treatments for pyruvate dehydrogenase deficiency?
there are no proven treatments.
How do other sugars get into the glycolytic pathway?
Galactose enters into the pathway at G6P.

Mannose enters in at F6P
Fructose (muscle) also at F6P

Fructose (liver) joins at G3P

They use different means to get there and you should know them.
Which alternate sugar provides a slower process, and steady supply of energy?
D-Fructose

it has to do with it's pathway.
Where are you likely to find regulation steps for pathways?
Irreversible reactions
Usually at early steps
What do regulation pathways do?
They slow down the pathway without using Energy.

protect against intermediate accumulation.
What regulates G-G6P. How, where and what is the difference?
hexokinase is allosterically inhibited by G6P only in the muscle.

Glucokinase, in the liver, is not regulated in this fashion.
What is the net yield for gluconeogenesis?
2 pyruvate + 4 ATP + 2 GTP + 2 NADH + 4 H20 ----> glucose + 4 ADP + 2 GDP + 6 Pi + 2 NAD+ + 2 H+
What are the four substrates for gluconeogenesis? (where are they from?)
Lactate - anerobic glycolysis
Glycerol - adipose stores of trigly's
Amino Acids - alanine - major gluconeogenic aa.
propionate - odd chain length fatty acids, obtained from veggies, minor precursor of glucose in humans.
What is the enzyme for lactate --> pyruvate? and what else is added as a co-factor?
Lactate dehyrogenase.

NAD+ added and NADH+ + H+ created.
What is the enzyme and cofactor for amino acid ---> pyruvate?
alanine aminotransferase

alpha keto acid is added... an amino acid comes out the other side.
enzymes/steps for glycerol --> dihydroxyacetone-3-phosphate.
glycerol -->(ATP required) glycerol kinase (NR) ----> glycerol-3-phosphate <-----> glycerol-3-dehydrogenase <-----> dihydroxyacetone-3-phosphate ------------> enters glycolysis/gluconeogenesis at this point.
Regulation of glucogenesis..

3 ways
glucose6p-ase just like glycolysis

f1,6bisP just like glycolysis

cAMP deactivates purvate kinase with a P,, activates by removing it.

Acetyl Co - A activates pyruvate carboxylase.
What is differenet about glucokinase when thinking about the differences in glycolysis and gluconeogenesis?
if gluconeogen is active then there isn't much glucose going around (fasting etc.) so glucokinase will be, in effect, be deactivated because of it's high Km for glucose
Glucagon (and insulin as the reverse action) considerations when fasting.
It will stimulate gluconeogenesis to get on the ball in the normal ways. pepck, f16bP, g6p, etc.

it will supress glucokinase (high km for glucose, when glucose levels are low)
PFK1, and pyruvate kinase.. in other words.. it will inhibit glycolysis.

insulin will do the opposite.
What are the major functions of the Pentose Phosphate Pathway? (PPP)
MAJOR source of NADPH in cells for the ff:

Shunt hexoses from glycolysis to form pentoses for form RNA/DNA biosynthesis.

Converts pentoses into hexoses and trioses so they can enter the glycolysis pathway when needed.
In PPP NADPH is used for detoxification..... what does the detox do?
reduction of oxidized glutathione

cytochrome P450 monooxygenases
In PPP NADPH is collected for reductive syntheses like ... what?
fatty acids
fatty acid chain elongation
cholesterol
neurotransmitters
nucleotides
What ist he overall equation for the PPP?
3 G-6-P + 6 NADP+ ---> 3 CO2 = 6 NADPH + 6 H+ + 2 F-6-P = glyceraldehyde-3P.
What are the two phases of the PPP and their purpose?
1. Oxidative

2. Non-oxidative.
What happens in the oxidative phase of PPP?
2 oxidative reactions provide NADPH
A hexose is decarboxylated to a pentose.
Isomerization - 2 reversible ones.
What happens in the non oxidative phase of PPP?
series of rearrangements and transfer reactions.
excess pentoses are converted to hexoses and trioses which can enter the glycolytic pathway.
for stage 1/2 of PPP what is the "So far. . . " reaction?
1 G-6-P = 1 NADPH + 1 R-5-P
In PPP what enzyme further convers G-3-P, and F-6-P ?
Transketolase and Transaldolase
What are the important things to remember about the non-oxidative phase of PPP?
transketolase, and transaldolase created a reversible link between PPP and glycolysis.

Excess ribose can be easily converted back to the glycolytic pathway.
What is the net reaction for the non-oxidative portion of the PPP?
3 R-5-P -----> 2 F-6-P + G-3-P

they are intermediates for glycolysis.. duh.
What is the regulator in oxidative PPP?
NADPH inhibits

Dephosphorylation of NADPH (NADP+) relieves the inhibition.
What is a major source of NADPH (from PPP) re-oxidation?
fatty acid synthesis in the liver.
how is the non-oxidative portion of PPP regulated?
substrate availability alone.
What happens in G6PD deficiency? What is it?
It is an inherited disease.

it is an inability to detoxify oxidizing agents

it is the most common disease producing enzyme in humans (7% world wide, 2% in humans)
What caused G6PD deficiency?
X-linked deficiency caused by >300 different mutations in G6PD gene. (only a portion of these cause clinical disease)
How does G6PD affect lifespan?
it shortens it due to chronic hemolysis complications
What are precipitating factors for G6PD deficiency?
oxidant drugs (AAA) antiboitics, anti-malarial, antipyretics.

Favism - fava bean puring glycosides

Normal infections (free radicals (ROS) form due to inflamm response)