Biochem test chapter 7
Sucrose
Common table sugar produced in the leaves and stems of plants, 1 molecule of glucose linked to 1 molecule of fructose linked by a A,B (1,2) glycosidic bond, a non-reducing sugar
Glycoproteins
Commonly defined as proteins that are covalently linked to carbs through N- and O- linkages
When humans consume ethanol , the first step in its metabolism is
Conversion to acetylaldehyde and the nacetic acid is formed from the aldehyde
What can all carbohydrates be considered to have derived from
D-glyceraldehyde or non-chiral dihydroxyacetone
Which of the following terms best describe an enzyme that catalyzes electron transfer reactions
Dehydrogenase
D-allows and D-galactose classfiy
Diastereomers
Epimers
Diastereomers that differ at a single chiral carbon
Proteoglycans
Distinguished from other glycoproteins by their increase carb content, occur on cell surfaces or are secreted to the ECM
Glycolysis
Do not require 02 to generate energy
D-ribose and L-ribose classify
Enantiomers
___________________ are nonsuperimposable , non mirror image stereoisomer
Enantiomers
PPP substrate and product
Glucose-6-phosphate NADPH, Ribose
Write the net reaction for glucoes —— lactate in fermentation
Glucose= 2 ADP + 2 Pi = 2 lactate, 2 ATP
Write the net reaction for glucose——— pyruvate in glycolysis
Glucose= 2 NAD+ + 2 ADP + 2 Pi = 2 ATP + 2NADH + 2 H2O + 2 pyruvate + 2H+
Polysaccharide
Glycans are composed of large #'s of monosaccharides connected by glycosidic linkages
The equilibrium for isomerization of dihydroxyacetone phosphate to glyceraldehyde-3-phosphate is favored because
Glyceraldehyde-3-phosphate is being continuously drained off for the subsequent reaction in the glycolytic pathway
Slightly different versions of a glycan component of glycoprotein are called _______________
Glycoforms
Glycogen breakdown substrate product
Glycogen glucose, glucose-6-phosphate
How are the linkages named in disaccharides
In the alpha (1,4)or beta (1,4) conformation and by which carbons are connected
Where does fructose enter glycolysis
In the liver which is phosphorylated into fructose-1,6-phosphate and breaks down into hydroxyacetone and glyceraldehyde. This is not good cause it is not regulated by hexokinase and PFK
Where are sulfate esters of carb molecules formed
In the proteoglycan components of connective tissue that take part in the formation of salt bridges between carb chains
What type of forms can participate in redox reactions
Open chain forms
Proteoglycans roles
Organizing ECM signal transduction metabolism of proteoglycans involved in many genetic disorders in clouding hurler's syndrome
Glucose
Originally called dextrose, found in large quantities throughout the natural world. Primary fuel for living cells preferred energy source for brain cells and cells without mitochondria
Is mutarotation spontaneous or nonspontaneous
Spontaneous process that produces an equilibrium mixture of both alpha and beta forms in both pyranose and furanose ring structure
In the down position what is it called
Alpha
In the conversion of glyceraldehyde-3-phosphate to 1,3 bisphosphoglycerate
An aldehyde is oxidized to cartboylic acid
Acetal linkage
An arrangement where 2 organic molecules are connected through an a 0-ch-o functional group
Oligosaccharide
An intermediate sized carb composed of 2-10 monosaccharide
D-glycan
An oligosaccharide linked to a protein bi an a;pha glycosidic bond to the hydroxyl oxygen of serine or threonine residues
N-glycan
An oligosaccharides linked to a protein via a B-glycosidic bond between the core N-acetylglucosamine anomeric carbon and a side chain nitrogen of an asapragine residu
Furan
An organic molecule with a 5 sided ring containing 1 oxygen atom
Pyran
An organic molecule with a 6 sided ring containing one oxygen atom
Anaerobic metabolism can occur in all these organism or cells except
Anaerobic metabolism can occur in all of these
_________________ are stereoisomers of sugars that differ only in the configuration at an acetal or ketal carbon
Anomer
Glycosaminoglycans (GAG)
Are linear polymers with disaccharide repeating units
Where is the most oxidized C found in a sterioisomer
At the top
O-linkage
Attached by a side chain of AA with an OH (Sergio nine and threonine)
N- linkage
Attached by side chain of protein asparagine
In the up position what is it called
Beta
Lectins
Binding proteins that are involved in translating the sugar code
The reduction of pyruvate to lactate
Allows for the recycling of NAD+
In the conversion of glucose to pyruvate, how many of the actual steps involve electron transfer
1
Anomer
1 of 2 possible diastereomers that they may form during the cyclization reaction of a hemiacetal or hemiketal
What is the net ATP yield per glucose during glycolysis
2
The first 5 reactions of glycolysis transform each glucose molecule that enters into
2 molecules of glyceraldehyde-3-phosphate
Anomers
2 possible diastereomers that form because of cyclization
There are approximately ________________ protein coding genes in the humam genomej
20k
Glycosidic linkage
A ancestral linkage formed between 2 monosaccharides
Glycolipid
A complex lipid molecule in which a monosaccharide, disaccharide or oligosaccharide is attached to a membrane lipid molecule through an o-glycosidic linkage
Lactone
A cyclic esster
Cellobiose
A degradation product of glucose linked with a B(1,4) glycosidic bond, does not exist freely in nature
Methanol is extremely toxic, but not directly. In the body, it is converted into formaldehyde; that's what's actually the poison. What kind of enzyme catalyses this conversion?
A dehydrogenase
Disaccharide
A glycosidic composed of 2 monosaccharides
Amino sugars
A hydroxyl group usually on carbon 2 is replaced with an amine group
Glycosaminoglycan
A long unbranched heteropolysaccharide chain composed of dissaccharide repeating units
Epimer
A molecule that differs from the configuration of another isomerby one asymmetric center
Ketose
A monosaccharide with a ketone functional group
Aldose
A monosaccharide with an aldehyde functional group
What is -2-deoxy-d-ribose found
A penthouse sugar found in DNA
Monosaccharide
A polyhydroxy aldehyde or Kentone containing at least 3 carbon atoms
Glycan
A polymer of monosaccharides; a polysaccharide
The reaction of fructose 1,6 bisphosphate to give glyceraldehyde-3-phosphate and dihydroxyacetone phosphate is an example of
A reverse Aldo condensation
Amadori products
A stable ketoamine formed from the rearrangement of a chiff base; an intermediate in glycation processes that produce advanced glycation end products
Alditol
A sugar alcohol; the product of the reduction of the aldehyde or ketone group of a monosaccharide
GPI anchor
A sugar and phosphate containing molecule that links peripheral proteins to membranes.
Reducing sugar
A sugar that can be oxidized by weak oxidizing agents
Amylose
A type of plant starch that is unbranched polymer of D-glucose residues linked with a 1,4 glycosidic linkages
Fructose can be found in
ABO blood group determinants
Which of the following exercises allosteric control in the reaction of phosphofructokinase
ATP fructose-2,6-bisphosphate
In humans, pyruvate can be converted to
Acetyl CoA and lactate
Explain how fructose-2,6-bisphosphate is created and degraded in the cell, how the metabolism of fructose-2,6-bisphosphate is regulated and the effect fructose-2,6-bisphosphate has on glycolysis and gluconeogenesis
Activator of glycolysis made from phosphofructose kinase 2 catalyzes to fructose-6-phosphate uses enzyme phosphates to fructose-6- bisphosphate in gig glucose activates glycolysis by activation on PFK2 and the nfructose 6 to 6-bisphosphate glucose bocks and works opposite
Amadori products can further react to form
Advanced glycation end products
Oxidation of the aldehyde group of sugar produces a(n) _______________ acid
Alditol
Which of the following enzymes catalyzes the cleavage of fructose bisphosphate into two 3C units
Aldolase
Oxiationof the aldehyde groups of a sugar produces a(n) ________________ acid
Aldonic
D-glyceraldehyde and dihydroxyacetone classify
Aldose-ketose pair
Diastereomers
All stereoisomers that are not enantiomers (Mirror images)
Fate of pyrucate
CAC lactate ehtnaol
During anaerobic metabolism in yeast, the carbons of glucose end up in
CO2 and ethanol
Glyceraldehyde structure
COH-CH(OH)-CH2OH
Where can the hydroxyl group on a hemiacetal occur on the carbon 1
Can be up above the ring or down position below the ring
Glycoprotein
Carb containing proteins; mono,di and oliogosacchariade that are covalently linked through N- or O- linkages
Which groups on monosaccharides can undergo several chemical reactions
Carbonyl and hydroxyl
Ligands bind specifically to ________________ by _______________
Carbs, hydrogen bonding, van Dee walls and hydrophobic interactions
___________________ is the structural glucose containing polysaccharide of plants
Cellulose
Dihydroxyacetone structure
Ch2(OH)-CO-CH2OH
Starting carbohydrate final carbon product yield of ATP Yield of NADP
Glucose pyruvate, lactate 2,2'2,0
Starch
Energy reservoir of plant cells and a significant source of carbs in human diet
Glycogen
Energy storage molecule in animals composed of glucose residues linked by a 1,4 and alpha 1,6 linkages
Starch and glycogen are what
Energy storage molecules
What is the wide variety of cellular functions that carbs have
Energy structure communication precursors for other biomolecules
D-Erythrose and D-threes are referred to as _____________ because of their structures only differ in the configuration at one asymmetric carbon atom
Epimer
Classify D-erythropoietin and D-threose
Epimers
D-glucose and D mannose classify
Epimers
What is the transformation of glucose referred to as
Erpimerization
Which of the following in not true
Every reaction in a metabolic pathway much have a negative DG, or the pathway cannot run
The reactions where glucose is converted to glucose-6-phosphate and fructose-6-phosphate is converted to fructose1,5 bisphosphate are examples of
Exergonic reactions priming reactions phosphorylation reactions kinase reactions
Ketal
Formed from the reaction of a hemiketal with an alcohol
Esterification
Free OH groups of carbs can be converted to esters by reactions with acids
Cyclic form of fructose is called
Fructofuranose
Which of the following in not an end product of glucose metabolism via either aerobic or anaerobic means
Fructose
The phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate is the committed step in glycolysis because
Fructose-1,6-bisphosphate can undergo no other reactions than those of glycolysis
The order of compounds in the conversion of glucose to pyruvate acid is as follows: PEP
Fuctose-6-phosphate, fructose-bisphosphate, 1,3-phosphoglyceric acid, 3-phosphoglyceric acid, PEP
5 membered rings are called
Furanoses
Galactosemia
Genetic disorder
Glucose in the pyranose form is called
Glucopyranose
The acetal of glucose and the ketals of fructose are called _____________ and _____________, respectively
Glucosdies, fructosides
Glycolysis substrate and product
Glucose pyruvate
Gluconeogenesis product and substrate
Glucose pyruvate, glycerol, lactate
In glycoproteins, what are the 3 AA residues to which carbs are most frequently linked? To what functional groups is the glycan linkedin eachcasae
Glycoproteins, carb moieties are most frequently linked to the aside nitrogenof asparagine and hydroxyl oxygen of serine and threonine residues
When catalyzed by glycosyl transferases what happens
Glycosidic bonds are formed between anomeric carbons in certain glycans and oxygen or nitrogen of other types of molecules, resulting in N- or O- bonds
Homoglycans
Have 1 type of monosaccharides and are found in starch, glycogen, cellulose and chitin (glucose monomer)
How do glycosidic formations form
Hemiacetal and hemiketals react with alcohols to form the corresponding acetal or ketal
Polysaccharides that contain more than one type of monosaccharides are called _______________________
Heteroglycans
What are the most abundant carbs in living cells
Hexoses and pentoses
Reactive carbonyl containing product
Highly reactive molecules produced from amadori products that cause protein linkages and adduct formation, the discard only compound glyoxal CHOCHO is an example
What classes have been polysaccharides been divided into
Homoglcans and heteroglycans
Starch
Homoglycan containing glucose monomers linked by alpha 1,4 glycosidic bond with branch points connected by alpha 1,6 glycosidic bonds
5 classes of GAGs
Hyaluronic acid chondroitin sulfate dermatan sulfate heparin and heparin sulfate keratin sulfate
When can lactose be produced in monosaccharide
If the carbonyl groups of idonic or uronic acids react with an OH group in the same molecule
Monosaccharide stereioisomer
Increase in # of chiral carbons increases the # of possible optical isomers
Heteroglycan
Increase molecular weight carb polymers that contain more than 1 type of monosaccharides
Homoglycan
Increase molecular weight carb polymers that contain only one type of monosaccharide
ATP acts as an important modulator of metabolic regulation. What is the effect of increasing cellular levels of ATP on phosphofructosekinase and hexokinase
Inhibits them
Thiamine pyrophosphate is a coenzyme
Involved in transfer of 2C groups
The phosphorylation of glucose to glucose-6-phosphate
Is an endergonic reaction that takes place because it is coupled to the exergonic hydrolysis of ATP
Maltose
Is an intermediate product of starch hydrolysis alpha (1,4) linkage between 2 molecules of glucose, does not exist freely in nature
Which of the following enzymes interconverts an aldose and a ketose
Isomerase
Which of the following terms describe an enzyme that transfers a phosphate group from ATP to a substrate
Kinase
Uronic acids
L-alpha-D-glucuronate and it's epidermis B-L-iduronate important in animals
During anaerobic metabolism in RBC, the carbons of glucose end up in
Lactic acid
_____________ is a dissacharide in which galactose is linked to glucose by a b-glycosidic linkage
Lactose
Proteoglycan
Large molecule containing large # of glycosaminoglycan chains linked to a core protein molecule
Polysaccharides can be
Linear or branched
Where is the greatest abundance of glycogen carbs stored in vertebrates
Liver and muscle
Oligosaccharides
Made up of smaller glycan of 10-15 monomers that are most often attached to polypeptides as glycoproteins
Lactose
Milk sugar- the disaccharide found in milk, 1 molecule of galactose linked to 1 molecule of glucose B(1,4) linkage
The fate of pyruvate produces during glycolysis depends primarily on the availability of
Molecular oxygen
Glycoconjugate
Molecule that possess covalently bond carb groups
Oxidation
Monosaccharides may readily undergo several oxidation reactions in the presence of metal ions or certain enzymes (aldehyde group)
Deoxy sugars
Monosaccharides that have an -OH replaced by and -H or -CH3
Isomerization
Monosaccharides that undergo several types of isomerization
Maillard reaction
Most researched example of the glycation reaction in the nonenzymatic glycation
_________________ is a glycoprotein component of ______________ a slippery substance that protects the surfaces of several cell types
Mucin and mucus
2 types of broad classes of oligosaccharides
N and O
Major types of heteroglycans
N- sand O- glycosaminoglycans glucosaminoglycans glycan components of glycolipids GPI anchors
Consider the following reaction catalyzed by lactate dehydrogenase and answer the following questions Pyruvate + NADH + H+ ——- lacatate+ NAD+ what is the reactant what reactant is being reduced what is the reducing agent what is the oxidizing agent
NADH pyruvate NADH pyruvate
Galactose
Necessary to synthesize a variety of important biomolecules like lactose, glyocolipids, phospholipids, proteoglycan and glycoproteins
Cellulose is
Nonreducing
Ribose is
Nonreducing
Sucrose is
Nonreducing
What is a starch
Nonreducing
Glycoproteins functions
Occur in cells as soluble and membrane bound forms and are nearly ubiquitous in living organisms
Acetal
One of a family of organic compounds with the general formula RCH(OR')2, formed form the reaction of a hemiacetal with an alcohol
Hemiketal
One of the family of an organic molecules with the general formula RRC(OR)OH that is formed by the reaction of a molecule of alcohol with a ketone
Hemiacetal
One of the family of organic molecules with the general formula RCH(OR)OH that is formed by the reaction of a molecule of alcohol with an aldehyde
Enterocyte
One of the numerous cells that line the small intestine; absorbs digested nutrients such as monosaccharides
Study the structure 1,3 bisphospholgycerate, an intermediate in glycolysis. Describe the chemical bond linkage for each phosphoryl group in the molecule. Why is the phosphoryl group linked to the carboxyl group more reactive than the phosphoryl group linked to the hydroxyl group
Phosphoanydride is more reactive than esters
Which enzyme is the key regulatory enzyme in glycolysis
Phosphofructokinase
Amylopectin
Plant starch that is the branched polymer containing an 1,4 and a 1,6 glycosidic linakges
__________________ are molecules with no foxed molecular weights
Polysacchardies
6 membered rings are called
Pyranoses
In aerobic metabolism, what is the fate of pyruvate by glycolysis
Pyruvate loses carbon dioxide, and the remaining two carbon atoms become linked to coenzyme a
If oxygen is available
Pyruvate will be converted to Acety-CoA and go into the CAC
Fructose is
Reducing
Sugars that react with Benedict's reagent are called _____________________
Reducing sugars
Optical isomers
Referenced carbon is the asymmetric carbon farthest from the carbonyl carbon
Fructose
Referred to as fruit sugar, 2x sweeter than sucrose ; used as sweetening agent in processed food
If glycolysis did not lead to the production of ATP, the overall process would
Release more energy
Glycoconjugates
Result from carbohydrates being linked to protein and lipids
The produce of the reaction between an aldehyde or ketone and an anime is called a _____________ base
Schiff
Amadori product
Schiff base that forms rearranges to a stable ketoamine
The _______________ are a family of lectins ont he surface of endothelial cells that act as a cell adhesion molecules
Selectins
Reduction of aldehyde group of a monosaccharide yields a ____________
Sorbitol
The enzyme glucokinase
Specifically phosphorylated glucose rather than other sugars
What is the structural differences between characterized starch, cellulose and glycogen
Starch and glycogen are branched and connected by a-1,4 linkages and 1,6 glycogen is way more branched than starch. Cellulose is a linear polymer of glucose linked by b-1,4 bonds
Diastereomer
Stereoisomers that are not mirror images of one another
Chitins purpose is what
Structural
Haworth structures
Structures more accurately depict bond angle and length in ring structures than the original Fischer structure
Reduction
Sugar alcohols (alditols) are produced by the reduction of aldehyde to ketone groups of monosaccharides used in processing and pharmaceuticals
What does the esterification of monosaccharides drastically change
Sugars chemical and physical properties
Reducing sugars
Sugars that can be reduced by weak oxidizing agents like Benedict's reagent needs an open chain so all Aldoses are reducing sugars and ketoses such as fructose and also due to isomerization
_______________ and ______________ are examples of heparin sulfate proteoglycans
Syndecans and glypians
Animals such as ___________ can use cellulose as an energy source
Termites
What structural relationship is indicated by the term D sugar? What are + glucose (shifts polarized light to the right) and - fructose (shift polarized light to the left) both classified as D sugars?
The OH on the chiral carbon furthest from the carbonyl group is on the right side in a Fischer projection formula. So both + glucose and - fructose and D-sugars despite their rotation of the plan polarized light in opposite directions
Glycoside
The acetal form of a sugar
Disaccharide
The acetal linkage is formed between the hemiacetal hydroxyl of one monosaccharide and the hydroxyl of another
How do ring formations occur
The aldehyde and Kenton groups react reversible with hydroxyl groups in an aqueous solution to form hemiacetals and hemiketals
Mutarotation
The alpha and beta forms of monosaccharides are readily inter converted in aqueous environments
Glycosidic linkage formed
The cyclic hemiacetal or hemiketals form of the monosaccharide reacts with an alcohol
Celloiose
The disaccharide product of cellulose degradation; 2 molecules of glucose linked by B 1,4 glycosidic bond
To tell whether the molecule is D or L what chiral carbon do you look for
The furthest chiral carbon from the most oxidized carbon
Schiff base
The imine product of a reaction between a primary amino group and carbonyl group
Enediol
The intermediate formed during the isomerization reactions of monosaccharides. It contains a double bond with a hydroxyl group on each carbon of the double bond.
Cellulose
The primary component of plant cell walls
Chitin
The principal structural component of the exoskeletons of Arthropoda and the cell walls of many fungi
Alaric acid
The product formed when the aldehyde and CH2OH groups of a monosaccharide are oxidized to carbolic acids
Uronic acid
The product formed when the terminal CH2OH group of a monosaccharide is oxidized
Adduct
The product of an addition reaction
Aldonic acid
The product of the oxidation of the aldehyde group of monosaccharides
Define the term reducing sugar and what structural feature does a reducing sugar have
The reducing sugar reduces CuII in Benedict's reagent. This reduction take place because the hemiacetal portion of a sugar can form an aldehyde functional group which can be oxidized to be carboxylic acid
Epimerization
The reversible inter conversion of epimers
Which of the following is required for substrate-level phosphorylation
The standard free energy of the hydrolysis reaction is more negative than that for hydrolysis of the new phosphate compound being formed
Why can aldoses and ketoses both behave as reducing sugars
They contain the required aldehyde and they are converted to aldoses in the alkaline reducing test
The fate of NADH from glycolysis depends open whether conditions are aerobic or aerobic
True
The DG values for glycolytic reactions at physiological conditions may be exergonic, even though the DG at standard conditions may be endergonic
True the Rt/Q ratio of the substrate/product is an important impact
Glycogen synthesis substrate and product
UDP-glucose glycogen
Glycogen synthesis product and substrate
UDP-glucose glycogen glycogen breakdown substrate and product
Monosaccharide derivatives
Uronic acids d- glucuronic acid amino sugars d-glucosamine and D-galactosamine deoxy sugars
D-glucuronic acid
Used in the liver to improve water solubility to remove waste molecules
Alcohol dehydrogenase resembles lactate dehydrogenase in that it
Uses NAD+ as a conenzyme
Lactate appears to be a dead-end waste product of the muscle cell that cannot be used for energy. Outline how it can be used to make glucose
Uses cori-cycle—lactate—blood stream —liver—glucose—muclse
How are gluconeogenesis and glycolysis regulated reciprocally
When glycolysis is activated gluconeogeneiss is inactivated
What is starch made up of
amylose and amylopectin
Glycosylation Reactions
attach sugar or glycans to proteins or lipids
How are carbs classified?
by the number of C atoms ie trioses, tetroses
What is the most abundant biomolecule in nature
carbohydrates
D-glucosamine (a) and D-galactosamine (b)
most common amino sugars often attached to proteins or lipids
In glycolysis, ATP is synthesized by
substrate-level phosphorylation