BioChemistry Quiz

L’acide phosphorique est tri-basique, avec des valeurs de pKa de 2.14, 6.88 et 12.4. Quelle forme ionique est prédominante à pH = 5.9 ?

• H3PO4

• H2PO4-

• HPO42-

• PO43-

What is the basic formula of Carbohydrates?

• Cn(OH)n

• Cn(CO2)n

• Cn(H2O)n

• C(H2O)n

Which of these is not these is not a polysaccharide?

• Cellulose

• Glycogen

• Starch

• Fructose

Long chains of single sugars covalently linked describes what types of carbohydrates?

• Oligosaccharides

• Multisaccharides

• Polysaccharides

• Megasaccharides

Which pair of molecules are epimers?

• D-Glucose and D-Galactose

• D-Glucose and L-Glucose

• Threose and Erythrose

• D-Glucose and D-Gulose

Which of these structures is glucose?

Galactose is a ___ epimer of glucose.

• C1

• C2

• C3

• C4

Which one of these is a ketohexose

• Fructose

• Glucose

• Ribose

• 2-Deoxy-Ribose

Which of these is not true?

• Enantiomers are stereoisomers that are not mirror images

• In sugars that contain the most chiral centers only the one that is the most distant from the caronyl carbon is designated as D or L

• hemiacetals are formed by alcohols attacking aldehydes

• Alcohol oxygen atom is nucleophilic

During the cyclisation of Monosaccharides which is/are true?

• The carbon atom furthest from the former carbonyl atom becomes the anomeric carbon

• The position of anomeric carbon's oxygen determines whether the anomer is α or β

• The position of the anomeric carbon's hydroxyl group determines whether the anomer is α or β

• The carbon atom furthest from the former carbonyl atom becomes the chiral center

Which of these are carbohydrates that have a chemical structure that includes a six-membered ring consisting of five carbon atoms and one oxygen atom?

• Furanoses

• Pyranoses

The disaccharide formed upon condesation of two glucose molecules via the 1-4 bond is called

• Trehalose

• Sucrose

• Maltose

• Lactose

Which of these describes cellobiose

• α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside

• β-D-glucopyranosyl-(1→4)-β-D-glucopyranose

• β-D-galactopyranosyl-(1→4)-α-D-glucopyranose

• α-D-glucopyranosyl-(1→4)-β-D-glucopyranose

Polysaccharides...

• can be branched but cannot have multiple monomer types

• cannot be unbrached

• have defined molecular weights

• with only two monomer types cannot be branched

Which one of these hetero-polysaccharides has the largest size

• peptidoglycan

• agarose

• hyaluronan

which of these is used in Algae cell walls

• Peptidoglycan

• hyaluronan

• agarose

Glucose is stored in animals as

• Glucagon

• Glycogen

• Glucose

• Insulin

• Starch

Which of the following is true

• Amylose is the branched form of starch

• α-amylase is a pancreatic enzyme that hydrolyses the α (1→4) linkages of starch

• Glycogen has less α (1→4) linkages than starch

• Glycogen has less α (1→6) linkages than starch

hydrolysis of cotton occurs

• at the β (1→2) linkages of D-glucose

• at the α (1→2) linkages of D-glucose

• at the β (1→4) linkages of D-glucose

• at the α (1→4) linkages of D-glucose

Which of the following is not true

• Glycosidic bonds can freely rotate

• more than 10^9 metric tonnes of cotton are produced/year

• Starch can be coiled into a helical structure

• Glycogen and amylopectin have only one reducing end

Which of these lack enzymes that can hydrolyse D-glucose β (1→4) linkages

• Fungi

• bacteria

• termites

• protozoa

Chitin

• is a heteropolymer

• consists of β (1→2) linkages of N-acetyl-D-glucosamine

• is insoluble

• once acetlated forms Chitosan

Sephadex gels separate proteins by

• size

• charge

• polarity

• shape

Which of these would you find in the first fractions after size exclusion chromatography

• acidic proteins

• the smallest proteins

• the largest proteins

• basic proteins

which of these are homoglycans

• Agar

• Dextrans

• Peptidoglycan

• None

Which of these can be linked to epichlorohydrin in sephadex beaded gels

• Agar

• Agarose

• Peptidoglycan

• Dextran

Agar is a complex mixture of heteropolysaccharides containing modified

• Glucose units

• Mannose units

• Fructose units

• None of the above

Which of these is false

• Agarose can be used for growing bacteria

• Agarose is a component of bacterial cell walls

• Agarose can be used for DNA separation

• Agar is a component of seaweed cell walls

N-acetyl-galactosamine is a ___ epimer of N-acetyl-glucosamine

• C3

• C2

• C4

• C6

Where wold yo expect to find hyaluronate

• ECM of Cartilage

• Hair

• Nails

• Horns

Which one of these glycosaminoglycans acts as a lubricant?

• Chondrotin-4-sulfate

• keratan sulfate

• heparin

• hyaluronate

which one of the has approximately 50'000 disaccharides per chain

• hyaluronate

• keratan sulfate

• heparin

• chondrotin-4-sulfate

Which one of these glycosaminoglycans consists of [galactose β(1,4) Glc-NAc6S] repeating disaccharides

• hyaluronate

• chondrotin-4-sulfate

• heparin

• keratan sulfate

Which of these repeating disaccharides make dermantan sulfate?

• glucaronic acid and N-acetylglucosamine

• glucaronic acid and N-acetylgalctosamine-4-sulfate

• Iduronic acid and N-acetylgalactosamine-4-sulfate

• Iduronic acid and N-acetylglucosamine

The cabohydrate attached to a protein in a Glycoconjugate attaches via...

• The C6 carbon

• The anomeric carbon

• The furthest carbon from the anomeric carbon

• The C2 carbon

Which of the following most likely contains the most glycosylated proteins (Glycoproteins)

• Humans

• E.coli

• Ebola virus

• Cats

Glycophorin A is the most important attachment site for which of the following parasites in order to enter erythrocytes

• Plasmodium falciparum

• Chilomastix mesnili

• Entamoeba coli

• Entamoeba dispar

Which of these sulfated glycosaminoglycans are attached to a protein anchored to a membrane lipid?

• syndecans

• glypicans

Which one of these is not a main component of the extracellular matrix (ECM)

• Proteoglycan aggregates

• Collagen fibers

• Elastin

• Fatty acids

Which one of these in not a characteristic of Glycosaminoglycans

• Negatively charged

• C5 oxidation

• one monomer is either N-acetyl-glucosamine or N-acetyl-galactosmine

• found in connective tissue

Plasmodium flaciparum requires which of these as an attachment site to enter erythrocytes

• Glycophorin A

• Hyaluronan

• syndecan

• Podocalyxin

Which of these about proteoglycans is not true

• Proteoglycan aggregates are found in articula cartilage

• Proteoglycans influence growth factor activation and adhesion

• glycosaminoglycans are linked to the core protein from the anomeric carbon

• proteoglycanaggregates form high friction material

Which of these are integral receptors for extracellular proteoglycans

• Integrins

• actin

• collagen fibers

• elastin

Which of these about enzymatic reactions is true

• Enzymes directly affect equilibrium (∆G)

• Entropy cost is paid during binding

• enzymes increse reaction rates (κ ) by increasing (∆G)

• slow reactions do not have high activtaion barriers

Which one of these describes a micelle

• individual units are wedge shaped

• artificial carriers of molecules

• individual units are cylindrical

• composed lipid-based structures that form pliable sheets

Which of these is false

• membranes vary from 3-10nm

• membranes form spontaneously by noncovalent forces

• membranes are symmetric

• membranes can be found within cells

Which of these is true about fatty acids

• Most natural fatty acids are branched

• Saturated fatty acids have double bonds between carbons in the chain

• Most natural fatty acids have an even number of C's

• linoleic acid is a saturated fatty acid

Which of these is false about fatty acids

• Fatty acids solubility decreases as the chain length increases

• Melting point decrases as the chain length decreses

• Melting point increases as the number of double bonds increases

• unsaturated cis fatty acids have a lower melting point than saturated fatty acids

Omega-3 (ω-3) fatty acids have

• a double bond between the 2nd and 3th carbon from the methyl end of the chain.

• a double bond between the 3rd and 4th carbon from the methyl end of the chain.

• a double bond between the 1st and 2nd carbon from the methyl end of the chain.

• a double bond between the 2nd and 3nd as well as 3rd and 4th carbon from the methyl end of the chain.

Which of these is untrue

• Triacylglycerols are polar

• Triacylglycerols are non hydrated

• Vegetable oils are composed of triacylglycerols with unsaturated fatty acids

• Animal fats are composed of triacylglycerols with saturated fatty acids

which of these is a greasy solid at room tempreature

• triacylglycerols with unsaturated fatty acids

• triacylglycerols with saturated fatty acids

which of these is a sphingolipid

Which of these is the head group of phosphatidylserine

• 

• A

• B

• C

• D

• E

Which of these has a net charge of -4 at pH7

• phosphatidylcholine

• cardilipin

• phosphatidylglycerol

• phosphatidylinositol 4,5- biphosphate

Which of these is the major component of most eukaryotic cell membranes

• phophatidylcholine

• phosphatidylglycerol

• cardiolipin

• phosphatidylethanolamine

a fatty acid is joined to sphingosine via an

• ester linkage

• amide linkage

• glycosidic linkage

• phosphodiester linkage

ganglioside GM2 has which of these as a head group

• glucose

• galactose

• di, tri, or tetrasaccharide

• complex oligosaccharide

The blood groups are determined in part by the

• type of sugars located on the head groups in glycosphingolipids

• type of sugars located on the head groups in glycolipids

• type of sphingolipids

• type of galactolipids

The structure of sugars located on the head groups in glycosphingolipids is determined by an expression of specific glycosyltransferases. Individuals with a glycosyltransferase that transfers an N-acetylgalactosamine group will

• will have the O antigen

• A blood group

• B blood group

• AB blood group

which of thes is false

• Cholesterol modulates cell membrane fluidity

• Mammals can not synthesize cholesterol

• cholesterol in loe density lipoproteins tend to deposit in arteries

• most bacteria lack sterols

which of these polyketides is an antibiotic

• erythromycin

• amphotericin B

• lovastatin

which of these lipids are hormone precursors

• vitamins E and K

• vitamins A and D

• steroid hormones

• eicosanoids

which of these lipids are paracrine hormones

• phosphatidylinositols

• vitamins A and D

• vitamins E and K

• Dienes

• eicosanoids

which of these is true

• cholesterol is predominant in mitochondrial membranes

• galactolipids are abundant in animals

• membranes have non-selective import and export across the membrane

• archaebacteria have monolayer instead of a bilayer

which of these is a type 6 integral membrane protein

Which of these amino acid residues would you find predominantly in the transmembrane segments of membrane proteins

• Tyr

• Thr

• Ser

• Pro

Proteins can be targeted to the INNER leaflet of the plasma
membrane by farnesylation. The primary sequence of the protein contains a signature for farnesylation which is

• CaaX

• MaaX

• CaX

• MaX

hutchinson-gilford progeria syndrome is caused by

• palmitoylation defect

• myristoylation defect

• farnesylation defect

which of these are only found on the outside of cell membranes

• proteins

• lipids

• carbohydrates

which of these statements about the physical properties of membranes is true

• Permeable to large polar solutes and ions

• Not permeable to small polar solutes and nonpolar
  compounds

• Permeability can be artificially increased by chemical
  treatment

• Exist in a single phase and cannot undergo phase
  transitions

Heating causes

• cell membrane transition from the gel to fluid

• cell membrane transition from the fluid to gel

• cell membrane changed to become not permeable to large polar solutes

• cell membrane changed to become permeable to small polar solutes and nonpolar compounds

Which of these statements on membrane fluidity is incorrect

• is determined mainly by the fatty acid composition

• more fluid membranes require shorter and more unsaturated fatty acids

• At higher temperatures cells need more saturated fatty
  acids to maintain fluidity

• Gel phase means that the individual molecules do not move
  around

which of these increase in membrane compisition percentage when temperatures increase

• Myristic acid

• palmitoleic acid

• oleic acid

• hydroxymyristic acid

Cell membranes of .... contain hopanols instead of sterols

• animals

• bacteria

• plants

• fungi

Membrane Dynamics: Transverse Diffusion.

Spontaneous flips of individual lipids from one leaflet to another are rare because...

• the hydrophobic head group must transverse the hydrophilic tail region of the membrane

• membrans are rigid and individual lipids cannot move at all

• the charged head group must transverse the hydrophobic tail region of the membrane

Which is false about flippases

• catalyze transverse diffusion

• catalyze lateral diffusion

• use ATP

• move lipids against the concentratiion gradient

Which of these is a membrane receptor that detects light

• opsin

• insulin receptor

• acetylcholine receptor

• maltoporin

Which of these is a membrane receptor that detects neurotransmitters

• opsin

• acetylcholine receptor

• maltoporin

• insulin receptor

Cystic fibrosis (Mucoviscidose) is caused by

• a mutation to a Cl- ion channel in epithelial cells

• a mutation to a K+ ion channel in epithelial cells

• a mutation to a Na+ ion channel in epithelial cells

• a mutation to a Ca2+ ion channel in epithelial cells

Which of these plasma proteins is the most abundant

• transferrin

• ceruloplasmin

• immunoglobulins

• albumin

Which of these are not a hematopoietic cells

• eosinophils

• basophils

• neutrophils

• thrombocytes

Which of these is derived from lymphoid stem cells

• erythrocytes

• T cells

• basophil

• neutrophil

Which one of these leukocytes secretes histamine and mediates inflammation

• neutrophils

• basophils

• eosinophils

• macrophages

Which of these leukocytes produces Ab (antibodies)

• Neutrophils

• T cells

• B cells

• Macrophages

Where is myoglobin found

• in the bone marrow

• freely circulating in the blood

• in skeletal and striated muscles

• restricted to erythrocytes

which of these is false

• myogloblin stores oxygen in the cytoplasm and delivers it to mitochondrion

• hemoglobin is restricted to erythrocytes

• Heme (B) is the oxygen binding molecule found only in hemoglobin

• the distal histidine of the myglobin protein hydrogen bonds with oxygen bound to the protein

Consider a process in which a ligand (L) bind reversibly to a site in a protein (P). After some time, the process will reach equilibrium where the Ka (association rate constant) and Kd (dissociation rate constant) rates are equal. which of these equations represents the equilibrium.

• kd [P].[L] = ka [PL]

• ka [P].[L] = kd [PL]

• [P].[L] = [PL]

• ka [P].[L] > kd [PL]

Which of these statements is false

• when the first binding event increases affinity at the remaining sites it is called positive cooperativity

• when the first binding event decreases affinity at the remaining sites it is called negative cooperativity

• oxygen binds to heme better than carbon monoxide

• nH( hill coefficient) > 1 equals positive cooperativity

Cooperativity can be described as

• positive homotropic regulation

• negative homotropic regulation

• positive heterotropic regulation

• negative heterotropic regulation

Which of these statement on hemoglobin is false

• oxygen binding triggers a tense to relaxed state conformational change

• tense state has a higher affinity for oxgen than the relaxed state

• conformational change from the T state to the R state invloves breaking ion pairs between the alpha1-beta2 interface of hemoglobin

• 2,3 -Bisphosphoglycerate is a negative heterotropic regulator of hemoglobin function

which of these is a non-phosphorylated nitrogenous base

• nucleoside

• nucleotide

• nucleobase

• nucleomide

Which of these statements about the purine and pyrimidine bases is true

• Cytosine is found in both DNA and RNA

• Neutral molecules at pH 7

• Guanine pKa at N7 is 2.4

• all the above

In nucleotides the pentose ring is attached to the nucleobase via a

• β -N-Glycosidic Bond

• α -N-Glycosidic Bond

• Hydrogen bond

• none of the above

In DNA structure there is free rotation about

• C-1’-N-glycosyl bond

• C-2’-N-glycosyl bond

• C-3’-N-glycosyl bond

• C-4’-N-glycosyl bond

How many base pairs do you find in the A form of DNA

• 10.5

• 11

• 12

• 13

The aromaticity of the nucleotide bases and their dipole moments is important for which interactions in DNA

• Van der Waal forces in base stacking

• link between base and sugar in a nucleotide

• the link between two different nucleotides

• interstrand bonding and complementarity

DNA sequences with a very high proportion of G residues forms which unusual DNA structure found on chromosome telomeres

• tetraplex DNA

• triplex DNA

• inverted repeats

• cruciforms

Which of these are a quaternary DNA structure

• Chromatin

• hairpin

• supercoil

• Triplex

In mammals ____ Functions as an autocoid, or "local hormone"

• Adenosine

• Guanine

• Cytosine

• Thymine

Which one of these is an RNase enzyme that prevents inbreeding of plants

• S-RNase

• RNase-P

• Dicer

• None of the above

_____ is an enzyme that cleaves double-stranded RNA into oligonucleotides

• S-RNase

• Dicer

• RNase P

Why would animal cells need an enzyme that cleaves double-stranded RNA into oligonucleotides

• processessing tRNA precursors

• protection from viral genomes

• using RNA as an energy source

• using RNA in Coenzymes

RNA would be unstable in which of the conditions listed below

• pH 1

• pH 3

• pH 6

• pH 10