BioChem test 1

A sugar molecule has six carbons with three asymmetric carbons. How many possible stereoisomers exist for this molecule?

eight

The sugar shown below is a sugar commonly found organisms. Is this a(n) (alpha or beta) isomer?

H

CH2OH----O---- ----

OH

Alpha

Glycosylation of hemoglobin is measure in a clinical setting to determine whether a person has uncontrolled diabetes. Glycosylation of a protein is a result of

a Free aldehyde on the linear form of a sugar nonspecifically reacting with a free amino group on a protein.

the Enantiomer refers to

isomers that are mirror images of one another

Most vertebrate Monosaccharides have ________________configuration.

D

Provide the appropriate names for the three sugars shown below.

A,B,C see diagram question 6

a. aldotetrose

b. ketopentose

c. ketohexose

Advanced glycation end products (AGEs) cause _______ in protein

crosslinking

the linkage shown below is an example of a(n)

(see diagram Q8)

o-linked glycosidic bond

Carbohydrates linked to a protein through a serine or threonine residue are referred to as

O-linked sugars

___________ is the structure of glucose-containing polysaccharide of plants

cellulose

Of the structures shown below, Which structures contain or are pentoses

(see diagram Q11)

A

Of the structures shown below, Which disaccharide consists of the same two monosaccharides?

(see diagram Q12)

D

of the sugars shown below, which ones are reducing sugars

(see diagram Q13)

D,E

Go to page 322 in your textbook. Look at the structures for D-ribose and D-mannose. Identify the properties common to these two monosaccharides.

both are reducing sugars

O-linked glycoproteins

contain oligosaccharides linked to the side chain of serine and threonine residues

Which of the following is true?

A. membranes are lipid bilayers

B. Membranes lipids have both hydrophobic and hydrophilic properties

C. Many membranes are electronically polarized

D. All the above

D

Unsaturated fatty acids within the lipid bilayer (increase or decrease) fluidity, why?

Increase because of the double bond with the carbon break the ability to be a solid.

Which of the following characteristics does not affect the melting point of a fatty acid.

A. the number of carbons/ chain length

B. saturation of the carbon chain

C. location of the fatty acid in the cell membrane (inner or outer side)

C

A fatty acid named, cis∆^9 - 16:1, tell you that

A. it has one double bond

B. it is unsaturated

C. it has 16 carbons

D. All of the above

D

You know the Keq of a chemical reaction that is occurring in a human cell when the individual is healthy ( assuming they are not fevered). This allows you to calculate the __________ of the chemical reaction?

Standard state delta G

The ___________ of a chemical reaction is a measure of a number of properties associated with that reaction including: 1) the basic chemical structure and energy associated with those structures under constant conditions, 2) the temperature at which the reaction is occurring, and 3) the concentration of products/reactants of the reaction.

Free energy change

Type one parameter of the Gibbs free energy equation (∆G=∆G⁰ +RTlnQ) that might be altered within a cell to change the overall ∆G of the reaction.

pH, T, Q

A reaction at equilibrium will alter the way in which Gibb's Free energy is calculated. Of the following choices, which is correct?

At equilibrium, Q=keq and ∆G=0

A reaction with -∆G will always occur rapidly and spontaneously.

True or False

False

Which of the following chemical reaction could ATP hydrolysis power?

ATP hydrolysis=-∆G 30.5kj/mol

one with a ∆G of 29.5kj/mol

ATP is less stable than its hydrolyzed products due to

A. resonance of ADP

B. resonance of Pi

C. repulsive forces of ATP's negatively charged phosphate group

D. ATPs phosphoanhydraide bonds that are highly unstable

E. B and C

F. A and D

E

One method that a cell could use to drive a nonspontaneous chemical reaction would be to employ the use of an enzyme to catalyze (speed up) the reaction.

True or False

False

The second law of thermodynamics explains that

A. the disorder of the universe is always increasing

B. the spontaneity of the reaction is affected by the change in entropy of a reaction.

C. a reaction with a -∆G value will occur spontaneously

D. All of the above

D

Work the following problem using the modified Gibb's free energy equation.

∆G⁰=-RTlnKeq

For the reaction, HC2H3O2 <----->C2H3O2 + H

(when at equilibrium). Assume that T=37⁰C. The equilibrium constant for acetic acid is 1.8e-5.

Is the ∆G⁰ value negative

Indicating that at equilibrium the forward reaction will predominate.

no

Which of the follow reaction could be driven by coupling to hydrolysis of ATP? ( the ∆G' value for each reaction is indicated in parentheses in units of kj/mol

ATP + H₂O<--->ADP +Pi (-30.5kj/mol)

A. Pyruvate + Pi --> Phosphoenolpyruvate(+31.7kj/mol)

B. Glucose + Pi -->glucose-6-phosphate (+13.8)kj/mol)

C. Fructose-6-phosphate-->Fructose + Pi (-15.9kj/mol)

D. Maltose + H₂O-->2 glucose (-15.5 kj/mol)

B

The pH of a biological reaction involving a weak acid can affect whether the weak acid remains intact or dissociated by

affecting the availability of H+, which will dictate whether the weak acid remains intact depending on its specific pKa

The hydrogen and oxygen atoms in a single water molecule are bound together by

A polar covalent bonds

Each molecule of water can form a maximum of

4 hydrogen bonds

Which of the following is NOT a property of water responsible for its unique characteristics?

A. the strength of its covalent bonds

B. the shape of the water molecule

c. Its polar nature

D. its capacity to form hydrogen bonds

A

Liquid water is more dense than solid water

True or False

True

Which of the following substances does water not dissolve?

A. polar

B. ionic

C. nonpolar

C

Polar molecules are often ______, while nonpolar molecules are often_______.

Hydrophobic or Hydrophilic

hydrophilic, hydrophobic

Bronsted-Lowry definition defines an acid as

A proton donor

The extent to which a weak acid dissociates in solution is described by its

Ka

Which of the following is NOT a property of an effective buffer.

A. contains equal concentrations of weak acid and its conjugate base

B. has a pH equal to its pKa

C. has a high Ka

C

Calculate the pH of a solution that contains

2.3e-8M H+

7.6

While creating an acetic acid buffer, you were supposed to add equal concentrations of acetic acid (the weak acid) to acetate (the conjugate base). However, you accidentally measured incorrectly and added double the acetic acid. You know that the pKa of acetic acid is 4.76. Calculate the pH of the accidental solution.

pH=pKa +log[A-]/[HA]

4.46

Lactic acid is produced through lactic acid fermentation in cells in response to low oxygen in the blood stream.

The pKa of lactic acid is 3.86

Predict whether lactic will be present intact or in the dissociated form upon production.

It will dissociate