chem 365 sdsu Dr. Love homework

How does the total number of negative and positive charges change following hydrolysis of a tetrapeptide that is made up of only alanine?
Selected Answer:

hydrolysis will result in a total of four negative charges and four positive charges

Which of the following amino acids has a sulfur atom in its side chain?
Answer

Cys

The protein insulin contains two polypeptides chains termed the A and B chains. Insulins from different organisms have been isolated and sequenced. Human and chameleon insulins have the same amino acid sequence, with the exception of six amino acids, as s

higher

Which amino acid does not have a primary ?-amino group?

proline

In the tripeptide His-Pro-Ile, there are ______ charged groups at pH 8.
Answer

two

Which of the following amino acids has an uncharged polar side chain at pH 7.0?
Answer

Thr

Which of the following is the correct number of heptapeptides that could be generated with the following set of amino acids?
Met, Ala, Val, Trp, Tyr, Cys, Leu
Answer

40,320

Which of the following amino acids does not have an ionizable side chain?
Answer

Asn

Patients with Parkinson's disease are sometime given the amino acid L-DOPA (see page 76, or 'google' L-DOPA). What neurotransmitter is produced by the decarboxylation of L-DOPA?
Answer

dopamine

The disulfide bond between two cysteine molecules

is a covalent bond formed by oxidation.

Which of the following sets of numbers represents the net charge of the predominant form of Asp at the following series of pH values? pH =1; pH =5; pH =7.5; pH =12
Answer

+1; -1; -1; -2

Zwitterions are

ions that bear both negatively and positively charged groups.

Which of the following tripeptides carries no net charge at pH 7.0?
Answer

Arg-Glu-Met

What is the net charge at neutral pH for a tetrapeptide that only contains phenylalanine (F)?
Answer

0

While proteins are usually composed of linear chains of amino acids, branched chains of amino acids and internally cross-linked chains can be found in certain proteins. Polypeptide chains are most commonly linked to each other through
Answer

disulfide bonds.

In some proteins the side-chain of certain serine residues appears to undergo ionization. Which of the following is the best reason as to why the ionization would be facilitated by the presence of an aspartic acid residue nearby?
Answer

Under the correct conditions the negative charge on the aspartic acid residue can function as a base and accept (pull) the hydrogen from the hydroxyl group on the serine residue.

RNA occurs primarily as single stranded molecules that contains _______ structures.

Stem- Loop

A double stranded DNA fragment contains 16% guanine residues. Calculate the percentage adenine residues.

34%

A diploid organism with a 45,000-kb haploid genome contains 21% A residues. Which of the following is the correct number of A, C, G, and T residues in the DNA of each cell in this organism?

G = 26,100-kb, C = 26,100-kb, A = 18,900-kb, T = 18,900-kb

A double stranded segment of DNA containing 20 bases total includes 6 guanine residues. Which of the following has the correct number of adenine and uracil residues that make up the segment?

4 adenine residues, zero uracil residues

Which of the following is the best reason as to why the strands of a DNA molecule are more easily separated at pH > 11?

The pKa values for some of the hydrogen bond donor groups (e.g., R-H2) are lower than 11 and therefore these groups will become deprotonated at pH values above 11. The deprotonated form of these groups cannot form the favorable cross-strand hydrogen bonds

Which of the following is the best reason as to why increasing the NaCl concentration increases the temperature at which the two strands of DNA "melt" apart?

Greater NaCl concentration correlates to greater negative charge neutralization (shielding). Greater negative charge shielding reduces cross strand repulsion and thus increases the melting temperature of the two strands.

It is impossible for RNA to store genetic information, because

None of the above answers is correct; RNA can store genetic information

Transfer RNA molecules are involved in

Translation

Which of the following DNA sequences is considered palindromic?

AAGCTT

Gel electrophoresis generally separates nucleic acids on the basis of

size

In Sanger dideoxy DNA sequencing, DNA polymerase I is used to add nucleotides to the ___ end of the growing polynucleotide chain.

3'

Which of the following is the best description of what might occur in a chain-termination sequencing reaction in which too little ddNTP is added?

When the concentration of ddNTP is too low, the frequency of incorporation of the ddNTP would also be low and therefore the longer fragments of DNA would be overrepresented relative to the shorter fragments.

Which of the following is the best description of what might occur in a chain-termination sequencing reaction in which too much ddNTP is added?

When the concentration of ddNTP is too high, the frequency of incorporation of the ddNTP would also be high and therefore the shorter fragments of DNA would be overrepresented relative to the longer fragments.

Which of the following is the best description of what might occur in a chain-termination sequencing reaction in which too few primers are present?

If the concentration of the primers is too low, the number of newly synthesized strands would also be low and therefore the resulting gel bands would appear faint.

Which of the following is the best description of what might occur in a chain-termination sequencing reaction in which the concentration of the primers is too high?

If the primer concentration is too high it will not affect the outcome of the reaction since the amounts of all of the other components are correct.

In molecular cloning, transformed organisms must be identified. One common method for accomplishing this involves the inclusion of ________ in the plasmid.

an antibiotic resistance gene

Which of the following is the best reason as to why a genomic DNA library is larger than a cDNA library from a given organism?

A genomic DNA library contains all of an organism's DNA whereas a cDNA library only contains the DNA from expressed genes.

Which of the following is the best reason as to why cDNA libraries derived from different cell types within the same organism differ from each other?

Different cell lines express different sets of genes.

Which of the following sequences for two 12-residue primers could used to amplify the following segment of template DNA using PCR?

5'ATAGGCATAGATACCCTAGTACTAGGTAACCAATGGACATTCGGATTCCCATATTATTATTAGGTCAG-3'
5'-ATAGGCATAGAT-3'; 5'-CTGACCTAATAA-3'

For the hydrolysis of ATP, does the magnitude for ?G increase, decrease or stay the same when the proton concentration [H+] is increased by 100 fold (i.e., is 100 times greater)?

decrease

Which of the following statements best describes why the ?G�' for hydrolytically removing a phosphoryl group from ATP is about twice as large as the ?G�' for hydrolytically removing a phosphoryl group from AMP?

There is essentially no electrostatic charge repulsion in AMP (1 negative charge) in comparison to ATP (3-4 negative charges).

The reaction for "activation" of a fatty acid (RCOO-), ATP + CoA + RCOO- ? RCO-CoA + AMP + PPi has a ?G�' = 4.6 kJ/mol. Although this reaction is non-spontaneous, it is an essential reaction and thus it does occur within our bodies. The thermodynamic driv

The reactant PPi is more stable relative to its hydrolysis products.

What is the ?G value for the reaction in which creatine kinase will generate either ATP or phosphocreatine at 25� C given the following solution concentrations: [ATP] = 4.70 mM, [ADP] = 0.270 mM, [phosphocreatine] = 3.52 mM, and [creatine] = 1.42 mM.
ATP

+7.77 kJ/mol
ATP synthesis

Consider the following metabolic reaction:
Succinyl-CoA + Acetoacetate ? Acetoacetyl-CoA + Succinate ?G�' = -1.25 kJ/mol
The ?G�' for the hydrolysis of Succinyl-CoA is -33.9 kJ/mol. What is the ?G�' for the hydrolysis of Acetoacetyl-CoA?

Acetoacetyl-CoA ? Acetoacetate + CoA -32.7 kJ/mol

If intracellular [ATP] = 5.37 mM, [AMP] = 0.592 mM, and [Pi] = 1.05 mM, which of the following is the correct concentration of ADP at pH 7.00 and 25� C under the condition that the adenylate kinase reaction is at equilibrium? To answer this question you w

0

A spherical fat cell has a diameter of 2.47 micrometers. The fat cell contains three copies of the protein azurin. What is the molar concentration of azurin within the fat cell?

6.32 x 10-10 M

Which of the following statements about the cell membrane is correct?

The cell membrane allows passage of specific compounds and molecules into and out of the cell and is thus considered semipermeable.