BioChem worksheet review

The enzyme that unwinds do you need during replication is called

DNA helicases

DNA sequences contain.... But mRNA sequence is contain... BUT Amino acid sequence is contain...

GCTA GCUA Terms like Tyr-Arg-Ser

What is the term for a three-nucleotide sequence that codes for an amino acid? a. base b. codon c. serine d. amine

b. codon

The stop codons in mRNA are UAA, UAG and UGA. Considering only the 3rd position of the codon, how many other codons are subject to sustaining a nonsense mutation that would lead to the production of one of these?

5

Which sequence of atoms can be found in the backbone of polypeptides? A. C-C-N-C B. N-C-C-C C. C-O-C-N D. C-N-N-C E. C-C-C-N

A. C-C-N-C

Collagen contains large amounts of which ONE of the following? A. Inter-chain hydrogen bonds B. Intra-chain hydrogen bonds C. ß-sheet D. α-helix E. 310 -helix

A. Inter-chain hydrogen bonds

A = 27% G = 30% T = 21% C = 22% If the genome of a newly isolated virus displays the base composition above, the virus most likely consists of ______. A. single-stranded DNA B. double-stranded DNA C. single-stranded RNA D. double-stranded RNA E. a double-stranded RNA:DNA heteroduplex

A. single-stranded DNA

The pH of a 10-8 M HCl solution prepared with pure water at pH 7.0 is closest to ____. A. 6.0 B. 6.9 C. 7.1 D. 7.9 E. 8.0

B. 6.9

The allosteric modifier is acting as which ONE of the following? A. An activator of the enzyme B. A competitive inhibitor of the enzyme C. A non-competitive inhibitor of the enzyme D. Insufficient data to make a determination

B. A competitive inhibitor of the enzyme

Which ONE of the following groups of amino acids would be characterized as entirely hydrophobic? A. His, Gly, Ala B. Phe, Ile, Val C. Trp, Glu, Val D. Asn, Glu, Arg E. Asp, Ser, Phe

B. Phe, Ile, Val

Concerning sickle cell anemia and the structure of hemoglobin S, which ONE of the following statements is INCORRECT? A. The molecular consequence of sickle cell anemia results from the mutation of glutamate 6 to valine in the β-chain of hemoglobin. B. The complementary hydrophobic pocket at the EF corner of the β-chain is inaccessible in the T form of hemoglobin S. C. Sickle cell formation is favored by low oxygen tension in the tissues. D. The solubility of deoxy-hemoglobin S is greatly reduced compared to the oxygenated form. E. Sickle cell anemia does not result from oxidation of the heme iron to the ferric form

B. The complementary hydrophobic pocket at the EF corner of the β-chain is inaccessible in the T form of hemoglobin S.

Transcription in prokaryotes requires all of the following components except for which ONE? A. DNA B. tRNA C. Mg2+ ions D. rNTP's E. RNA polymerase

B. tRNA

Which ONE of the following is most responsible for the maintenance of protein secondary structure? A. Hydrophobic interactions B. van der Waals forces C. Hydrogen bonds D. Disulfide cross-links E. Salt bridges

C. Hydrogen bonds

Which ONE of the following statements is TRUE concerning sickle cell anemia (hemoglobin SS)? A. It's inheritance follows an autosomal dominant pattern B. It's patients have an elevated level of hemoglobin A2 C. Premature red cell breakdown leads to anemia D. Heart attacks are common among children with the disease

C. Premature red cell breakdown leads to anemia

The basis of precipitation of proteins by ammonium sulfate is best described by which of the following statements? A. Proteins are rendered insoluble when they bind the ammonium ion. B. Proteins are rendered insoluble when they bind sulfate ion. C. Addition of ammonium sulfate adjusts the pH to the isolectric point of the proteins. D. Ammonium sulfate binds water molecules, making them less available for hydration of proteins. E. Ammonium sulfate amidates carboxyl groups on the proteins, rendering the proteins insoluble.

D. Ammonium sulfate binds water molecules, making them less available for hydration of proteins.

DNA replication requires primers in order to proceed because of which ONE of the following? A. DNA primase cannot work de novo B. DNA polymerases need a template from which to copy DNA C. Replication origins cannot be melted in their absence D. DNA polymerases require free 3' ends in order to both make DNA and check it E. DNA primase only works at replication origins

D. DNA polymerases require free 3' ends in order to both make DNA and check it

Which ONE of the following statements is TRUE for collagen? A. The fundamental collagen polypeptide is an alpha-chain that forms alpha-helices. B. Collagen fibrils are formed by the self-assembly of procollagen molecules. C. The carbohydrate residues are bound to hydroxyproline. D. Glycine makes up nearly one third of the amino acid residues. E. Arrangement of collagen fibrils is determined by the presence of alanine.

D. Glycine makes up nearly one third of the amino acid residues.

In a multisubunit protein such as hemoglobin, the individual polypeptide chains are usually bound to one another by all of the following EXCEPT for which ONE? A. hydrogen bonds B. electrostatic interactions C. hydrophobic interactions D. peptide bonds

D. peptide bonds

Several different proteins can be synthesized from a typical prokaryotic mRNA because of which ONE of the following? A. Any of the 3 reading frames can be used B. There is redundancy in the choice of codon/tRNA interactions C. The gene contains several operator sequences from which to initiate translation D. Alternative splicing events are commonly found E. Many mRNAs are organized in a series of consecutive translational cistron

E. Many mRNAs are organized in a series of consecutive translational cistron

At their isoelectric point proteins exhibit which ONE of the following? A. no ionized groups. B. no positively charged groups. C. no negatively charged groups. D. all of their acidic groups protonated. E. no tendency to migrate in an electric field.

E. no tendency to migrate in an electric field.

TRUE or FALSE Double stranded regions in RNA occur by parallel base pairing rather than the antiparallel base pairing characteristic of DNA

F

TRUE or FALSE G-C base pairs require less energy to disrupt than A-T base pairs

F

TRUE or FALSE Retroviruses are the only known source of dogma-violating reverse transcriptases

F

TRUE or FALSE The concentration of mRNA in the cell is necessarily proportional to its rate of transcription

F

During DNA replication, a DNA strand that has the base of CTAGGT produces a strand with the bases:

GATCCA

Adenine:thymine::

Guanine and Cytosine

What makes up amino acid?

Hydrogen, Amino group, Carbon group, R group

AUG is the code on for

The start signal for translation

What makes up a nucleotide?

phosphate, sugar, base

Nucleic acids are composed of which of the following component parts? This question may have more than one correct answer. A. Nitrogen-containing heterocyclic bases B. Diphosphate linkages C. Sugars with 6 carbon atoms comprising the ring structure D. 5' to 3' phosphodiester linkages E. Deoxyglucose sugars F. 2' hydroxyl or 2' deoxy substituents G. Peptide linkage between sugar and base

A, D, F

How many amino acids are used to make up the all of the proteins in the human body? a. 46 b. 16 c. 23 d. 20

d. 20

How many hydrogen bonds can a water molecule potentially take in liquid form? a. one b. two c. three d. four e. none of the above

d.4

For protein synthesis, an amino acid needs to be attached by its ______ group to the _____ of the tRNA molecule. A. amino; phosphoryl group on the 5'-end B. carboxyl; phosphoryl group on the 3'-end C. carboxyl; hydroxyl group on the 5'-end D. carboxyl; hydroxyl group on the 3'-end E. amino; base on the 5' -end

D. carboxyl; hydroxyl group on the 3'-end

Which of the following lists represent bonding interactions in their general order of strength on a "per bond" basis from lowest to highest? A. hydrogen, ionic, hydrophobic, covalent B. hydrogen, hydrophobic, ionic, covalent C. ionic, hydrophobic, hydrogen, covalent D. hydrophobic, hydrogen, ionic, covalent E. covalent, hydrophobic, hydrogen, ionic

D. hydrophobic, hydrogen, ionic, covalent

TRUE or FALSE Uracil is not found in DNA because it would base pair with G

F

The central dogma of molecular biology states that information flows in one direction from a. ribosomes to proteins to DNA. b. DNA to RNA to proteins. c. nuclei to RNA to cytoplasm. d. genes to nuclei to ribosomes.

b. DNA to RNA to proteins.

4. How does the hydrophobic effect influence the structures of large molecules? a. Nonpolar molecules are not easily solubilized in water and aggregate b. Polar groups are oriented on the surface, interacting with the water c. Nonpolar molecules can mask the polar characteristics of the hydrophilic molecules d. a) and b) e. a) and c)

d. a) and b)

Experiments on denaturation and renaturation after the reduction and reoxidation of the -S-S- bonds in the enzyme ribonuclease (RNase) have shown that: a. folding of denatured RNase into the native, active conformation requires the input of energy in the form of heat b. native ribonuclease does not have a unique secondary and tertiary structure c. the completely unfolded enzyme, with all -S-S- bonds broken, is still enzymatically active d. the enzyme, dissolved in water, is thermodynamically stable relative to the mixture of amino acids whose residues are contained in RNase e. the primary sequence of RNase is sufficient to determine its specific secondary and tertiary structure

e. the primary sequence of RNase is sufficient to determine its specific secondary and tertiary structure

TRUE or FALSE Cancer is a common consequence of mutation in DNA repair genes

t

Which ONE of the following is directly responsible for initiation of triple helix formation during procollagen biosynthesis? A. deamination of lysine residues to form an aldehyde group and formation of crosslinks. B. intra-peptide disulfide bond formation in the N- terminal pro-peptide of procollagen. C. hydroxylation of lysine residues in the procollagen protein. D. inter-peptide disulfide bond formation between C- terminal pro-peptides of procollagen. E. removal of cross-linked C- terminal pro-peptides in mature collagen

D. inter-peptide disulfide bond formation between C- terminal pro-peptides of procollagen.

Choose the nucleotide sequence of the RNA strand that would be complementary to the following DNA strand: GTAGTCA. a. CAUCAGU b. CATCAGT c. ACGACTG d. UATUAGA

a. CAUCAGU

A tRNA that carries the amino acid methionine pairs with which type of codon? a. tRNA codon b. start codon c. serine codon d. anticodon

b. start codon

Which of the following is the site of translation? a. vacuole b. lysosome c. nucleus d. ribosome

d. ribosome

The process of making new DNA molecules is semiconservative. This means that every new DNA molecule is composed of

On original and one new strand of DNA

In the α helix the hydrogen bonds: a. are roughly parallel to the axis of the helix b. are roughly perpendicular to the axis of the helix c. occur mainly between electronegative atoms of the R groups d. occur only between some of the amino acids of the helix e. occur only near the amino and carboxyl termini of the helix

a. are roughly parallel to the axis of the helix

Which of the following processes would NOT increase the chances of causing mutations in DNA? This question may have more than one correct answer. A. Exposure to UV light B. Incorrect charging of tRNA C. Loss of 3' to 5' exonuclease activity in DNA polymerase D. Translational frameshifting by ribosomes E. Deamination of cytosine bases F. Eating large quantities of wild mushrooms

b d f

Which would be best to separate a protein that binds strongly to its substrate? a. Gel filtration b. Affinity chromatography c. Cation exchange d. Anion exchange e. Cation or anion exchange

b. Affinity chromatography

Which phrase best describes translation? a. produces RNA from DNA molecules b. converts mRNA into a polypeptide c. recycles tRNA molecules for reuse d. catalyzes bonds between amino acids

b. converts mRNA into a polypeptide

A primary difference between transcription and replication is that transcription a. is catalyzed by large and complex enzymes. b. happens repeatedly throughout a single cell cycle. c. occurs within the nucleus of eukaryotic cells. d. proceeds according to careful cellular control.

b. happens repeatedly throughout a single cell cycle.

The purity of an enzyme at various stages of purification is best measured by: a. Total protein b. Total enzyme activity c. Specific activity of the enzyme d. Percent recovery of protein e. Percent recovery of the enzyme

c. Specific activity of the enzyme

Which of the following events occurs directly after RNA polymerase recognizes the transcription start site of a gene? a. The polymerase strings amino acids into a polypeptide. b. A complementary RNA strand detaches itself from the DNA. c. The DNA strand begins to unwind, separating the two strands. d. Free-floating nucleotides pair up with exposed DNA bases

c. The DNA strand begins to unwind, separating the two strands.

Two amino acids of the standard 20 contain sulfur atoms. They are: a. cysteine and serine b. cysteine and threonine c. methionine and cysteine d. methionine and serine e. threonine and serine

c. methionine and cysteine

An octapeptide composed of four repeating glycylalanyl units has: a. one free amino group on an alanyl residue b. one free amino group on an alanyl residue and one free carboxyl group on a glycyl residue c. one free amino group on a glycyl residue and one free carboxyl group on an alanyl residue d. two free amino and two free carboxyl groups e. two free carboxyl groups, both on glycyl residues

c. one free amino group on a glycyl residue and one free carboxyl group on an alanyl residue

The main function of tRNA is to a. form a portion of ribosomes, a cell's protein factories. b. string together complementary RNA and DNA strands. c. carry a message that, when translated, forms proteins. d. bring amino acids from the cytoplasm to the ribosomes.

d. bring amino acids from the cytoplasm to the ribosomes.

The major reason that antiparallel β-stranded protein structures are more stable than parallel β-stranded structures is that the latter a. are in a slightly less extended configuration than antiparallel strands b. do not have as many disulfide crosslinks between adjacent strands c. do not stack in sheets as well as antiparallel strands d. have fewer lateral hydrogen bonds than antiparallel strands e. have weaker hydrogen bonds laterally between adjacent strands

e. have weaker hydrogen bonds laterally between adjacent strands

Myoglobin and the subunits of hemoglobin have: a. no obvious structural relationship b. very different primary and tertiary structures c. very similar primary and tertiary structures d. very similar primary structures, but different tertiary structures e. very similar tertiary structures, but different primary structures

e. very similar tertiary structures, but different primary structures