BMED Midterm Review

Cholesterol ia a/an

steroid

The lagging strand in DNA synthesis

is synthesized in the opposite 3'-5' direction different from the leading strand

Which of the following can be classified as a molecule and a compound?

I. NH3

II. NaCl

III.O2

IV.K

I and II

Glycosidic bonds are formed by a reaction and broken by a ___ reaction.

dehydration, hydrolysis

During the replication of DNA, the synthesis of DNA on the lagging strand takes place in segments. These segments are called

Okazaki fragments

Which of the following is true about a phosphodiester bond?

I. Holds two DNA strands together

II. Holds together the sugar phosphate backbone of the polynucleotide

III. Is a covalent bond

IV.Is a hydrogen bond

II and III

What is the name (I, II, Ill and IV) of the following functional groups?

Hydroxyl, Aldehyde, Carboxyl, Ketone

Hyperventilating can results in respiratory ____ and when our body has trouble ventilating, respiratory ___ can occur. 

alkalosis, acidosis

How does the process of transcription differ from DNA replication?

Primers are required only for DNA replication, not for transcription.

Why are telomeres important regions of linear chromosomes?

Because they protect genes from being deleted

Which of the following is true?

I. An acid is a substance that increases the concentration of H+ (or H3O+)in a solution

II. A base is a substance that increases the concentration of H+ (or H3O+) in a solution

III. An acid is a proton acceptor

IV. A base is a proton acceptor

I and IV

Which type of bonds must be broken for water to vaporize?

hydrogen bonds

Which of the following does not contribute to the quaternary protein structure?

α-helices

What is the main function of RNA in relation to protein synthesis

Identify amino acids and transport them to ribosomes

An mRNA has the following order of bases AGCUUGCA (5 to 3'). Which of the following is the order of bases (3' to 5') in its DNA template?

TCGAACGT

The portions of pre-mRNA that are excluded in the final mRNA molecule are called ____. Pre-mRNA are cut by ___ to remove the non-coding regions.

introns, spliceosomes

Which of the following are the peptide bonds in the polypeptide chain below?

2 and 5

All halogens have similar reactivity because:

they have similar outer shell electron configurations

Which of the following is true about DNA and RNA?

RNA encodes the information from a gene and carries to the machinery that decodes the mRNA and makes proteins

Which of the following is not true about the difference in the regulation of gene expression in prokaryotic and eukaryotic organisms?

I. DNA in prokaryotic organisms is found in the cytoplasm whereas DNA in eukaryotic organisms is confined to the nucleus (mitochondria)

II. RNA transcription and protein formation occurs almost simultaneously in both types of organisms

III. Gene expression in eukaryotic organisms is regulated only at the transcriptional level

II Only

Polar R-groups in a protein can form hydrogen bonds with?

A. other polar R-groups

B. carbonyl and amino groups in the peptide backbone

C. water molecules in the surrounding fluid

D. All of the above

D. All of the above

If an error in base pairing occurs, which enzyme is involved in removing and replacing mismatched nucleotide?

DNA polymerase

Which of the following is true?

I. Acid is a proton donator

II. A base has more OH- than H+

III. An acid is a substance than increase the amount of OH- in a solution

III. Pure water has unequal amount of H* and OH-

I and II

Match the role of the component (I, II, III) of a bacterial gene operon to the correct operon components?

I. Site of RNA polymerase binding for transcription initiation

II. Transcribed to form repressor protein

III. Binding site for repressor protein

promoter, regulator gene, operator

Molecules that differ in the spatial arrangement around an asymmetrical carbon are called

enantiomers

Triglycerides are typically found as fat globules within the cytosol of cells. These globules are not surrounded by a membrane. Describe the features of triglycerides that enable them to form distinct fat globules

Triglycerides are hydrophobic, so in an aqueous environment such as the cytosol, they clump together, which minimizes their disruption of hydrogen bonds between water molecules.

Which of the following is not a post-translational modification that can be modified to regulate gene expression in eukaryotic organisms?

Alternative splicing

During your summer job at a forensic lab, you try to identify the source of blood on a suspect's shirt. His wife was murdered and it is suspected that his shirt contains blood from his wife. He claims that he works as a butcher at HEB and the blood is either from cutting up pork, beef, chicken, or rabbit. Cow DNA has a G content of 25%, human DNA has a G content of 24%, rabbit has a G content of 26%, pig has a G content of 20%. Analysis of the DNA from the bloodstain reveals that it is composed of a double stranded DNA molecule containing 24% A (adenine). Based on this information, what would you conclude the stain to come from?

rabbit

What is a major difference between eukaryotic DNA replication and prokaryotic DNA replication?

Prokaryotic chromosomes have a single origin of replication, while eukaryotic chromosomes have multiple origins of replication.

DNA is ___ into an mRNA which is ___ into a protein.

transcribed, translated

Which of the following is true about chromatin?

Histone methylation leads to increased binding of histones to DNA, and decreases the availability of DNA for transcription

Frameshift mutations

A. can occur when one or more nucleotides are inserted into a DNA sequence
B. can result in a completely new codon sequence that results in the production of non-functional proteins
C. can occur when one of more nucleotides is deleted from a DNA sequence
D. All of the choices are correct

D. All of the choices are correct

Which of the following is not directly synthesized from a DNA template?

amino acids

Which of the following is not true about LDL and/or HDL?

HDL transports cholesterol to the liver for storage

Binding of a molecule at a site that is different from the enzyme's active site changes the enzyme conformation which causes the the enzyme to be turned "off". This molecule is a

allosteric inhibitor

Which of the following protein structure involves hydrogen bonding?

Secondary, tertiary and quaternary structures

Why does water have a high surface tension?

cohesion between molecules

Complementary base pairs in the DNA double helix between two different DNA strands are held together by what types of bonds?

hydrogen bonds

There are 64 possible codons and only 20 amino acids. How is this discrepancy linked to a characteristic of the codon system?

Each amino acid is encoded by more than one codon

When trypsin convert chymotrypsinogen to chymotrypsin, some molecules of chymotrypsin bind to a repressor, which in turn binds to the operator and prevents further transcription of trypsin. This is an example of a?

Repressible operon

PTEN is one of the most commonly deleted/mutated gene in human prostate cancer. The mutation and loss of PTEN can result in increased cell proliferation and reduced cell death. PTEN is an example of a/an

tumor suppressor

Which of the following is not true?

A. Mass number is the number of protons plus neutrons
B. Atomic number is the number of electrons in an element
C. The nucleus of an atom consist of protons and neutrons
D. Isotopes have same number of protons but different number of neutrons

B. Atomic number is the number of electrons in an element

The enzyme responsible for DNA strand elongation in prokaryotes is?

DNA polymerase

Which of the following is/are post-transcriptional modifications occurring in eukaryotic mRNAs?

A. addition of a poly (A) tail to the 3' end
B. addition of a methyl-guanosine cap (5'-cap)
C. removal of introns
D. all of the above

D. All of the above

Which of the following is not a post-translational modification that can be modified to regulate a gene in eukaryotic organisms?

chromatin remodeling

Order the monomers for the biomolecules: amino acid, monosaccharide, nucleotide, fatty acid

II, IV, III, I

If a gene sequence (coding strand, 5'-3' direction) is TAACCGGTA, what protein does it code for? Use codon table below.

Tyr-Arg-Leu

Point mutations

A. are due to a change in one DNA nucleotide
B. may change a codon so that chain termination occurs
C. may have no effect on an organism
D. All of the choices are correct

D. All of the choices are correct

During protein synthesis, an anticodon on tRNA pairs with

mRNA nucleotide bases

Negatively charged phosphate groups in the DNA backbone must be neutralized in order for folding of DNA to occur. In bacterial DNA, this charge neutralization is carried out by small positively charged molecules called polyamines. What proteins carry out this same function in eukaryotic cells?

Histones

Which of the following proteins is not necessary during DNA replication?

RNA polymerase

What would be the most comprehensive description of a gene? A gene is a ___.

sequence of DNA capable of directing the synthesis of one or more related polypeptides

The lac operon is typically found in prokaryotes in order to utilize lactose in the event that glucose is absent. How does the presence of lactose affect the lac operon?

It binds to the lac repressor, causing it to detach from the operator

Which of the following accurately describes the promoter?

A sequence of DNA used to signal the beginning point of transcription

What type of tertiary bond usually forms between valine (left) and isoleucine (right)?

hydrophobic interaction

Enzymes…

I. decreases activation energy
II. does not change activation energy
III. is used up during a reaction
IV. is not used up during a reaction

I and IV

Given that water has a pH of 7 and lemon juice has a pH of 2, which statement is correct?

Water is 100,000 less acidic than lemon juice

Which parts of amino acids are linked together through a dehydration synthesis reaction to form the backbone of a polypeptide

amino groups and carboxyl groups

In DNA replication, why does the lagging strand need more than one primer?

because replication of the lagging strand is discontinuous

Which of the following amino acids is basic and thus can have a positive charge?

C. lysine, arginine, and histidine