o chem practice exam 3 Flashcards
Which of the following fatty acids is most likely to be a liquid at room temperature?
A
Consider the statements below and choose the letter that describes them all:
(1) Cholesterol is both a steroid and a membrane lipid.
(2) Waxes are made from sphingosine and a long chain alcohol.
(3) Sphingolipids are components of cell membranes.
Statements (1) and (3) are true.
The following reaction would most likely be catalyzed by an enzyme of which class?
isomerase
Chemical messengers can interact with receptors through
A) hydrogen bonds
B) electrostatic interactions
C) hydrophobic interactions
D) all of the above
E) none of the above
All of the above
Which choice is an example of passive transport across a cellular membrane?
A) passing protons through the proteins against a concentration gradient
B) oxygen passing directly through a membrane
C) K+ passing through an ion pump fueled by the energy from ATP
D) cholesterol interacting with hydrophobic portions of glycerolphospholipids
E) none of the above
B
Adding a phosphate group to the active site of an enzyme to reversibly block the active site is an example of using _______________________ to control enzyme activity.
A) covalent modifications
B) feedback control
C) specificity
D) genetic regulation
E) hydrolysis
covalent modifications
Enzymes are catalysts because they
A) change the value of the free energy change to a more favorable value.
B) change the value of the equilibrium constant to a more favorable value.
C) lower the value of the activation energy.
D) increase the amount of time needed to reach equilibrium.
E) become one of the reactants.
lower the value of the activation energy.
The following reaction would most likely be catalyzed by enzymes of which class?
hydrolase
What class of chemical messenger does the following molecule belong
Bile salt
- What class of chemical messenger does the following molecule belong
adrenergic
Which statement is true regarding chemical messengers?
A) Chemical messengers catalyze reactions to turn on enzyme activity.
B) Chemical messengers bind to receptors irreversibly.
C) The endocrine and nervous systems utilize chemical messengers to maintain homeostasis.
D) Chemical messengers cannot affect protein synthesis.
E) None of these are true
c
Which of the following is the typical shape of a plot showing the rate of an enzyme-catalyzed reaction as a function of substrate concentration
B
Which of the following is the typical shape of a plot showing the rate of an enzyme-catalyzed reaction as a function of Ph concentration
D
- Which of the following is the typical shape of a plot showing the rate of an enzyme-catalyzed reaction as a function of enzyme concentration
A
- How many H2 molecules are necessary to completely hydrogenate the following molecule?
3
- The molecule shown can be classified as a(an
Glycerophosoplid
- The molecule below is the substrate for the enzyme malate dehydrogenase.
C
- Which of the following enzymes associated with DNA replication is paired with its correct function?
A. DNA helicase; connection of Okazaki fragments
B. DNA polymerase; formation of phosphodiester linkages
C. DNA ligase; unwinding of the DNA helix
D. more than one correct response
E. no correct response
B
- When a mature mRNA is made from the DNA strand shown, its base sequence will beComplementary (coding) strand of DNA: 5’ TTACGGAT 3’
Template strand of DNA: 3’ AATGCCTA 5’
A) 5’ TTACGGAT 3’.
B) 5’ AACUA 3’.
C) 5’ UUACGGAU 3’.
D) 5’ AAUGCCUA 3’.
E) 5’ UUGAU 3’
c
- Sickle cell anemia is an example of a disease caused by an SNP, single nucleotide polymorphism, because …
A) it is caused by the deletion of a single nucleotide and is common in a given population.
B) it is caused by the insertion of a single nucleotide and is common in a given population.
C) it is caused by a point mutation and is common in a given population.
D) it is caused by a point mutation and is specific to an individual.
E) it is caused by a point mutation.
C
- Which of the following is a coding portion of a DNA molecule (i.e. it codes for a protein)?
A) telomere
B) centromere
C) exon
D) intron
E) promoter sequence
C
- The molecule below is
A) a nucleoside that contains a purine.
B) a nucleoside that contains a pyrimidine.
C) a nucleotide that contains a purine.
D) a nucleotide that contains a pyrimidine.
A
- All of the statements about RNA are true except
A) RNA can exist in multiple forms including: rRNA, tRNA, and mRNA.
B) RNA molecules are synthesized by RNA polymerase.
C) Hydrogen bonding between bases is not important to RNA translation.
D) Transfer RNA delivers amino acids for the protein chain as it is being manufactured.
E) mRNA contains the instructions to make peptide chains.
C
- The translation occurs in the ________.
A) mitochondria
B) cytosol
C) ribosome
D) Golgi apparatus
E) nucleus
C
- Recombinant DNA is the process of
A) combining two genes into a new piece of DNA that does not exists in nature.
B) copying DNA using DNA polymerase.
C) using the chromosome from one species to express proteins.
D) introducing mutations to treat a disease caused by an overactive protein.
E) cross breeding two closely related species to produce a hybrid.
A
