BIOC 384 UPDATED ACTUAL Exam
Questions and CORRECT Answers
What experiment did Eduard Buchner perform in the late 19th century concerning yeast? What
has this done for modern biochemistry? - CORRECT ANSWER - Buchner used an in vitro
reaction to show that brewer's yeast can produce CO2 and ethyl alcohol from sugar. It introduced
the idea of enzymes which can increase the rate of chemical reactions in living systems
What type of molecules are enzymes? Name the physiologic processes that involve enzymes. -
CORRECT ANSWER - most enzymes are proteins, though sometimes they are RNA
molecules. Enzymes catalyze reactions in respiration, fermentation, nitrogen metabolism, energy
conversion, and programmed cell death.
Briefly describe the field of biochemistry and its goals. - CORRECT ANSWER - Biochem
is the study of biological processes at the molecular and cellular level Its goal is to understand
the structure and function of biological molecules using hypothesis-driven experiments designed
to answer specific questions.
what are the 4 main types of biomolecules? - CORRECT ANSWER - Amino acids,
nucleotides, simple sugars, and fatty acids
What are the 7 levels of biochemical hierarchy in increasing order of complexity? - CORRECT
ANSWER - elements, functional groups, biomolecules, biopolymers, metabolism, cells,
organisms, and ecosystems
what element must a molecule contain to be considered organic? Why is this element so critical
to the formation of organisms? - CORRECT ANSWER - it must have at least one carbon
atom. carbon can make up to four covalent bonds, and provide stable backbones for complex
organic molecules
name four important functions of nucleotides - CORRECT ANSWER - energy conversion,
coenzymes, information storage, and signaling
,what are the 3 basic parts of nucelotides? - CORRECT ANSWER - a nitrogenous base, a
five-carbon robose/deoxyribose sugar, and one to three phosphate groups
what is base stacking and how does it contribute to the stability of the DNA helix? What other
factors helps to stabilize this helix? - CORRECT ANSWER - base stacking involves
noncovalent aromatic ring interactions between adjacent nitrogenous bases of the DNA helix.
Hydrogen bonding between complementary base pairs also stabilizes the DNA helix.
identify 3 types of RNA and describe their functions - CORRECT ANSWER - mRNA: is
the template for protein synthesis
snRNA: has a role in RNA processing
miRNA: regulates translation
rRNA: is a component of ribosomes
tRNA: provides AA to the ribosime for translation
explain how DNA mutations can have deleterious effects - CORRECT ANSWER -
mutations in a gene can change codons in the mRNA transcript, which lead to changes in the
AAs incorporated into protein. Changes in AA sequence can lead to protein denaturation or loss
of function, which could affect function of biochemical pathways and even lead to disease or
death
explain why gene duplication is evolutionarily important - CORRECT ANSWER - gene
duplication might lead to evolutionary change, for ex if doubling the amount of gene product
(protein) increases fitness for an organism, then the duplicate copy would be maintained. if there
was no fitness advantage from doubling the amount of product, the duplicated gene could be
mutated and possibly confer new fitness advantages or be lost by natural selection if it conferred
deleterious qualities
write out the chemical rxns in fermentation that are responsible for (a) carbonation in beer and
(b) the ethanol in vodka; include the names of the enzymes required. (c) is acetaldehyde a
reactant or produce in these rxns? - CORRECT ANSWER - (a) pyruvate --> acetaldehyde
+ CO2
(b) acetaldehyde + NADH + H --> ethanol + NAD
(c) acetaldehyde is a product in (a) and a reactant in (b)
, describe 3 things that Buchner did differently from Pasteur that are thought to have contributed
to his success - CORRECT ANSWER - Buchner (1) used a different strain of yeast, (2)
prepared the yeast extract using quartz mixed with diatomaceous earth rather than glass, (3) his
extract buffer contained glucose - the Carbon source for fermentation
calculate the total number of possible dodecanucleotides that can be synthesized using the four
nucleotides found in RNA. What is the maximum number of peptide sequences that can be
encoded by this collection of dodecanucleotides using all 20 AA? - CORRECT
ANSWER - dodecanucleotides: 4^12 = 16,777,216
tetraoeotides: 20^4 = 160,000
explain why amylose and cellulose, both polymers of glucose, are not of equal nutritional value
to humans. Explain why horses, which have similar digestion enzymes encoded in their genomes
to those of humans, can live on cellulose-based foods for long periods of time and humans
cannot. - CORRECT ANSWER - Amylose is a glucose polymer with alpha(1-->4)
glycosidic bonds that can be cleaved by the human enzyme amylase. Cellulose is a glucose
polymer with beta(1-->4) glycosidic bonds, cleaved by cellulase, an enzyme not found in
humans. Horse's intestines have bacteria that secrete cellulase, which aids the horse to digest
plant material
peptide hormones, like insulin and glucagon, are extracellular molecules that circulate in the
blood and transmit signals to the inside of target cells by binding to transmembrane receptor
proteins. Considering that both insulin and glucagon are secreted from the pancreas into the
blood and have equal access to all cells in the body, explain why insulin activates signaling
pathways in liver cells but not in skeletal muscle cells, - CORRECT ANSWER - liver cells
and skeletal muscle cells both contain insulin receptors, but only liver cells contain glucagon
receptors; skeletal muscle cells do not
dsDNA: what is the sequence of the corresponding mRNA transcript? What is the AA sequence
of the encoded pentapeptide?
coding strand: 5' - AAAAAATTTAAATTT - 3'
template strand: 3' - TTTTTTAAATTTAAA - 5' - CORRECT ANSWER - mRNA: 5' -
AAAAAAUUUAAAUUU - 3'
Questions and CORRECT Answers
What experiment did Eduard Buchner perform in the late 19th century concerning yeast? What
has this done for modern biochemistry? - CORRECT ANSWER - Buchner used an in vitro
reaction to show that brewer's yeast can produce CO2 and ethyl alcohol from sugar. It introduced
the idea of enzymes which can increase the rate of chemical reactions in living systems
What type of molecules are enzymes? Name the physiologic processes that involve enzymes. -
CORRECT ANSWER - most enzymes are proteins, though sometimes they are RNA
molecules. Enzymes catalyze reactions in respiration, fermentation, nitrogen metabolism, energy
conversion, and programmed cell death.
Briefly describe the field of biochemistry and its goals. - CORRECT ANSWER - Biochem
is the study of biological processes at the molecular and cellular level Its goal is to understand
the structure and function of biological molecules using hypothesis-driven experiments designed
to answer specific questions.
what are the 4 main types of biomolecules? - CORRECT ANSWER - Amino acids,
nucleotides, simple sugars, and fatty acids
What are the 7 levels of biochemical hierarchy in increasing order of complexity? - CORRECT
ANSWER - elements, functional groups, biomolecules, biopolymers, metabolism, cells,
organisms, and ecosystems
what element must a molecule contain to be considered organic? Why is this element so critical
to the formation of organisms? - CORRECT ANSWER - it must have at least one carbon
atom. carbon can make up to four covalent bonds, and provide stable backbones for complex
organic molecules
name four important functions of nucleotides - CORRECT ANSWER - energy conversion,
coenzymes, information storage, and signaling
,what are the 3 basic parts of nucelotides? - CORRECT ANSWER - a nitrogenous base, a
five-carbon robose/deoxyribose sugar, and one to three phosphate groups
what is base stacking and how does it contribute to the stability of the DNA helix? What other
factors helps to stabilize this helix? - CORRECT ANSWER - base stacking involves
noncovalent aromatic ring interactions between adjacent nitrogenous bases of the DNA helix.
Hydrogen bonding between complementary base pairs also stabilizes the DNA helix.
identify 3 types of RNA and describe their functions - CORRECT ANSWER - mRNA: is
the template for protein synthesis
snRNA: has a role in RNA processing
miRNA: regulates translation
rRNA: is a component of ribosomes
tRNA: provides AA to the ribosime for translation
explain how DNA mutations can have deleterious effects - CORRECT ANSWER -
mutations in a gene can change codons in the mRNA transcript, which lead to changes in the
AAs incorporated into protein. Changes in AA sequence can lead to protein denaturation or loss
of function, which could affect function of biochemical pathways and even lead to disease or
death
explain why gene duplication is evolutionarily important - CORRECT ANSWER - gene
duplication might lead to evolutionary change, for ex if doubling the amount of gene product
(protein) increases fitness for an organism, then the duplicate copy would be maintained. if there
was no fitness advantage from doubling the amount of product, the duplicated gene could be
mutated and possibly confer new fitness advantages or be lost by natural selection if it conferred
deleterious qualities
write out the chemical rxns in fermentation that are responsible for (a) carbonation in beer and
(b) the ethanol in vodka; include the names of the enzymes required. (c) is acetaldehyde a
reactant or produce in these rxns? - CORRECT ANSWER - (a) pyruvate --> acetaldehyde
+ CO2
(b) acetaldehyde + NADH + H --> ethanol + NAD
(c) acetaldehyde is a product in (a) and a reactant in (b)
, describe 3 things that Buchner did differently from Pasteur that are thought to have contributed
to his success - CORRECT ANSWER - Buchner (1) used a different strain of yeast, (2)
prepared the yeast extract using quartz mixed with diatomaceous earth rather than glass, (3) his
extract buffer contained glucose - the Carbon source for fermentation
calculate the total number of possible dodecanucleotides that can be synthesized using the four
nucleotides found in RNA. What is the maximum number of peptide sequences that can be
encoded by this collection of dodecanucleotides using all 20 AA? - CORRECT
ANSWER - dodecanucleotides: 4^12 = 16,777,216
tetraoeotides: 20^4 = 160,000
explain why amylose and cellulose, both polymers of glucose, are not of equal nutritional value
to humans. Explain why horses, which have similar digestion enzymes encoded in their genomes
to those of humans, can live on cellulose-based foods for long periods of time and humans
cannot. - CORRECT ANSWER - Amylose is a glucose polymer with alpha(1-->4)
glycosidic bonds that can be cleaved by the human enzyme amylase. Cellulose is a glucose
polymer with beta(1-->4) glycosidic bonds, cleaved by cellulase, an enzyme not found in
humans. Horse's intestines have bacteria that secrete cellulase, which aids the horse to digest
plant material
peptide hormones, like insulin and glucagon, are extracellular molecules that circulate in the
blood and transmit signals to the inside of target cells by binding to transmembrane receptor
proteins. Considering that both insulin and glucagon are secreted from the pancreas into the
blood and have equal access to all cells in the body, explain why insulin activates signaling
pathways in liver cells but not in skeletal muscle cells, - CORRECT ANSWER - liver cells
and skeletal muscle cells both contain insulin receptors, but only liver cells contain glucagon
receptors; skeletal muscle cells do not
dsDNA: what is the sequence of the corresponding mRNA transcript? What is the AA sequence
of the encoded pentapeptide?
coding strand: 5' - AAAAAATTTAAATTT - 3'
template strand: 3' - TTTTTTAAATTTAAA - 5' - CORRECT ANSWER - mRNA: 5' -
AAAAAAUUUAAAUUU - 3'
