BIOL 400 EVALUATION EXAMS ACTUAL QUESTIONS AND
ANSWERS SURE A+
✔✔What happens to new polypeptides? - ✔✔-fold into proteins
-many undergo post-translational modification (chemical changes)
✔✔What can happen in post-translational modification? Where? - ✔✔Chemical
Changes
-removal of AAs
-covalent attachment of chemical groups
-occur in cytoplasm for prokaryotes & products of nuclear genes in eukaryotes
✔✔What's a stop transfer sequence? - ✔✔Causes protein (hydrophobic region) to stays
in the bilayer
-stops polypeptide moving further through membrane
✔✔*make card for example 1 & 2 fate of polypeptides - ✔✔
✔✔Describe the linear nature of genetic info - ✔✔5' to 3' sequence of the non-template
strand parallels the...
-5' to 3' mRNA sequence
-N to C AA sequence
*explains why any change in the DNA sequence can affect the polypeptide's AA
sequence
✔✔What are point mutations and what are they caused by? - ✔✔DNA changes that
affect single base pairs
-caused by errors in DNA replication or repair & mutagens
✔✔What are mutagens? - ✔✔physical or chemical agents that damage DNA
✔✔What are the 2 types of point mutations? - ✔✔1) Nucleotide-pair substitution
-replacement of 1 bp
-can cause protein mutations: silent, nonsense & missense
2) Frameshift mutation
-insertion or deletion of bp which shifts downstream reading frame in proteins
-can cause protein mutations: missense & nonsense
✔✔What is single nucleotide polymorphism (SNP)? - ✔✔Replacement of 1 bp
✔✔What's a silent mutation? - ✔✔change in nucleotides causes no change in AA
sequence
✔✔What's a nonsense mutation? - ✔✔change in nucleotides changes an AA codon to a
stop codon
, -shortens the protein
✔✔What's a missense mutation? - ✔✔Change in nucleotides changes one AA
✔✔How can mutations affect phenotype (protein function and regulation)? -
✔✔*depends on the type of mutation and its location on gene
1) no effect
2) partial loss of function
3) complete loss of function
4) gain of new function
✔✔What's a common example of a mutation that causes GAIN of a function? -
✔✔lactase persistence aka lactose tolerance
✔✔What's a neutral mutation? - ✔✔one that has no effects on protein
function/regulation
✔✔**edit name examples of loss or gain of function being harmful vs helpful - ✔✔
✔✔How much of their genes do cells use at a given time? - ✔✔5-20%
✔✔What do the types of genes used by cells depend on? - ✔✔-type of cell
-external conditions (cellular signals)
-internal conditions (AA availability)
✔✔What are two major points of gene regulation and examples? - ✔✔1) Controlling
protein activity
-ex: feedback inhibition in tryptophan (trp) synthesis pathway
2) Controlling TXN
-ex: turning off genes for enzymes that synthesize trp
✔✔Positive vs Negative Transcription Regulation - ✔✔1) Positive: TXN requires help
due to a weak promoter that can't bind RNA pol
-requires DNA binding
proteins aka transcription factors that can be activated by STPs and be cell
type specific
2) Negative: blocks TXN of genes whose default is on
-genes with strong promoters
✔✔What are the 2 components involved in Negative TXN regularion? - ✔✔1) Operator:
part of operon promoter sequence
2) Repressor protein: active form blocks TXN
-made in inactive form and allows TXN to proceed if [trp] is low
-if [trp] is high, it binds to the repressor which allosterically changes the repressor to
bind the operator and block TXN
ANSWERS SURE A+
✔✔What happens to new polypeptides? - ✔✔-fold into proteins
-many undergo post-translational modification (chemical changes)
✔✔What can happen in post-translational modification? Where? - ✔✔Chemical
Changes
-removal of AAs
-covalent attachment of chemical groups
-occur in cytoplasm for prokaryotes & products of nuclear genes in eukaryotes
✔✔What's a stop transfer sequence? - ✔✔Causes protein (hydrophobic region) to stays
in the bilayer
-stops polypeptide moving further through membrane
✔✔*make card for example 1 & 2 fate of polypeptides - ✔✔
✔✔Describe the linear nature of genetic info - ✔✔5' to 3' sequence of the non-template
strand parallels the...
-5' to 3' mRNA sequence
-N to C AA sequence
*explains why any change in the DNA sequence can affect the polypeptide's AA
sequence
✔✔What are point mutations and what are they caused by? - ✔✔DNA changes that
affect single base pairs
-caused by errors in DNA replication or repair & mutagens
✔✔What are mutagens? - ✔✔physical or chemical agents that damage DNA
✔✔What are the 2 types of point mutations? - ✔✔1) Nucleotide-pair substitution
-replacement of 1 bp
-can cause protein mutations: silent, nonsense & missense
2) Frameshift mutation
-insertion or deletion of bp which shifts downstream reading frame in proteins
-can cause protein mutations: missense & nonsense
✔✔What is single nucleotide polymorphism (SNP)? - ✔✔Replacement of 1 bp
✔✔What's a silent mutation? - ✔✔change in nucleotides causes no change in AA
sequence
✔✔What's a nonsense mutation? - ✔✔change in nucleotides changes an AA codon to a
stop codon
, -shortens the protein
✔✔What's a missense mutation? - ✔✔Change in nucleotides changes one AA
✔✔How can mutations affect phenotype (protein function and regulation)? -
✔✔*depends on the type of mutation and its location on gene
1) no effect
2) partial loss of function
3) complete loss of function
4) gain of new function
✔✔What's a common example of a mutation that causes GAIN of a function? -
✔✔lactase persistence aka lactose tolerance
✔✔What's a neutral mutation? - ✔✔one that has no effects on protein
function/regulation
✔✔**edit name examples of loss or gain of function being harmful vs helpful - ✔✔
✔✔How much of their genes do cells use at a given time? - ✔✔5-20%
✔✔What do the types of genes used by cells depend on? - ✔✔-type of cell
-external conditions (cellular signals)
-internal conditions (AA availability)
✔✔What are two major points of gene regulation and examples? - ✔✔1) Controlling
protein activity
-ex: feedback inhibition in tryptophan (trp) synthesis pathway
2) Controlling TXN
-ex: turning off genes for enzymes that synthesize trp
✔✔Positive vs Negative Transcription Regulation - ✔✔1) Positive: TXN requires help
due to a weak promoter that can't bind RNA pol
-requires DNA binding
proteins aka transcription factors that can be activated by STPs and be cell
type specific
2) Negative: blocks TXN of genes whose default is on
-genes with strong promoters
✔✔What are the 2 components involved in Negative TXN regularion? - ✔✔1) Operator:
part of operon promoter sequence
2) Repressor protein: active form blocks TXN
-made in inactive form and allows TXN to proceed if [trp] is low
-if [trp] is high, it binds to the repressor which allosterically changes the repressor to
bind the operator and block TXN
