chapter 9 & 10 practice
what proportion of the DNA in the human genome codes for proteins or functional rna
2%
in a growing dna strand, each monomer is added to which carbon of the deoxyribose
3'
sequence 5'-ATTCCG-3' would have the complementary strand of
5'-CGGAAT-3'
corepressor
A lack of which molecule would result in the cell's inability to "turn off" genes
activator
A protein that binds to DNA and stimulates transcription of a specific gene.
which is not directly involved in translation
DNA
Why do histones bind tightly to DNA?
Histones are positively charged, and DNA is negatively charged.
for a repressible operon to be transcribed, which must be true
RNA polymerase must bind to the promoter, and the repressor must be inactive
which best describes termination of transcription in prokaryotes
RNA polymerase transcribes through the terminator sequence, causing the polymerase to fall off the DNA and release the transcript
which is analogous to a frame shift mutation (THECATATETHERAT)
THECATATTHERAT
which statement about tRNAs is false
They have an anticodon at their 5' end and an amino acid attachment site at their 3' end
Promoter
a mutation in this section of dna could influence the binding of rna polymerase to the dna
what is a ribozyme
an enzyme made of rna
a eukaryotic gene typically has all the following features except
an operator
The role of a metabolite that controls a repressible operon is to
bind to the repressor protein and activate it
repressor
can inhibit transcription by blocking the binding of positively acting transcription factors to the dna
Ribosomes
carry out translation
a mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in
continuous transcription of the structural gene controlled by that regulator
dna polymerase and rna polymerase differ in that
dna polymerase requires a primer, rna polymerase doesn't
the molecules that function to replicate dna in the cell are
dna polymerases
why is rna incorporated into the dna molecule during dna replication
dna polymerases can only add on to an existing strand
genetic code is the same for all organisms. one can assume that
dna was the first genetic material
what are the coding segments of a stretch of eukaryotic dna called
exons
the enzyme dna ligand is required continuously during dna replication because
fragments of the lagging strand must be joined together
If you were to observe the activity of methylated DNA, you would expect it to
have turned off or slowed down transcription
In a nucleosome, the DNA is wrapped around
histones
nitrogenous bases are held together by
hydrogen bonds
in dna replication, the processive nature of dna polymerase
increases the number of nucleotides that can be polymerized per enzymatic cycle
what is the effect of a nonsense mutation
introduces a stop codon into the mRNA
which component of transcribed rna in eukaryotes in the primary transcript but is removed before translation occurs
intron
what is not found in prokaryotic dna
introns
the primer used for dna replication
is needed only once on a leading strand
repressor protein
is produced by a regulatory gene
which statement about pre mRNA is false
it is common in prokaryotes
a codon
may code for same amino acid as another codon
posttranslational alterations of proteins
may include the addition of polysaccharides to proteins.
In eukaryotes, the first amino acid in a growing polypeptide chain is always _______ because the only codon for this amino acid is also the _______ codon.
methionine. start
During DNA replication
methylation of the DNA is maintained because methylation enzymes act at DNA sites where one strand is already methylated and thus correctly methylates daughter strands after replication.
the energy necessary for making a dna molecule comes from
phosphate ions
sickle cell disease is the likely result of which kind of mutation
point
which is the most common mutation
point mutation
What local effect would an RNA synthesis inhibitor have on DNA replication?
primase would not be able to provide primers for dna polymerases
a significant difference between eukaryotes and prokaryotes is that
prokaryotic genes do not contain introns
which component is required for the initiation of transcription
promoter dna sequence
what are ribosomes composed of
rRNA & protein
in the elongation stage of translation
rRNA is catalytically active.
during splicing, which component of the spliceosime catalyze the excision reaction
rna
which component is not involved in the elongation step of translation
rna polymerase
dna polymerases differ from rna polymerases in that
rna polymerases are less effective at proofreading than dna polymerases
a protein destined for a lysosome carries a signal peptide for the
rough ER
Suppose a new type of replicating molecule (TNA) is found. At the end of TNA replication, two TNA molecules are produced, each one consisting of a parental TNA strand and a new TNA strand. This is an example of
semiconservative replication
UAU and UAC both code for tyrosine. A change from UAU to UAC would thus be a _______ mutation; a change from UAU to UAG would be a _______ mutation.
silent. nonsense
terminator
site in the dna located near the end of the final exon, encoding an rna sequence that determines the 3' end of the transcript
which is least related to the other terms (anticodon, snRNP, tRNA, wobble, triplet code)
snRNP
which is not part of the eukaryotic transcription initiation complex
snRNP
why did the one gene one enzyme hypothesis have to be modified
some enzymes are made up of more than one polypeptide
transcription of the structural genes in an inducible operon
starts when the pathways substrate is present
what is an anticodon part of
tRNA
at the imitation complex of translation in eukaryotes
the anticodon of tRNA charged with methionine binds to mRNA associated with the small ribosomal subunit
where is eukaryotic ribosomal RNA transcribed
the nucleolus
which statement about operons is true
the trypophan operon is a repressible operon
which statement about histones is incorrect
they're found in mammals, but not other animals or plants
During protein synthesis, ribosomes
translate mRNA into polypeptides.
which is least related to (transcription, TATA box, template strand, translation, rna polymerase II)
translation
Which single-base substitution in the template strand of DNA would result in the premature termination of translation (sequences are written 5′ to 3′)?
ttg to tta
which is the least related to the others (tumor suppression, protein degradation, ubiquitin, cyclins, proteasomes)
tumor suppression
the tryptophan operon is a repressible operon that is
turned off whenever tryptophan is added to the growth medium