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