Chapter 15:

Each aminoacyl-tRNA syntheses present in a cell recognizes (blank) of the 20 common amino acids (indicate the number)

1

Order the steps in the targeting of proteins to the ER, starting at the top.

1. Ribosome begins synthesizing protein. 2. Signal sequence on the protein is recognized by the SRP. 3. The SRP/protein complex is recognized by a receptor on the ER. 4. The ribosome is docked on the ER. 5. AS the protein is assembled, it passes through a channel in the docking complex and enters the ER lumen.

Oder the events during the splicing reaction, starting at the top.

1. The 5' end of an intron is cleaved. 2. The 5' end of the intron is attached to the 2' OH of the branch point A. 3. The 3' end of the first exon displaces the 3' end of the intron. 4. The intron is released as a lariat.

Of the three RNA polymerase (1,2,and 3), RNA polymerase (blank) promoters are found to be internal to the gene itself.

111

Translocation:

A piece of a chromosome is broken off and joined to another chromosome.

In most cases, what codon is used as a start codon?

AUG

The two functional ends if tRNA are which of the following?

Acceptor stem and anticodon loop

According to current estimates, how widespread is alternative splicing in the human genome?

According to some estimates, as many as 95% of genes are alternatively spliced.

Identify the stage of transcription where the bacterial RNA polymerase binds to the promoter.

After binding, RNA polymerase begins to unwind the DNA helix. Initiation.

Consider the pathway for synthesis of arginine from glutamate by Neurospora crassa as shown on the diagram. A mutant for the orgG gene will be able to grow on minimal media supplemented with which of the following?

Arginine and Arginosuccinate.

How was the genetic code deciphered?

By using cell-free biochemical systems to produce proteins based on synthetic mRNAs.

Which of the following individuals performed experiments that confirmed that codons are unspaced?

Crick and Brenner

The central dogma describes information flow in cells as:

DNA to RNA to protein

Select the functions of the ribosome.

Decoding the transcribes message and forming peptide bonds.

Which of the following is a mutation that changes the structure if the chromosome itself?

Duplication.

In the ribosome, no additional input of energy is needed when peptide bonds are formed. Why?

During the charging reaction, an ATP is used to attach the amino acid to the tRNA, producing an activated intermediate.

True or false: Eukaryotic transcripts are not modified after transcription.

False

Select characteristics of gene expression in prokaryotes.

Genes do not contain introns. Transcription & translation are coupled. Several genes can be organized into an operon.

SRP RNA: micro-RNA: Very short regulatory RNAs.

Important for synthesis of polypeptides on the rough ER.

According to our current understanding, where in the ribosome does the peptidyl-transferase activity reside?

In an rRNA.

In transcription elongation complex of eukaryotes, what is the function of the CTD?

It acts as a platform, which recruits elongation factors and RNA-modifying enzymes.

More than one codon can specify the same amino acid in the genetic code. Because of this, how do we describe the genetic code?

It is degenerate.

Choose all statements that accurately describe the transcription bubble.

It moves along the DNA at a rate of about 50 nt/sec. The growing RNA strand protrudes from the bubble. It contains an RNA-DNA hybrid, about 9 nt long.

The GTP necessary in the formation of the 5' cap on the transcript is modified by the addition of which of the following groups?

Methyl group.

Select characteristics of gene expression in Eukaryotes.

Most genes contain introns, Transcription occurs in the nucleus.

Identify all of the following that are components of the prokarayotic core RNA polmerase.

One B' subunit, One B subunit, and two identical a subunits.

This type of mutation happens when a single base in DNA is substitutes with another base, for example, an A becomes a G.

Point

snRNA:

Processing of eukaryotic pre-mRNAs.

In eukaryotes, the TATA box is an element of the core promoter for which RNA polyerase?

RNA polymerase 2.

Which of the following is thought to occur for the majority of genes in eukaryotic multicellular organisms shortly after elongation begins?

RNA polymerase can pause.

Which of the eukaryotic RNA polymerase requires promoters that are internal to the gene itself.

RNA polymerase.

Which of the following accurately describes a difference in the way ribosomes in mitochondria "read" the genetic code?

The UGA codon is not used as a stop codon.

What defines the reading frame of an mRNA?

The first codon that is read.

Which of the following describes how proteins are targeted for translation to the rough ER?

The initial amino acid sequence of these proteins serves as a signal sequence that targets them to the rough ER.

If a scientist introduces a deletion of three nucleotides in a gene, what is the expected effect of that deletion on the amino acid sequence following it?

The sequence of amino acids following the deletion will be normal.

The prokaryotic translation initiation complex consists of:

The small ribosomal subunit, an mRNA molecule, and a special initiator tRNA charged with N-formylmethionine.

In transcription, the DNA strand that is copied is called which of the following?

The template strand.

Which of the following accurately describes the distribution of introns in eukaryotic genes.

There appear to be no rules governing how many introns are present in a eukaryotic gene.

How do eukaryotic transcription factors help form the initiation complex?

They recruit RNA polymerase to the promoter.

In eukaryotas, mRNAs have a modified guanosine covalently attached at the 5' end.

This is known as the: cap

Select the components of the eukaryotic initiation complex.

Transcription factors, RNA polymerase 2, promoter.

What is the name of the process that makes an RNA copy of DNA?

Transcription.

What process involves the synthesis of a protein, and takes place on the ribosome?

Translation

Identify the three stop codons of the genetic code.

UAA, UGA, and UAG

micro-RNA:

Very short regulatory RNAs.

Which term refers to the tRNAs being able to read more than one codon in the mRNA?

Wobble pairing

Prokaryotes have:

a single RNA polymerase.

RNA polymerase 1 promoters:

are specific for each species.

In transcription, the DNA strand that is not copied is called the (blank) strand.

coding

The universality of the genetic code is evidence for which of the following?

common evolutionary heritage.

Duplication:

copying a portion of a chromosome.

In prokaryotes, the (blank) polymerase can synthesize RNA using a DNA template, but cannot initiate synthesis accurately.

core

In eukaryotes, translation can be carried out by ribosomes located (1) in the (blank), or (2) on the rough endoplasmic reticulum. (RER)

cytoplasm

Beadle and Tatum proposed the one-gene/one-(blank) hypothesis. Today this relationship is referred to as the one-gene/one-(blank) hypothesis.

enzyme and polypeptide

The coding DNA sequences of a eukaryotic gene are called which of the following?

exons

The term gene (blank) refers to gene function either at the level of traits or at the molecular level.

expression

Eukaryotic genes may contain non-coding regions known as (blank) because they interrupt the sequence of a gene.

introns

To create a functional RNA, the pre-mRNA undergoes a process known as splicing. During splicing process, the (blank) are removed and the remaining (blank) are connected to each other.

introns exons

Deletion:

loss of a portion of a chromosome.

Ribosomes move relative to which of the following RNAs?

mRNA and tRNAs

AUG serves as the start condon, as well as, to encode for the amino acid (blank)

methionine

Most mature eukaryotic mRNAs have a string of mucleotides referred to as a:

poly-A tail.

Which of the following is a way in which some tRNAs can achieve wobble pairing?

presence of modified bases in the anticodon loop.

Transcription and translation of an mRNA molecule occur simultaneously in:

prokaryotes.

During the initiation stage of transcription in prokaryotes, the stigma subunit of the RNA polymerase holoenzyme recognizes the -35 sequence in the:

promoter

In a bacterial transcription unit, the role of the (blank) is to form a recognition and binding site for the RNA polymerase.

promoter

Frame shift mutations alter the (blank) frame of the genetic message.

reading

In translation termination, stop codons are recognized by what type of proteins?

release factors.

What class of viruses can convert their RNA genome into a DNA copy using reverse transcriptase?

retrovirus.

In translation, the initiation, elongation, and termination steps all take place on the:

ribosome

Inversion:

segment of chromosome is broken in 2 places, reversed, and put back together.

The hypothesis called exon (blank) suggests that exons represent functional domains of proteins, and that arrangement of introns and exons found in genes represents the moving around of these functional units over long periods of evolutionary time.

shuffling

The complex is composed of snRNPs and other proteins is responsible for splicing the introns.

spliceosome

The 25,000 genes of the human genome can encode for more than 100,00 proteins due to alternative (blank) of mRNA transcripts.

splicing

The process of alternative (blank) can produce different transcripts from the same gene in eukaryotes.

splicing

Within introns, there is a conserved A nucleotide, called the branch point, which is important for the (blank) reaction.

splicing

During the (blank) stage of transcription, the RNA transcript is released from the DNA template.

termination

The end of a bacterial transcription unit is marked by a:

terminator sequence.

What sequence signals the location on a gene where transcription should stop?

terminator sequence.

The association of transcription factors and RNA polymerase 2 at the eukaryotic promoter is called:

the initiation complex

How many RNA polymerases do eukaryotes have?

three

How many nucleotide bases are in one codom?

three

The genetic code is read in continuous increments of (blank) nucleotides.

three

RNA polymerase 2:

transcribes mRNA

RNA polymerase 1:

transcribes rRNA

RNA polymerase 3:

transcribes tRNA

During gene expression, the DNA-to-RNA step is know as (blank), while the RNA-to-protein step is known as (blank).

transcription and translation