Chapter 17

A-site

At which site do new aminoacyl tRNAs enter the ribosome during elongation?

Organelles

DNA does not store the information to synthesize which of the following?

a) formation of ribosomal subunits b) attachment of an amino acid to tRNA c) translation of cytoplasmic proteins d) transcription and RNA processing e) translation of secreted proteins

Drag the labels to the appropriate targets to identify where in the cell each process associated with protein synthesis takes place

the base sequence of the gene's promoter

During transcription in eukaryotes, a type of RNA polymerase called RNA polymerase II moves along the template strand of the DNA in the 3'→5' direction. However, for any given gene, either strand of the double-stranded DNA may function as the template strand. For any given gene, what ultimately determines which DNA strand serves as the template strand?

5 bases

Life as we know it depends on the genetic code: a set of codons, each made up of three bases in a DNA sequence and corresponding mRNA sequence, that specifies which of the 20 amino acids will be added to the protein during translation. Imagine that a prokaryote-like organism has been discovered in the polar ice on Mars. Interestingly, these Martian organisms use the same DNA → RNA → protein system as life on Earth, except that there are only 2 bases (A and T) in the Martian DNA, and there are only 17 amino acids found in Martian proteins. Based on this information, what is the minimum size of a codon for these hypothetical Martian life-forms?

1. transcription/RNA processing: a) snRNA c) mRNA e) pre-mRNA 2. translation b) tRNA f) rRNA 3. not used in protein synthesis d) RNA primers

RNA plays important roles in many cellular processes, particularly those associated with protein synthesis: transcription, RNA processing, and translation. Drag the labels to the appropriate bins to identify the step in protein synthesis where each type of RNA first plays a role. If an RNA does not play a role in protein synthesis, drag it to the "not used in protein synthesis" bin. 1. transcription/RNA processing 2. translation 3. not used in protein synthesis a) snRNA b) tRNA c) mRNA d) RNA primers e) pre-mRNA f) rRNA

PFK: cytoplasm insulin: ER--> Golgi--> outside cell

The DNA in a cell's nucleus encodes proteins that are eventually targeted to every membrane and compartment in the cell, as well as proteins that are targeted for secretion from the cell. For example, consider these two proteins: Phosphofructokinase (PFK) is an enzyme that functions in the cytoplasm during glycolysis. Insulin, a protein that regulates blood sugar levels, is secreted from specialized pancreatic cells. Assume that you can track the cellular locations of these two proteins from the time that translation is complete until the proteins reach their final destinations. For each protein, identify its targeting pathway: the sequence of cellular locations in which the protein is found from when translation is complete until it reaches its final (functional) destination. (Note that if an organelle is listed in a pathway, the location implied is inside the organelle, not in the membrane that surrounds the organelle.)

start/methionine AUG stop codon UAA UAG UGA amino acid AAA AUC CAC GCA ACU UGC

Use the table to sort the following ten codons into one of the three bins, according to whether they code for a start codon, an in-sequence amino acid, or a stop codon 1. start/methionine 2. amino acid 3. stop codon GCA UGC AUG UGA AUC UAA UAG AAA AUC CAC ACU

Met-Ser-Cys-His

What amino acid sequence does the following DNA nucleotide sequence specify? 3′−TACAGAACGGTA−5′

It is free to bind to another promoter and begin transcription.

What happens to RNA polymerase II after it has completed transcription of a gene?

Ribosome

Where does translation take place?

Deletion of one nucleotide

Which of the following mutations would likely be most dangerous to a cell? a) Deletion of one nucleotide b) Deletion of three nucleotides c) Substitution of one nucleotide for another

The promoter is a nontranscribed region of a gene.

Which of the following statements best describes the promoter of a protein-coding gene?

GTTACG CAAUGC

Which of these correctly illustrates the pairing of DNA and RNA nucleotides? GTTACG CAATCG GTTACG CAAUGC GTTACG GTTACG GTTACG ACCGTA GTTACG UAACAU

RNA polymerase

In the diagram below, the gray unit represents _____.

the promoter

In the diagram below, the green unit represents _____

DNA

In the diagram below, the two blue strands represent _____.

Base pairing between the DNA template strand and the RNA nucleotides

What determines which base is to be added to an RNA strand during transcription?

mRNA

Which nucleic acid is translated to make a protein?

The ribosome slides one codon down the mRNA.

What is meant by translocation?

Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes. A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA. A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.

After transcription begins, several steps must be completed before the fully processed mRNA is ready to be used as a template for protein synthesis on the ribosomes. Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus? A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA. Coding sequences called exons are spliced out by ribosomes. Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes. A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA. A translation stop codon is added at the 3' end of the pre-mRNA

Met-Ala-Arg-Lys

During translation, nucleotide base triplets (codons) in mRNA are read in sequence in the 5' → 3' direction along the mRNA. Amino acids are specified by the string of codons. What amino acid sequence does the following mRNA nucleotide sequence specify? 5′−AUGGCAAGAAAA−3′

UGAGCC

Suppose that a portion of double-stranded DNA in the middle of a large gene is being transcribed by an RNA polymerase. As the polymerase moves through the sequence of six bases shown in the diagram below, what is the corresponding sequence of bases in the RNA that is produced? Enter the sequence of bases as capital letters with no spaces and no punctuation. Begin with the first base added to the growing RNA strand, and end with the last base added

5' —> 3'

The direction of synthesis of an RNA transcript is _____.

A site in DNA that recruits the RNA Polymerase

Transcription begins at a promoter. What is a promoter?

False

True or false. A tRNA with an anticodon complementary to the stop codon catalyzes the reaction by which translation is terminated.

Transcription

What is the process called that converts the genetic information stored in DNA to an RNA copy?

Messenger RNA Ribozymes

Which of the following molecules are produced by transcription? (choose 2) a) Messenger RNA b) Ribozymes Ribosomal proteins

Phosphorylation

Which of the following processes is an example of a post-translational modification? a) Phosphorylation b) Elongation c) Initiation d) Peptide bond formation

The large ribosomal subunit joins the complex.

Which of the following steps occurs last in the initiation phase of translation? a) An aminoacyl tRNA binds to the start codon. b) The large ribosomal subunit joins the complex. c) The small subunit of the ribosome binds to the 5' cap on the mRNA. d) A peptide bond is formed between two adjacent amino acids

Complementary

Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?