Chapter 13. D.C. General Biology

The total number of different three-base combinations of the four nucleic acid bases is:

64

The 3' end of eukaryotic pre-mRNA's are changed by:

Adding 100-250 adenine nucleotides

Uracil forms a complimentary pair with _______________ in RNA and _________________ in DNA.

Adenine; adenine

What conclusions did Beadle and Tatum reach with their studies of neurospora?

Each mutant gene affected only one enzyme.

RNA differed from DNA in all of the following except:

RNA contains Cytosine

A sequence of bases located upstream from a reference point occurs:

Toward the 5' end of the mRNA sequence.

Introns in pre-mRNA are known to:

Undergo excision, whereby they are spliced out of the message

How is the 4-letter language of nucleus acids converted into the 20-word language of amino acids?

The 4 nucleic acids combine in 3-letter sequences that define different amino acids.

Which of the following serves as an "adapter" in protein synthesis and bridges the gap between mRNA and proteins?

tRNA

Beadle and Tatum irradiated neurospora and initially grew the mutant strains on complete medium. How were they able to determine what type of mutation each strain had?

By growing the mold on minimal media supplimented with dofferent combinations of amino acids, vitamins, etc...

Garrod first proposed that:

Metabolic defects were due to lack of an enzyme.

In essentially all organisms, the AUG codon codes for:

The initiation translation

Frameshift mutations result from:

The insertion or deletion of one or two base pairs.

Refer to figure 13-3. The transcription process most likely began in the area labeled:

E.

5' cap

Protects mRNA from degradation

The codon is found in the:

mRNA

Which of the following is made from DNA?

mRNA, tRNA, rRNA

One of the mRNA codons specifying the amino acid leucine is 5'-CUA-3'. It's corresponding anticodon is:

3'-GAU-5'

RNA synthesis is also known as:

Transcription

The portion of the molecule in figure 13-2 that contains the anticodon is:

3

The process illustrated in figure 13-3 is:

Transcription

Which of the following numbered events represents the correct sequence of events of prokaryotic translation initiation? 1) large ribosomal subunits bind to initiation complex 2)initiation tRNA binds to small ribosomal subunits 3) initiation complex binds to the ribosome recognition sequence on mRNA

2, 3, 1

Which of the following numbered terms represents the correct order of sequences in a prokaryotic mRNA molecule as it was synthesized? 1) 3' trailing sequence 2)coding sequences 3)leader sequence 4)termination sequences

3, 2, 4, 1

A gene can now be defined as:

A DNA nucleotide sequence that carries information to produce a specific polypeptide.

A polyribosome is:

A complex of many ribosomes and an mRNA

Beadle and Tatum began their studies with wild-type neurospora, which is:

A normal phenotype that will grow on a minimal medium.

Initiation of transcription requires:

A promoter sequence

Leader sequences contain signals that:

Allow the ribosomes to be properly positioned to translate the message.

Ribose differs from deoxyribose by having:

An extra hydroxy group

Where is the amino acid binding sit located on the tRNA molecule?

At the end of the 3' end of the molecule

During protein synthesis, ribosomes:

Attach to the mRNA molecule and travel along its length.

Why is it important in the studies of Beadle and Tatum that Neurospora is haploid?

Because a mutation that arises is not masked by a normal allele on a homologous chromosome.

Why is only one strand of DNA transcribed into mRNA

Because transcribing both DNA strands would produce different amino acid sequences.

Aminoacyl-tRNA synthetases ________ link _________ to their respective tRNA molecules.

Covalently; amino acids

The transcript in figure 13-3 is labeled:

D

Binding of the appropriate aminoácidos-tRNA to the A site requires:

Energy supplied by GTP

The translocation process requires:

Energy supplied by GTP

Interrupted coding sequences include long sequences of bases that do not code for amino acids. These non-coding sequences, called _________, I found in __________ cells.

Introns; only eukaryotic

A mutation that replaces one amino acid in a protein with another is called a __________ mutation.

Missense

Following the peptide bond formation between the amino acid in the A site on the ribosome and the growing polypeptide chain, the tRNA in the A site:

Moves to the P site of the ribosome.

Proteins synthesized in bacteria have which of the following at their amino terminal ends?

N-formyl-methionine

Which of the following is not a reason why neurospora is an ideal organism to study the effects of genetic mutations?

Neurospora contains homologous chromosomes that are easily viewed with a light microscope.

Substitution of one of the base pair for another can result in a ___________ mutation that results in the conversion of an amino acid specifying codon to a termination codon.

Nonsense

The enzyme peptidyl transferase, which catalyzes the transfer of the polypeptide chain attached to the tRNA in the __________ site to the aminoacyl tRNA in the _____________ site, is thought to be a(n) ______________ molecule and not a protein.

P; A; rRNA

Refer to figure 13-3. The component labeled B is:

RNA polymerase

Retroviruses or RNA tumor viruses use _________ to make DNA.

Reverse transcriptase

Translocation is the process whereby the ___________ moves in order to place the tRNA bound to the growing polypeptide chain in the__________ site, thereby freeing the ____________ site for a new aminoacyl tRNA.

Ribosome; P; A

Walter Gilbert proposed that exons are:

Sequences that code for protein domains that are shuffled to form new proteins

The wobble hypothesis states that:

Some amino acids are coded for by more than one codon

Which of the following is a characteristic of uracil?

The ability to bind with adenine.

Refer to figure 13-2. The portion of the molecule labeled 5 is:

The attached amino acid

How does the first nucleotide at the 5' end of a new mRNA chain differ from the other nucleotides in the chain?

The first nucleotide retains its triphosphate group, while the others do not.

The experimental design in figure 13-1 was used to examine:

The relationship between genetic changes and metabolic enzymes.

Linus Pauling demonstrated that:

The structure of hemoglobin was altered by a mutation of a single gene.

All of the following characteristics of tRNA molecules are true except:

They are considerably larger than rRNA molecules.

If a human gene mRNA were placed into a cell of yeast, it would be:

Translated into the protein that is found in humans

The conclusion associated with mutant strain III in figure 13-1 was that it:

Was missing an enzyme for metabolism and could not synthesize arginine.