Biology Chapter 17
What is the proper order of the following events in the expression of a eukaryotic gene? 1. translation 2. RNA processing 3. transcription 4. modification of protein
3, 2, 1, 4
Missense Mutation
A base-pair substitution that results in a codon that codes for a different amino acid.
silent mutation
A mutation that changes a single nucleotide, but does not change the amino acid created.
nonsense mutation
A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.
How many nucleotides are needed to code for a protein with 450 amino acids?
At least 1,350
Who formulated the one gene-one enzyme hypothesis?
Beadle and Tatum
a post-translational modification of a polypeptide?
Cleavage of a polypeptide into two or more chains
exons
Coding segments of eukaryotic DNA.
Transcription Factors
Collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription.
What is a key difference in gene expression between eukaryotic and prokaryotic cells?
In prokaryotic cells, the mRNA transcript is immediately available as mRNA without processing.
poly-A tail
Modified end of the 3' end of an mRNA molecule consisting of the addition of some 50 to 250 adenine nucleotides.
framshift mutation
Mutation that shifts the "reading frame" of the genetic message by inserting or deleting nucleotides
Introns
Noncoding segments of nucleic acid that lie between coding sequences.
RNA splicing
Process by which the introns are removed from RNA transcripts and the remaining exons are joined together.
Genetic information of eukaryotic cells is transferred from the nucleus to the cytoplasm in the form of __________.
RNA
Which of the following catalyzes the linkage between ribonucleotides to form RNA during gene expression?
RNA polymerase
5' cap
The 5' end of a pre-mRNA molecule modified by the addition of a cap of guanine nucleotide.
one gene-one polypeptide hypothesis
The premise that a gene is a segment of DNA that codes for one polypeptide.
best describes the arrangement of genetic information in a DNA molecule?
The three-nucleotide words of a gene are arranged in a nonoverlapping series on the DNA template strand.
__________ is the synthesis of RNA using information in the DNA.
Transcription
__________ is the synthesis of a polypeptide using information in the mRNA.
Translation
When RNA is being made, the RNA base _________ always pairs with the base __________ in DNA.
U; A
insertion/deletion
additions or losses of nucleotide pairs in a gene
Point mutations
changes in a single nucleotide pair of a gene
Because the bacterial cell's DNA is not surrounded by a nuclear envelope, __________ occur(s).
coupled transcription and translation
The function of tRNA during protein synthesis is to __________.
deliver amino acids to their proper site during protein synthesis
Stop codons are unique because they __________.
do not code for amino acids that allow a releasing factor to bind to the A site of the ribosome
The TATA box is a __________ that allows for the binding of __________ and __________.
eukaryotic promoter; transcription factors; RNA polymerase II
Insertions and deletions are called __________ mutations.
frameshift
Polysomes may be defined as __________.
groups of ribosomes
The bonds that hold tRNA molecules in the correct three-dimensional shape are __________.
hydrogen bonds
The sickle-cell β-globin mutation is an example of a __________.
missense mutation
The type of point mutation that results in a premature stop codon is called a _________ mutation.
nonsense
By bombarding the fungus Neurospora crassa with X-rays, Beadle and Tatum were able to study __________ and characterize enzymes in a __________.
nutritional mutants; biochemical pathway
The structures called snRNPs are __________.
part of a spliceosome
One strand of a DNA molecule has the following sequence: 3-AGTACAAACTATCCACCGTC-5. In order for transcription to occur in that strand, there would have to be a specific recognition sequence, called a(n) __________, to the left of the DNA sequence indicated.
promoter
RNA molecules that function as enzymes are called __________.
ribozymes
In eukaryotic cells, a __________ by a __________ targets a growing peptide to the endoplasmic reticulum.
signal peptide; signal-recognition particle
Promoter
specific region of a gene where RNA polymerase can bind and begin transcription
polyribosome
string of ribosomes simultaneously translating regions of the same mRNA strand during protein synthesis
An exception to the one gene-one enzyme hypothesis is __________.
that not all genes code for enzymes; some genes code for structural proteins such as keratin
Eukaryotic processing of the primary transcript includes __________.
the addition of a 5ꞌ cap, a 3ꞌ poly-A tail, and the splicing out of introns
Bacteria can transcribe and translate human genes to produce functional human proteins because __________.
the genetic code is nearly universal
Gene expression is __________.
the process by which DNA directs the synthesis of proteins
The "triplet code" refers to the fact that _________.
three nucleotides code for a single amino acid
