Bio test 3
How many subunits a ribosome has?
2
What are the two general categories of point mutation?
Base-pair substitutions and frameshift mutations
nonsense mutation
change an amino acid codon into a stop codon, nearly always leading to a nonfunctional protein
What is a mutation?
changes in the genetic material of a cell
catalyzes the elongation of a DNA strand in the 5' to 3' direction by adding new nucleotides to the 3' end______________________
dna polymerase 1
separates the DNA strands during replication ______________
helicase
What is the first phase of transcription called?
initiation
What are the three stages of translation?
initiation elongation termination
What are the possible consequences of a point mutation?
lead to the production of an abnormal protein
synthesizes short segments of RNA _____________
primase
What is transcription?
process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA)
What is gene expression?
the process by which DNA directs protein synthesis, includes two stages: transcription and translation
What is translation?
the process of translating the sequence of a messenger RNA (mRNA) molecule to a sequence of amino acids during protein synthesis
What are the nucleotide bases in DNA?
thymine adenine cytosine guanine
What is the one-gene one-polypeptide hypothesis?
The theory that each gene is responsible for the synthesis of a single polypeptide.
What do you call this triplet of nucleotides? __________
codon
help to hold the DNA strands apart while they are being replicated ___________
single strand binding proteins
How many types of amino acids are used to make proteins?
20
How many DNA nucleotides make an order for one amino acid?
3
How many binding sites for tRNA does the ribosome have?
3
105. The DNA double helix has a uniform diameter because ________, which have two rings, always pair with ________, which have one ring. A) purines; pyrimidines B) pyrimidines; purines C) deoxyribose sugars; ribose sugars D) ribose sugars; deoxyribose sugars E) nucleotides; nucleoside triphosphates
A
What kind of chemical bond is found between paired bases of the DNA double helix? A) hydrogen B) ionic C) covalent D) sulfhydryl E) phosphate
A
When one DNA molecule is replicated to make two DNA molecules, the new DNA contains A) 25% of the parent DNA. B) 50% of the parent DNA. C) 75% of the parent DNA. D) 100% of the parent DNA. E) none of the parent DNA
B
The monomers of DNA and RNA are A) amino acids. B) monosaccharides. C) nucleotides. D) fatty acids. E) nucleic acids
C
Which of these is a difference between a DNA and an RNA molecule? A) DNA contains uracil, whereas RNA contains thymine. B) DNA is a polymer composed of nucleotides, whereas RNA is a polymer composed of nucleic acids. C) DNA is double-stranded, whereas RNA is single-stranded. D) DNA contains five-carbon sugars, whereas RNA contains six-carbon sugars. E) DNA contains nitrogenous bases, whereas RNA contains phosphate groups
C
All of the following are functions of DNA polymerase in DNA replication except A) covalently adding nucleotides to the new strands. B) proofreading each added nucleotide for correct base pairing. C) replacing RNA primers with DNA. D) initiating a polynucleotide strand. E) none of the above
D
Which of these is always true with regard to a DNA double helix? A) The amount of adenine is equal to the amount of uracil, and the amount of guanine is equal to the amount of cytosine. B) The amount of adenine is equal to the amount of thymine, and the amount of guanine is equal to the amount of uracil. C) The amount of adenine is equal to the amount of guanine, and the amount of thymine is equal to the amount of cytosine. D) The amount of adenine is equal to the amount of thymine, and the amount of guanine is equal to the amount of cytosine.
D
removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments ___________________________
DNA polymerase 1
Performs 5'-3' polymerase function
DNA polymerase 3
What is the chain of command (i.e. the flow of information) to make a polypeptide (protein) from DNA?
Dna, pre-mrna, mrna, protein
The leading and the lagging strands differ in that: A) the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. B) the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. C)the leading strand is synthesized continuously, whereas the lagging strand is synthesized in short fragments called Okazaki Fragments that are ultimately stitched together. D) both A and B E) both A and C
E
What is the name of the DNA sequence where RNA polymerase attaches to initiate transcription?
TATA box
When RNA is being made, the RNA base A, U, C, OR G (CHOOSE ONE) always pairs with the base adenine (A) in DNA.
U
frameshift mutation
a genetic mutation caused by a deletion or insertion in a DNA sequence that shifts the way the sequence is read
insertion
addition of one or more nucleotide base pairs into a DNA sequence.
which nitrogenous bases are the purines
adenine and guanine
Complete this sentence: The codon is a part of (m- or t-) RNA, while the anticodon is a part of (m- or t-) RNA.
anticdon to tRNA codon to mRNA
We would expect that a 15-nucleotide sequence will direct the production of a polypeptide that consists of A) 2 amino acids. B) 5 amino acids C) 15 amino acids. D) 3 amino acids. . E) 7 amino acids.
b
Which one of the following is not a function of tRNA? A) joining to only one specific type of amino acid B) recognizing the appropriate codons in mRNA C) transferring nucleotides to rRNA D) helping to translate codons into amino acids E) All of the choices are functions of tRNA.
b
silent mutation
base substitutions that result in no change of the amino acid
What is a nucleotide?
building block of amino acids
Where does translation take place in the cell
cytoplasm
DNA replication A) occurs by the addition of nucleotides to the end of the DNA molecule. B) results in the formation of four new DNA strands. C) produces two daughter DNA molecules that are complementary to each other. D) uses each strand of a DNA molecule as a template for the creation of a new strand. E) begins when two DNA molecules join together to exchange segments
d
What is point mutation?
genetic changes in just one base pair of a gene
covalently connects segments of DNA _______________
ligase
DNA-cutting enzymes used in the repair of DNA damage ___________________
nuclease
where does transcripton takes place in the cell
nucleus
Deletion
one or few nucleotide base pairs are deleted or lost from a chromosome especially during the replication of genetic material
Define a base-pair substitution mutation
replaces one nucleotide and its partner with another pair of nucleotides
What is the enzyme that catalyzes RNA synthesis? ________ _________
rna polymerase
missense mutation
still code for an amino acid, but not the correct amino acid
Components of nucleotide
sugar, nitrogenous base, 5 carbon sugar
What type of RNA transfers the amino acids to the ribosomes?
tRNA
which nitrogenous bases are the pyrimidines
thymine and cytosine
What are the two major stages of gene expression?
transcription and translation
When does termination of translation take place?
when a stop codon is reached.