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.