Chapter 9

Mutations that involve the addition, deletion or substitution of one or a few bases are referred to as _______ mutations. A. frameshift B. back C. wild-type D. point

D

triplet code

3 consecutive bases, represents a code for a particular amino acid

lagging strand

3' to 5', cannot by synthesized continuously the polymerase adds nucleotides in direction away from fork

leading strand

5' to 3' can be synthesized continuously

Genetic inheritance in microorganisms is best defined by which term? A. Heredity B. Mutation C. Recombination D.Phenotype

A

The enzyme involved in replicating a new DNA strand is DNA polymerase _____, and DNA polymerase _____ is involved in removing the RNA primer, closing gaps, and repairing mismatched bases. A. III, I B. I, III C. III, IV D. IV, I E. II, IV F. IV, II

A

Which DNA sequences are found within a gene but do not encode the protein specified by that gene? A. Introns B. Exons

A

Which pentose sugar is found in DNA? A. Deoxyribose B. D-galactose C. Glucose D. Ribose

A

Which term, synonymous with codon, describes a trinucleotide sequence coding an amino acid in DNA? A. Triplet B. Anticodon C. Inversion

A

ribose

A 5-carbon monosaccharide found in RNA.

Mutation

A change in a gene or chromosome.

Which best describes the flow of genetic information in a cell? A. RNA encodes DNA which encodes protein B. Protein encodes RNA which encodes DNA C. DNA encodes RNA which encodes protein

C

Which of the following is NOT a type of RNA? A. tRNA B. mRNA C. dRNA D. rRNA

C

analogs

Chemical mimics that are incorporated into DNA during replication; lead to mistakes in base- pairing; many are carcinogens.

Pyrimidines

Cytosine and Thymine

A nucleotide contains which of the following? A. 5 carbon sugar B. nitrogen base C.phosphate D. all of these

D

point mutation

Gene mutation involving changes in one or a few nucleotides. a single base pair in DNA has been changed

antiparallel arrangement

Halves are not oriented in the same direction; one helix runs 5' to 3' direction & the other runs 3' to 5' direction.

protein

Predominant organic molecule in cells, formed by long chains of amino acids.

During semiconservative the DNA is duplicated prior to binary fission.

Replication

nucleosome

Structure in the packaging of eukaryotic DNA formed when the DNA strands wrap around histone proteins, forming an arrangement that looks like beads on a chain.

replication fork

The Y-shaped point on a replicating DNA molecule where the DNA polymerase is synthesizing new strands of DNA.

lagging strand

The newly forming DNA strand that is discontinuously replicated in short segments (Okazaki fragments) because the template cannot be continuously read by the DNA polymerase.

deoxyribose sugar-phosphate backbone

alternate creating a repetitive molecular skeleton; two phosphates are bonded covalently to on deoxyribose sugar. One bond is 5' carbon and the other is 3' carbon.

silent mutation

alters a (last) base but does not change the AA, has no effect

leading strand

The newly forming DNA strand that is replicated in a continuous fashion without fragments because it is oriented in the correct 3′ to 5′ direction for the DNA polymerase.

deoxyribonucleic acid (DNA)

The nucleic acid often referred to as the "double helix." DNA carries the master plan for an organism's heredity.

ribonucleic acid (RNA)

The nucleic acid responsible for carrying out the hereditary program transmitted by an organism's DNA

Ribonucleic acid (RNA)

The nucleic acid responsible for carrying out the hereditary program transmitted by an organism's DNA.

uracil (U)

The only nitrogen base existing in RNA but not in DNA. It is a pyrimidine and the mate of adenine during transcription.

guanine (G)

The purine nitrogen base found in DNA and RNA that pairs with cytosine.

Anticoden

at bottom of cloverleaf exposes a triplet that both designates the specificity of the tRNA and compliments mRNA's codon

nitrogenous base

attach by covalent bonds at the 1' sugar position, the bases are attached to each other by hydrogen bonds

In RNA, which nitrogenous base pairs with adenine?

Uracil

Which nitrogenous base is found in RNA but not found in DNA?

Uracil

Chloramphenicol/ lincomycin/ tetracycline

bind to the ribosome to prevent elongation of the polypeptide

Actinomycin D

binds to DNA/halts mRNA chain elongation it's mode of action is not selective for bacteria

Transfer RNA (tRNA)

carries amino acids to ribosome during translation A transcript of DNA that specializes in converting RNA language into protein language.

Messenger RNA (mRNA)

carries master message that instructs which amino acids are added during translation

Tranfer RNA (tRNA)

carries the amino acid that will match the correct codon on mRNA

nonsense mutation

changes a normal codon into a stop codon that does not code for an AA and stops the protein production wherever it occurs

missense mutation

code change that leads to placement of a different amino acid

The nitrogen base in DNA is bonded to the

deoxyribose

The pentose sugar found in DNA is .

deoxyribose

acridine dyes

insert across DNA helices between adjacent bases to produce a frameshift mutation/distorts helix.

The DNA of a chromosome is -stranded.

double

Exons

expressed sequence of DNA; codes for a protein information used in translation

Plasmids and genomes

extra- chromosomal info

are DNA sequences found within a gene that do not encode the protein corresponding to the gene.

intron

point mutation

involve addition/ deletion/ substitution of a few bases

transcription

mRNA synthesis; the process by which a strand of RNA is produced against a DNA template.

frameshift mutation

mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide

Ribosomal RNA (rRNA)

forms major parts of a ribosome and participates in protein synthesis

bacterial genome

free in cytoplasm, haploid

Gene

fundamental unit of of heredity (genetics)

What is the smallest unit of heredity (genotype)?

gene

Genotype

genetic makeup of an organism

the complete set of chromosomes and genes in an organism is referred to as the .

genome

inversion mutation

occurs when 2 nucleotides have switched their order. which will nearly always change the amino acid, as we see by inverting GUC(valine) to GCU (threonine)

mitochondria and chloroplasts

have own DNA

The first three events of translation in the correct order are , , followed by protein folding and processing.

initiation, elongation, and termination.

Mutagen

physical and chemical agents that interact w/ DNA that cause mutations

Phenotype

physical characteristics of an organism

splicosomes (snRNA)

remove introns from eukaryotic RNA, catalyzes reactions

The enzymes responsible for building the DNA strand, proofreading newly produced DNA strands, and removing the RNA primer are DNA I and III.

polymerase

palindrome

replication begins at a repeated sequence- orgin of replication

spontaneous mutations

random change in the DNA due to errors in replication that occur without known cause

RNA primer

short segment of RNA used to initiate synthesis of a new strand of DNA during replication

Ribosomes

sites of protein assembly by mRNA and tRNA

induced mutations

result from exposure to known mutagens

Translocation

ribosome shifting to the right causes the blank tRNA 1 to be discharged from the ribosome and tRNA 2 brought to P site

During DNA replication, the newly made double helices are composed of one parent template and one newly synthesized strand.

semiconservative

Genome

sum total of genetic material of an organism, appears as neatly packed organism

Gyrase

supercoiling

genome

the complete set of chromosomes and genes in an organism.

Recombination

the genetic process by which one chromosome breaks off and attaches to another chromosome during reproductive cell division the acquisition of new genes through mechanisms

anticodon

the triplet sequence in transfer RNA that is complementary to the triplet sequence of messenger RNA (the codon).

Which term, synonymous with codon, describes a trinucleotide sequence coding an amino acid in DNA?

triplet

The term , or codon, is a sequence of 3 nucleotides in DNA that encodes an amino acid.

triplets

True or false: A mutation is an alteration in the DNA sequence or content of a cell that is passed on when the cell divides.

true

back mutation

when a gene that has undergone mutation reverses to its original base composition

In a chromosome, the DNA is composed of ______ strands.

2

Ames test

A method for detecting mutagenic and potentially carcinogenic agents based upon the genetic alteration of nutritionally defective bacteria.

missense mutation

A mutation in which a change in the DNA sequence results in a different amino acid being incorporated into a protein, with varying results.

nonsense mutation

A mutation that changes an amino acid-based codon into a stop codon, leading to premature termination of a protein during translation.

back-mutation

A mutation that counteracts an earlier mutation, resulting in the restoration of the original DNA sequence.

silent mutation

A mutation that, because of the degeneracy of the genetic code, results in a nucleotide change in both the DNA and mRNA but not the resultant amino acid and, thus, not the protein.

pyrimidine

A nitrogen base that helps form the genetic code on DNA and RNA. It is composed of a single-ring structure and is smaller than a purine. Thymine, cytosine, and uracil are the most important pyrimidines.

purine

A nitrogen base that is an important encoding component of DNA and RNA. It is composed of a basic two-ring structure and is larger than a pyrimidine. The two most common purines are adenine and guanine.

adenine (A)

A purine nitrogen base found in DNA and RNA that pairs with the pyrimidine thymine.

Messenger RNA (mRNA)

A single-stranded transcript that is a copy of the DNA template that corresponds to a gene; it generally carries the genetic code for a protein.

gene

A site on a chromosome that provides information for a certain cell function. A specific segment of DNA that contains the necessary code to make a protein or RNA molecule.

Codon

A specific sequence of three nucleotides in DNA or mRNA that constitutes the genetic code for a particular amino acid.

codon

A specific sequence of three nucleotides in DNA or mRNA that constitutes the genetic code for a particular amino acid.

transfer RNA (tRNA)

A transcript of DNA that specializes in converting RNA language into protein language.

Which of the following are functions of RNA polymerase? A. Unwinds the DNA so that transcription can take place B. Seals the fragmented pieces of RNA together after synthesis C. Terminates the transcription process D. Synthesizes an RNA molecule from DNA template

A, D

Uracil, the nitrogenous base unique to RNA molecules, pairs with the nitrogenous base

Adenine

translation

Also termed protein synthesis; the process of decoding a messenger RNA code into a polypeptide.

ligase

An enzyme required to join nucleotides together to complete the final attachment of the ends of two fragments of DNA; this enzyme also works in DNA technology to attach sticky ends of DNA pieces during splicing.

Ligase

An enzyme that connects two fragments of DNA to make a single fragment synthesizes RNA primer

gyrase

An enzyme that functions in packaging of DNA in bacterial chromosomes by preventing excess distortion of the molecule as it is coiling.

Primase

An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template. synthesizes RNA primer

Helicase

An enzyme that untwists the double helix of DNA at the replication forks.

Phenotype

An organism's physical appearance, or visible traits. the expression of inherited genes.

What must occur prior to cell division to ensure that each new cell has a complete set of DNA chromosome(s)? A. Translation B. Replication C. transcription D. Transformation

B

DNA polymerases are responsible for. A. binding the nicks in DNA. B. proofreading/repair. C. supercoiling of DNA. D. unwinding the helix. E. building the DNA chain.

B. E

Purines

Bases with a double-ring structure. Adenine and Guanine

Which is true regarding DNA replication? A. The lagging strand is synthesized continuously B. The new strand is synthesized in the 5' to 3' direction on the leading strand, and in the 3' to 5' direction on the lagging strand. C. at least one answer is true D. Each new DNA helix contains one parent strand and one newly synthesized strand

D

Transcription

DNA is first copied to an mRNA molecule

The flow of genetic information in a cell is a process starting with which encodes which encodes protein.

DNA, RNA

The main enzyme responsible for transcription is A. ligase. B. gyrase. C. DNA polymerase. D. helicase. E. RNA polymerase.

E

DNA polymerase I

Enzyme responsible for the replication of DNA. Several versions of the enzyme exist, each completing a unique portion of the replication process.

DNA polymerase III

Enzyme responsible for the replication of DNA. Several versions of the enzyme exist, each completing a unique portion of the replication process.

topoisomerase

Enzyme that can add or remove DNA twists and thus regulate the degree of supercoiling

plasmid

Extrachromosomal genetic unit characterized by several features. A plasmid is a double-stranded DNA that is smaller than and replicates independently of the cell chromosome; it bears genes that are not essential for cell growth; it can bear genes that code for adaptive traits; and it is transmissible to other bacteria.

is another term for genetics--the study of inheritance in living things.

Heredity

DNA polymerase ____ is the main enzyme involved in the building of the new DNA chain, whereas DNA polymerase ____ is involved mostly with removing the primers and repairing damaged DNA.

III/I

semiconservative replication

In DNA replication, during the synthesis of new DNA strands (the daughter DNA), the parent strand template DNA is retained in the final molecule.

Okazaki fragment

In replication of DNA, a segment formed on the lagging strand where biosynthesis is conducted in a discontinuous manner as required by the DNA polymerase orientation.

Introns

Noncoding segments of nucleic acid that lie between coding sequences.

back mutation

Occurs when a gene that has undergone a mutation reverses to its original

cytosine (C)

One of the nitrogen bases found in DNA and RNA, with a pyrimidine form.

thymine (T)

One of the nitrogen bases found in DNA but not in RNA. Thymine is a pyrimidine that pairs with adenine.

Translation

RNA message is decoded by special cell components into proteins

The main enzyme responsible for transcription is

RNA polymerase

primer

Short segment of RNA that serves as binding sites for DNA polymerase to start adding nucleotides to the new strand of DNA.

Rifamycin

TB, bind to RNA polymerase; blocking the initiation step of transcription, more selective against bacterial RNA polymerase than the eukaryotic enzyme

genotype

The genetic makeup of an organism as inherited from parents. The genotype is ultimately responsible for an organism's phenotype, or expressed characteristics.

chromosome

The tightly coiled bodies within cells, composed of DNA, that are the primary locations for genetic material.

wild type

a microorganism that exhibits a natural, non-mutated characteristic

wild type mutation

a microorganism that exhibits a natural, non-mutated characteristic

Mutation

any permanent change in a gene or chromosome of a cell; may be beneficial, harmful, or have little effect on an organism

Eukaryotic genome

in nucleus, diploid or haploid

Aminoglycosides (streptomycin)

inhibit peptide initiation and elongation

mutant strain

microorganism that bears a mutation

hairpin loops

molecule bends back upon itself forming a cloverleaf pattern and becomes 3-D

A permanent inheritable alteration in the DNA sequence of a cell is a(n)

mutation

erythromycin and spectinomycin

prevent translation by interfering with the attachment of mRNA to ribosomes

The three types of RNA are RNA, RNA, and RNA.

transfer messenger ribosomal