Chapter 7 Flashcards

Question

What is a mutagen?

Answer 1

Physical or chemical agents called mutagens that induce mutations

Answer 2

A virus that infects bacteria -they reproduce in bacteria

Answer 3

Thin, proteinaceous tubes extending from the surface of a cell Conjugation pili mediate the transfer of DNA from one cell to the othervia a process termed *conjugation*

Answer 4

a new strand formed during replication that is synthesized 5' to 3' but in short segments that are later joined

Answer 5

triplet sequence of nucleotides

Answer 6

Cells that have the ability to take up DNA from their environment Competence results from alterations in the cell wall and cytoplasmic membrane that allow DNA to enter the cell.

Answer 7

A transfer RNA (tRNA) molecule is a sequence of about 75 ribonucleotides that curves back on itself to form three main hairpin loops held in place by hydrogen bonding between complementary nucleotides.

Answer 8

Messenger RNA molecules carry genetic information from chromosomes to ribosomes as triplet sequences of RNA nucleotides (codons) that encode the order of amino acid sequences in a polypeptide.

Answer 9

- Replication * Cell division * Need accurate copy - Gene expression * DNA * RNA * Protein

Answer 10

Process in wich cells build proteins. DNA is simply a set of instructions on how to make proteins. DNA tells you which amino acids to use, and in what order to assemble those amino acids to produce thecorrect protein.

Answer 11

special arrangements of prokaryotic genes that play roles in gene regulation ## Footnote They consists of a promoter, a series of genes that code for enzymes and structures such as channel proteins needed in response to changed environmental conditions, and an adjacent regulatory element called an operator

Answer 12

– Point mutations ## Footnote * Most common * One base pair is affected * Insertions, deletions, and substitutions

Answer 13

Frameshift mutations ## Footnote * Nucleotide triplets after the mutation are displaced * Insertions and deletions

Answer 14

Some base-pair substitutions produce silent mutations because the substitution does not change the amino acid sequence due to the redundancy of the genetic code For example, when the DNA triplet AAA is changed to AAG, the mRNA codon will be changed from UUU to UUC; however, because both codons specify phenylalanine, there is no change in the phenotype—the mutation is silent because it affects the genotype only

Answer 15

A change that speciﬁes a different amino acid is called a missense mutation; what gets transcribed and translated makes sense, but not the right sense. T

Answer 16

mutation occurs when a base-pair substitution changes an amino acid codon into a stop codon. Nearly all nonsensemutations result in nonfunctional proteins.

Answer 17

– Xray/gamma ray (ionizing) causes electrons to excite which can cause covalent bond breakage of the sugar phosphate backbone of DNA ## Footnote – UV (nonionizing) causes pyrimidine dimers (covalent bonding) warping the shape of DNA.

Answer 18

These compounds look like normal nucleotides, and when available may be erroneously substituted for nucleotides. ## Footnote – Can be useful antiviral or anticancer drugs due to heightened replication of these cells.

Answer 19

1. Nucleotide Analogs 2. Nucleotide-Altering Chemicals 3. Frameshift Mutagens

Answer 20

Conjugation – primitive “mating” between bacteria

Answer 21

DNA exits one cell, taken up from the environment by another cell Artificially induced in laboratory * - Cells that take up DNA are termed “Competent” * - useful tool for recombinant DNA technology

Answer 22

horizontal gene transfer, called transduction, involves the transfer of DNA from one cell to another via a replicating virus ## Footnote Transduction – Bacterial DNA transferred from one bacteria to another via a bacteriophage

Answer 23

type of mutation involving replacement or substitution of a single nucleotide base with another in DNA or RNA molecule.

Answer 24

Donor cell contributes part of genome to recipient cell

Answer 25

1. • Transformation 2. • Transduction 3. • Bacterial conjugation

Answer 26

Transduction – Bacterial DNA transferred from one bacteria to another via abacteriophage A bacteriophage Is a virus that infects bacteria

Answer 27

have fun :)