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90 terms

Micro Chapter 8 Key Terms

Tortora, Funke, Case Ch 8 Microbial Genetics
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alarmone
A chemical signal that promotes a cell's reponse to environmental stress
Ames test
A procedure using bacteria to identify potential carcinogens
anticodon
The three nucleotides by which a tRNA recognizes an mRNA codon
auxotroph
A mutant microorganism with a nutrional requirement that is absent in the parent
bacteriocin
An antimicrobial peptide produced by bacteria that kills other bacteria
bacteriophage (phage)
A virus that iinfects bacterial cells
base pairs
The arrangement of nitrogenous bases in nucleic acids based on hydrogen bonding; in DNA, base pairs are A-T and G-C; in RNA, base pairs are A-U and G-C
base substitution
The replacement of a single base in DNA by another base, causing a mutation; also called point mutation
carcinogen
Any cancer-causing substance
catabolite repression
Inhibition of metabolism of alternate carbon sources by glucose
chromosome
The structure that carries hereditary information, chromosomes contain genes
codon
A sequence of three nucleotides in mRNA that specifies the insertion of an amino acid into a polypeptide
Competence
The physiological state in which a recipient cell can take an incorporate a large piece of donor DNA
conjugation
The transfer of genetic material from one cell to another involving cell-to-cell contact
conjugative plasmid
A prokaryotic plasmid that carries genes for sex pili and for transfer of the plasmid to another cell
corepressor
A molecule that binds to a repressor protein, enabling the repessor to bind to an operator
crossing over
The process by which a portion of one chromosome is exchanged with a portion of another chromosome
cyclic AMP (cAMP)
A molecule derived from ATP, in which the phosphate group has a cyclic structure; acts as a cellular messenger
degeneracy
Redundancy of the genetic code; that is, most amino acids are encoded by several codons
dissimilation plasmid
A plasmid containing genes encoding production of enzymes that trigger the catabolism of certain unusual sugars and hydrocarbons
DNA gyrase
See topisomerase
DNA ligase
An enzyme that covalently bonds a carbon atom of one nucleotide with the phosphate of another nucleotide
DNA polymerase
Enzyme that synthesizes DNA by copying a DNA template
donor cell
A cell that gives DNA to a recipient cell during genetic recombination
exon
A region of a eukaryotic chromosome that encodes a protein
F factor (fertility factor)
A plasmid found in the donor cell in bacterial conjugation
frameshift mutation
A mutation caused by the addition of deletion of one or more bases in DNA
free radical
A compound with an unpaired electron. See superoxide
gene
A segment of DNA (a sequence of nucleotides in DNA) encoding a functional product
generalized transduction
The transfer of bacterial chromosome fragments from one cell to another by a bacteriophage
genetic code
The mRNA codons and the amino acids they encode
genetic recombination
The process of joing pieces of DNA from different sources
genetics
The science of heredity and gene function
genome
One complete copy of the genetic information in a cell
genomics
The study of genes and their function
genotype
The genetic makeup of an organism
Hfr cell
A bacterial cell in which the F factor has become integrated into the chromosome; Hfr stands for high frequency of recombination
horizontal gene transfer
Transfer of genes between two organsims in the same generation. See also vertical gene transfer
inducer
A chemical of environmental stimulus that causes transcription of specific genes
induction
The process that turns on the transcription of a gene
insertion sequence (IS)
The simplest kind of transposon
intron
A region in a eukaryotic gene that does not code for a protein or mRNA
lagging strand
During DNA replication, the daughter strand that is synthesized discontinuously
leading strand
During DNA replication, the daughter strand that is synthesized continuously
light-repair enzyme
See photolyase.
Messenger RNA (mRNA)
The type of RNA molecule that directs the incorporation of amino acids into proteins
methylase
An enzyme that attaches methyl groups (-CH3) to a molecule; methylated cytosine is protected from digestion by restriction enzymes
microRNA (miRNA)
Small, single-stranded RNA that prevent translation of a complementary mRNA
missense mutation
A mutation that results in the substitution of an amino acid in a protein
mutagen
An agent in the environment that brings about mutations
mutation
Any change in the nitrogenous base sequence of DNA
mutation rate
The probability that a gene will mutate each time a cell divides
negative (indirect) selection
The process of identifying mutations by selecting cells that do not grow using replica plating
nonsense codon
A codon that does not encode any amino acid
nonsense mutation
A base substitution in DNA that results in a nonsense codon
nucleotide excision repair
The repair of DNA involving removal of defective nucleotides and replacement with functional ones
operator
The region of DNA adjacent to structural genes that controls their transcription
operon
The operator and promoter sites and structural genes they control
phage
See bacteriophage
Phenotype
The external manifestations of an organism's genotype, or genetic makeup
photolyase
An enzyme that splits thymine dimers in the presence of visible light
point mutation
See base substitution
positive (direct) selection
A procedure for picking out mutant cells by growing them
promoter
The starting site on a DNA strand for transcription of RNA by RNA polymerase
R
Used to represent nonfunctional groups of a molecule See also resistance factor
r-determinant
A group of genes for antibiotic resistance carried on R factors
recipient cell
A cell that receives DNA from a donor cell during genetic recombination
replica plating
A method of inoculating a number of solid minimal culture media from an original plate to produce the same pattern of colonies on each plate
replication fork
The point where DNA strands separate and new strands will be synthesized
repression
The process by which a repressor protein can stop the synthesis of a protein
repressor
A protein that binds to the operator site to prevent transcription
resistance (R) factor
A bacterial plasmid carrying genes that determine resistance to antibiotics
resistance transfer factor (RTF)
A group of genes for replication and conjugation on the R factor
RNA primer
A short strand of RNA used to start synthesis of the lagging strand of DNA, and to start the polymerase chain reaction
semiconservative replication
The process of DNA replication in which each double-stranded DNA molecule contains one original strand and one new strand
sense codon
A codon that codes for an amino acid
short tandem repeats (STRs)
Repeating sequences of 2- to 5- nucleotides
snRNP
Small nuclear ribonucleoprotein (pronounced "snurp") - Short RNA transcript plus protein that combines with pre-mRNA to remove introns and join exons together
specialized transduction
The process of transferring a piece of cell DNA adjacent to a prophage to another cell
spontaneous mutation
A mutation that occurs without a mutagen
structural gene
A gene that determines the amino acid sequence of a protein
terminator
The site on a DNA strand at which transcription ends
topoisomerase
Enzyme that relaxes supercoiling of DNA ahead of replication form; separates DNA circles at the end of DNA replication
transcription
The process of synthesizing RNA from a DNA template
transduction
The transfer of DNA from one cell to another by a bacteriophage. See also generalized trasduction; specialed transduction
transfer RNA (tRNA)
The type of RNA molecule that brings amino acids to the ribosomal site where they are incorporated into proteins
transformation
(1) The process in which genes are transferred from one bacterium to another as "naked" DNA in solution. (2) The changing of a normal cell into a cancerous cell
translation
The use of mRNA as a template in the synthesis of protein
transposon
A small piece of DNA that can move from one DNA molecule to another
vertical gene transfer
Transfer of genes from an organism or cell to its offspring