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microbiology chapter 8 ttc

Terms in this set (40)

Genetics:
the study of inheritance, or heredity of living things
Genome:
sum total of genetic material of an organism (including junk DNA)
Gene
a segment of DNA that codes for a functional product
Genotype
the sum of all gene types; an organism's distinctive genetic makeup
Phenotype
The expression of the genes to create certain traits (structures or functions)
Nucleotide
basic unit of DNA structure
Topoisomerase
unwinds the supercoils and larger coils of the DNA
Helicase
unwind and separate the helix by breaking the hydrogen bonds that hold the two sides together. This creates an area called the replication fork.
primase
Creates an RNA primer on the leading strand
DNA polymerase
attach to the RNA primer and synthesize DNA in the direction of the opening replication fork.
Rnase H
removes the RNA primer
DNA ligase
covalently bonds the two pieces together.
Primase
will create RNA primers and the helix opens
DNA polymerase
synthesize DNA, replaces RNA primers
Okazaki fragments
Chunks of DNA segments that are formed in the opposite direction on the lagging strand.
Ligases
move along the lagging strand to link the fragments and complete the synthesis and separation of the two daughter molecules.
Transcription
master code of DNA used to synthesize an RNA molecule from a gene, process of making an RNA copy of a gene
Translation
formed RNA is used to produce protein
Initiation
During initiation RNA polymerase binds to a section of DNA at the beginning of a gene called a promoter
Elongation
The ribosome moves along the mRNA reading one codon at a time, adding the amino acids.This is the step where the protein is made
Termination
The ribosome continues moving along the mRNA until a stop codon is reached. An enzyme attaches and releases all the components - the ribosome, the last tRNA, the mRNA and the finished protein
Inducible genes
usually not active but can be "turned on"
Repressible genes
usually active but can be "turned off"
Operons:
Only found in bacteria.Consist of a coordinated set of genes regulated as a single unit. Can be inducible or repressible
lac operon
inducible operon - it is off unless lactose is present and then it can be activated.
Recombination
occurs when one bacterium donates DNA to another bacterium. End result is a new strain different from both the donor and the original recipients
Recombinant:
any organism that contains genes that originated in another organism
Horizontal gene transfer
is any transfer of DNA that results in organisms acquiring new genes that did not come from parent organisms
Gram-negative conjugation
Contact is made when a pilus grows out from the F+ cell, attaches to the surface of the F- cell, contracts, and draws the two cells together. One strand of the plasmid is transferred from the F+ cell to the F- cell. Both single strands of DNA are replicated. Now both cells have the plasmid and are F+ cells
Gram-positive conjugation
An opening is created between two adjacent cells (no pili). Replicated DNA passes across from one cell to another. Have to bump into each other.
Transformation
involves the transfer of naked DNA (DNA in solution) from a donor cell to a recipient cell. A chromosome released by a lysed (dead) cell breaks into fragments small enough to be accepted by a recipient cell.
Transduction
Transfer of DNA from a donor cell to a recipient cell inside a bacteriophage (virus that infects bacteria)
Transposons
"Jumping genes". are segments of DNA capable of moving from one part of the genome to another
Mutation
Any change to the nucleotide sequence in the genome is a___
Spontaneous mutation
a random change in the DNA arising from errors in replication (not common)
Induced mutations
result from exposure to known mutagens, which are primarily physical or chemical agents that disrupt DNA
Missense mutation:
A change in the code that leads to the placement of a different amino acid. Can create a faulty, nonfunctional protein. Can produce a protein that functions differently. Can cause no significant alteration
Nonsense mutation
one nucleotide change that changes a normal codon into a stop codon. Produces an incomplete protein.
Silent mutation
alters a base, but does not change the amino acid, and has no effect
Frameshift mutation:
One or more bases are inserted or deleted. Changes the reading frame of the mRNA. Nearly always results in a nonfunctional protein
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