Chapter 9: Microbial Genetics Flashcards
structural genes
genes that code for proteins
regulatory genes
genes that control gene expression
how may chromosomes does the human cell have
46
how many chromosomes doe e. coli have
1
where is DNA replicated in prokaryotes
cytoplasm
where is DNA replicated in eukaryotes
nucleus
transcription
DNA is copied to mRNA with RNA polymerase
translation
ribosome translates language of nitrogen bases to proteins
what are introns
“trash” DNA that does not code for anything
how are introns cleaned
with ribozymes
basic DNA structure
deoxyribose sugar
phosphate group
nitrogenous base
- nucleotides bonded to form a sugar-phosphate backbone
DNA strands are ___________ to one another.
antiparallel
what is the semiconservative process
Parent DNA is uncoiled. Strands are separated and serve as templates. Complementary strands are synthesized.
what is the replication site and replication forks
The origin of replication site is where replication is initiated. Replication forks is where DNA is synthesized.
what happens in DNA replication
- Helicase unwinds the DNA, forming a replication fork and two template strands, the leading and lagging strands.
2a. The leading strand is oriented 3’ - 5’ so DNA can be synthesized continuously and smoothly.
2b. The lagging strands runs the opposite way (5’ - 3’) so synthesis involves several steps and is done backwards. - A primase adds an RNA primer to direct DNA polymerase III. This creates an Okazaki fragments, unlinked segments of RNA primer and new DNA.
- DNA polymerase I replaces RNA primers with complementary DNA nucleotides.
- Unjoined ends of nucleotides, nick, are conjoined with ligase.
what is a codon
three consecutive nitrogen bases
what does tRNA do
- translates mRNA into protein
- provides anticodon
what is the universal language of life
genetic code
what are the three stages of transcription
- initiation
- elongation
- termination
initiation
RNA polymerase binds to promoter region where DNA is unwound
elongation
adds nucleotides complimentary to the template strand
termination
RNA polymerase recognizes STOP
what is the start codon
AUG; methionine
what are the termination codons
UGA, UAG, UAA
how many times does the translation of one codon happen per second
17
where does translation occur
cytoplasm
where does transcription
nucleus
what percentage of the human genome are exons
2%
what are exons
DNA that can be encoded; unlike introns
Lac operon segments
- regulator: codes for repressor
- control locus: has promoter and operator
- structural locus: codes for enzyme needed to catabolize lactose
spontaneous mutation
random change in DNA with no known cause
induced mutation
caused by mutagens
point mutation
addition, deletion, or substitution of nitrogen bases
missense mutation
changes a single amino acid
- can be unnoticeable or severe
nonsense mutation
changes normal codon to a stop codon
silent mutation
base changed, but amino acid stays the same
back-mutation
mutated gene changes back to original form
frameshift mutation
insertion or deletion of a base that changes the entire mRNA is altered
wild-type sequence
non mutated
inversion mutation
bases exchange places
conjugation
plasmid transferred through direct contact with the use of a pilus
transformation
DNA comes from a dead cell
transduction
donor is a lysed bacterial cell
transposons
“jumping genes”
