CH13 Flashcards
The principle of transformation was first demonstrated by which of the following individuals or groups of individuals?
Griffith
A complex consisting of a single mRNA molecule with several ribosomes is called a
polysome.
When an F plasmid integrates into the host chromosome, the strain is referred to as
Hfr.
When bacterial genes are transferred to another bacterium by a virus, it is called
transduction.
Which of the following types of mutation may play an important role in driving evolution because they are often nonlethal and, therefore, remain in the gene pool?
missense
_______ are strains that are unable to grow on a minimal medium that supports growth of the wild type strain but are able to grow on the minimal medium if one or more nutritional supplements are added.
Auxotrophs
________ molecules deliver amino acids to ribosomes during translation.
Transfer RNA (tRNA)
Transfer of genetic information via direct cell-cell contact is called
conjugation.
The Ames test
is used to measure the mutagenicity of chemicals.
The strand of DNA for a particular gene that is copied by the RNA polymerase to form mRNA is called the __________ strand.
template
When a DNA molecule is replicated, the daughter molecules contain one strand of parental DNA and one strand of newly synthesized DNA; this is called __________ replication.
semiconservative
When a recipient cell acquires a piece of naked DNA from the environment, it is called
transformation.
You have taken E. coli strain A, which has its own plasmids, and mixed it with E. coli B strain without plasmids. E. coli B cells now have plasmids but, in addition, they also carry some genes from E. coli A strain. An explanation for this:
some F+ E. coli A cells became Hfr cells.
Which of the following is not a termination codon? UGA AUG UAA UAG
AUG
The region at which the RNA polymerase binds is the __________ region.
promoter
The portion of the tRNA molecule that binds to the codon on the mRNA is called the
anticodon.
After an F+ × F- mating, the donor is __________ and the recipient is __________.
F+; F+
If 20% of nucleotides in the DNA of a particular organism contain thymine, estimate the percentage of cytosine that is present in the DNA.
30%
The transcribed, but not translated, sequence that is immediately upstream of the region that encodes the functional product is called the __________ region.
leader
A __________ mutation is one that causes premature termination of the synthesis of the protein product.
nonsense
Which of the following best represents the order of gene transfer in an Hfr × F- mating?
part of the plasmid followed by part of the chromosome
In order to take up a naked DNA molecule, a cell must be __________, which may occur only at certain stages in the life cycle of the organism.
competent
During replication the 2 strands of the DNA molecule are unwound from one another by enzymes called
helicases.
In __________ ribosomes can attach to the mRNA and begin translation even though transcription has not been completed.
prokaryotes
Plasmids that have genes that decrease bacterial susceptibility to antibiotics are called __________ factors.
resistance
what is the central dogma of DNA replication
DNA–replication–>DNA–transcription–> RNA (can reverse transcription back to DNA) –translation–>protein
compare/contrast DNA replication in bacteria and eukaryotes
-in bacteria
single origin, bidirectional
2 replication forks going in opposite directions
-in eukaryotes
multiple origins, linear
multiple replication forks
describe how DNA replicates
- DNA B helicase is responsible for separating the two strands of parental DNA.
- The strands are kept apart by single-stranded DNA binding proteins (SSB), allows for synthesis of an RNA primer by DNA primase.
- DNA gyrase eases the strain.
- The lagging strand is synthesized in short fragments called Okazaki fragments.
- A new RNA primer is required for the synthesis of each Okazaki fragment.
replication fork movement is in the _______ direction
3’-5
RNA primer adds ____ bases
10
new DNA is added at __ side
3’
DNA polymerase adds new dna in opposite direction of
replication fork
are okazaki fragments larger in bacteria or eukaryotes?
bacteria
how are RNA primers removed
- DNA polymerase 1 removes RNA primer and fills gap with DNA on lagging strand, nick remains
- DNA ligase links Okazaki fragments together by sealing nicks
- complete chromosome produced
-nucleic acid on lagging strand during replication made up of 10 RNA bases
Okazaki Fragments
removes RNA primer and puts in DNA
DNA polymerase I
nucleotide sequence that codes DNA
gene
how many RNA polymerase do bacteria and eukaryotes have
bacteria-1
eukaryotes-3
describe transcription
- Transcription begins at the +1 position in DNA and proceeds to the right (3’-5’ direction)
- RNA polymerase recognition site is at -35 and RNA polymerase binding site (Pribnow box) is at -10 in the promotor region
- template strand transcription starts synthesizing RNA
- translation stop codon is right before the trailer
- mRNA is produced
all cellular organisms use ___ as start codon
AUG
describe translation
- template produced from transcription serves as code
- codons mRNA codons are formed with corresponding bases, U instead of T
- start codon is at AUG with corresponding anticodons that make the tRNA with functional AA protein attached
begins translation in bacteria
FMET
if the mRNA strand is AUG AGC GAC, then the anticodons are
UAC UCG CUG
if the template strand is TAC TCG CTG, then the mRNA codons are
AUG AGC GAC
codons that don’t have corresponding RNA are
stop codons
ex: UAA, UAG, UGA
what happens in eukaryotic RNA processing
- entire gene both intron and exons, transcribed to RNA by RNA poly (eukaryotic DNA)
- introns removed
- exons spliced together without introns forming mRNA that will pass thru nuclear membrane into cytoplasm
- become ribosomes for translation
segments of DNA that are non-coding sequences
introns
bacteria and archaea have transcription/ translation linked because
they don’t have a nucleus or introns
how was insulin revolutionized for diabetes
since eukaryotic genes cannot work in bacteria, human insulin took processed mRNA (exons) and made DS RNA
