unit 4 Flashcards
A particular triplet of bases in the template strand of DNA is 5’ AGT 3’. The corresponding codon for the mRNA transcribed is______
3’ UCA 5’
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is ________.
AAA
During elongation, which site in the ribosome represents the location where a codon is being read?
A site
T or F. RNA is synthesized during a process called transcription.
true
What type of mutation introduces a premature stop codon into the mRNA?
nonsense
What type of mutation covered would have the least impact?
silent
What are the coding segments of the mRNA transcript called?
exons
What part of a gene marks the end and causes transcription to stop?
terminator
T or F. One of the functions of tRNA is to transfer nucleotides to rRNA.
false
What modification happens to the mRNA transcript at the 3’ end?
poly A tide
Name one difference between DNA and RNA.
T vs. U, # of strands, type of sugar
What enzyme is responsible for separating the two strands of DNA during replication?
Helicase
What is the strand called that has Okazaki fragments?
lagging
What enzyme is responsible for adding nucleotides to the growing strand of DNA
during replication?
DNA polymerase
Why type of base is cytosine?
pyrimidine
What keeps the two strands of DNA from coming back together after they have been separated?
single stranded binding proteins
Name the enzyme responsible for adding the primer to the template DNA strand.
primase
People with Xeroderma pigmentosum lack repair enzymes that proofread DNA and repair it this way.
nucleotide excision repair
ame the enzyme responsible for joining Okazaki fragments together.
DNA ligase
What type of base is adenine?
purine
What type of base is guanine?
purine
What type of base is thymine?
pyrimidine
What type of base is uracil?
nitrogenous
Who studied streptococcus pneumoniae?
Frederick griffith
Which strain is harmless, rough or smooth?
rough
what is transformation?
a change in geno. & pheno. due to the assimilation of a foreign substance
what is nucleotide made of
nitrogen base, DNA and phosphate
what is the chargaff’s rule
A-T
G-C
how accurate is semiconservative model of replication?
only 1 error per billion nucleotides
where is dna replication?
s phase
Are single-stranded binding proteins polar?
true
does 3 phosphates need to be present for replication?
true
what are the strands in the double helix?
antiparallel
Is OH group from 3´ or 5´?
3
Is the phosphate group from 3´ or 5´?
5’
what order is elongation?
5’ —-> 3’
differences in leading and lagging strand?
leading; 3’ —> 5’
lagging: 5’ —> 3’
what joins okazaki fragments?
DNA ligase
what does a leading strand require?
formation of only a single primer
what does a lagging strand require?
formation of a new primer
what are the 2 steps of DNA repair?
- proofreading
- a nuclease cuts out a segment of a damaged strand
T or F. Does DNA get longer each time it is replicated
F
do telomeres allow DNA to get shorter?
T
telomere is in every cell
false
where does DNA transcribe into RNA?
nucleus
where is RNA transcribed into protein?
cytoplasm
which is the only RNA that gets translated?
mRNA
how are rna molecules read?
5’ —-> 3’
what starts transcription?
Rna polymerase
how much time RNA polymerase unwind during elongation?
10-20x
what segments get removed ?
noncoding/ introns
what 2 rna only help during translation?
tRNA & rRNA
what is wobble?
3rd pairing of complementary base pairings doesn’t need to match
how do know a tRNA will carry a certain aa?
each active site has a specific tRNA and aa combo
where does termination occur during translation?
when 1/3 stop colons reaches A site
polyribosome fxn
trail along the same mRNA to make copies polypeptide
how long does it take for a ribosome to translate?
1 min
what happens in translocation?
codons are decoded into a sequence of aa
what are codons made up of?
3 blocks of nucleotides
what happens in transcription?
DNA template strand turns into rna
what are the stop codons?
UAA
UAG
UGA
what is a smaller scale mutation?
point mutation
what does nonsense mutations nearly always lead to?
nonfunctional protein
the small, Xtra chromosomal DNA found in bacteria is called
A. Restriction enzymes
B. Plasmids
C. Bacteriophage
D. PCR
B. Plasmids
T or F. bacteria is the workhouse of modern biotechnology
True
what is the 2 steps of recombinant DNA
- a bacterial plasmid
- the gene of interest
how will we get the gene of interest to the plasmid?
a. really small scissors
b. gel electrophoresis
c. PCR
d. restriction enzymes
d. restriction enzymes
how do you prove that 2 samples of DNA come from the same person?
- STR (short tandem repeats)
- gel elecotrophoresis
you isolate DNA from blood left at crime scene–whats next?
a. call in CSI Raleigh
b. use PCR to amplify DNA
c. splice it into plasmid
d. use gel electrophoresis to break up the DNA
b. use PCR to amplify DNA
