ASCP Technologist in Molecular Biology board exam prep
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Course
ASCP Technologist in Molecular Biology
Institution
ASCP Technologist In Molecular Biology
ASCP Technologist in Molecular Biology board exam prep
bond
One carbon ring
Cytosine, Thymine, Uracil
Two carbon rings
Adenine, Guanine
How are nucleotides joined together? Condensation to form phosphodiester
Carries genetic info out of nucleus
Transcript translated to protein
Carries aa t...
ASCP Technologist in Molecular Biology board exam prep
One carbon ring
Pyrimidine
Cytosine, Thymine, Uracil
Two carbon rings
Purine
Adenine, Guanine
Condensation to form phosphodiester
How are nucleotides joined together?
bond
Carries genetic info out of nucleus
What is the function of mRNA?
Transcript translated to protein
Carries aa to ribosome
What is the function of tRNA? Anticodon pairs with codon on mRNA
strand
part of ribosome structure
most abundant RNA
What is the function of rRNA?
coordinated coupling of tRNA to mRNA
codons
Product of pathway is noncompetitive in-
hibitor
Feedback inhibition
Binds to allosteric site to slow down rxn
b/c too much product
Degrades nucleic acids by removing one
terminal nt at a time
Exonucleases Cleaves phosphodiester bond at end of
chain
5' --> 3' and 3' --> 5'
Restriction enzymes
Cleaves phoshpodiester bonds w/i
Endonucleases (Prok) poly-nt chain
Recognition site is palindromic sequence
Types I-V
ORI sites nt sequence where replication is initiated
Induces ss breaks
Remove DNA supercoils during TXN and
Topoisomerase I
DNA replication; for strand breakage dur-
ing recombination; for chr condensation;
, ASCP Technologist in Molecular Biology board exam prep
and to disentangle intertwined DNA dur-
ing mitosis
cuts both strands of one DNA double he-
lix, passes another unbroken DNA helix
topoisomerase II
through it, and then reanneals the cut
strands
Unwinds supercoiling caused by unwind-
Gyrase (topoisomerase II)
ing at the rep fork by introducing DSBs
Breaks H-bonds of double helix at the
Helicase
replication fork
DNApol ± D( NA dep RNA pol)
adds short segments of complementary
Primase
RNA to ssDNA template (primers),
serves as starting points for replication
Binds ssDNA and prevents it from re-an-
single-strand DNA binding proteins (SS-
nealing during TXN, replication, repair,
BPs)
and recombination
Short fragments of DNA synthesized by
Okazaki fragments DNApol ´using the lagging strand (3'->5')
as a template
Closes gaps in DNA
Ligase Catalyzes phosphodiester bond be-
tween 3'OH and 5'P
1. Initiate
What are the steps in DNA replication? 2. Elongate
3. Terminate
Repeat sequence (TTAGGG) at the ends
Telomeres
of chr, protect chr from degradation
DNA dependent RNApol
RNA polymerase Transcribes DNA template to RNA
(3'-->5'; anti-parallel)
Complex of snRNPs
Splicesomes Removes introns from pre-mRNA and
splices exons together
,ASCP Technologist in Molecular Biology board exam prep
Short regions of DNA that bind proteins
Enhancers (TXN factors) that enhance TXN of a
gene
Prevents mRNA from being degraded in
Poly-A tail cytoplasm
100-250 A's at 3' end
5'-5' pyrophosphate bridge to a methylat-
ed G added to 5' end of a mRNA
5' cap
Protects against degradation and as a
recognition signal for TLN apparatus
aminoacyl tRNA tRNAs that carry amino acids
Where TLN occurs
Prok: 30s and 50s
Ribosomes
Euk: 40s and 60s
Catalyzes peptide bond between a.a.'s
What is the path of a tRNA in a ribo-
Acceptor > Peptidyl > Exit
some?
small rRNA (40S) subunit binds mRNA
and scans for start codon (AUG)
How is translation initiated?
Met-tRNA is brought to the P site
Large rRNA (60S) subunit binds
Occurs when stop codon enters A site
Release factor recognizes stop codon,
How is translation terminated?
hydrolyzes ester bond with P site, releas-
ing aa chain
enzyme that transcribes RNA to cDNA
Reverse transcriptase (lacks introns)
RNA --> RNA:DNA --> cDNA (dsDNA)
a single gene controls the expression of
Pleiotrophy many phenotypic traits
ie Sickle Cell Anemia
intron free complementary DNA
cDNA
can be inserted into a plasmid
helps carry DNA into cell
Vector
ie plasmids, virus
, ASCP Technologist in Molecular Biology board exam prep
sections of DNA that begin with start
codons and end with stop codons
DNA: 5' --> 3'
Open Reading Frame (ORF)
transcription: 3' --> 5' DNA --> RNA (pro-
moter)
translation: 5' --> 3' mRNA
Measures amount of light absorbed
Spectrophotometer Quantitative measurement of
[DNA/RNA]
At what wavelength does DNA and RNA
260 nm
absorb?
At what wavelength does protein ab-
280 nm
sorb?
1. Lyse
2. Add phenol/ chloroform > vortex/spin
3. Transfer aqueous layer (top) to new
tube
4. Add chloroform:IAA (removes phenol)
Organic isolation method
> vortex/spin
5. Transfer aqueous layer to new tube
6. Add NaOAc and EtOH > vortex/spin
7. Decant
8. Resuspend
200C for 2 hrs
How do you inactivate RNases? 30 min in 1M NaOH or quanidinum isoth-
iocyanate
2 ssDNA molecules of comp base se-
Hybridization
quence can form a ds hybrid (duplex)
What does the incubation step in hy-
Allows formation of ds molecules
bridization do?
minimizes probe binding to nonspecific
Blocking DNA (Hybridization) sequence
ie salmon sperm DNA, Human LINE-1
Blocking Proteins (Hybridization)
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