How are nucleotides joined together? -
ANSWER>>>>>Condensation to form phosphodiester bond
What is the function of mRNA? - ANSWER>>>>>Carries genetic
info out of nucleus
Transcript translated to protein
What is the function of tRNA? - ANSWER>>>>>Carries aa to
ribosome
Anticodon pairs with codon on mRNA strand
What is the function of rRNA? - ANSWER>>>>>part of ribosome
structure
most abundant RNA
coordinated coupling of tRNA to mRNA codons
Feedback inhibition - ANSWER>>>>>Product of pathway is
noncompetitive inhibitor
Binds to allosteric site to slow down rxn b/c too much product
Exonucleases - ANSWER>>>>>Degrades nucleic acids by
removing one terminal nt at a time
,Cleaves phosphodiester bond at end of chain
5' --> 3' and 3' --> 5'
Endonucleases (Prok) - ANSWER>>>>>Restriction enzymes
Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site is palindromic sequence
Types I-V
ORI sites - ANSWER>>>>>nt sequence where replication is
initiated
Topoisomerase I - ANSWER>>>>>Induces ss breaks
Remove DNA supercoils during TXN and DNA replication; for
strand breakage during recombination; for chr condensation; and
to disentangle intertwined DNA during mitosis
topoisomerase II - ANSWER>>>>>cuts both strands of one DNA
double helix, passes another unbroken DNA helix through it, and
then reanneals the cut strands
Gyrase (topoisomerase II) - ANSWER>>>>>Unwinds supercoiling
caused by unwinding at the rep fork by introducing DSBs
Helicase - ANSWER>>>>>Breaks H-bonds of double helix at the
replication fork
Primase - ANSWER>>>>>DNApol α (DNA dep RNA pol)
adds short segments of complementary
RNA to ssDNA template (primers), serves as starting points for
replication
single-strand DNA binding proteins (SSBPs) -
ANSWER>>>>>Binds ssDNA and prevents it from re-annealing
during TXN, replication, repair, and recombination
,Okazaki fragments - ANSWER>>>>>Short fragments of DNA
synthesized by DNApol δ using the lagging strand (3'->5') as a
template
Ligase - ANSWER>>>>>Closes gaps in DNA
Catalyzes phosphodiester bond between 3'OH and 5'P
What are the steps in DNA replication? - ANSWER>>>>>1.
Initiate
2. Elongate
3. Terminate
Telomeres - ANSWER>>>>>Repeat sequence (TTAGGG) at the
ends of chr, protect chr from degradation
RNA polymerase - ANSWER>>>>>DNA dependent RNApol
Transcribes DNA template to RNA (3'-->5'; anti-parallel)
Splicesomes - ANSWER>>>>>Complex of snRNPs
Removes introns from pre-mRNA and splices exons together
Enhancers - ANSWER>>>>>Short regions of DNA that bind
proteins (TXN factors) that enhance TXN of a gene
Poly-A tail - ANSWER>>>>>Prevents mRNA from being
degraded in cytoplasm
100-250 A's at 3' end
5' cap - ANSWER>>>>>5'-5' pyrophosphate bridge to a
methylated G added to 5' end of a mRNA
Protects against degradation and as a recognition signal for TLN
apparatus
aminoacyl tRNA - ANSWER>>>>>tRNAs that carry amino acids
, Ribosomes - ANSWER>>>>>Where TLN occurs
Prok: 30s and 50s
Euk: 40s and 60s
Catalyzes peptide bond between a.a.'s
What is the path of a tRNA in a ribosome? -
ANSWER>>>>>Acceptor > Peptidyl > Exit
How is translation initiated? - ANSWER>>>>>small rRNA (40S)
subunit binds mRNA and scans for start codon (AUG)
Met-tRNA is brought to the P site
Large rRNA (60S) subunit binds
How is translation terminated? - ANSWER>>>>>Occurs when
stop codon enters A site
Release factor recognizes stop codon, hydrolyzes ester bond with
P site, releasing aa chain
Reverse transcriptase - ANSWER>>>>>enzyme that transcribes
RNA to cDNA (lacks introns)
RNA --> RNA:DNA --> cDNA (dsDNA)
Pleiotrophy - ANSWER>>>>>a single gene controls the
expression of many phenotypic traits
ie Sickle Cell Anemia
cDNA - ANSWER>>>>>intron free complementary DNA
can be inserted into a plasmid
Vector - ANSWER>>>>>helps carry DNA into cell
ie plasmids, virus
Open Reading Frame (ORF) - ANSWER>>>>>sections of DNA
that begin with start codons and end with stop codons
DNA: 5' --> 3'
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