Dna And Rna: Replication, Transcription, Translation

Front 1

Helicase

Back 1

Unwinds DNA at replication fork

Front 2

Single-stranded binding proteins

Back 2

prevents strands from reannealing

Front 3

DNA topoisomerase

Back 3

nicks helix to relieve supercoils during replication

Hint 3

Fluoroquinolones - inhibit DNA gyrase (prikaryotic topoiomerase II)

Front 4

Primase

Back 4

Makes RNA primer on which DNA polymerase III can initiate replication

Front 5

DNA polymerase III

Back 5

Prokaryotic ONLY. Elongates strand by adding nucleotides to the 3' end. Elongates lagging strand until it reaches primer of the preceding fragment. 3'-5' exonuclease proofreads added nucleotides

Hint 5

5'-3' synthesis and proofreads with 3'-5' exonuclease

Front 6

DNA polymerase I

Back 6

Prokaryotic ONLY. Degrades RNA primer and replaces with DNA

Hint 6

Same function as DNY polymerase III but also excises RNA primer with 5'-3' exonuclease.

Front 7

DNA ligase

Back 7

Catalyzes phosphodiester bond within a strand of double-stranded DNA. Joins Okazaki fragments

Front 8

Telomerase

Back 8

Adds DNA to 3' end of chromosomes to avoid loss with each successive duplication

Front 9

Nucleotide excision repair

Back 9

Repairs helix-distorting lesions (ie pyramidine dimer from UV light exposure). Endonucleases release the damaged bases, DNA polymerase and ligase fill and reseal the gap.

Hint 9

Mutated in Xeroderma Pigmentosum

Front 10

Base excision repair

Back 10

Glycosylases recognize and remove damaged bases (ie spontanious/ toxic deamination) apurinic/apyramidinic endonuclease cuts DNA, empty sugar is removed, gap is filled/resealed

Front 11

Mismatch repair

Back 11

Newly synthesized strand is recognized, mismatch nucleotides are removed, gap is filled and resealed.

Hint 11

Mutated in Hereditary nonpolyposis colorectal cancer (HNPCC)

Front 12

Non-homologous end joining

Back 12

Brings together 2 ends of DNA fragments to repair double-stranded breaks. Homology not required.

Hint 12

Mutated in ataxia telangiectasia

Front 13

rRNA

Back 13

ribosomal RNA

Hint 13

most abundant (r=Rampant)

Front 14

mRNA

Back 14

messenger RNA

Hint 14

longest (m=Massive)

Front 15

tRNA

Back 15

transfer RNA

Hint 15

smallest (t=Tiny)

Front 16

mRNA start codons

Back 16

AUG (GUG)

Hint 16

eukaryotes: methionine. removed before translation is complete

prokaryotes: formylmethionine (f-met)

Front 17

mRNA stop codons

Back 17

UGA
UAA
UAG

Hint 17

UGA = U Go Away
UAA = U Are Away
UAG = U Are Gone

Front 18

Promoter

Back 18

RNA polymerase and other transcription factors bind to DNA upstream from gene locus (AT-rich upstream sequence with TATA and CAAT boxes)

Hint 18

mutation results in dramatic decrease in gene transcription

Front 19

Enhancer

Back 19

Stretch of DNA that alters gene expression by binding transcription factors

Hint 19

May be located close to, far from, or within (intron) the genes they regulate

Front 20

Silencer

Back 20

Site where negative regulators (repressors) bind

Hint 20

May be located close to, far from, or within (intron) the genes they regulate

Front 21

RNA polymerase I (eukaryote)

Back 21

makes rRNA

Front 22

RNA polymerase II (eukaryote)

Back 22

Makes mRNA. Opens DNA at promotor site.

Hint 22

α-amanitin (in Amanita phalloides) inhibits - causes hepatotoxicity.

Front 23

RNA polymerase (prokaryote)

Back 23

multisubunit complex makes all 3 types of RNA

Front 24

RNA processing (eukaryote)

Back 24

hnRNA (if it's to be translated = pre-mRNA)
- 5' cap (7-methylguanosine)
- polyadenylation of 3' (200 As) by Poly-A polymerase which does not require a template (AAUAAAA = signal)
-Splicing out of introns

Front 25

pre-mRNA splicing

Back 25

-snRNPs and proteins make spliceosome
-Lariat intermediate
-Lariat released, exons joined

Hint 25

Antibodies to step 1 formed in lupus

Front 26

tRNA

Back 26

75-90 nucleotides, 2º structure, cloverleaf shape. CCA at 3' end with chemically modified bases. Amino acid covelently bound to 3' end

Front 27

Charging tRNA

Back 27

Aminoacyl-tRNA synthetase (1 per amino acid, uses ATP) adds correct amino acid (removes incorrect)

Hint 27

Tetracyclines inhibit

Front 28

Silent point mutation

Back 28

same amino acid (usually a change in 3rd position of codon)

Front 29

Missense point mutation

Back 29

changed amino acid (conservative - new amino acid is similar in structure)

Front 30

Nonsense point mutation

Back 30

Change results in early stop codon

Front 31

Frameshift mutation

Back 31

Change results in misreading ALL nucleotides downstream - usually a truncated or nonfunctional protein

Front 32

tRNA wobble

Back 32

accurate base pairing is only required for the first 2 nucleotide positions, so different 3rd positions can code for the same tRNA/amino acid

Front 33

Protein synthesis - Initiation

Back 33

activated by GTP hydrolysis, initiaion factors assemble subunits with initiator tRNA, released when complex assembles
Eukaryotes: 40S + 60S => 80S
proaryotes: 30S + 50S => 70S

Hint 33

Aminoglycosides

Front 34

Protein synthesis - Elongation

Back 34

1) Aminoacyl-tRNA binds to A site
2) Ribosomal rRNA ("ribozyme") catalyzes peptide bond, transfers to A site
3) Ribosome advances 3 nucleotides (toward 3' end)

A site = incoming Aminoacyl-tRNA
P site = accomodating growing Peptide
E site = holds Empty tRNA as it Exits
=> APE

Hint 34

Tetracyclines inhibit 1)
Chloramphenicol inhibits 2)
Macrolides inhibit 3)

Front 35

Posttranslational modification: Trimming

Back 35

Removal of N' or C' propeptides from zymogens

Front 36

Posttranslational modification: Covalent alteration

Back 36

Phosphorylation, glycosylation, hydroxylation, methylation, and acetylation.

Front 37

Posttranslational modification: Proteasomal degradation

Back 37

Attachment of ubiquitin to defective proteins to tag them for breakdown.