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110 Cards in this Set
- Front
- Back
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S-Phase
Chemotherapeutic agents |
Methotrexate, 5-flurouracil, hydroxyurea
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G2-Phase
Chemotherapeutic agents |
bleomycin
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Mitosis
Chemotherapeutic agents |
paclitaxel, vincristine, vinblastine
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Cell cycle non-specific
Chemotherapeutic agents |
cyclophosphamide, cisplastin
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Adenisine deaminase
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deamintes amino group of adenine to the carbonyl group of guanine
deficiency leads to SKIDS |
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Thymidylate synthase
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dUMP --> dTMP
blocked by methotrexate |
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Nucleoside
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Nitrogen base + pentose sugar
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Nucleotide
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Nitrogen base + pentose sugar + phosphate group
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What bond links nucleotides?
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3'-5' phosphodiester bond
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How many base pairs make up one turn of the double helix?
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10 base pairs
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Chargaff's Rules
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% A = % T (% U)
% G = % C % Purine = % Pyrimidine If bases do not follow Chargaff's rules, then is likely viral DNA |
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Daunorubicin/Doxorubicin
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used in treatment of leukemia
intercalates between DNA bases interferes with topoisomerase II activity |
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Cisplastin
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used in treatment of bladder and lung tumors
binds tightly to DNA, thereby causing structural distortion and malfunction |
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Negative Supercoil
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DNA wound more loosely than Watson-Crick DNA
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Positive Supercoil
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DNA wound more tightly than Watson-Crick DNA
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Histone amino acid composition
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rich in lysine and arginine
does NOT contain histidine |
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DNA methylation
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inactivates transcription
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Histone acetylation
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activates transcription
lessens overall positive charge lessens interaction with DNA |
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Histone phosphorylation
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activates transcription
lessens overall positive charge lessens interaction with DNA |
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Nucleolus
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area where rRNA is produced
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Euchromatin
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light staining
active |
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Heterochromatin
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dark staining
inactive (Barr body) |
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Prokaryote DNA Replication
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1 origin of repilcation; 2 replication forks
Bidirectional |
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Eukaryote DNA replication
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Multiple origins of replication; 2 replication forks at each origin
Bidirectional |
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DNA/RNA Polymerase Similarities
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Synthesize new strand in 5'-->3' direction
Template strand is read 3'-->5' direction NTP added to 3' OH (PPi is released) |
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DNA/RNA Polymerase Differences
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DNA polymerase requires a RNA primer
DNA polymerase has proofreading function (3'-->5' exonuclease) |
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Helicase
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In DNA replication:
Breaks H bonds holding base pairs together Allows for DNA to begin unwinding and forms two replication forks |
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Single-stranded DNA binding protein (SSB)
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In DNA replication:
Binds to single strand to prevent degradation and re-association of the strands |
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Primase
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In DNA replication:
Synthesizes short RNA primer in the 5'-->3' direction (allows for a 3' OH) Forms Okazaki fragments on the lagging strand |
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DNA Polymerase III
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In DNA replication:
Only in prokaryotes Synthesizes DNA on the leading and lagging strand in a 5'-->3' direction |
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DNA Polymerase alpha
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In DNA replication:
Only in eukaryotes Synthesizes DNA on the leading and lagging strand in a 5'-->3' direction |
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DNA Polymerase delta
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In DNA replication:
Only in eukaryotes Synthesizes DNA on the leading and lagging strand in a 5'-->3' direction |
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DNA Polymerase I
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In DNA replication:
In prokaryotes only Removes RNA primers (5'-->3' exonuclease) Replaces discarded RNA with DNA |
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RNAase H
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In DNA replication:
In eukaryotes only Removes RNA primers (5'-->3' exonuclease) |
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DNA ligase
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In DNA replication:
Joins the Okazaki fragments |
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DNA topoisomerase II
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In DNA replication:
Removes positive supercoils ahead of advancing replication forks DNA gyrase in prokaryotes |
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DNA gyrase
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In DNA replication:
Removes positive supercoils ahead of advancing replication forks Another name for DNA topoisomerase II |
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p53 gene
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Tumor suppressor gene that prevents damaged DNA from entering the S phase
Inactivation of deletion associated with Li Fraumeni syndrome and many solid tumors |
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ATM gene
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Encodes a kinase essential for p53 activity
Inactivated in ataxia telangiectasia, characterized by hypersensitivity to x-rays and predisposition to lymphomas |
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BRCA-1
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Tumor suppressor gene associated with breast, prostrate and ovarian cancer
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BRCA-2
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Tumor suppressor gene associated with breast cancer
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Rb
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Retinoblastoma gene was the first tumor suppressor gene cloned
Negative regulator of the cell cycle through its ability to bind the transcription factor E2F and repress transcription of genes required for S phase |
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Thymine dimers
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Caused by UV radiation
An excision endonuclease (exinuclease) removes the defective oligonucleotide Fixed in G1 |
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Cytosine deamination
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Occurs spontaneously or due to heat
Converts cytosine to uracil Uracil is recognized and removed by uracil glycosylase Fixed in G1 |
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Base excision repair
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Area is recognized and removed by AP endonuclease
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Xeroderma pigmentosum
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AR disease (1/250,000)
Extreme sensitivity to sunlight, skin freckling, ulcerations and skin cancer Caused by deficiency of excision endonucleases |
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Lynch syndrome
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Hereditary nonpolyposis colorectal cancer
Caused by defect in hMLH1 or hMSH2 Results in high rate of intestinal cancer Usually shows microsatellite instability |
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Microsatellite instability
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Variation in the number of tandem repeats in the non-coding region
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Telomerase
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Completes replication of telomere sequence at both ends of eukaryotic chromosome
Present in embryonic cells, fetal cells and certain adult stem cells NOT present in adult somatic cells Activity can sometimes be seen in cancers |
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mRNA is identical to which strand?
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The coding strand (except the Ts and replaced by Us)
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snRNA
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small nuclear RNA
Main function is to participate in the splicing of introns from pre-mRNA |
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RNA Polymerase (prokaryotes)
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Single RNA polymerase makes all the RNA
Requires sigma factor to start transcription Sometimes Rho factor is required to end transcription Inhibited by rifampin Actinomycin D binds to DNA preventing transcription |
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Sigma factor
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Protein factor in prokaryotes needed to start transcription
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Rho factor
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Protein factor needed sometimes to end transcription
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Rifampin
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Inhibits prokaryotic RNA polymerase
Will cause urine to turn orange-colored |
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RNA Polymerase 1
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rRNA except 5s rRNA
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RNA Polymerase 2
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hnRNA/mRNA and some snRNA
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RNA Polymerase 3
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tRNA and 5s rRNA
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TFIID
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Transcription factor 2 D
Can help RNA P2 to initiate transcription |
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Actinomycin D
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Binds to DNA, preventing transcription
Affects both eukaryotes and prokaryotes |
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Alpha-amanitin
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Inhibits RNA P2
Found in mushrooms |
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What direction does RNA polymerase synthesize RNA?
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5'-->3' direction
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What are the two consensus sequences in prokaryotic mRNA?
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Pribnow box (TATA box)
-35 sequence |
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What two ways does transcription end in prokaryotic mRNA?
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Stem and loop + UUUUUU
Stem and loop + rho factor (Stem and loop is GC rich area at 3') |
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16s rRNA binds to what sequence?
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Shine-Dalgarno
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Shine-Dalgarno sequence
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Located in the 5' UTR of prokaryotic mRNA
Used to recruit ribosomes to mRNA to start protein synthesis |
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Prokaryotic mRNA is polycistronic.
TRUE or FALSE |
TRUE
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What are the two consensus sequences in eukaryotic mRNA?
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TATA box (Hogness box)
CAAT box |
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7-Methyl Guanosine cap
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Added to the 5' end co-transcriptionally
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What sequence is cut by an endonuclease at the 3' end prior to addition of poly-A tail?
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AAUAAA
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Poly-A polymerase
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Adds 200 As to the 3' end of an mRNA
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Splicesome
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Cuts out introns at 5' (donor) and 3' (acceptor) site
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In what structure are introns removed?
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Lariat
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Eukaryote Ribosomes
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40s + 60s = 80s
Has 5.8s 18s recognizes the 7-MG cap |
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Prokaryote Ribosomes
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30s + 50s = 70s
16s recognizes the Shine-Dalgarno sequence |
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tRNA 3' site
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Is the location where the amino acid is added
CCA are the bases at the 3' site |
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tRNA Anticodon
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Is complimentary and antiparallel to the codon in the mRNA
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Aminoacyl tRNA synthetase
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Will bind the appropriate amino acid to the tRNA with the help of ATP
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What is the start codon?
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AUG (Methionine)
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What are the stop codons?
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UAG, UGA and UAA
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Silent mutations
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Have no effect on the protein
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Missense mutation
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Alters the amino acid in a codon (could alter function)
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Nonsense mutation
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Alters the codon to a stop codon
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Frameshift mutation
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Adds or deletes 1 or 2 base pairs
Alter the reading frame |
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Sickle cell anemia
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Codon 6 of Beta-globin gene is altered
Changed glutamate to valine |
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Large segment deletions
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Due to unequal crossing over in Prophase 1
Ex. alpha thalassemia, Cri-du-chat |
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Huntington's Disease
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AD disease caused by trinucleotide repeat expansion of glutamine (CAG)
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Reaction that binds amino acid to tRNA
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tRNA + amino acid + aminoacyl-tRNA synthetase + ATP
---------> Aminoacyl-tRNA + AMP + PPi |
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Initiator tRNA in prokaryotes
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Will carry fMet
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Initiator tRNA in eukaryotes
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Will carry Met
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P site
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Where fMet-tRNAi initially binds
After formation of the first peptide bond, the P site is a binding site for the growing peptide chain |
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A site
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Binds each new incoming tRNA molecule carrying an activated amino acid
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Peptidyl transferase
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An enzyme that is part of the large subunit
Forms the peptide bond between the new amino acid and the carboxyl end of the growing polypeptide chain |
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How is eEF-2 inactivated?
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Through ADP-ribosylation by Pseudomonas and Diphtheria toxins
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Chloroamphenicol
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Inhibits peptidyl transferase
Acts on 50s Has an associated toxicity that can lead to Gray- baby syndrome and aplastic anemia |
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Erythromycin
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Inhibits elongation
Acts on 50s |
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Aminoglycoside
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Inhibits initiation
Works on 30s |
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Tetracycline
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Binds to the A site and inhibits elongation
Works on 30s |
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Gray baby syndrome
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Results from administration of chloramphenicol to babies
Drug has adverse effects because they do not have enough UDP-glucuronyl transferase (this causes buildup of drug in blood) Symptoms include: Cyanosis, Death and low blood pressure |
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Cystic Fibrosis
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Majority of cases arise from deletion of phenylalanine at the position 508 (deltaF508)
The CFTR is degraded instead of being transported to the cell membrane |
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I cell disease
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When the mannose residues on lysosomal enzymes are not phosphorylated
Symptoms include: Coarse facial features, death in first decade, clubfoot, claw-hand, growth retardation and psychomotor retardation |
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Collagen
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Composed of repeating tripeptide Gly-X-Y-Gly-X-Y
Hydroxyproline is an amino acid unique to collagen Made by fibroblasts |
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Scurvy
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Caused by deficient hydroxylation secondary to ascorbate (Vitamin C) deficiency
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Osteogenesis imperfecta
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Mutation in collagen genes
Tell-tale symptom is blue sclera |
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Ehlers-Danlos (ED) Type 4
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AD disease
Caused by mutations in the gene for type-3 collagen |
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Upstream Promoter Elements
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CCAAT box
GC-rich sequence |
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CCAAT box
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Upstream Promoter Element (around -75)
Binds transcription factor NF-1 |
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GC-rich Upstream Promoter Element
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Binds a general transcription factor SP-1
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Enhancers
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DNA binding sites for activator proteins
May be up to 1,000 base pairs away from gene |
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Zellweger syndrome
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Deficieincy of peroxisomes that causes an accumulation of very long chain fatty acids and several unusual fatty acids
Symptoms include: hepatomegly,high blood levels of Cu and Fe, and vision problems |
