Flashcards in Biochemistry - Cellular Deck (29)
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Methylation of DNA and Histone
Methylation makes DNA Mute regardless of whether its a histone or CpG Island
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Acetylation of HISTONE
Acetylation of the Histone makes DNA ACTIVE!
- Relaxes the coiling, allows for transcription
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AAs needed for Purine Synthesis
GAG
Glycine
Aspartate
Glutamate
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AAs need to pyrimidine synthesis
Aspartate
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Adenosine Deaminase Deficiency (ADA)
Purine Salvage Deficiency
SCIDS
- results in reduced lymphocyte production because of dec. DNA synthesis
Mechanism:
- No ADA means that Adenine cannot be converted back into IMP--> results in excess ATP and dATP --> negative feedback--> prevents DNA synthesis --> dec. lymphocyte count
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Lesch-Nylan Syndrome
Purine Salvage Deficiency
Defect in HGPRT (converts guanine to GMP, and Hypoxanthine to IMP)
Accumulation of uric acid
H: hyperuricemia
G: Gout
P: Pissed off
R: retarded
T: DysTonia
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DNA replication direction and enzymes
DNA pol3= synthesize the strands in eukaryotes
-Direction of DNApol3= 5'-3' direction for leading and lagging
-Direction of exonuclease activity= 3'-5'
Topoisomerase= Double and single stranded breaks to add/remove supercoils
DNA ligase: synthesized a phosphodiester bond to join the lagging strand fragments or to seal breaks due to DNA editing
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Missense mutation example
Sickle Cell
- Glutamic Acid replaced by valine
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Frameshift mutation
Duchenne muscular dystrophy
- results in dysfunctional/truncated protein
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Nucleotide Excision Repair
Disease: Xeroderma Pigmentosum (can't repair pyrimidine dimers because of lack of NER)
NER: used to repair helix-distorting lesion- resects oligonucleotides and replaces with DNA pol 3 and seals with ligase
- occurs in the G1 phase of the cell cycle
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Base Excision Repair
Base specific glycoslyase cleaves the base out and makes it apurinic/apyrimidinic
AP-endonuclease at the 5' end, lyase at the 3' end
DNA pol B and ligase fill the gap
- USED FOR SPONTAENOUS/TOXIC DEAMINATION
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DNA mismatch Repair
Newly synthesized strand is recognized and editing for mismatched nucleotides- the mismatch nucleotides are removed and the gap is filled-
- Occurs during the G2 PHASE of the cell
- Defective in HNPCC
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Non-homologous End joining (DNA repair)
Double stranded DNA repair
Brings two ends of DNA together, DNA may be lost because may not be homologous
ATAXIA TELANGIECTASIA
FACONI ANEMIA
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Start Codon
AUG (EUK)
- methionine
fMET (PROK)
- stimulates NT chemotaxis
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Stop Codon
UGA (U GO AWAY)
UAA (U ARE AWAY)
UAG (U ARE GONE)
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RNA Polymerase I, II, III
RNA pol 1: rRNA
RNA pol 2: mRNA
RNA pol 3: tRNA
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P- Bodies
Cytoplasmic bodies where the mRNA is stored, also responsible for quality control
contain: microRNA, decapping enzymes, exonucleases
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Antibodies to snRNP (anti-smith)
associated with SLE
- snRNP: associated with splicing introns
- lariat intermediate
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Antibodies to U1-RNP
mctd
mixed ct tissue disorder
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Permanent Cell
Neurons, skeletal muscle, cardiac muscle, and RBC
G0 permanently
stem cell reproduction
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Stable (quiescent cell)
When stimulated go from G0- >G1
hepatocytes, lymphocytes
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Labile
Constantly reproducing (highly mitotic)
Colon, hair, bone marrow, germ cells
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Collagen Type I
Bone, tendons, dentin, fascia, CORNEA, late wound repair
Dec prodcution in Type 1 osteogenesis imperfecta
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Collagen Type 2
Cartilage, inc hyline, vitreous body, nucleous pulposus
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Collagen Type 3
Skin, BV, fetus, uterus, and granulation tissue (early wound healing)
Ehlers-Danlos syndrome
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Collagen Type 4
BM, basal lamina, lens
Goodpastures syndrome, Alports
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Osteogenesis Imperfecta
Genetic disorder that results in brittle bones
- dec production of Type 1 collagen
SX: multiple fractures with little force, BLUE SCLERA, minimal dentin, Hearing loss, curved bones
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Menkes Diseases
X linked recessive disorder that results in loss of protein (ATP7A) necessary to absorb and transport copper --> results in loss of lsysl oxidase activity (requires copper) --> loss of collagen crosslinking
sx: brittle kinky hair, growth retardation, and hypotonia
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