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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

1

Acetylation of HISTONE

Acetylation of the Histone makes DNA ACTIVE!
- Relaxes the coiling, allows for transcription

2

AAs needed for Purine Synthesis

GAG
Glycine
Aspartate
Glutamate

3

AAs need to pyrimidine synthesis

Aspartate

4

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

5

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

6

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

7

Missense mutation example

Sickle Cell
- Glutamic Acid replaced by valine

8

Frameshift mutation

Duchenne muscular dystrophy
- results in dysfunctional/truncated protein

9

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

10

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

11

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

12

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

13

Start Codon

AUG (EUK)
- methionine

fMET (PROK)
- stimulates NT chemotaxis

14

Stop Codon

UGA (U GO AWAY)
UAA (U ARE AWAY)
UAG (U ARE GONE)

15

RNA Polymerase I, II, III

RNA pol 1: rRNA
RNA pol 2: mRNA
RNA pol 3: tRNA

16

P- Bodies

Cytoplasmic bodies where the mRNA is stored, also responsible for quality control
contain: microRNA, decapping enzymes, exonucleases

17

Antibodies to snRNP (anti-smith)

associated with SLE
- snRNP: associated with splicing introns
- lariat intermediate

18

Antibodies to U1-RNP

mctd
mixed ct tissue disorder

19

Permanent Cell

Neurons, skeletal muscle, cardiac muscle, and RBC
G0 permanently
stem cell reproduction

20

Stable (quiescent cell)

When stimulated go from G0- >G1
hepatocytes, lymphocytes

21

Labile

Constantly reproducing (highly mitotic)
Colon, hair, bone marrow, germ cells

22

Collagen Type I

Bone, tendons, dentin, fascia, CORNEA, late wound repair
Dec prodcution in Type 1 osteogenesis imperfecta

23

Collagen Type 2

Cartilage, inc hyline, vitreous body, nucleous pulposus

24

Collagen Type 3

Skin, BV, fetus, uterus, and granulation tissue (early wound healing)
Ehlers-Danlos syndrome

25

Collagen Type 4

BM, basal lamina, lens
Goodpastures syndrome, Alports

26

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

27

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

28

Marfan Syndrome

Defect in fibrillin- a glycoprotein that forms a sheath around the elastin