Chapter 4 Flashcards

Question

What does aminoglycoside do? Examples?

Answer 1

Inhibits 30S (small prokaryotic ribosomal subunit) by bidning to Shine-Dalgarno Examples: streptomycin, gentamycin

Answer 2

Binds to 50S (large prokaryotic ribosomal subunit) and inhibits initiation phase of translation

Answer 3

**Each cycle uses 4 high energy bonds** --2 from ATP used in amino acid activation to charge tRNA and 2 from GTP **1)** Charged tRNA binds in A site **2)** peptidyl transferase (part of large subunit) forms peptide bond and bond of growing peptide to the tRNA in P site is broken and growing peptide attached to tRNA in A site **3)** translocation--ribosome moves three nucleotides --accomplished by elongation factor 2 (eEF2) in eukaryotes

Answer 4

inactivates eEF-2 through ADP-ribosylation

Answer 5

Clip adenine residue from 28S rRNA in the 60S subunit, which stops protein synthesis in eukaryotic cells

Answer 6

inhibits codon-antidon binding in 30S region of ribosome so no protein synthesis in prokaryotes

Answer 7

Innhibits peptidyl transferase

Answer 8

Bind to 50S subunit and inhibit elongation by blocking translocation

Answer 9

Binds to 50S subunit and inhibits elongation

Answer 10

3 stop codons move into A side, peptidyl transferase + release factors hydrolyzes the completed protein from the final tRNA in the P site mRNA, ribosome, tRNA, and factors can be reused for additional protein synthesis

Answer 11

several ribosomes translate message at same time found in cytoplasm or attached to RER

Answer 12

premature babies given chloramphenicol--used to fight bacterial infections, including meningitis in newborn, can trigger deadly reaction because babies don't have enough UDP\_glucuronyl transferase needed to excrete drug Drug builds up in bloodsteam and leads to: - blue lips, nail beds, skin (cyanosis) - death - low BP

Answer 13

1. primary: sequence of amino acids 2. secondary: folding of amino acid chain; reinforced by H-bonds --alpha-helix and beta-pleated sheet 3. tertiary: positionary of secondary structures in relation to each other; stabilized by weak bonds or strong, covalent disulfid bonds --globular, fibrous --heat or urea can disrupt tertiary structure to denature proteins, causing loss of function 4. quaternary: multiple subunits

Answer 14

Begin on ribosomes free is cytoplasm 1) assocated with RER: secreted proteins, proteins inserted into cell membrane, lysosomal enzymes 2) free cytoplasmic ribosomes: cytoplasmic proteins, mitochondrial proteins (encoded by nuclear genes)

Answer 15

Assist in protein folding

Answer 16

1. defective copies are covalently marked for destruction by addition of many copies of ubiquitin (with ATP) 2. polyubiquinated proteins go to proteasomes for destruction 3. proteasomes: large cytoplasmic complexes with multiple proteases that digest damaged proteins to peptides --also play role in producing antigenic peptides for presntation by class I MHC molecules

Answer 17

alpha-1 anti trypsin misfolds because mutation in gene or mutation in chaperone --inclusion bodies form in hepatocytes --proteasome is in cytoplasm so can't clear misfolded proteins

Answer 18

deletion of phenylalanine at position 508 (∆F508), which interferes with proper protein folding and post-translational processing of oligosaccharide side chains --abnormal chloride channel protein (CFTR) is degraded by cytosolic proteasome complex instead of being translocated to cell membrane

Answer 19

1) N terminal hydrophobic signal sequence --\> translation on RER a) secreted proteins or lysosomal proteins b) translate signal sequence--\>RER with hep of signal recognition particle--\>nascent protein goes in lumen and signal sequence cleaved in RER c) in transit to Golgi, proteins get oligosaccharide chains attached at serine or threoniine residues (O-linked) or asparagine residues (N-linked) 2) phosphorylation of mannose residues in oligosaccharide chains --\>enzymes goes to lysosome a) enzyme=n-acetylglucosamine 1 phosphotransferase

Answer 20

defect in mannose reside phophorylation of lysosomal enzyme (phosphotransferase)--\> lysosomal enzymes released into extracellular space--\>inflammation --inclusion bodies accumulate in cell and compromise its function (lysosomes and endosomes fuse but no enzymes)

Answer 21

\*course facial features, gingial hyperplasia, macroglossia \*craniofacial normalities, joint immobility, clubfoot, claw-hand, scoliosis \*psychomotor retardation, growth retardation \*cardiorespiratory failure, death in first deade \* bone fracture and deformities \*mitral valve defect \*secretion of active lysosomal enzymes into blood and extracellular fluid

Answer 22

glycoproteins sugars added to asparagine (N) by dilichol-P

Answer 23

co-translational: N-glycosylation in ER lumen Post-translational: O-glycosylation in Golgi

Answer 24

digest materials that cell has ingested by endocytosis contains enzymes that digest carbohydrates (glycosylases), lipids (lipases), and proteins (proteases) prominent in neutrophils and macrophages

Answer 25

lysosomal enzyme is missing so undigested substrate accumulates in cell

Answer 26

1) glycosylation: addition of oligosaccharide as proteins go through ER and Golgi 2) proteolyssi: cleaage of peptide bonds to remodel proteins and activate them (proinsulin) 3) phosphorylation: addition of phosphate by protein kinases 4) gamma carboxylation: produces Ca2+ binding sites prenylation: addition of farnesyl or geranylgeranyl lipid groups to certain membrane associated proteins

Answer 27

1) prepro-alpha chains contains hydrophobic signal sequences are made by ribosomes attached to RER 2) hydrophobic signal sequence emoved by singal peptidase in RER toform pro-alpha chains 3) some prolines and lysines are hydroxylated by prolyl- and lysyl hydroxylases --enzymes located in RER requires ascorbate (vitamin C) --Ehler-Danlos VI: defected proline hydroxylase 4) selected hydroxylysines are glycosylated 5) 3 pro-apha chains form triple helical structure (procollagen) 6) procollagen secreted from cell 7) propeptides cleaved from ends of procollagen by proteases --\> collagen (tropocollagen) 8) collagen molecules assemble into fibrils; cross-linking by lysyl oxidase (requires O2 and copper) 9) fibrils aggregate and cross-link to form collagen fibers

Answer 28

repeating tripeptide --Gly-X-Y-Gly-X-Y hydroxyproline: amino acid unique to collagen --produced by hydroxylation of prolyl resides at Y positions in procollagen chains as they go through RER

Answer 29

deficiency in ascorbate (vitamin C) --needed for prolyl and lysyl hydroxylase activity **Symptoms:** hyperelastic skin, petechiae, ecchymoses, loose teeth, bleeding gums, poor wound healing, poor bone development

Answer 30

bundles of fibers, high tensile strength --bones, skins, tendons DISEASES=osteogenesis imperfecta (easy fracturing in utero, skeletal deformities, blue sclera), Ehler-Danlos

Answer 31

thin fibrils, structural --cartilage, vitreous humor

Answer 32

thin fibrills, pliable --blood vessels, granulation tissues DISEASES: Ehlers-Danlos Type IV, Keloid formation

Answer 33

Amphorphous --basement membranes DISEASES: goodpasture syndrome, alport disease (problem with arteries) epidermolysis bullosa

Answer 34

mutations in collagen genes and lysyl hydroxylase gene **symptoms: ** hyperextensible, fragile skin, hypermobile joints, dislocations, varicose veins, ecchymoses, arterial and intestinal ruptures Ex. Type IV, vascular type --autosomal dominant disease caused by mutations in gene for type 3 procollagen --thin, translucent skin, arterial, instestinal or uterine rupture and easy bruising

Answer 35

Ehlers Danlos syndrome type IX X linked recessive mutations in gene APT7A--encodes ATP dependent copper efflux protein in intestine --copper can be absorbed into mucosal cell but not transported to blood stream deficient cross-linking secondary to functional copper deficiency (lysyl oxidase can't work) **Symptoms:** depigmented (steely) hair, arterial tortuosity and rupture, cerebral degeneration, osteoporosis, anemia

Chapter 4 Flashcards

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