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80 Cards in this Set
- Front
- Back
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What type of bond is formed between amino acids?
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peptide bond
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What is an important element in the side chain of methionine?
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Sulfur
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What is the important characteristic of the side chain of a tyrosine?
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it contains a phenol group
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in what direction are proteins synthesized?
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they are synthesized in the amino to carboxy direction
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What are the two sites of a ribosome?
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P site and A site
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What does P site stand for?
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it is the peptide site
this is where the peptide is held |
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What does A site stand for?
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it is the accceptor site is where the incoming tRNA with it's amino acid would bind to
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What initiates translation of mRNA?
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the small ribosomal subunit must recognize the 5' methyl cap in the eukaryote or the shine dalgamo sequence in the prokaryote
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What is the name of the small ribosomal subunit that recognizes the shine dalgamo sequence?
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16S subunit
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Which ribosomal site does the initial methionine bind to?
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the P site
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What energy is used in the initiation of translation?
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GTP, not ATP, connects the large ribosomal subunit to the small ribosomal subunit along with the mRNA
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What are the three steps of elongation?
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1. aminoacyl-tRNA binds to A site
2. peptide Bond Forms 3. Translocation of ribosome to next codon |
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What are the needed elements for the Aminoacyl-tRNA binding to the A site?
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GTP
EF's in prokaryotes eEF's in eukaryotes |
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What are the needed elements for the peptide bond formation between the amino acid in the A and p site?
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peptidyl transferase in large subunit
Uses the 2 ATP used when the aminoacyl-tRNA was activated by placing an amino acid at the 3' end acceptor arm of the tRNA |
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What are the needed elements for the translocation of ribosome along RNA?
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GTP
EF's in prokaryotes eEF's in eukaryotes |
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What are the stop codons?
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UAG
UGA UAA |
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What is the elongation factor in eucharyotes which is needed for the translocation of ribosome along the mRNA?
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eEF-2
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Why is eEF-@ significant
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it is needed for the transloation of ribosomes during translation
pseudomonas and diphtheria have toxins which are able to inhibit eEF-2 by ADP rebosylation of eEF-2, thus inhibiting synthesis of proteins |
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What is the form of energy used in translation?
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GTP
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How many high energy bonds are used for each added amino acid to the chain?
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4 high energy bonds
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what is a polysome?
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aka - polyribosome
this is when multiple ribosomes are reading a single strand of RNA at the same time |
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What types of antibiotics inhibit the 30S subunit of prokaryotic ribosomes?
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aminoglycosides and tetracyclins
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How do aminoglycosides work?
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they inhibit the initiation of translation by binding the 30S subunit in the in the initiation complex, and NOT ALLOWING THE BINDING THE THE INITIAL tRNA to the P SITE
they also kink, or distort, the mRNA in prokaryotes to where the genetic code is unreadable |
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What are the side effects of aminoglycosides?
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nephro and oto-toxicity
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What is the mechanism of tetracyclins?
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They bind in the A site of ribosomes, thus preventing elongation by preventing the binding of the next aminoacyl-tRNA
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How do you recognize a tetracyclin drug by name?
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they all end in -cyclin
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In what types of infections are tetracyclins expecially used?
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chlamydia or rickettsia
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What are the side effects of tetracyclins?
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fairly minimal...they cause kilation, which is the discoloring of bone and teeth, and thus tetracyclins are not given to pregnant mother or children
And if a patient takes expired tetracyclins they can cause symptoms of renal failure known as a fanconi (Sp?) like syndroe |
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Waht are the inhibits or the 50S subunit of ribosomes?
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chloramphenical
macrolides clindomycin |
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What is the mechanism of chloramphenical?
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it binds to the 50S subunit and inhibits the peptidyl transferase enzyme
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For what disease is chloramphinicol used for?
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meningitis caused by h. Influenzae
bacause soluble through the blood brain barrier |
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What are the two point that chloramphenical is famous for?
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The is associated with grey baby syndrome
and aplastic anemia |
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What is the mechanism of action of macrolides and clindomycin?
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inhibits the translocation of ribosomes
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What are macrolides regularily used against?
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mycobacterium
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What type of diseases is clindomycin commonly used against?
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bone infection
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What is one main side effect of clindomycin use?
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Clostridium difficil
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What is the primary structure of the proteins?
secondary? tertiary? quaternary? |
primary = actual amino acid sequence
secondary = folding of amino acids into ALPHA HELIX or BETA PLEATED SHEATS tertiary = this is the way that the alpha helixes and beta pleated sheets arrange themselves in 3D. quaternary = refers to multi-subunit proteins, such as RNA polymerase of prokaryotes and hemoglobin |
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what type of bonds form the quaternary structure?
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disulfide
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What is the first characteristic of proteins that will be targeted (destined for somewhere other than the cytoplasm)?
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Their N-terminus will be very hydrophobic. this is known as a SIGNAL SEQUENCE.
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What is the first step in targeting of proteins?
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Due to the hydrophobic signal sequence the ribosome will hooked by SIGNAL RECOGNITION PARTICEL (SRP) onto the membrane of the ER
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What does this ribosomal binging to the ER by signal recognition particle (SPR) cause?
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This is what forms the RER.
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What happens to the protein after the ribosome is bound to the ER?
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The signal sequence is removed by SIGNAL PEPTIDASE
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what happens to the proteins after the signal sequence has been recomed by signal peptidase?
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The proteins are glycosylated in the ER and continues in the golgi
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Where do the glucose molecule bind to the protein?
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Glycosylation occurs on the N (nitrogen of key amino acids) of key amino acids
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What molecule of glycosylation require?
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Dolichol-P
(Dolichol-Phosphate) |
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Where does Dolichol-Phosphate come from?
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it is an intermediate of cholesterol metabolism
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How are newly synthesized proteins packaged into lysosomes?
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After the protein which started with the N terminus hydrophobic region has been gylcosylated in the ER and golgi, in the golgi some of the sugars will be phosphorylated.
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Which sugars are phosphorylated in the golgi, thus tagging the protein to be destined to the lysosome?
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mannose
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What enzyme in the golgi phosphorylates the mannose sugars on the new protein?
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phosphotransferase
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What disease results from a lack of phosphotransferase?
What is the mechanism? |
I cell disease
Without the hydrolysing enzymes in the golgi apparatus, debri is not broken down, and thus inclusion (hence I cell) bodies build up. These hydrolytic enzymes are also free in the to do damage to the cell |
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What does gamma-carboxylation do?
Which amino acid does it work on? |
This is the addition of an extra carboxyl group on glutamate amino acids
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What is the result of gamma-carboxylation?
Why is this important? |
produces Ca2+ binding sites
Calcium is an important modulating factor in systems such as clotting factors |
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Which clotting factors require gamma carboxylation and therefore Ca++ bonding?
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2,7,9,10
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What is the mechanism of warfarin?
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it inhibits the gamma-carboxylation of glutimates in factors 2,7,9, and 10
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What is prenylation?
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it is the addition of turpins to the protein to give it the ability to anchor inself within the membrane
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What is the smallest amino acid?
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glycine
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What is the significance of glycine in collogen?
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it is every third amino acid
it form a very tight helix for collogen |
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Besides glycine, what are two other main amino acids in collogen?
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Proline and Lysine
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Why ar eproline and lysine important in collogen?
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They are hydroxylated in the ER by HYDROXYLASES
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What is a co-factor for hydroxylases?
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Vitamin C
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What is the result of a lack of vitamin C?
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No Vitamin C...No hydroxylation of proline or lysine...no hydroxylation of proline and lysine in collogen.....breakdown of collogen...THIS IS THE DISEASE KNOWN AS SCURVY
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What happens to collogen after the proline and lysine has been hydrolysed?
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it is glycosylated
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What happens after the collogen has been glycosylated?
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three pro-alpha chains will wrap together to form a triple helix
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What happens to the triple helix?
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it is finally secreted form the RER and the peptide ends are cleaved to form (mature)COLLAGEN, ALSO KNOWN AS TROPOCOLLAGEN
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What happens after the mature collogen is formed?
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it is assembled into fibrils (large fibers of collogen)
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What are these fibrils (bundles of collagen) stabilized by?
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Lysyl oxidase
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What is the co-factor for lysyl oxidase?
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Cu+
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Which enzymes in the production of collogen require co-factors?
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hydroxylases = require Vitamin C for hydroxylation of proline and lysine
extracellular lysyl oxidase = requires copper to stabilize the fibrils of collogen |
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What are two diseases in which there is a dificiency in copper?
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menkes disease
wilson's disease |
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Which enzyme needs copper as a cofacter?
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lysyl oxidase
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What is the mechanism for menkes disease?
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there is a deficit in an efflux protein that is found in the GI epithelial cells. This deficient protein is necessary for copper to be absorbed in our body.
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Why does menkes disease present with steely hair?
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tyrosinase is another enzyme that requires copper as a cofactor. tyrosinase is an enzyme that produces melanin.
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What does tyrosinase deficiency itself result in?
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albinism
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What is osteogenesis imperfecta due to?
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mutations in collagen genes that are autosomal dominant
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What is pathomneumonic for osteogenesis imperfecta?
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blue sclera
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What is ehler-danlos syndromes due to?
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mutations in collagen genes
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Where is the mutation is ehlers-danlos type 9?
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lysine hydroxylase
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What does Ehlers Danlos type 4 have a problem making?
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collagen type III - found in skin, blood vessels and GI walls because it is strong but very flexible.
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What is one major cause of death in ehlers-danlos patients?
what are they famous for? |
they are extremely flexible but can rupture their aorta very easily
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What is required placing of proteins into the lysosomes.
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phosphorylation of mannose residues
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