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34 Cards in this Set

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  • Back
the chemical modification of a protein after it has been translated occurs in ... and ...
rough endoplasmic reticulum (RER)
Golgi apparatus
post-translational modification does what:
1.
2.
3.
4.
1. attaches functional groups
2. change the chemical characteristics of specific amino acids
3. structural changes protein to obtain maximal function
4. a regulatory mechanism
signal peptide exists at the amino terminal of a protein and is recognized and bound by ... which in turn binds to an ... receptor within the ER membrane
signal-recognition particle
SRP
new ... may be added to individual amino acids or added directly to the peptide backbone or ... and ... terminal ends
functional groups
C-
N-
selenocysteine is sometimes called the 21st amino acid and has its own ...
tRNA
why are amino acids post-transitionally modified?
1.
2.
3.
4.
regulate activity of the protein
target or anchor the protein in membranes
enhance protein’s association with another proteins
target protein for destruction
what is glycosylation:
addition of sugar to protein forming a glycoprotein
the addition of selenium to cysteine forming selenocysteine is an example of ...
addition of functional groups
why glycosylation?
1. glycosylation makes proteins more hydrophilic
2. helps proteins bind to receptors
3. allows recognition of misfolded proteins
4. reduces proteolysis of newly formed proteins by blocking proteases
what are the 2 types of glycosylation?
1.
2.
O-glycosylation
N-glycosylation
in O-glycosylation, where does the sugar attach?
to the –OH group of serine, threonine, or tyrosine
in N-glycosylation, where does the sugar attach?
to the –NH2 group of asparagine
what is prenylation?
addition of a 15-carbon farnesyl group or a 20-carbon geranylgeranyl group to a Cys residue
what do farnesyl groups do?
anchor proteins in membranes
what are 4 common amino acid modifications?
phosphorylation
acetylation
carboxylation
oxidation
what is ubiquitination?
the adding of ubiquitin to other proteins or peptides
why ubiquitination?
label old, damaged, or misfolded proteins for destruction in a proteosome
describe clinical relevance for ubiquitin:
in diagnostics to identify abnormal accumulations of proteins
the making of disulfide bridges only occurs in ... where ... enzyme is present
only occurs in the RER
protein disulfide isomerase (PDI)
pro-proteins are ...
inactive precursor proteins that are activated by removal of polypeptides
removal of the initiation methionine residue by a specific amino peptidase is an example of
proteolytic cleavage ...
collagen makes up about ... of the dry weight of human skin
75%
Type I collagen is the most abundant protein in mammals
consists of (how many...) peptide chains interwoven into a helix, providing great tensile strength to connective tissue
three
what is the amino acid sequence pattern of collagen I ...
Gly-X-Pro
collagen synthesis requires hydroxylation of ... and ... by ...
proline
lysine
vitamin C
... is dietary deficiency in vitamin C that reduces activity of prolyl and lysyl hydroxylase
scurvy
... is a genetic mutation resulting in substitution of another amino acid for Gly that leads to improper collagen folding
osteogenesis imperfecta
... are genetic mutations in lysyl oxidase or hydroxylase
Ehlers-Danlos Syndrome
... is a genetic disorder resulting in poor absorption and distribution of copper that leads to reduced activity of copper-containing enzyme lysyl oxidase
Menkes Disease
in scurvy you lack the ability to hydroxylate ... and ... for the synthesis of collagen due to ...
proline
lysine
lack of vitamin C
what are the symptoms of scurvy:
1.
2.
3.
4.
5.
1. weakness
2. anemia
3. hemorrhage
4. bleeding gums, gingivitis
5. corkscrew hair growth

abnormal bone growth (in infants)
in ... you get common bone fractures, blue-colored sclera, malformed teeth
Osteogenesis Imperfecta
a symptom of ... is unstable, highly flexible joints, highly elastic, overly stretchable skin and eye problems
Ehlers-Danlos Syndrome
in ... the hallmarks include: developmental delays or loss of developmental milestones, hypopigmented kinky hair, severe neurodegeneration, arterial weakness, weakened bones, seizures, and low body temperature.
Menkes Disease