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40 Cards in this Set

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what is the chemical modification of a protein after it has been translated by a ribosome?
post-translational modification
post-translational modification occurs within the ... and ...
ER
Golgi
purposes of post-translational modification:
-extends ... of the protein by attaching to it other functional groups
-changes ... of an AA within the protein
-produces necessary ... in the protein
-controls or ... of the protein
-range of functions
-chemical nature
-structural changes
-regulates function
proteins destined for the extracellular matrix, RER, SER, Golgi, lysosomes, and peroxisomes must be threaded through the ... membrane first
RER
These nascent (newly formed) proteins begin with an N-terminal .../signal peptide (13-36 hydrophobic residues) recognized and bound by ..., which in turn binds to an ... within the ER membrane
-signal sequence
-signal recognition particle (SRP)
-SRP receptor
The protein is targeted to the RER when the SRP meets joins with the ...
SRP receptor
When the signal sequence is cleaved by a signal peptidase, it is the ... in modification
1st step
the 4 types of post-translational modifications that can occur to proteins in cells are:
-addition of ...
-addition of other ... or ...
-changing the chemical nature of ...
-major ... changes
-functional groups
-proteins or peptides
-amino acids
-structural
New functional groups may be added to individual amino acids ... the polypeptide chain, or added directly to the peptide ... and C- and N-terminal ends

An example is the addition of selenium to cysteine forming ...
-within
-backbone

-selenocysteine
post-translational modifications of AAs result in over # different forms of AAs in the body.

modification of AAs is a specific ...-mediated process
200
enzyme
purposes of modified amino acids:
-... of protein
-... or ... the proteins in membranes
-... protein's association with another proteins
-target protein for ...
-regulate activity
-target or anchor
-enhance
-destruction
there are (few/many) post-translational modifications of proteins
many
glycosylation involves the addition of a ... to a protein, forming a ...
sugar
glycoprotein
common sugars used for glycosylation are ..., galactose, fucose, mannose, ...(N-acetyl-galactosamine), ... (N-acetyl-glucosamine), and sialic acid
glucose
GaINAc
GlcNAc
The 2 types of glycosylation are ... (in which the sugar is attached to the -OH group of serine, threonine, or tyrosine), and ... (in which the sugar is attached to the -NH2 group of asparagine)
O-glycosylation
N-glycosylation
5 purposes of glycosylation:
-makes proteins more ...
-allows proteins to bind to ...
-... of proteins to different cellular locations
-allows recognition of ... proteins (targets for destruction)
-reduces ... of newly formed proteins by blocking proteases (protects from destruction)
-hydrophilic
-receptors
-targeting
-misfolded
-proteolysis
different types of glycosylation occur in different regions as the protein moves from the ... through the ...
RER
Golgi
What is this post-translational modification called?
-addition of a 15-carbon farnesyl group (can anchor proteins to membranes) or 20-carbon geranylgeranyl group (derived from cholesterol biosynthesis)
-attached to Cys residues in a thioether linkage (-C-S-C-)
-GTP binding proteins often go through this modification after translation
prenylation
One of the most common protein additions to a newly formed protein is ...

-it is used to label old, damaged, or misfolded proteins for destruction in a proteosome

-forms amide linkages with lysine residues on a protein chain

-multiple of this molecule can bind to the same protein
ubiquitin
It appears that the linkage ... and the ... linkages determines the fate of the tagged protein by ubiquitin.
positions
number of
other applications of Ubiquitin:
-can be utilized in ... of certain diseases, particularly diseases that involve abnormal accumulation of protein.
-... of diseases including Alzheimer's, parkinson's, pick's, alcoholic liver disease, and motor neuron disease
diagnostics
markers
-one common structural change in proteins is the formation of .../...
-they are covalent linkages between 2 cysteine residues, forming a cystine moiety
-only occurs in the RER, where ... and oxidizing conditions are present
disulfide bond/bridges

protein disulfide isomerase (PDI)
-the simplest form of modification through proteolytic cleavage is the removal of the initiation codon amino acid ... using a specific amino peptidase enzyme.
-inactive precursor proteins that are activated by removal of polypeptides are called ...
methionine

pro-proteins (such as the proenzymes are called zymogens)
another example of proteolytic processing is with pro-opiomelanocortin.

Following the translation and synthesis of this large protein precursor, smaller ... protein fragments are generated through proteolysis
active
Another protein that is post-translationally activated through proteolysis is ...

-in addition to proteolytic cleavage, disulfide bond formation is extremely important in the formation of active, functional ...
insulin
insulin
If the signal sequence is still attached to the protein, it has the prefix "..." attached
pre
Collogen
-fibrous protein produced by fibroblasts, muscle cells, and epithelial cells
-Type 1 collogen is the most abundant protein in ...
-consists of 3 peptide chains interwoven into a ..., providing great tensile strength to connective tissue
-... pattern (triplet repeat is vital for collagen structure and function)
mammals
helix
Gly-X-Pro
modifications of collagen occur within the ... of the cell, and includes ... of both proline and lysine residues, glycosylation of hydroxylated residues, ... bond formation, oxidative deamination and crosslinking of lysine residues, and proteolytic cleavage.
RER
hydroxylation
disulfide
hydroxylation occurs in the presence of ... (or vitamin C), therefore a diet deficient in vitamin C would lead to aberrations in collagen structure (as is the case with scurvy)
ascorbate
oxidative deamination by ... initiates collagen cross linking
-cross link formation (inter- and intra- molecular)
-increases strength, toughness
Lysyl Oxidase
vitamin C deficiency results in impaired ... of proline and lysine residues during collagen synthesis
hydroxylation
what are the 4 main diseases of disruption in collagen synthesis?
scurvy
osteogenesis imperfecta
ehlers-danlos syndrome
mankes disease
which disease is this?
-genetic mutation resulting in substitution of other amino acid for Gly --> improper collagen folding
osteogenesis imperfecta
which disease is this?
-genetic disorder resulting in poor absorption and distribution of copper --> reduced activity of copper-containing enzyme lysyl oxidase
menkes disease
which disease is this?
-genetic mutations in lysyl oxidase or hydroxylase
Ehlers-Danlos syndrome
which disease is this?
-dietary deficiency in vitamin C --> reduced activity of prolyl and lysyl hydroxlase
scurvy
which disease are these symptoms of?
weakness, anemia, hemorrhage, bleeding gums, gingivitis, corkscrew hair growth, abnormal bone growth (in infants)
scurvy
which disease is this?
-glycine mutation
-symptoms: common bone fractures (even during birth) "brittle bone disease", curved, malformed bones, blue colored sclera, malformation of teeth, autosomal dominant
osteogenesis imperfecta
which disease is this?
-mutation in Lysyl Oxidase or Hydroxylase
-symptoms: unstable, highly flexible joints, highly elastic, overly stretchable skin, eye problems
Ehlers-danlos syndrome
which disease is this?
-impaired copper transport/lysyl oxidase
-symptoms: severe delays in development (presents itself between 2-3 months), failure to thrive, kinky, colorless fragile hair ("pili torti"), neurodegeneration, arterial disease, weakened bones, seizures, low body temperature
menkes disease