Exam 1 Cell Bio Flashcards
Protein Disulfide Isomerase
catalyzes the formation and breakage of disulfide bonds
(S-S bonds in cysteine)
Chaperone proteins
Proteins that guide the folding of a newly synthesized polypeptide chain
chaperone proteins isolation chamber process
Partially folded protein inserted into chamber
Sequester in hydrophobic chamber with a chamber cap
Proteins folds correctly
Chamber cap dissociates and properly folded protein released
The Unfolded Protein Response
sensor molecules (Ire1) in the ER lumen detect the misfolded proteins
The Unfolded Protein Response Process
Translation stopped
Chaperone protein production increased
ER increases in size
Chaperones attempt refolding misfolded proteins in ER
Proteasome
Complex protein that degrades misfolded proteins in the cytoplasm
Process of Proteasome
- Ubiquitin bonds to misfolded proteins to form a polyubiquitin chain
- Proteins then targeted by polyubiquitin-site on proteasome
- Ubiquitin recycled as slightly unfolded protein fed through central cylinder
- Protein degraded into peptide chunks or amino acids
Lysosomes
Proteins created in the ER, or at least their polypeptide components
Contain many enzymes including proteases
Maintains pH 5.0 or so
Lysosome process
Proteins enters lysosome in microautophagy and encapsulated.
Low pH environment begins denaturing of proteins
Protease further breaks down protein into amino acids
apoptosis
cell death
Chromatin condenses, membrane distorts and cell collapses
mRNA Sequence
Decoded in Sets of Three Nucleotides to form amino acids
PKU (Phenylketonuria)
caused by a single nucleotide change in the gene that encodes the enzyme Phenylalanine Hydroxylase (PAH)
Buildup of phenylalanine in the brain causes neurological damage intellectual deficiencies
Treatment includes a diet low in phenylalanine
Phenylalanine Hydroxylase (PAH)
An enzyme that converts L-phenylalanine into L-tyrosine
Mutant type has a misaligned tetramerization domain
Enzymes
Catalyze covalent bond breakage or formation
Structural proteins
Provide mechanical support to cells and tissues
Transport proteins
Carry small molecules or ions
Motor proteins
Generate movement in cells and tissues
Storage proteins
Store amino acids and ions
Signal proteins
Carry extracellular signals from cell to cell
Receptor proteins
Detect Signals and transmit them to cell’s response machinery
Transcription Regulators
Bind to DNA to switch genes on and off
Special-Purpose Proteins
Highly variable
peptide bonds
Amino acids linked together N-C-C-N-C-C, etc
protein
made of amino acids linked together into a polypeptide chain
Three types of noncovalent bonds that help proteins fold
Hydrophobic forces
Hydrogen bonds
Van der Waals forces
