Proteins Flashcards
What are some functions of proteins?
-Enzymes to catalyze synthesis of carbohydrates in mitochondria
-Structure of an organism
-Structures that move individual cells, large cargo, or molecules within cells
-Cell-cell signalling
-Antibodies to destroy viruses and bacteria
What is the nucleus
Contains DNA, has a double membrane
What is the nucleolus
produces and assembles ribosomes and transcribes rRNA
Describe the nuclear envelope
-Non fluid
-Contains nuclear pore complexes to move material in and out (RNA, enzymes, DNA building materials)
-Double membrane
Where are ribosomes located
-In cytosol
-Attached to endoplasmic reticulum
How do amino acids bond to form polypeptides
-Formed by condensation or broken by hydrolysis
-Peptide bonds between carboxyl and amino groups of 2 amino acids
What determines amino acid properties and 3D folding shape
Side chains
What is a primary structure
Simple sequence infromation
What are the 2 secondary structures
Alpha helix
-Amino and carboxyl groups attached by peptide bonds
-Coiled by hydrogen bonds between carbonyls and carboxyls
Beta Pleated Sheet
-Parallel protein strands with hydrogen bonds between carboxyl and amino groups of adjacdent strands
What is a tertiary structure
3D shape formed by bonds between R groups
Shape formed by secondary structures and side chain interactions
Contains hydrogen bonds, van der waal interactions, covalent and ionic bonds, disulfide bonds, hydrophobic interactions
What assists with protein folding
Molecular chaperones
-Bind to hydrophobic regions and prevent incorrect folding
Chaperonins
-Molecule complexes that act as isolation chambers for a forming polypeptide
What is a quaternary structure
Assembly of polypeptide subunits that form the final functional protein
What is found in the endomembrane system
Nuclear envelope, endoplasmic reticulum, lysosomes, gilgi apparatus
How does a polypeptide enter the endoplasmic reticulum lumen
-Sequence causes ribosome to attach to ER
-It binds a signal recognition particle which then binds to a SRP receptor in the ER membrane
-The polypeptide then goes through a channel into the lumen
What is glycolysation
The addition of carbohydrate chains which helps with protein stability, folding, and cell-cell recognition
Which proteins end up in the cell membrane
porins and receptors
Which proteins exit the cell
Antibodies, hormones, enzymes
How do proteins get to their destinations
Tags allow them to be transported a certain way (often by transport vesicles) and released
What are plasmids
Circular Prokaryotic DNA containing 1 or 2 genes that replicate independently and transfer between cells
Describe Fred Neufeld experiment
Observed virulent (S) and non-virulent (R) strains of streptococcus pneumoniae, s-strain produces a smooth carbohydrate coating that masks the bacteria from the immune system and r-strain does not
Describe Frederick Griffith experiment
Heated and exploded virulent bacteria leaving macromolecules intact, mixed exploded s-strain with r-strain and it resulted in death. Therefore, r-strain transformed into virulent strain
Desccribe Avery McCarty, MacLeod experiment
Made heat killed virulent strain samples, added r-strain to each with a different enzyme that would destroy a particular molecule.
By process of elimination, mouse lived when DNA was destroyed therefore DNA is the hereditary material
What defines non-polar side chains
-Hydrophobic
-Includes hydrocarbon chains or benzene
-Ex. Alanine, valine, leucine, isoleucine, methionine, phenylalanine, tryptophan, tyrosine
What defines a polar side chain
-Hydrophilic
-Can form H-bonds
-ex. lysine, arginine, histidine, aspartic acid, glutanic acid, asparagine, glutamine, serine, threonine
What is a monogenic disease
Caused by a mistake in 1 gene (ex. cystic fibrosis)
Symptoms of cystic fibrosis
-cough
-wheezing
-thick mucus
-respiratory infections
-constipation
-salty sweat
-Impacts lungs and digestion
DIfference between healthy and CF airways
Healthy: movement, pink colour, cartilage, clear mucus, capillaries
CF: Inflammed capillaries, narrow airways, thick yellow mucus (must be removed through aspiration to prevent infection)
What causes cystic fibrosis symptoms
Incorrect unbalanced transport of ions and water across the cell membranes, resulting in maany ducts being compromised
How do ciliated cells work
Sweep in the same direction, covered by airway surface liquid, undercurrent sweeps mucus upwards. ASL must be the height of the cilia
What is the genetic cause of cystic fibrosis
-Deletion mutation in CFTR protein causing frameshift
-Protein can not fold, should be a protein channel but sometimes does not make it out of ER to function in cell membrane
What is the cystic fibrosis transmembrane conductance regulator protein
-Channel protein
-Moves chloride ions across epithelial membranes into ASL and regulates Na ions brought into cell
-Creates balanced ASL liquid height
-If built incorrectly, ER holds it back
