1.2 Proteins Flashcards
What are the features of a Basic amino acid?
Generally have an NH2 on the R group. Allows them to accept H+ and become positively charged and strongly hydrophilic.
What are the features of an Acidic amino acid?
Have a COOH on the R group. This allows them to donate a proton and become negatively charged and strongly hydrophilic.
What are the features of a Polar Amino Acid?
All have O2, N2 or S8 on their side chain. They are hydrophilic and have no charge
What are the features of a hydrophobic Amino acid?
The R group doesn’t contain OH, COOH, NH2 or SH
Uncharged and hydrophobic
What are the three secondary protein structures?
Alpha helix and Beta sheets and Turns
What does the alpha helix do?
Twists into a spiral with the R groups sticking outwards
What do the Beta Sheets do?
The R groups sit above and below the sheets. Polypeptide chains can fold back to form a turn.
Can be parallel or antiparalell
(tertiary) What are hydrophobic Interactions?
The hydrophobic R groups are repelled by water
(Tertiary) What are ionic bonds?
Occur between oppositely charged R groups
(Tertiary) What are LDFS?
Weak but collectively contribute to maintaining protein structures
(Tertiary) what are hydrogen bonds?
Occurs when an electropositive hydrogen atom is shared between two electronegative atoms
(Tertiary) what is a disulphide bridge?
Form between R groups and contains sulphur
What are Quaternary proteins?
Proteins with several connected polypeptide subunits and hells together by Tertiary interactions
What are prosthetic groups?
Additional non protein structures that are associated with the protein molecule or give it is final functionality e.g. chlorophyll
What can temperature do when it denatures a protein?
Disrupts bonds
What can pH do when it denatures a protein?
Ionic bonds between R groups are lost
Alternative RNA splicing…
Results in different exons being spliced into the mature transcripts
What are the factors that can change protein expression?
Metabolic activity of the cell
Cellular stress
Response to signaling molecules
Disease
Membranes within the cell are called
Intracellular membranes
What is the Endoplasmic Reticulum?
A network of membrane tubules continuous with the nuclear membrane
What are lysosomes?
Membrane bound organelles that contain a variety of hydrolases
What are hydrolases?
Enzyme that catalyse the cleavage of a covalent bond with water
What do vesicles do?
Transport materials between membrane compartments
What is the difference between the rough and smooth endoplasmic reticulum?
Rough has ribosomes on its cytosolic face and smooth lacks them
Two examples of Post Translational Modification?
The addition of carbohydrate groups
Proteolytic Cleavage
Cooperativity is when..
the binding of a ligand to one subunit of the protein increases the ligand affinity of the remaining subunits.
ER stands for?
Endoplasmic Reticulum
Definition of primary structure?
Order of amino acids.
A prosthetic group is?
A non protein structure that gives final functionality e.g. chlorophyll
Addition or removal of a phosphate causes…
…a reversible conformational change to the protein
Kinase catalyses…
The transfer of phosphate
Phosphatase catalyzes..
dephosphorylation
