Cells And Proteins Flashcards
Why is having a cytoskeleton important to a cell?
Retains cell shape, keeps structure of cell and things in the correct place.
What is the cytosol and what cellular functions take place there?
Metabolism, contains cytoskeleton so allows things to move through the cell
Why do cells need lysosomes and peroxisomes?
Lysosomes- mainly degrade proteins
Peroxisomes- remove H2O2 and other toxic substances, as well as lipids
Why does a mitochondrion need a double membrane to produce energy for the cell?
To set up a Proton gradient, for the ETC. Inner membrane increases SA for ETC, in cellular respiration
Why are the functions of the Golgi apparatus required in a cell?
Needed to package proteins and add components to proteins, finishing protein synthesis. Makes lysosomes
What are the functions of the endoplasmic reticulum and what is the difference in function between “rough” and smooth endoplasmic reticulum?
Smooth has no ribos; rough does.
Smooth- processes lipids
What cellular functions does the nucleus perform ?
Stores DNA in form of chromatin. Most of the DNA in a eukaryotic cell is stored inside of it.
What do microtubules do?
Provide a structure for things to prove through or from
What is the primary structure of a protein?
Aa sequence
What’s the secondary structure of a protein?
Initial folding of pp chain
What’s the tertiary structure of a protein?
The overall shape
What are chaperones?
Proteins that help other proteins fold
How are peptide bonds between amino acids formed?
Carboxylic acid group of 1 aa reacts w amine group of another
Types of R group
Charged, non-polar aliphatic, polar uncharged (hydrophobic), aromatic
What determines amino acid properties
The R group
What determines protein structure?
R groups, environment, chaperones
What type of bond stabilises alpha helixes (and beta pleated sheets) within the secondary protein structure?
H bonds. R groups face outwards
How is the tertiary structure of a protein determined?
By the lowest energy route. Ie not -ve and -ve, or hydrophobic and hydrophilic next to each other
What’s the quaternary structure of a protein?
A complex of 1 or more pp chain
Types of tertiary protein structures
Beta pleated sheet, fibrous, globular, helix
How do we determine protein structure (shape)?
X ray cystallography, NMR
Why may proteins be globular?
For secretion
Why may proteins be elongated?
For strength
What do multi-polypeptide complexes contain?
Homomers or Heteromers. Eg haemoglobun
Describe how proteins aren’t rigid structures
Conformation is flexible and dynamic
Post translational modification (phosphorylation)
Function due to changes in conformation- eg enzyme and substrate
Protein functions (4)
Binding- ligands, receptors
Catalysis
Switching- cell signalling pathways
Structural- cytoskeleton
What’s the regulatory protein for the cell cycle’s CdK?
Cyclin
What’s CdK?
Cyclin dependent kinase. The catalytic protein in regulating the cell cycle.
Where does P53 tumour suppressor protein bind?
To DNA, to control transcription
Why do we need to know about proteins?
To target them with drugs. Eg blocking active site
Where are most proteins synthesised?
On ribosomes on the rER
What directs proteins to the correct site in the cell as part of localisation?
Sorting signals
What transports proteins from 1 compartment to another?
Transport vesicles
What do specialised cells have for carrying the secretions?
Secretory vesicles . They store hormones, enzymes,. They require an extracellular signal for exocytosis
What are the 3 aa that phosphate covalently bonds to on the side chains?
Tyrosine, serine, Theronine
