Proteins Flashcards
What is the proteome
The entire set of proteins expressed by a genome
Why is the proteome much larger
As more than one protein can be produced from a single gene resulting from alternative RNA splicing
In what case are not all genes expressed as a protein
In a particular cell type
What can happen to the set of proteins expressed by a given cell type
It can vary over time and under different conditions
What factors ca affect the set of protein expressed by a given cell type
- Metabolic activity of cell
- cellular stress
- response to signalling molecules
What ratio do eukaryotic cells present in terms of size
A relatively small surface area to volume ratio
How does the small plasma membrane of the eukaryote affect its roles
As the plasma membrane is too small an area, it cannot carry out all of the vital functions carried out by membranes
What type of system do eukaryotic cells have
Eukaryotic cells have a system of internal membranes that increases the total area of membrane
What is the endoplasmic reticulum (ER)
The endoplasmic reticulum forms a network of membrane tubules continuous with the nuclear membrane
(Where lipids and proteins are synthesised)
What is the Golgi apparatus
The Golgi apparatus is a series of flattened membrane discs
Where proteins undergo post translational modification
What are lysosomes
Lysosomes are membrane bound organelles containing a variety of hydrolases that digest proteins, lipids, nucleic acids and carbohydrates
What are vesicles
Vesicles carry out the transport of materials between membrane compartments
What are proteins polymers of
Amino acid monomers
What are the four distinct stages after translation that proteins are synthesised in
- Primary structure
- Secondary structure
- Tertiary structure
- quaternary structure
What is the primary structure of a protein
The sequence in which the amino acids are synthesised into the polypeptide
What groups are attached onto amino acids
Amine group (NH3) Carboxylic acid (COOH) Hydrogen R variable group
H | H3N—C—C= O | \ OH R
What are the 5 ways R groups can differ
- size
- shape
- charge
- Hydrogen bonding capacity
- chemical reactivity
What are the 4 amino acid classes
- Acidic Carboxylic acid COOH
- Basic Amine group (NH3)
- Polar Hydroxide -OH
- Hydrophobic Hydrocarbon -CH
What charge are amino acids and the key component of acid amino acid R group
Negatively charged with key component being Carboxylic acid
What charge are basic amino acids and their key r group component
Positively charged with key component being amine group (NH2)
What is the charge of polar amino acids and their r group key component
Very slightly charged and hydrophobic with key component of hydroxyl group -OH
What are hydrophobic amino acids and their key component r group
They are non-polar with key component of hydrocarbon group -CH3
What class is a benzene ring
Hydrophobic
How are peptide bonds formed
An enzyme causes a condensation reaction between two adjacent amino acids
How is the secondary structure stabilised
Secondary structure of protein is stabilised by hydrogen bonds along the backbone of the protein strand
What are the 3 main components of the secondary structure
1) Alpha helix
2) Beta pleated sheets
3) turns
What is the alpha helix
It is a spiral with the R groups sticking outwards
R groups such as acidic,basic,polar etc
What are beta pleated sheets
It has parts of the chain running along side each other to form a corrugated sheet. R groups sit above and below the sheet