Protein Structure and Function Flashcards
What is the genome?
It is like the blueprint for life, all necessary info to make an animal is present in it’s genome.
The genome has 3% genes and is separated by regulatory molecules.
What is the transcriptome?
The transcriptome is the complement of genes that are transcribed.
All an organism’s cells will have the same genome but a different transcriptome.
What is the proteome?
The proteome is the complement of proteins in the cell.
What are the 4 levels of protein structure?
- Primary
- Secondary
- Tertiary
- Quaternary
What is the primary structure of proteins?
The amino acid sequence
What is the secondary structure of proteins?
The amino acids then fold into secondary structures such as a-helices and B-sheets.
What is the tertiary structure of proteins?
The proper folding of the protein into its final shape.
What is the quaternary structure of proteins?
Is the coming together of sub-units to form the overall functional protein.
How and why do proteins fold?
They fold due to:
-hydrphobicity/hydrofillicity
-disulfide bonds (covalent bonds that hold structures together
Folding is essential for protein function.
What is the importance of amino acid R groups fro function?
Amino acids can be polar, non polar, positively or negatively charged.
These features are important as they play a major role in protein folding and 3D structure which impacts function.
What are examples of post translational modifications impacting function?
- Glycosylation (addition of sugar chains)
- Phosphorylation (addition of phosphate group)
How does glycosylation impact protein function?
- Help it to interact with partner proteins, they are also very large so help protect the protein as enzymes cant reach it.
- Increases half life
- Important for orientation
How does phosphorylation impact protein function?
- Receptor signalling is dependant on this
- Helps in intracellular communication
- Important for control of enzyme function, some enzymes dont activte until phosphorylated.
What are the phases of assembling a protein?
The genome is transcribed to mRNA then translated to protein (large parts are not translated)
What phases can translation be split into?
- Initiation
- Elongation
- Termination
What happens in initiation?
-Initiation- tRNA carrying amino acid methionine binds to start codon of mRNA sequence.
Large ribosomal subunit binds to form complete initiation complex
What happens in elongation?
Ribosome continues to translate each codon in turn, this continues until all codons are read.
What happens in termination?
Ribosome reads stop codon, protein is released and translation complex comes apart.
How are proteins localised?
Proteins carry signal peptides that are recognised by signal receptors that guide them to their target site.
What are some mutations that alter protein function?
- Sickle cell disease
- Cancer
How is sickle cell disease called?
It is caused by a mutation in B-globin gene (one base in 1 codon), this changes an amino acid and totally changes the structure and function of cells produced.
What happens in sickle cell disease?
Red blood cells become sickle shaped, causing blockages and damaging vital organs and tissue, the sickle cells are destroyed rapidly, causing anemia.
How are some cancers caused by mutation?
Ras (a signalling molecule) is mutated, usually a mutation in codon 12, 13, 59, 61 as they are key regulatory parts of the protein.
In cancer Ras becomes hyperactive.
Why is knowledge of protein structure important?
Helps rational drug design
Why do all protein structural alterations from mutation not cause damage?
The mutation needs to be very specific to cause damage.
How can you get more than 1 protein per gene?
Proteins are decorated with molecular suffixes and prefixes
What is the start codon called?
Methionine
