Unit 1-Protein structure Flashcards
Definition of the Genome
All of the hereditary information in the DNA/The complete set of genes and genetic information present in an organism or cell.
Definition of the Proteome
The complete set of proteins that can be expressed by the genome.
Why is the proteome bigger than the genome?
Alternative RNA splicing and post translational modification mean one gene can code for many proteins.
Definition of the transcriptome
The collection of all the RNA molecules produced by the genome. This includes mRNA, tRNA, rRNA and non-coding RNA.
How do scientists analyse which genes are being expressed in different cell types?
Reverse transcription polymerase chain reaction (RT-PCR). An enzyme called reverse transcriptase converts mRNA into a copy of DNA (cDNA) and this can then be analysed.
What four groups do all amino acids contain attached to a central carbon?
Amine, hydrogen, carboxylic acid and R group.
What are the four groups of amino acid based on the R group and give an example of each?
Polar R group e.g. Tyrosine
Non-Polar R group e.g. Valine
Positive/Basic R group e.g. Lysine
Negative/Acidic R group e.g. Aspartic Acid
Definition of Primary Structure (and bonds present)
The linear sequence of amino acids known as the polypeptide chain (peptide bonds)
Definition of Secondary Structure
This is the result of the reactions between amino acids along the length of the polypeptide chain forming hydrogen bonds along the backbone of the protein strand resulting in the folding of the chain.
Two types of Secondary Structure
Alpha Helix- this is a spiral with R groups sticking outwards.
Beta Pleated Sheet- sheets that can run parallel or antiparallel to each other with the R groups sitting above and below the sheets.
Definition of Tertiary Structure
This refers to the overall folding of the polypeptide chain and the protein’s final shape.
Explain the bonds present in tertiary structure.
Disulphide bridge- This is bonds formed between SH groups.
Hydrogen Bonds- Bonds formed between hydrogen and either oxygen, nitrogen or fluorine.
Ionic bonds- bonds formed between oppositely charged ions which are held together by electrostatic attraction.
Hydrophobic effect- This is considered to be the driving force for the folding of globular proteins. The hydrophobic effect causes hydrophobic groups to cluster together on the interior of a protein away from the surface and hydrophilic groups will predominate at the surface of a soluble protein.
Definition of Quaternary Structure
This is the number and arrangement of multiple folded protein subunits in a multi-subunit complex. The connected polypeptide subunits are linked together by bonds between R groups on the polypeptide chain.
Definition of a prosthetic group
A non-protein unit tightly bound to a protein and necessary for its function.
What forms of structure are disrupted when a protein is denatured?
Secondary and tertiary.
