Proteins and genetics Flashcards
How is an amino acid structured?
Aminos contain: an amine group (NH2), a carboxyl group (COOH), an R-group (above the C). Hydrogen is below the C.
How are peptide bonds formed?
Condensation reactions between the carboxyl group of one amino and the amine group of another (C-N).
Describe the primary and secondary structure of proteins
PS - sequence of AAs in the polpeptide chain.
SS - the hydrogen bonds between the AAs determine whether the protein coils into an alpha helix or a beta pleated sheet.
Describe the tertiary and quaternary structure of proteins
TS - the further folding of the protein due to ionic and hydrogen bonds, disulfide bridges and hydrophobic/hydrophilic interactions, forming the final 3D structure.
QS - how the multiple polypeptide chains of some proteins are assembled, such as haemogloin.
What are the different bonds involved in the four protein structures?
PS - peptide bonds
SS - hyrogen bonds
TS - dilsulfide bridges, H bonds, ionic bonds, hydrophilic/hydrophobic interactions.
QS - dependent on the TS of the different polypeptide chains.
What are the features of Globular proteins?
- Round, compact and made up of multiple polypeptide chains.
- Coiled, hydrophilic parts of the chains are on the outside which makes them soluble (easy transport in fluids).
- Example is Haemoglobin.
What are the features of Fibrous proteins?
- Long, insoluble poplypeptide chains.
- Tightly coiled, rope-like fashion.
- Chains are held together by lots of bonds, making the proteins strong.
- Often found in supportive tissue.
- Example is Collagen.
How do enzyme-substrate complexes lower activation energy?
If two substrates need to be joined, the enzyme holds the molecules close together, reducing any repulsive forces.
In a breakdown reaction, fitting the substrates into the active site induces strain on the substrate bonds, making splitting easier.
What are the three components of a mononucleotide?
A phosphate group, a pentose sugar and a nitrogen-containing base.
What are the key differences between RNA and DNA?
RNA contains ribose and replaces thyamine with uracil.
RNA is a one-stranded polynucleotide.
What are the key differences between mRNA and tRNA?
mRNA is made in the nucleus, tRNA is found in the cytoplasm. Three adjacent mRNA bases are called a codon, the three bases on a tRNA molecule are called an anticodon.
What are two features of the genetic code?
Non-overlapping - base triplets don’t share bases, each is read separately from the preceding and the next one.
Degenerate - more possible combos of triplets than there are aminos, so one amino can be coded for by multiple triplets.
