MBLG1901 tutorial 11. DNA and RNA code for the amino acids through ‘codons’ – groups of 3 DNA

bound together form a codon, and each of the 3 DNA have 3 possible values – A,T,G or C. now 4^3 gives us 64 different combinations, which allows us to code for all the amino acids. Additionally, we use DNA and RNA because they can be read and replicated easily whilst proteins cannot.

2. a. No functional group is ionic in tyrosineb. No functional group is ionic in cysteinec. The side chains do not deprotonate at any pH, meaning they cannot be

considered acidic or basic – however, they can donate and receive hydrogen bonding, making them polar, but non-ionic.

3. a. Carbon based life means we are largely made out of a carbon-backbone

structure. For example, DNA and RNA have deoxyribose and ribose rings which is a carbon-based ring. Proteins used in our body are largely made out of carbons.

b. An element must be able to caternate to support biopolymer formation – that is, they must be able to bind to themselves (e.g. C and C can form a bond)

c. Carbon and silicon are candidates for this roled. Silicon forms a much stronger bond with oxygen than with itself, meaning

it would much rather form silica than an Si-Si bond. Carbon on the other hand have a similar strength carbon-oxygen and carbon-carbon bond, meaning it is much more stable.

e. On biopolymers such as DNA, there is phosphorus and oxygen. Oxygen allows DNA to form hydrogen bonds, as well as a potential place for instability (e.g. in RNA 2’ oxygen) and phosphorus allows the dNTPs to react on, as well as being a position of potential DNA weakness (target of phosphorylases). In proteins, there are oxygens as well as nitrogens. Nitrogen introduces instability and is a position for hydrolysis. Sulfur allows the formation of disulfide bridges in a reducing environment.

4. C5.

a. Yes, because the tyrosine absorbs light at 280nmb. D because it is an acidic side chainc. Cd. Ae. Nonef.

i. pH 1 – 1ii. pH 7 – 2iii. pH 13 – 1

g. i. pH 1 – 2ii. pH 7 – 4iii. pH 13 – 3

h.