1. Targetted suppression of gene expression is achieved by:
(A) T-DNA insertion
(C) RNAi: the expression of a targeted gene is effectively knocked down/silenced by the process of RNA interference. This process selectively inactivating its corresponding mRNA by double-stranded RNA (dsRNA)
(D) Gamma ray
2. Cystic fibrosis is due to:
(A) defective chloride channel: The mutations in the CFTR gene cause Cystic fibrosis. These mutations prevent the right folding of the protein and successive degradation, resulting in lowered amounts of chloride channels in the body. The decrease in chloride channels cause mucus to build up in the body and chronic infections.
(B) defective LDL receptor
(C) High levels of HDL
(D) increased dopamine
3. The main difference between active transport and facilitated diffusion is that:
(A) in active transport, the molecules move from areas of high concentration to areas of lowconcentration
(B) carrier protein is involved only in case of active transport
(C) in active transport, energy is consumed to move molecules against a concentration gradient
(D) in active transport, only water molecules are transported
4. In competitive inhibition
(A) Km increases, V max constant: Competitive inhibitors binds to enzyme’s active sites decreasing the ligand/substrate-binding amount to enzyme. This results to an increase in the Km while maintaining the Vmax.
(B) Km decreases, Vmax constant
(C) Km constant, Vmax increases
(D) Km decreases, Vmax increases
5. The endogenous GTPase activity of G-proteins serves to:
(A) stimulate the activity of enzymes by producing energy
(B) synthesizecGMP as a second messenger
(C) synthesize GTP as an energy source
(D) hydrolyze GTP returning the G protein to a pre-stimulated level of activity: responses to signals from outside the cell ought to be reversible.