Biochem week 11-12

Amplification

A single signal molecule activates an enzyme, leading to the activation of multiple downstream enzymes in a cascade.

Integration

Combination of multiple signals in signal transduction resulting in specific cellular responses like survival, division, differentiation, or death.

RTK Activation Steps Order

Ligand binds to receptor -> Receptor dimerizes -> Receptor auto-phosphorylates -> Receptor phosphorylates downstream proteins.

Mutation in RTK and Cancer

Mutation in RTK can lead to uncontrolled cell division if it locks the receptor in an active conformation, causing continuous signaling for cell division.

Processes Affecting Protein Steady-State Concentration

Initiation of RNA synthesis, mRNA processing, mRNA degradation, protein synthesis, posttranslational modification, protein targeting/transport, protein degradation.

Gene Expression in Bacteria

Constitutive (constant gene expression) and regulated (inducible or repressible gene expression).

Positive Regulation

Involves activators and increases gene expression.

Negative Regulation

Involves repressors and decreases gene expression.

Corrected Statements

Operon; negative; negative; positive.

Regulation of lac Operon

Transcription of lactose metabolism genes is repressed in the absence of lactose but derepressed in its presence.

Protein DNA-Binding Motifs

Helix-turn-helix; zinc finger; leucine zipper.