Energy and Metabolism (Enzymes and Protein Synthesis)

These flashcards cover the key vocabulary terms related to enzymes and protein synthesis as discussed in the lecture notes.

Enzyme

A protein that acts as a biological catalyst to speed up chemical reactions in the body.

Substrate

The reactants that bind to an enzyme during an enzymatically catalyzed reaction.

Isozyme

Different forms of an enzyme that catalyze the same reaction but may differ in their kinetics or inhibition.

Cofactor

A non-protein chemical compound that is required for the biological activity of a protein, usually an enzyme.

Coenzyme

An organic molecule that acts as a cofactor, often derived from vitamins.

Enzymatic Reaction Rate

The speed of an enzymatic reaction, measured by how fast products are formed or substrates are used.

End-Product Inhibition

A regulation mechanism where the final product of a metabolic pathway inhibits an earlier step to prevent overproduction.

Proenzyme (Zymogen)

An inactive precursor of an enzyme that requires a biochemical change to become an active enzyme.

Phosphorylation

The addition of a phosphate group to a molecule, often used to activate or deactivate enzymes.

Transcription

The process by which a gene's DNA sequence is copied to produce an RNA molecule.

Translation

The process of synthesizing proteins from mRNA in the ribosome.

Codon

A sequence of three nucleotides that corresponds to a specific amino acid.

Alternative Splicing

A process that enables a single gene to code for multiple proteins by including or excluding certain RNA segments.

Post-Translational Modification

The chemical modification made to a protein after its translation, which is crucial for its final functional form.

Ubiquitination

The process of tagging a protein with ubiquitin to mark it for degradation by the proteasome.

Proteasome

A complex that degrades and recycles proteins that are damaged or no longer needed by the cell.

What is tRNA?

tRNA, or transfer RNA, is a type of RNA that helps decode a messenger RNA (mRNA) sequence into a protein.

What is the function of mRNA?

mRNA, or messenger RNA, serves as a template for protein synthesis by carrying genetic information from DNA to the ribosome.

What does rRNA do?

rRNA, or ribosomal RNA, is a component of ribosomes, which are the cellular machinery that synthesizes proteins by translating mRNA.

What are the steps of transcription?

1. Initiation: RNA polymerase binds to the promoter region of DNA, unwinding the DNA strands.
   2. Elongation: RNA polymerase synthesizes a complementary RNA strand by adding nucleotides based on the DNA template.
   3. Termination: Transcription ends when RNA polymerase reaches a termination signal, releasing the newly formed RNA molecule.

What are the stages of translation?

1. Initiation: The ribosomes assemble around the mRNA, and the first tRNA carries the start codon.
   2. Elongation: tRNA molecules bring amino acids to the ribosome, where they are added to the growing polypeptide chain based on the sequence of mRNA.
   3. Termination: The process stops when a stop codon is reached, leading to the release of the completed polypeptide.

What are the steps of transcription?

1. Initiation: RNA polymerase binds to the promoter region of DNA, unwinding the DNA strands. 2. Elongation: RNA polymerase synthesizes a complementary RNA strand by adding nucleotides based on the DNA template. 3. Termination: Transcription ends when RNA polymerase reaches a termination signal, releasing the newly formed RNA molecule.

What are the stages of translation?

1. Initiation: The ribosomes assemble around the mRNA, and the first tRNA carries the start codon. 2. Elongation: tRNA molecules bring amino acids to the ribosome, where they are added to the growing polypeptide chain based on the sequence of mRNA. 3. Termination: The process stops when a stop codon is reached, leading to the release of the completed polypeptide.

What is post-translational modification?

Post-translational modification refers to the chemical modification of a protein after its translation, which can include phosphorylation, glycosylation, ubiquitination, and cleavage, affecting the protein's function, activity, stability, and localization.