Chapter 4 – Metabolism, Enzymes, and Protein Synthesis

 Anabolism

builds larger molecules from smaller ones (requires energy).

Catabolism

breaks down larger molecules (releases energy).

Enzymes

biological catalysts that speed up chemical reactions by lowering activation energy.

 Factors increasing enzyme activity

higher temperature (to a point), optimal pH, substrate concentration.

Vitamins

act as coenzymes to help enzymes function properly.

 Lactase

enzyme that breaks down lactose (milk sugar).

 ATP (Adenosine Triphosphate)

main energy currency of the cell.

Cellular respiration

process of producing ATP from glucose.

Anaerobic

no oxygen (produces lactic acid, 2 ATP).

Aerobic

requires oxygen (produces 36–38 ATP).

Glycogen

storage form of glucose in liver and muscles

 DNA

double helix made of nucleotides (A, T, G, C)

DNA replication

copying DNA before cell division

Proteins

perform structural, enzymatic, and regulatory functions

Protein synthesis

transcription (DNA → mRNA) and translation (mRNA → protein).

Codon

3-base sequence on mRNA that codes for an amino acid

Anticodon

complementary sequence on tRNA

 Genetic code

universal code that determines which codons correspond to amino acids

mRNA

carries genetic code from nucleus to ribosome

 tRNA

brings amino acids to ribosome

Mutation

change in DNA sequence that can alter protein function