ATP Powers Active Transport Across Membranes
Definition
Active transport
Active transport is the movement of molecules or ions across a membrane against their concentration gradient (from low to high concentration), which requires energy.
- Cells often need to move substances against their concentration gradient, from areas of low concentration to high concentration.
- This process of active transport, requires energy.
- Don’t confuse active transport with passive transport.
- Passive transport doesn’t require energy because it moves substances down their concentration gradient.
- The sodium-potassium pump is a classic example.
- It uses ATP to move sodium ions out of the cell and potassium ions into the cell, maintaining essential ion gradients for nerve impulses and muscle contractions.
ATP Powers The Synthesis of Macromolecules (Anabolism)
- Cells constantly build complex molecules like proteins, DNA, and polysaccharides.
- These anabolic reactions require energy because they are endothermic (energy-absorbing).
- Each monomer added to a growing polymer, such as a nucleotide in DNA or an amino acid in a protein, requires ATP.
Definition
Anabolic Reactions
Anabolic reactions are metabolic processes in which smaller molecules are built into larger, more complex molecules using energy.
Examples of Anabolic Processes
- DNA Replication: ATP provides energy to link nucleotides into long DNA strands.
- Protein Synthesis: During translation, ATP powers the formation of peptide bonds between amino acids.
- Polysaccharide Formation: ATP is used to assemble glucose molecules into glycogen or starch for energy storage.
