Protein Structure
What type of bond links amino acids together?
Peptide bond
What is the energy barrier that enzymes help overcome?
Activation energy
What is metabolism?
All chemical reactions within an organism.
Where does glycolysis occur?
Cytoplasm
What type of reaction forms a peptide bond?
Dehydration synthesis
Which level of protein structure is determined directly by the sequence of amino acids?
Primary structure.
Enzymes speed up reactions without changing what key thermodynamic value?
ΔG (free energy change)
What do catabolic reactions do?
Break down molecules and release energy.
How many ATP are net produced by glycolysis per glucose molecule?
2
How is ATP used in both protein synthesis and active transport?
It provides energy for forming peptide bonds during translation and for pumping ions or molecules across membranes.
Name one interaction that stabilizes tertiary structure.
Hydrogen bonds, ionic bonds, disulfide bridges, hydrophobic interactions.
What type of reaction releases energy (ΔG < 0)?
Exergonic
What do anabolic reactions do?
Build complex molecules and require energy.
What molecule enters the citric acid cycle after pyruvate oxidation?
Acetyl-CoA
Explain how glycolysis and the citric acid cycle are connected.
Glycolysis produces pyruvate, which is converted into acetyl-CoA — the molecule that enters the citric acid cycle
What happens to a protein when it denatures?
It loses its 3D structure and function
When ATP is hydrolyzed to ADP + Pi, is energy released or required?
Released
State the first law of thermodynamics.
Energy cannot be created or destroyed, only transformed.
What is the role of oxygen in the electron transport chain?
Final electron acceptor; forms water.
Describe how the energy stored in glucose ends up in the phosphate bonds of ATP.
Glucose is oxidized during cellular respiration; electrons are transferred to NADH and FADH₂, which power the electron transport chain. The resulting proton gradient drives ATP synthase to form ATP from ADP and Pi.
What the name of proteins that help other proteins fold correctly?
Chaperones
What model describes how an enzyme changes shape slightly when binding a substrate?
Induced fit model
According to the second law of thermodynamics, what increases in every energy transfer?
Entropy (disorder)
About how many ATP molecules are produced per glucose by aerobic respiration?
~32 ATP
Why can all living organisms — even plants — be considered dependent on cellular respiration?
Because respiration provides ATP needed for all cellular work. Even photosynthetic organisms must break down sugars to release usable energy, especially when sunlight is unavailable.