Chapter 10: Enzymes, Photosynthesis and Respiration Flashcards
What does metabolism mean?
The sum of all biochemical reactionsin an organism, made up of catabolic and anabolic reactions
What are anabolic reactions?
The reaction in living things that synthesise complex molecules from simple ones, they require energy to form new bonds
What are catabolic reactions?
The reaction in living things that break down complex molecules to from simple ones, they release energy from breaking bonds
What is a biochemical pathway?
They are chains of enzyme regulated chemical reactions (catabolic and anabolic) that occur in cells
What is an enzyme and what is its function?
It is a biological catalyst that increases the rate of a chemical reactionwithout being altered, by lowering the amount of energy for the reaction to start
What’s the difference between exergonic and endergonic reactions?
- Exergonic: breaks molecular bonds and releases energy
- Endergonic: forms chemical bonds and uses energy
What is activation energy and where dows the energy come from?
The minimum amount of energy requires to start a chemical reaction. The reactants absorb heat energy from their surrondings
How does an enzyme work?
The substrate molecules temporarily join to the enzymes active cite ormimg an enzyme-substrate complex, the enzyme weakens the bonds within a reaction to lower the activation energy, and the products are released from the active cite
What are the key points of the lock-and-key model and the induced-fit model, and which is more widely accepted?
- Lock-and-key: substrate fits the specific enzyme active site, which is a fixed shape
- Induced-fit (more widely accepted): when the substrate joins to the active site, the site changes shape slightly to fit the substrate exactly
What are the 4 factors that affect enzyme activity?
- Temperature
- pH
- Substrate & enzyme concentration
- Inhibitors
What is an inhibitor? Give 3 examples.
It is a substance that competes with substrates to bind to an enzyme’s active site, preventing the substrate binding to the enzyme to form a chemical reaction. Examples include:
- Toxins
- Poisons
- Antibiotics
Explain the ATP cycle
When a cell requires energy, the high energy bonds attaching the last phosphate group to the ATP is broken, releasing energy and leaving ADP. And then when energy is obtained from respiration, the extra phosphate group can be added back onto the ADP making it ATP again.
What is phosphorylation?
When a bond forms between a phosphate group and an ADP molecule, resulting in ATP
Where does the light dependent stage of photosynthesis occur?
Thylakoids
Explain the light dependent stage of photosynthesis
Chlorophyll in the thylakoid membrane absorbs light energy, and electrons in the chrorophyll molecule become energised. The energy is used to split water molecules into hydrogen ions and oxygen and form ATP. Electrons are donated to NADP to form NADPH, which is used with ATP in light independent reactions.
