22 Questions
What is the primary function of an enzyme in cellular metabolism?
To speed up the rate of a specific chemical reaction
What type of reaction is characterized by the breakdown of larger molecules into smaller ones?
Catabolic reaction
What is the term for the sum total of all chemical reactions that occur in a cell?
Metabolism
What is the characteristic of anabolic reactions in cellular metabolism?
They require energy
What is the arrangement of chemical reactions in cellular metabolism?
A combination of linear, circular, and spiral pathways
What is the characteristic of enzymes in cellular metabolism?
They are specific to a particular chemical reaction
What happens to the active site of an enzyme when a competitive inhibitor binds to it?
The substrate molecule is prevented from binding
What is the term for a pocket or cleft on the enzyme molecule where the substrate binds?
Active site
What is the effect of an inhibitor on enzyme activity?
It decreases the reaction rate
What is the term for the complex formed when an enzyme binds to its substrate?
Enzyme-substrate complex
What is the effect of a change in pH on an enzyme's activity?
It can denature the enzyme
What is the term for the original molecule that the enzyme acts on?
Substrate molecule
What is the effect of an optimum temperature on an enzyme's activity?
It increases the reaction rate
What is the term for a substance that decreases an enzyme's activity?
Inhibitor
What do green plants use to build sugar molecules during photosynthesis?
Energy from sunlight
What is the main difference between photosynthesis and cellular respiration?
The source of energy
What is produced during cellular respiration as a waste product?
Carbon dioxide
What is the primary function of sugar molecules produced during photosynthesis?
To provide energy to plants
What is the role of oxygen in cellular respiration?
To combine with food molecules
What is the relationship between plants and animals in terms of cellular metabolism?
Plants help animals, and animals help plants
Why do plants release most of the oxygen produced during photosynthesis into the air?
Because they do not need it for their own life processes
What is the primary source of energy for animals?
Food molecules
Study Notes
Cellular Metabolism
- Cells generate and store energy through photosynthesis and respiration.
- Photosynthesis: green plants manufacture sugar molecules (fructose and glucose) using energy from sunlight, carbon dioxide, and water, producing oxygen as a byproduct.
- Plants use sugar for plant structure and energy, and release excess oxygen into the air.
- Animals, including humans, obtain energy from food (plants and/or other animals) through cellular respiration, combining oxygen with food molecules to release energy.
- Cellular respiration produces carbon dioxide as a waste product, which is released into the air.
Metabolic Reactions
- Metabolism: the sum total of all chemical reactions that occur in a cell.
- Catabolic reactions (catabolism): decomposition reactions that break down larger molecules to form smaller ones, releasing energy.
- Anabolic reactions (anabolism): synthesis reactions that join smaller molecules to form larger ones, requiring energy.
Metabolic Pathways
- Metabolic pathways consist of thousands of chemical reactions, arranged in linear, circular, or spiral topologies.
- Each reaction's product is the reactant (substrate) for the next reaction.
- Enzymes catalyze every chemical reaction in metabolism, speeding up the rate of specific reactions.
Enzymes
- Enzymes are biological catalysts, typically proteins, that speed up specific chemical reactions in the cell.
- Enzymes are not destroyed during the reaction and are reused.
- A cell contains thousands of different types of enzyme molecules, each specific to a particular chemical reaction.
- Enzyme names often end in -ase.
Mode of Action of Enzymes
- Enzymes have an active site, a pocket or cleft for substrate binding, forming an enzyme-substrate complex.
- Any chemical or physical condition that affects the enzyme's three-dimensional shape can change the reaction rate.
- Optimum temperature and pH are required for enzyme activity, and denaturation can render an enzyme inactive.
Regulation of Enzyme Activity
- Inhibitors: substances that bind to enzymes and decrease their activity.
- Competitive inhibitors: compete with substrates for active site binding.
- Non-competitive inhibitors: bind to other sites on the enzyme, altering its shape and reducing activity.
This quiz covers the basics of cellular metabolism, including energy generation and storage, types of metabolic reactions, and aerobic vs anaerobic metabolism.
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