Topic 2 - Metabolism, Enzymes, Cell Respiration Flashcards
(40 cards)
1
Q
Define Metabolism
A
- Refers to all the chemical reactions which occur in cells which keep organisms alive
- Metabolism maintains the balance between energy use and energy release (catabolism/anabolism)
2
Q
Types of Metabolism
A
Catabolism:
- Breaks down large molecules into smaller units
- Releases energy (e.g. digestion)
Anabolism:
- Builds up molecules into larger ones
- Requires energy (e.g. protein synthesis
3
Q
What are the Nutrient Groups needed for metabolism
A
- These are the substances needed for growth, repair, and metabolism
- The six groups include: Water, minerals, vitamins, proteins, carbohydrates, and lipids.
4
Q
What are organic compounds
A
- Compounds which contain carbon chains and may include hydrogen, oxygen, nitrogen, and sulfur
5
Q
Carbohydrates - Function, Structure, and Types
A
Function:
- Used in cellular respiration to release energy
- Complex carbohydrates, such as starch, are broken down into simple sugars
Structure:
- Composed of carbon, hydrogen, and oxygen
- Hydrogen atoms are double the oxygen atoms.
Types:
Monosaccharides (Simple Sugars):
- Glucose, fructose, galactose
Disaccharides (two simple sugars combined):
- Sucrose, maltose, lactose
Polysaccharides (Complex Carbohydrates)
- Made up of simple sugars linked together
- e.g. Glycogen, cellulose, starch
- Function: Energy storage and structural support
6
Q
Lipids and Fats - Structure, Function, and Examples
A
Structure:
- One glycerol + one to three fatty acid molecules
- Triglycerides (main fat in the body) contain glycerol + three fatty acids.
Function:
- Energy storage (broken down into fatty acids and glycerol)
- Glycerol enters cellular respiration like glucose to release energy.
Examples:
- Phospholipids - Cell Membrane.
7
Q
Proteins - Definition, Function
A
Definition:
- Organic compounds made up of amino acids.
Function:
- Enzymes (Control chemical reactions in metabolism)
- Can serve as an energy source is carbohydrates and lipids are unavailable.
8
Q
Amino Acids - Definition, Peptide Bonds, Protein Chains
A
Definition:
- Molecules that contain an amino group, and a carboxyl group. There are 20 different amino acids found in proteins.
- They make up proteins
Peptide Bonds:
- Form when 2 amino acids join, releasing a water molecules (condensation reaction).
Protein Chains:
- Proteins consists of 100+ amino acids.
- Each protein has a characteristic shape due to the folding of the chain
Dipeptides: Two amino acids linked together.
Polypeptides: More than 10/many amino acids linked together
9
Q
Proteins - Shape
A
Folding pattern - determines their function.
10
Q
Nucleic Acids - Definition and Types
A
Definition:
- Organic compounds that store and transmit genetic information.
Types:
DNA (Deoxyribonucleic Acid):
- Consist of two chains of nucleotides
- Contains deoxyribose sugar
- Store inherited genetic information in the nucleus
RNA (Ribonucleic Acid):
- Single-stranded nucleotide chain
- Carries genetic information from DNA to ribosomes for protein production
11
Q
What are Inorganic Compounds
A
- Compounds which do not have a carbon chain
- Examples: Water, minerals, vitamins
12
Q
What are the Functions of Inorganic Compounds
A
Water: Essential for metabolism
Minerals: Can be part of enzymes or act as cofactors. Some contribute to ATP production.
Vitamins: Function as coenzymes, aiding chemical reactions in metabolism
13
Q
What are Monomoers
A
A monomer is a small molecule that can bind to other similar molecules to form a polymer through chemical reactions.
- Building blocks of macromolecules, like carbs, proteins, nucleic acids, and lipids
14
Q
Activation Energy
A
AE: The minimum amount of energy required for a chemical reaction to occur.
- Reacting particles must collide with sufficient energy to break bonds
- Higher temperature increases the number of particles with enough energy to react.
15
Q
What are catalysts
A
- A substance that lowers activation energy, making reactions happen faster.
They are not consumed in the reaction, meaning they can be reused.
16
Q
What are Enzymes
A
- Biological catalysts that speed up chemical reactions in living organisms.
- Allow reactions to occur quickly at body temperature.
- Without enzymes, reactions in the body would be too slow to sustain life.
17
Q
How do enzymes work?
A
- Enzymes are specific to one reaction, acting on a molecule called the substrate.
- The active site of the enzyme binds to the substrate, forming an enzyme-substrate complex.
18
Q
The Lock and Key Model of Enzyme Action
A
- The enzyme’s active site has a fixed shape, complementary to the substrate.
- The substrate fits perfectly into the enzyme’s active site.
Once the reaction occurs:
- The substrate is converted into products.
- The enzyme remains unchanged.
19
Q
Induced-Fit Model of Enzyme Action
A
- The active site is flexible and changes shape slightly when binding to a substance.
- This ensures a better fit and helps the enzyme perform the reaction more efficiently.
- Once the reaction is complete: The enzyme returns to its original shape.
20
Q
Key Differences Between Enzyme Models
A
Lock and Key:
- Fixed and doesn’t change
- Perfect Fit
- Rigid Structure
- Less accepted due to rigidity
Induced-Fit Model:
- Adjusts to fit substrate
- Binding causes shape change
- More dynamic
- More widely accepted, as it explains enzyme flexibility and binding of similar but not identical substrates
21
Q
Factors Affecting Enzyme Activity and Reaction Rate
A
1) Enzyme Concentration
- Increasing enzyme concentration speeds up the reaction (more enzymes available to act on substrates).
- If substrate is limited, adding more enzymes won’t increase the reaction rate.
2) Substrate Concentration
- More substrate = increased reaction rate (more enzyme-substrate complexes form).
- Once enzymes are saturated, increasing substrate won’t speed up the reaction.
- Reaction products must be removed to maintain efficiency.
3) Temperature
- Higher temperature → Faster reaction rate (particles collide more often).
- Optimal temperature: 30-40°C in humans (enzymes work best).
- Above 45-50°C, enzymes denature (lose shape and function).
4) pH Levels
- Each enzyme has an optimal pH for maximum activity.
- Deviations from this reduce enzyme activity by altering the active site shape.
5) Cofactors and Coenzymes
- Cofactors: Non-protein molecules or ions that help enzymes function.
- Coenzymes: Organic cofactors (e.g., vitamins) that assist enzymes in catalysis.
6) Enzyme Inhibitors
- Inhibitors slow or stop enzyme activity.
- Types of Inhibitors: Some are used in drugs (e.g., penicillin stops bacterial enzymes). Cells use inhibitors to regulate reactions and control product amounts.
22
Q
Active Site Definition
A
The region where the substrate binds to and undergoes a chemical reaction
23
Q
Cellular Respiration - Definition, Energy Sources, Equation, Key Points
A
Definition:
- Cellular respiration is the process by which organic molecules, taken in as food, are broken down in the cells to release energy for the cell’s activities.
- The process occurs in every cell in the body to supply each cell with the energy it needs in the form of ATP and heat.
Energy Sources:
- Cellular respiration can release energy from:
- Glucose (main energy source)
- Amino acids
- Fatty acids Glycerol
Equation:
- C6H12O6+6O2→6CO2+6H2O+Energy (ATP and heat)
Key Points:
- This summary makes respiration look like a simple reaction, but the breakdown of glucose to carbon dioxide and water involves more than 20 separate reactions, occurring in a series.
- At each step, an intermediate compound is formed, and each step is catalyzed by a different enzyme.
- Small amounts of energy are released gradually, ensuring controlled energy release rather than a sudden burst.
24
Q
Energy From Cellular Respiration - Elaboration
A
- In the breakdown of glucose to carbon dioxide and water, about 60% of the energy is released as heat
- Cells cannot utilize heat energy, but it helps maintain constant body temperature.
- Heat is continuously lost to the environment, so a constant heat supply is needed to maintain body temperature.
- The remaining energy from cellular respiration is used to form adenosine triphosphate (ATP).
25
What is ATP
ATP (Adenosine Triphosphate) acts as an energy carrier, transferring energy between cellular respiration and cellular processes that require energy.
- Primary energy currency of the cell
26
ATP Structure
Composed of:
- Adenosine (made of the nucleic acid base adenine and the sugar ribose).
- Three phosphate groups.
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How ATP Stores and Releases Energy
- ATP Formation: ATP is formed when an inorganic phosphate group is joined to a molecule of adenosine diphosphate (ADP).
- High-Energy Bonds: The phosphate groups in ATP are joined by high-energy chemical bonds. Some energy from cellular respiration is stored in the bond between ADP and the third phosphate group.
- ATP Breakdown for Energy Release: The bond between the third phosphate group and ADP is easily broken, releasing energy when needed. This energy is then used for cellular processes that require energy.
- ATP Recycling: After ATP is broken down into ADP + Pi, it can be reused to store more energy from cellular respiration.
28
What is Glycolysis
The first phase in the breakdown of glucose does not require oxygen.
This process is called glycolysis, meaning ‘splitting glucose’.
A glucose molecule is broken down into two molecules of pyruvate in a series of 10 steps.
Sometimes, this molecule is called pyruvic acid, though they slightly differ in structure.
29
What is Anaerobic Respiration
- If no oxygen is available, pyruvate undergoes fermentation, producing lactic acid.
- This is called anaerobic respiration, meaning respiration without oxygen.
- No additional ATP is produced beyond glycolysis, but it allows cells to continue producing energy in oxygen-limited conditions.
-The enzymes for anaerobic respiration are found in the cytosol, so glycolysis and fermentation occur in the cytoplasm.
30
Anaerobic Respiration in Relation to Exercise
- Anaerobic respiration becomes essential during intense exercise, when oxygen supply is insufficient.
- It provides extra energy for muscle contractions, though it results in lactic acid buildup, leading to muscle fatigue.
31
Lactic Acids and Oxygen Debt in Anaerobic Respiration
- Lactic acid is transported to the liver, where it is converted back into glucose when oxygen becomes available.
- This process requires extra oxygen, known as oxygen debt.
- Heavy breathing after exercise helps repay this oxygen debt and remove excess lactic acid.
32
Aerobic Respiration Definition
- Respiration with oxygen
- Complete breakdown of glucose to carbon dioxide and water requires oxygen.
- Aerobic respiration occurs in the mitochondria and produces significantly more ATP than anaerobic respiration.
33
Stages of Aerobic Respiration
**1) Pyruvate to Acetyl
Coenzyme A (Acetyl CoA)**
- Pyruvate is converted into Acetyl CoA by removing one carbon dioxide molecule.
- This step occurs in the mitochondria and prepares the molecule for further breakdown.
**2) Citric Acid Cycle (Krebs Cycle)**
- Acetyl CoA enters the citric acid cycle (Krebs cycle).
- Carbon atoms from Acetyl CoA are released as carbon dioxide.
- Produces 2 ATP per glucose molecule.
**3) Electron Transport Chain (ETC)**
- This is the final stage of cellular respiration and requires oxygen.
- Electrons are passed along a series of molecules, eventually combining with oxygen to form water.
- Generates between 26-34 ATP molecules per glucose.
34
ATP Yield - Definition
ATP Produced
**Theoretical Maximum ATP Production:**
Glycolysis → 2 ATP
Krebs Cycle → 2 ATP
Electron Transport Chain → 26-34 ATP
Total: Up to 38 ATP per glucose molecule
Actual ATP Yield:
Often lower due to energy losses.
35
Energy Use by the Cells
Cells need energy stored in ATP for a variety of processes.
Only 40% of the energy from cellular respiration is converted into ATP.
The remaining 60% is lost as heat, requiring continuous food intake to replenish energy.
36
Catabolic and Anabolic Reactions
- Cellular respiration is a catabolic process (breaking down large molecules to release energy).
- ATP transfers energy to drive anabolic reactions (building large molecules like glycogen and proteins).
37
Formation of ATP
ATP is formed when a phosphate (Pi) is added to ADP in cellular respiration.
This stores energy in a high-energy bond.
38
High-Energy Phosphate Bonds - ATP
- ATP has three phosphate groups held together by high-energy bonds.
- The third phosphate bond is easiest to break.
- Breaking this bond releases energy for cellular processes.
39
Energy Release and Recycling - ATP
- When ATP is broken down into ADP + Pi, energy is released.
- ADP can be recycled by adding another phosphate group
40
Cellular Functions of ATP
Provides energy for:
Muscle contractions
Active transport Biosynthesis (building proteins, lipids, etc.)
