Metabolism: Total of all chemical reactions in the body.
Cellular Metabolism: Refers specifically to all chemical reactions within a cell, typically occurring in pathways or cycles.
Types of Metabolic Reactions:
Anabolism: Process where small molecules are combined into larger molecules, requiring energy (ATP).
Catabolism: Process where larger molecules are broken down into smaller molecules, releasing energy.
Anabolism Functions:
Provides materials for maintenance and growth.
Requires ATP produced during catabolic processes.
Example - Dehydration Synthesis:
Smaller molecules bonded to form larger molecules;
Water (H2O) is produced.
Important for producing polysaccharides, proteins, and triglycerides.
Catabolism Functions:
Breaks down larger molecules, producing ATP.
Example - Hydrolysis:
Used to decompose carbohydrates, proteins, and lipids;
Water is utilized to split substances;
Opposite of dehydration synthesis.
All cells perform both anabolic and catabolic reactions.
Balance of catabolism and anabolism is crucial.
Enzymes:
Regulate rates of both catabolic and anabolic reactions;
Significantly increase reaction rates.
Definition: Series of enzyme-controlled reactions leading to product formation.
Each substrate is a product of the previous reaction.
Each step is catalyzed by different enzymes.
Rate-limiting Enzyme:
Regulatory enzyme that determines the rate of the entire pathway;
Usually the initial enzyme in the sequence.
Can be inhibited by the end product as a form of negative feedback.
Energy: Capacity to modify something or perform work.
Forms of Energy Include: Heat, light, sound, electrical energy, mechanical energy, chemical energy.
Principle of Energy: Energy cannot be created or destroyed, only transformed.
Cellular Respiration: Transfers energy from molecules for cellular use.
Many metabolic processes utilize chemical energy stored in ATP.
Energy is released when chemical bonds are broken.
Oxidation: Releases energy from glucose through loss of hydrogen atoms and electrons.
Enzymes reduce activation energy required for oxidation in cellular respiration.
ATP (Adenosine Triphosphate): Main energy-carrying molecule in cells.
Structure: Contains adenine, ribose (sugar), and three phosphate groups.
High-energy bonds exist between second and third phosphates; energy can be funneled into other chemical reactions.
ATP to ADP Conversion:
When ATP loses its terminal phosphate, it converts to ADP (Adenosine Diphosphate).
ADP can return to ATP through phosphorylation, which requires energy from cellular respiration.
Processes Involved:
Glycolysis (anaerobic)
Citric Acid Cycle (aerobic)
Electron Transport Chain (aerobic)
Glycolysis and the Electron Transport Chain are sequential, while the Citric Acid Cycle is a metabolic cycle.
Final Products:
Carbon dioxide and water produced during respiration alongside 40% ATP and 60% heat.
Distinction between:
Anaerobic reactions: No O2, produce less ATP.
Aerobic reactions: Require O2, yield higher ATP.
First step in glucose breakdown, occurring in the cytosol.
Process:
Consists of 10 reactions splitting glucose (6-carbon) into two 3-carbon pyruvic acid.
Generates 2 ATP molecules per glucose.
Phases of glycolysis:
Phosphorylation of glucose.
Splitting into two 3-carbon molecules.
Production of NADH, ATP, and pyruvic acid.
In the presence of O2, NADH delivers electrons to the Electron Transport Chain (ETC).
In absence of O2, lactate forms, inhibiting glycolysis and reducing ATP production.
Aerobic Pathways:
Begin with pyruvic acid entering mitochondria to form Acetyl CoA and proceed to produce more ATP.
End Products of Aerobic Processes: CO2, H2O, up to 36 ATP per glucose.
Initiated when Acetyl CoA combines with oxaloacetic acid.
Continues producing ATP, hydrogen atoms, and CO2.
Each cycle returns to oxaloacetic acid enabling repetition as long as substrates are present.
NADH and FADH2 carry hydrogen and high-energy electrons to ETC in the inner mitochondrial membrane.
Electrons are used to create a proton gradient, driving ATP synthase for ATP production.
Summary:
Glycolysis: 2 ATP.
Citric Acid Cycle: 2 ATP.
Electron Transport Chain: 28 ATP.
Carbohydrates can enter pathways for energy or be stored.
Excess glucose converts to:
Glycogen: Stored primarily in liver and muscle.
Fat: Stored in adipose tissue.
Deoxyribonucleic Acid (DNA): Stores genetic information within nucleotide sequences directing protein synthesis.
Codes for various proteins including enzymes, structural proteins, antibodies, and membrane components.
DNA Sequences: Encode instructions for constructing proteins.
Gene: Single DNA segment coding for one protein.
Genome: Complete genetic information in a cell.
Exome: Protein-coding portion of the genome.
Gene Expression: Regulation of protein production.
DNA forms a double helix structure, comprising two nucleotide chains with specific base pair connections (A-T, C-G).
Contains deoxyribose sugar, phosphate group, and nitrogenous bases.
Antiparallel Structure: Chains run in opposite directions, maintaining the double helix integrity.
Necessary for cell division, ensuring daughter cells receive identical DNA.
Replication Process:
Hydrogen bonds break, separating strands.
New nucleotides pair through DNA polymerase activity.
New sugar-phosphate backbones unite; resulting in two identical DNA strands.
Involves two key processes:
Transcription: Transfer of genetic information from DNA to mRNA.
Translation: Conversion of mRNA sequence into polypeptide chains.
A sequence of three nucleotides (codon) determines each amino acid's representation.
Differs from DNA in structure and types:
Structure: Single-stranded, contains ribose, includes uracil in place of thymine.
Types of RNA: mRNA, tRNA, and rRNA, each playing distinct functional roles in synthesis.
Occurs in the nucleus where DNA remains.
RNA polymerase facilitates complementary mRNA formation from the DNA strand.
The mRNA exits the nucleus, carrying the genetic information.
Synthesizes proteins in the cytoplasm via ribosomes:
tRNA conveys amino acids to ribosomes, supporting polypeptide formation.
Peptide bonds join amino acids until a stop codon is reached, releasing the completed protein.
Variations among human genomes play significant roles in health and appearance.
DNA repair mechanisms exist for correcting mismatches and mitigating mutation effects.
Repair Enzymes: Correct nucleotide mismatches; genetic code redundancies often protect against mutations affecting proteins.
1. Define metabolism and its types.
Metabolism: Total of all chemical reactions in the body.
Cellular Metabolism: All chemical reactions within a cell, typically occurring in pathways or cycles.
2. Differentiate between anabolism and catabolism.
Anabolism: Builds larger molecules from smaller ones, requiring energy (ATP).
Catabolism: Breaks down larger molecules into smaller ones, releasing energy.
3. What is the importance of enzymes in metabolic reactions?
Enzymes regulate the rates of anabolic and catabolic reactions and significantly increase reaction rates.
4. Explain the concept of metabolic pathways.
Series of enzyme-controlled reactions leading to product formation, where each substrate is a product of the previous reaction.
5. What are the end products of cellular respiration?
Carbon dioxide, water, ATP (40%), and heat (60%).
6. Describe the process of glycolysis.
Occurs in the cytosol; glucose (6-carbon) is split into two 3-carbon pyruvic acid, producing 2 ATP.
7. Differentiate between aerobic and anaerobic reactions.
Aerobic: Requires oxygen and yields higher ATP; Anaerobic: Does not require oxygen and produces less ATP.
8. Summarize the transcription and translation processes in protein synthesis.
Transcription: Converts DNA information to mRNA in the nucleus.
Translation: Synthesizes proteins in the cytoplasm via ribosomes where tRNA conveys amino acids.
9. What is the structure of DNA?
DNA forms a double helix with two nucleotide chains running antiparallel, contains deoxyribose sugar, phosphate group, and nitrogenous bases (A-T, C-G).
10. How do DNA repair mechanisms protect against mutations?
Repair enzymes correct mismatches, and genetic code redundancies protect against mutations affecting proteins.