Chapter 4 Review

Metabolism

• Metabolism is the collective chemical reactions that acquire, store, and release energy within cells.
• Anabolism is the building of larger molecules from smaller ones, requiring energy. It involves dehydration synthesis, where a water molecule is removed to join two smaller molecules. An example of this is joining two monosaccharides to form a disaccharide.
• Catabolism is the breakdown of larger molecules into smaller ones. This process uses hydrolysis, where a water molecule is added to break chemical bonds within a larger molecule. An example of this is breaking down sucrose (a disaccharide) into glucose and fructose (monosaccharides).

Enzymes

• Enzymes regulate the rate of metabolic reactions within a cell. They don't change during the reactions.
• Enzymes increase reaction rates by lowering the activation energy.
• A substrate is the specific molecule an enzyme acts upon and transforms into a different product.
• The active site is the region where a substrate molecule binds and undergoes a chemical reaction with a specific part of the substrate by temporarily forming an enzyme-substrate complex.

Metabolic Pathways

• A metabolic pathway is a series of enzyme-controlled reactions that work together; either for synthesis or breakdown of substances. These reactions often feed into each other.
• Cofactors are non-protein components (Often vitamins or derived from vitamins). Coenzymes are small organic cofactors essential for enzyme function.

Energy in Cells

• The primary energy source for cells is Adenosine Triphosphate (ATP).
• ATP has three phosphate groups, whereas ADP has two.

Cellular Respiration

• Aerobic respiration requires oxygen to produce energy.
• Anaerobic respiration does not require oxygen.
• Cellular respiration involves three major processes: Glycolysis, the Citric Acid Cycle, and the Electron Transport Chain.

Glycolysis

• Location: cytoplasm
• Aerobic/Anaerobic: Anaerobic
• Starting Chemicals: 6 carbon glucose molecule.
• Products: 2 pyruvic acid molecules, 2 ATP, high-energy electrons

Citric Acid Cycle

• Location: mitochondria
• Aerobic/Anaerobic: Aerobic
• Starting Chemicals: Pyruvic acid converted to Acetyl CoA.
• Products: carbon dioxide, 2 ATP, and high-energy electrons

Electron Transport Chain

• Location: mitochondria

• Aerobic/Anaerobic: Aerobic

• Starting Chemicals: NADH and FADH2

• Products: Water, ATP

• The complete oxidation of one glucose molecule produces a maximum of 38 ATP molecules.

Oxygen Debt

• Oxygen debt is the extra oxygen needed after intense exercise to restore normal metabolic processes, removing lactic acid build-up.

Genetic Information

• DNA is a double helix, made of nucleotides with adenine, guanine, cytosine, and thymine bases.
• DNA replication is the process where DNA copies itself to ensure each new cell receives the complete genetic information.
• RNA is single-stranded, using uracil instead of thymine, and its sugar is ribose rather than deoxyribose.
• A triplet is a three-base sequence in DNA/RNA that codes for an amino acid, also called a codon.

Transcription and Translation

• Transcription is the process of copying a specific DNA sequence into an mRNA molecule, which occurs in the nucleus.

• Translation is the process where the mRNA sequence dictates the assembly of an amino acid chain (protein), guided by tRNA and occurring at ribosomes.

• Three types of RNA and their functions include:

  • mRNA (messenger RNA): carries the genetic code from DNA to the ribosomes, specifying the amino acid sequence.
  • tRNA (transfer RNA): carries specific amino acids to the ribosome, matching them to the codon on the mRNA.
  • rRNA (ribosomal RNA): forms the structural component of ribosomes and catalyzes the formation of peptide bonds between amino acids.

• mRNA codons and tRNA anticodons are complementary sequences.

• Genes are segments of DNA that contain instructions for making specific proteins.

Additional Information

• The organelle where aerobic respiration happens is the Mitochondria.
• ATP's phosphate bonds hold the energy used in metabolism.
• The DNA's genetic information is stored in the nitrogenous bases.
• Anaerobic respiration happens in the cytoplasm.
• Chemical reactions can be sped up by an enzyme, called catalysis or using chemical energy. This process is called catalysis.