Review Slides

• • Fermentation can be lactic acid fermentation or alcoholic fermentation
  • Metabolic pathways are interrelated and regulated through negative and positive feedback controls
  • Allosteric regulation of glycolysis and the citric acid cycle involves ATP and NADH as inhibitors and ADP and NAD+ as activators
• Photosynthesis and Cellular Respiration:

  • Photosynthesis has 2 parts: light reactions and carbon fixation
  • Light reactions collect light energy, oxidize H2O, and store energy as ATP and NADPH
  • Carbon fixation uses ATP and NADPH to reduce CO2
  • Cellular respiration starts with glycolysis, which breaks down glucose into pyruvate
  • Pyruvate oxidation and the citric acid cycle produce NADH and FADH2
  • The respiratory chain and ATP synthase produce ATP by a chemiosmotic mechanism
  • ATP can be generated in oxygen-poor environments through glycolysis followed by fermentation
• Bond Types:

  • Ionic bonds involve the complete transfer of electrons, forming cations and anions
  • Hydrogen bonds can form between or within molecules
  • Water is a polar molecule and can form hydrogen bonds with other polar molecules
  • Functional groups give molecules specific properties in organic chemistry
• Inputs and Outputs in Glycolysis:

  • Inputs: glucose, 2 NAD+, 2 ADP + 2Pi
  • Outputs: 2 molecules of pyruvate, 2 NADH, 2 ATP (net)
  • Glycolysis involves 10 enzyme-catalyzed reactions, with an energy investment phase and an energy payout phase
• Vesicles and Protein Channels:

  • Vesicles are present in the endomembrane system and shuttle substances between organelles like the nuclear envelope, endoplasmic reticulum, Golgi, lysosomes, and plasma membrane
  • Proteins channels are used for transporting materials across membranes
• Gluconeogenesis and Allosteric Regulation:

  • Gluconeogenesis is the synthesis of glucose from non-carbohydrate precursors
  • Allosteric regulation of glycolysis and the citric acid cycle involves ATP and NADH as inhibitors and ADP and NAD+ as activators
• Osmolarity and Tonicity:

  • Osmolarity refers to the concentration of a solution
  • Osmotic pressure is the pressure needed to prevent the movement of water across a semipermeable membrane
  • Tonicity refers to the effect of a solution on cell volume
  • Urea and NaCl can have equal osmolarity but different tonicity
• Endosymbiosis Theory:

  • The endosymbiosis theory proposes that chloroplasts and mitochondria were once free-living prokaryotic organisms that were engulfed by ancestral eukaryotic cells
  • This theory explains the presence of double membranes and circular DNA in these organelles
• Photosystem I vs. Photosystem II:

  • Photosystem I and Photosystem II are part of the light reactions in photosynthesis
  • Photosystem I absorbs light at a wavelength of 700 nm, while Photosystem II absorbs light at a wavelength of 680 nm
  • Photosystem I produces NADPH, while Photosystem II produces ATP
• Inductive vs. Deductive Reasoning:

  • Inductive reasoning is used to form a hypothesis based on specific observations
  • Deductive reasoning is used to create testable predictions assuming the hypothesis is supported
  • Inductive reasoning leads from specific observations to a generalization, while deductive reasoning goes from a generalization to specific predictions
• Structure of Nucleic Acids Includes Sugars
• Linking nucleotides forms nucleic acid
• Base Pairing in DNA is Complementary
• Nucleotides are added to the 3′ end during DNA synthesis
• Energy for the formation of the phosphodiester bond between nucleotides comes from the exergonic cleavage of the pyrophosphate from the triphosphate of the incoming nucleotide
• Chargaff’s Rule: A+G = C+T, amount of A=T and G=C in DNA
• DNA consists of 2 chains of deoxyribose-containing nucleotides with bases A, C, G and T
• The two chains are antiparallel and bases are paired in the middle
• Amino Acids
• Amino acids with electrically charged hydrophilic side chains can interact with water or with ions of opposite charge
• Hydrophilic amino acids with polar but uncharged side chains form hydrogen bonds
• Amino acids with nonpolar hydrophobic side chains can form S-S bridges with another Cys, fit in tight corners in a folded protein, or cause a kink or turn in a folded protein
• Synthesis of Proteins
• Proteins grow from N-terminus to C-terminus; each additional amino acid is joined to the C-term of the previous one
• Proteins fold into specific, reproducible shapes as a result of the amino acid composition and order
• Some proteins are made from just one polypeptide, while others are made from several
• Inhibitors
• Inhibitors are naturally occurring (and man-made) molecules that bind to enzymes and slow reaction rates
• Competitive inhibitors compete with the natural substrate for binding sites
• Noncompetitive inhibitors bind to the enzyme at a different site and alter the active site
• Reversible inhibitors bond noncovalently to the enzyme, while irreversible inhibitors covalently bond to side chains of the enzyme
• Allosteric Regulation of Enzyme Activity
• Noncovalent binding can influence (activate or inactivate) an enzyme
• Allosteric regulation involves a non-substrate molecule binding to a site other than the active site (the allosteric site)
• Allosteric regulation can activate or inactivate enzymes by changing the enzyme's shape
• Allosteric Regulation by Phosphorylation
• Covalent binding can influence (activate or inactivate) an enzyme
• Phosphorylation is a reversible process by which cells regulate many enzymes and other proteins
• Protein phosphatases remove phosphate groups from proteins
• All membranes are a fluid mosaic of lipids, proteins, and carbohydrates