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• Types of nucleic acids

  • Deoxyribonucleic acid (DNA)
  • Ribonucleic acid (RNA)

  
• The genetic information found in DNA is copied and transmitted to daughter cells through DNA replication
• The DNA contained in a fertilized egg encodes the information that directs the development of an organism
• Nucleotide


  The subunits of DNA, consisting of a sugar (deoxyribose), a phosphate group, and a nitrogenous base

  
• Nitrogenous bases in DNA

  • Adenine (A)
  • Guanine (G)
  • Cytosine (C)
  • Thymine (T)

  
• Formation of phosphodiester bond

  Covalently linked by 3'→5' phosphodiester bonds
• Base pairing in DNA

  Adenine (A) is always paired with thymine (T)

  Cytosine (C) is always paired with guanine (G)

  
• The hydrogen bonds between base pairs, plus the hydrophobic interactions between the stacked bases, stabilize the structure of the double helix

  
• DNA replication


  1. Initiation

  2. Elongation

  3. Termination
• Leading strand


  The strand that has a 3'-end, where nucleotides can be easily attached

  
• Primase


  • Synthesizes short RNA primers to initiate DNA synthesis
• DNA ligase


  • Joins the Okazaki fragments on the lagging strand
• Steps in prokaryotic DNA synthesis

  1. Separation of the two complementary DNA strands

  2. Formation of the replication fork

  3. Synthesis of the leading and lagging strands
• DNA helicases and single-stranded DNA-binding proteins are responsible for maintaining the separation of the parental strands and unwinding the double helix ahead of the advancing replication fork

  
• Large-scale mutations often occur due to errors in gamete formation
• Carbohydrate Metabolism


  Metabolism of carbohydrates in organisms

  
• Welcome To Asynchronous Class
• Digestion of carbohydrates


  1. Absorption of carbohydrates

  2. Cellular Respiration

  3. Metabolism of glycogen

  
• Carbohydrate Digestion


  1. Digestion In Mouth

  2. Digestion In Stomach

  3. Digestion in small Intestine

  
• Salivary α-amylase


  Digestive enzyme that hydrolyzes starch into maltose and other small glucose polymers

  
• Food remains in the mouth only for a short time, so less than 5% of total starch is hydrolyzed in mouth
• Starch digestion sometimes continues in the stomach
• Amylase is essentially inactive as an enzyme once the pH of the medium falls below about 4.0
• Pancreatic amylase


  Secreted by the pancreas into the small intestine, optimum pH is 6.7–7.0
• After the chyme empties from the stomach into the duodenum and mixes with pancreatic juice, virtually all the carbohydrates will have become digested

  
• Dietary carbohydrate digestion


  • Salivary α-amylase
  • Pancreatic α-amylase
  • Intestinal disaccharidases

  
• Absorption of carbohydrates


  Carbohydrates are mainly absorbed as monosaccharides, about 80% is glucose, 20% is galactose and fructose

  
• Cellular respiration


  Series of chemical reactions that break down glucose to produce ATP to power reactions

  
• One molecule of glucose can produce a net of 30-32 ATP
• Stages of cellular respiration

  1. Glycolysis

  2. Citric Acid Cycle (TCA) or Kreb's Cycle

  3. Electron transport chain (Oxidative Phosphorylation)

  
• The TCA cycle and oxidative phosphorylation require oxygen, while glycolysis can occur in anaerobic conditions

  
• Glycolysis


  Glucose is broken down to form two molecules of pyruvic acid, produces 4 ATP and 2 NADH

  
• Pyruvate Oxidation


  Pyruvate is modified in a series of steps to form Acetyl-CoA in the mitochondrial matrix
• Krebs Cycle (Citric Acid cycle)

  Occurs in the mitochondria, forms carbon dioxide, ATP, NADH, and FADH2

  
• Electron Transport Chain (ETC)


  Occurs in the cristae of the mitochondria, electrons in NADH and FADH2 flow through a series of electron transport acceptors to form ATP
• Krebs Cycle (Citric Acid cycle)

  1. 3 molecules of carbon dioxide are produced from one pyruvic molecule

  2. 5 pairs of hydrogen atoms are removed by coenzymes NAD and FAD
• Krebs Cycle (Citric Acid cycle)


  Forms (per two molecules of pyruvic acid) carbon dioxide, two ATP molecules, 6 NADH molecules, and 2 FADH2 molecules
• Krebs Cycle (Citric Acid cycle)

  Oxaloacetate + acetyl-CoA + ADP + Pi + 3 NAD+ + FAD ---> CoA + ATP + 3NADH + 3H+ + FADH2 + 2CO2 + Oxaloacetate
• Electron Transport Chain (ETC)


  • Occurs in the cristae of the mitochondria where a series of cytochromes and coenzymes exist
  • The electrons in NADH and FADH2 flow through a series of electrons transport acceptors
  • The electron pass through a series of oxidation- reduction reaction, giving up energy to form ATP
  • At the end, the electrons, hydrogen ions, and free oxygen combine to form water molecules
  • During this process, ATP is made by adding inorganic phosphate to ADP
  • Most of the ATP produced during cellular respiration is made during this stage

  
• NADH & FADH2


  Contain energized electrons