Lab - 3B

Cellular respiration

• C₆H₁₂O₆ + 6O₂ → 6 CO₂ + 36 ATP + 6H₂O

• Glycolysis is anaerobic and occurs in cytoplasm

• Kreb’s cycle and ETC are aerobic

• Each step is reaction that requires specific enzyme

• As glucose is broken down, energy is released

  • Released energy is used to make ATP

  • Energy-requiring processes are fueled by splitting molecules of ATP

Carbohydrates

• Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen

Monosaccharides

• Simple sugar

• Glucose and fructose

• Glucose is preferred molecule for fuel

Disaccharides

• Simple sugars

• 2 monosaccharides linked together

• Sucrose (glucose and fructose) and maltose (glucose and glucose)

Polysaccharides

• Complex carbohydrates

• Long chains of monosaccharide monomers

• Starch (stored glucose)

• Glycogen (stored glucose in animals)

Fermentation

• Occurs after glycolysis if oxygen is not available; products of glycolysis remain in cytoplasm

• Anaerobic

• Fewer steps than aerobic respiration pathway that occurs in mitochondria

• Fewer ATP are produced per glucose molecule

ETC

• Cristae of mitochondria

• Carrier molecules transfer electrons through redox reactions

• Produces majority of ATP (32-34 ATP molecules)

• NADH and FADH₂ are electron carriers

• Membrane protein pumps pump hydrogen ions across membrane creating concentration gradient outside membrane

• Oxygen is final electron acceptor, which generates water

ATP synthase

• Generates ATP

• Hydrogen ions move down concentration gradient

• ADP is converted to ATP

ATP cycle

• Used for growth, homeostasis, manufacturing compounds and cell structures, transporting vesicles, contracting fibers, and pumping materials in and out of cell

• When energy is needed, ATP is split to ADP and phosphate group, which releases energy; energy that remains after cellular processes is released as heat

• ADP and P can rejoin to make ATP during catabolism

Structure of ATP

• Nitrogen base (adenine), ribose sugar, 3 phosphate groups

• Phosphates extend from molecule like a tail

• Bond that holds 3rd phosphate in place is high-energy phosphate bond; takes energy to form bond and breaking it releases energy

• Cells use energy from cellular respiration to attach 3rd phosphate group to form ATP from ADP

• 3rd phosphate is cleaved off to release energy when its needed

Lactic acid fermentation (animal and bacterial cells)

• Main product is lactic acid along with pyruvate and NAD⁺ (2 of everything)

• Difficult to measure in animals, so yeast is often used

Alcoholic fermentation (plant and yeast cells)

• Produces ethanol and carbon dioxide and NAD⁺ (2 of everything)

• Makes wine and beer

Gluconeogenesis

• Reverse of glycolysis

• Pyruvate to glucose to metabolic intermediates

Respirometer

• Compares fermentation of different carbs by yeasts

• Small and large test tubes

1. Small tube is filled with yeast solution to be tested

2. Large test tube is place over small one, and they are inverted together (turn upside down) introducing as little air as possible. The solution in the small tube is now contained in a closed system.

3. The size of the gas bubble on top of the small tube will change depending on the gas produced by the yeast.

• A drop of red marker fluid is placed inside graduated sidearms to aid in reading volume

• Gas bubble should be read by leading edge

Microbial growth

• Affected by atmospheric gases, temperature, pH, radiation, osmotic pressure, and availability of nutrients

• Psychrophiles (low temperatures), psychotrophs (between psychrophiles and mesophiles) mesophiles (middle temperatures), and thermophiles (high temperatures)

• Obligate aerobe: oxygen is required for metabolism; can detoxify oxygen products

• Microaerophile: small amount of oxygen required for metabolism; cannot detoxify oxygen products at reduced levels

• Facultative anaerobe: can use oxygen for metabolism but not required; can detoxify oxygen products

• Aerotolerant anaerobe: use of oxygen in metabolism not required; can detoxify oxygen products

• Obligate anaerobe: oxygen not required for metabolism; can’t detoxify oxygen products

• Toxic by-products of oxygen are superoxide ion, peroxide, and hydroxyl radicals; need catalase, superoxide dismutase, or peroxidase to degrade them

Anaerobe jar

• Inoculated plates are placed in jar and chemical envelope is activated and added; chemical catalyze reactions to remove oxygen from jar; indicator strip is used to verify conditions inside jar; indicator strip will change colors in presence of oxygen, indicating chemical reaction did not take place

Fluid thioglycollate medium (FTM)

• Liquid medium used to support growth of aerobes and anaerobes

• Contains indicator that turns pink where oxygen is present

• Contains agar to localize organisms into area of tube where oxygen conditions are most favorable for their growth

• Oxygen levels are highest at top (pink) and lowest at bottom (yellow)

  • Obligate aerobes will only grow on surface of tube

  • Obligate anaerobes will only grow on bottom of tube

  • Facultative anaerobes will grow throughout tube

  • Microaerophiles will appear as small thin band of growth near but not at top of tube

Identify type of microorganism

• S. aureus: facultative anaerobe

• M. luteus: obligate aerobe

• C. botulinum: obligate anaerobe

Identify type of microbe

• Facultative anaerobe