A Closer Look at Cellular Respiration

1
A Closer Look at Cellular Respiration

• Chapter 9 continued

2
Steps in Aerobic Respiration

• 1. Glycolysis (yields 2 ATP)
• 2. Krebs Cycle (yields 2 ATP)
• 3. Electron Transport Chain (32 ATP)
• About 38 of glucoses energy is released.
• Remaining 62 lost as heat.
• More efficient than typical car engine.

3
Glycolysis(cytoplasm of cell)

• 2 ATP are spent to split a 6-carbon glucose
  molecule into 2 3-C molecules.
• Those molecules are converted to pyruvic acid.
• 4 ATP and 2 NADH are produced.

4
Krebs Cycle(matrix of mitochondrion)

• Pyruvic acid (3-C) loses a carbon, forming CO2 1
  NADH produced.
• Remaining 2-C join with Coenzyme A, to form
  acetyl-CoA.
• 2-C leave the acetyl-CoA to join with 4-C,
  forming citric acid.
• CO2 and NADH formed again twice, leaving a 4-C
  molecule which continues in the cycle 1 ATP, 1
  FADH2, and another NADH formed.

5
Electron Transport Chain(inner membrane of
mitochondrion)

• NADH and FADH2 lose high energy electrons to
  carrier proteins hydrogen ions pumped across
  membrane and water is formed.
• H ions diffuse back through a special membrane
  protein (ATP synthase), forming ATP.

6
Anaerobic Pathways

• Cells can still release energy from sugars
  without adequate oxygen -- fermentation.
• Starts with glycolysis (glucose split into 2
  pyruvic acids).
• Pyruvic acid ? ethanol CO2
• -OR-
• Pyruvic acid ? lactic acid
• 2 ATP released by fermentation.

7
Glucose, Glucose http//www.science-groove.org/
Now/Glucose.mp3

• Glucose -- ah, sugar sugar --You are my favorite
  fuelFrom the blood-borne substrate pool.Glucose
  -- monosaccharide sugar --You're sweeter than a
  woman's kiss'Cause I need you for glycolysis.
• I just can't believe the way my muscles take you
  in.(For you, they'll open the door.)All it
  takes is a little bit of insulin(To upregulate
  GLUT4).

8

• Ah, glucose -- ah, sugar sugar --You help me
  make ATPWhen my predators are chasing me.Ah,
  glucose -- you're an aldehyde sugar,And you're
  sweeter than a woman's kiss'Cause I need you for
  glycolysis.
• I just can't believe the way my muscles break you
  down.(My glycogen is almost gone.)A few more
  seconds and I'll be rigor mortis-bound.(Acidosis
  done me wrong.)

9

• Your sweet is turning sour, baby.I'm losing all
  my power, baby.I'm gonna make your muscles
  ache.No, no, no!I'm swimming in lactate,
  baby.Yes, I'm swimming in lactate, baby.Now I'm
  drowning in lactate, baby.I'm gonna make your
  muscles ache.No, no, no!I'm drowning in
  lactate, baby.

10

• Ah, glucose -- ah, sugar sugar --I used you up
  and you left me flatNow I'll have to get my
  kicks from fat.Oh, glucose, glucose, sugar,
  sugar,The honeymoon is over now.