Ch 9: Energy Metabolism

compounds formed in a pathway

biochemical reactions that occur in progression from beginning to end

pathways that build compounds (uses energy)

pathways that break compounds (release energy)

• the entire network of chemical processes involved in maintaining life
• encompasses all of the sequences of chemical reactions that occur in the body

oxidation of food molecules to obtain energy

• body's source of energy derived from catabolic reactions
• bonds between phosphates are high energy bonds

0.22 lbs at one time

electrons (and H+ ions) are transferred through reactions from energy-yielding compounds to oxygen

• loses one or more electrons/hydrogens
• OR
• gains one or more oxygen molecules
• highly reactive

• gains one or more electrons/hydrogens
• OR
• loses one or more oxygen molecules

• remove H+ from energy-yielding nutrients
• H+ transferred to O- to form water (H2O)
• energy transferred to ADP to generate ATP

• assist enzymes
• NAD+
• FAD

• NAD+
• made of vitamin Niacin
• becomes NADH + H+ in oxidation-reduction reactions

• FAD
• contains vitamin Riboflavin
• becomes FADH2

• direct phosphorylation
• glycolysis

• transition reaction
• citric acid cycle
• electron transport chain

• creatine phosphate
• stored in muscle
• when it splits, it donates a phosphate to ADP to make ATP

• anaerobic - 2 ATP
• aerobic - 30-32 ATP

• break down carbs to generate energy
• provide building blocks for synthesizing other compounds

• enter - glucose
• exit - 2 pyruvates

• pyruvate is converted to lactate in the absence of oxygen
• lactate is then picked up by liver to synthesize compounds used in aerobic metabolism

• synthesis of acetyl-coA
• occurs in mitochondria
• 0 ATP produced

• acetyl-coA + oxaloacetate -> citrate
• which is then converted back to oxaloacetate
• 1 ATP from each GTP = 2 ATPs

• requires oxygen + copper and iron
• electrons pass along ETC -> H+ are pumped into intermembrane space -> creates concentration gradient -> ATP synthase allows H+ back in and captures energy for production of ATP
• 32 ATP total

• vitamin B6 converts it into glucose-posphate
• which then enter glycolysis

• lipolysis = triglycerides broken into fatty acids and glycerols
• beta-oxidation = fatty acids broken into many acetyl-coA molecules
• the acetyl-coA then enters the citric acid cycle
• 7 atp/carbon from each fatty acid

• without it, CTA cycle slows down, and ATP wont be produced
• combines with acetyl-coA to form citrate

• by incomplete fatty acid oxidation
• due to inadequate insulin production

too many ketone bodies

• lack of insulin inhibits normal CHO and fat metabolism
• excess of ketones in blood
• excretion in urine also depletes Na and K
• blood becomes acidic
• can lead to coma or death, needs to be treated with insulin/fluid/electrolytes

• low carb diet ->
• not enough oxaloacetate ->
• citric acid cycle activity decreases while lipolysis continues meaning buildup of acetyl-coA ->
• acetyl-coA cant enter CTA bc no oxaloacetate ->
• so they join together and form ketone bodies

removal of amino group

forming glucose from glucogenic amino acids and other compounds

• initially body uses stored glycogen and fatty acids from adipose
• as glycogen stores decrease, lean muscle broken down to convert AA to glucose (gluconeogenesis)
• loss of protein from body tissues occurs til body adapts to using ketones for fuel