Lecture 9 - Cellular Respiration Flashcards
What is cellular metabolism?
the sum of all chemical reactions in the cell
What is cellular respiration? What is the point?
catabolic to release energy in glucose
- convert the energy stored in glucose into ATP
- requires complete oxidation of glucose
What are the three phases of cellular metabolism?
1) glycolysis (in the cytoplasm, anaerobic, occurs in all three domains)
2) Citric Acid Cycle (Kreb’s and in matrix of mitochondria)
3) Oxphos. (across mitochondria inner membrane)
Organisms can be _______ or _______
anaerobic, aerobic
What are the different types of anaerobes and aerobes?
- obligate anaerobe = oxygen is toxic
- aerotolerant anaerobe = does not use oxygen
- obligate aerobes = oxygen is required
- facultative anaerobes = use oxygen when available
What is redox reactions?
- cellular respiration relies heavily on energy released during redox reactions
- LEO the lion says GER
- organic carbon acts as an electron donor
- carbon is oxidized = energy released
- oxygen is the best electron acceptor because it is the most electronegative
- oxygen is the best terminal electron acceptor (TEA)
What is Glycolysis?
- conversion of glucose to pyruvate
What is the point of glycolysis?
begin the oxidation of glucose
What is the energy investment phase?
- first five reactions
- glucose is relatively stable (the addition of inorganic phosphate from ATP makes glucose more reactive)
- overall this process used two ATP
- glucose splits into two three-carbon chains G3P
What is the energy payoff phase?
- second five reactions (each occurs twice)
- produces 4 ATP/glucose and 2 NADH/glucose
- NADH is an electron carrier in catabolic reactions when it is produced it means organic carbon has been partially oxidized
- 4 ATP is produced by substrate-level phosphorylation
- NET = 2 ATP/glucose –> 2 used, 4 produced
What are mitochondria?
- site of cellular respiration
- arose from the endosymbiotic hypothesis
- inside… complete oxidation of glucose and use energy to make ATP
- structure: mito outer membrane (MOM), intermembrane space (IMS), mito inner membrane (MIM), matrix (site of Kreb’s)
What is the transition reaction?
- occurs across both MOM and MIM into the matrix
- catalyzed by pyruvate dehydrogenase
- pyruvate is oxidized, where NADH and carbon dioxide is produced
- oxidation of pyruvic acid to Acetyl CoA when pyruvates enter the mitochondria
What is the point of the Kreb’s/TCA/Citric Acid Cycle?
- complete oxidation of glucose
- carbon dioxide is released
- notes: occurs in the matrix, per glucose the Kreb’s cycle turns twice (review this!!)
What is the electron transport chain?
- a set of increasing strength of electron receptors
- strongest oxidizing agent = oxygen
- electron source = glucose
- sits across the MIM
- electrons get transferred between complexes using redox reactions
- redox reactions power pumping of H+ (active transport)
- FADH2 donates electrons at a lower energy level than NADH
- oxygen as TEA allows the electron to leave the ETC
- energy conversion: energy from electrons is converted into a [H+] gradient
What is Chemiosmosis?
- synthesis of ATP using a [H+] gradient
- if energy for [H+] gradient comes from light = photophosphorylation
- if energy comes from redox = oxidative phosphorylation
