Lecture 11 Flashcards
what are the two mechanisms that provide ATP to certain types of cells without relying on oxygen as a final electron acceptor in ETC?
1) anaerobic respiration
2) fermentation
what are the two types of anaerobes?
1) obligate anaerobes
2) facultative anaerobes
what are obligate anaerobes?
- organisms that can only live in anaerobic conditions
- oxygen is toxic to these organisms
- they are certain microorganisms ( i.e. archaea and bacteria ) that live in stagant ponds or deep soil
- these organisms rely on ATP from glycolysis and the regeneration of NAD+ through fermentation or anaerobic respiration
what are facultative anaerobes?
- organisms + cells that can thrive in both anaerobic ( no oxygen ) and aerobic ( oxygen present ) conditions
- O2 present = aerobic cellular respiration
- O2 absent = fermentation
- yeats and bacteria can swtich between aerobic and anaerobic metabolisms
- animal muscle cells also fit this definiton
what do both fermentation and anaerobic regulation have to do inorder for glycolysis to continue?
they must provide a means of recycling NAD+
NADH must be oxidized to replenish NAD+
what is one main difference between anaerobic and aerobic respiration?
other than oxygen present or absent
in anaerobic respiration the amount of ATP made is less than aerobic respiration
the final electron acceptors are not as electronegative as oxygen
what are the steps to anaerobic respiration?
1) sugars are oxidized during glycolysis, producing NADH. This NADH carriers electrons ( is an electron carrier ) to the ETC in the mitochondria
2) In the ETC NADH and FADH2 are oxidized thereby donating their electrons to the various electron carriers of ETC ( *the final electron acceptor is not oxygen ) *
3) ATP is made by ATP synthase through chemiosmosis (using H+ gradient )
how does fermentation work?
a way of harvesting energy and making ATP without the need of oxygen, or ETC ( no cellular respiration needed )
NAD+ is recycled by the susbstrate-level phosphorylation so that glycolysis can continue
what are the two types of fermentation?
- alchohol fermentation
- lactic acid fermentation
what happens in alcohol fermentation?
pyruvate is converted into ethanol through two steps:
1) co2 is released from the pyruvate which makes acetaldehyde
2) the acetaldehyde is reduced by NADH to ethanol which results in NAD+
fermentation
how does bread rise?
the co2 bubbles generated by baker’s yeast during alcohol fermentation
what happens in lactic acid fermentation?
pyruvate is directly converted to lactate which regenerates NAD+
- no release of CO2
- used in the dairy industry ( cheese and yogurt )
- *takes place within our muscle cells under anaerobic conditions *
when do human muscle cells make ATP by lactic acid fermentation?
when oxygen in the body is scarce
glucose catabolism > rate of oxygen intake = lactice acid
- occurs during strenuous exercise (when the sugar requirements for ATP are too high compared to the muscle’s supply)
- glycolysis with fermentation is about 2.5 times faster than aerobic cellular respiration however it incompletely breaks down glucose and produces less ATP overall
- lactic acid build up can cause muscle fatigue and pain
where does lactate get transported to in the body?
transported via blood to the liver where it is converted back to glucose or pyruvate
because there is oxygen in the liver, pyruvate can enter the mitochondria in liver cells and complete cellular respiration
what are two types of byproducts capable of producing fermentation ?
acetone and methanol
prior to entering cellular respiration, amino acids must have their amino groups removed by what?
removed by deamination
removed amino groups must be converted into urea and excreted or else it will result into ammonia which is toxic
review
what is the last intermediate of the energy investement phase of glycolysis?
G3P
glycerol is converted into G3P
what is beta oxidation?
a process where fatty acids are broken down
- NADH and FADH2 are also generated during beta oxidation- they enter the ETC leading to further ATP production
fatty acids in cell are transported into mitochondrial matrix
this process yields a significant amount of energy = 1 gram of fat yields more than twice the amount of ATP as 1 gram of carbohydrates
true or false
fats produce more ATP than carbohydrates
true
because fats produce more ATP, fat reserves will deplete more slowly than carbohydrate reserves
