Cell Respiration C1.2 Flashcards
What does cellular respiration do?
produces the energy required by organisms to live in the form of Adenosine Triphosphate (ATP) by breaking down nutrients and food using enzymes into CO2, H2O, and ATP.
What are organic compounds?
molecules which contain carbon-carbon or carbon-hydrogen bonds such as glucose or fatty acids.
What are organic compounds in cellular respiration?
the initial source of energy and through a number of metabolic steps the molecules are oxidized and potential energy stored is transferred to ATP.
How is ATP created from ADP?
by attaching a phosphate group to ADP, requiring energy coming from food.
What is energy transfer in cellular respiration?
in small quantities rather than one big release.
Why is energy transfer in cellular respiration only in small quantities?
if all given out, most energy will be lost as heat to the surrounding. so, energy is transferred to ATP in many small steps.
What are properties of ATP that make it suitable as energy source?
- contains chemical energy locked up in its structure
- energy can be released in small manageable quantities by hydrolyzing ATP into ADP
- very reactive molecule
- small and can be moved easily into cells by facilitated diffusion
- cannot simply move through membranes and therefore is under control
How are phosphorylated intermediated formed?
from ATP reacting with other metabolites
What does phosphorylation mean?
ATP –> ADP –> ATP
What do muscle contractions cause muscles to do?
to shorten in length due to actin and myosin protein filaments sliding in and out.
What does the sliding of protein filaments in muscles depend on?
hydrolysis of ATP and energy released used for the “power stroke”
What are the uses of ATP?
- electrical energy when transmitting a nerve impulse
- kinetic energy when muscles contract
- light energy in bioluminescence
- other forms of chemical energy during synthesis of molecules/transporting materials
What are the three main types of uses for ATP?
- synthesizing macromolecules
- movement
- active transport
What are examples of synthesizing macromolecules using ATP?
- production of proteins at ribosomes during translation
- DNA replication
- synthesis of starch from glucose in plants
- transcription
What are examples of movement using ATP?
- muscle contractions
- movement of flagella or cilia
- centrioles and spindle fibers during meiosis and mitosis
What are examples of active transport using ATP?
- transport of substances against the concentration gradient
- endocytosis and exocytosis
How is anaerobic respiration done? How much is yielded?
pyruvate is broken down in anaerobic respiration without any oxygen. 2 mol. ATP yielded.
When is anaerobic respiration used?
- short rapid bursts of ATP needed
- oxygen supplies run out in respiring cells
- in environments which are oxygen deficient
- high intensity workouts
Why is anaerobic respiration needed in high intensity workouts?
- not enough time to deliver O2 to cells for aerobic respiration
- supply of energy needs to be fast and quickly available for power to be maximized
How is aerobic respiration done? How much is yielded?
pyruvate is gradually broken down into CO2, water, and 36-38 molecules of ATP in the mitochondria. > 30 mol. ATP
What are the steps of aerobic respiration?
- glucose & oxygen transported down bloodstream and absorbed into the cytoplasm
- glucose turned into pyruvate during glycolysis and produces a small amount of ATP
- if oxygen is available, pyruvate is transported into the mitochondria where it is broken into CO2, H2O, and ATP.
- CO2 is a waste product that is then diffused into the bloodstream into the lungs to be exhaled out.
What is oxidation?
the loss of electrons through loss of hydrogen. Also means gain of O2
What is reduction?
the gain of electrons through the gain of hydrogen. Also a loss of O2
What is NAD?
nicotinamide adenine dinucleotide is the main electron carrier/hydrogen acceptor during cellular respiration
What happens to the atoms during cell respiration as it relates to redox reactions?
glucose is oxidized into carbon dioxide and oxygen is reduced to water.
What is the equation for oxidation of NAD?
NAD+ + 2e- + 2H+ –> NADH + H+
What are the 4 main stages of cell respiration?
- glycolysis
- linkage
- krebs cycle
- electron transport chain
What is glycolysis?
the conversion of glucose to pyruvate by reactions.
What is stage 1 of glycolysis?
glucose –> glucose-6-phosphate (G6P)
ATP -> ADP
G6P –> fructose-6-phosphate (F6P)
F6P –> fructose-1, 6-biphosphate
ATP -> ADP
What is stage 2 of glycolysis?
lysis:
fructose-1, 6-biphosphate –> 2 triose phosphate
ATP -> ADP
What is stage 3 of glycolysis?
oxidation:
triose phosphate –> biphosphoglycerate
NAD+ -> NADH + H+
DO THIS TWICE BECAUSE 2 TRIOSE FROM STAGE TWO
What is stage 4 of glycolysis?
biphosphoglycerate –> pyruvate
ADP -> ATP ADP -> ATP
DO THIS TWICE BECAUSE 2 BIPHOSPHOGLYCERATE FROM STAGE THREE
What are the net products of glycolysis per one glucose?
2x ATP
2x NADH + H+
2x pyruvate
What does the phosphorylation in stage 1 of glycolysis do?
- makes the molecule less stable and lowers activation energy for lysis
- prevent the phosphorylated molecule to be transported through cell membrane. (pumps don’t recognize)
What happens after glycolysis?
aerobic vs. anaerobic respiration. after glycolysis, pyruvate depend on oxygen availability to determine for aerobic or anaerobic.
What does anaerobic respiration do with the pyruvate after glycolysis?
does not produce any further ATP and recycles NAD+ for continued production of pyruvate. either through alcoholic fermentation or lactic acid fermentation.
What are the steps of alcoholic fermentation?
2 pyruvate –> 2 ethanol
OUT CO2, 2 NADH -> 2NAD+
2NAD+ goes back to glycolysis and oxidizes to form more pyruvate
What are the steps of lactic acid fermentation?
2 pyruvate –> 2 lactate
2 NADH -> 2 NAD+
2NAD+ goes back to glycolysis and oxidizes to form more pyruvate
What is the purpose of the different fermentation methods?
recycle NAD+ for pyruvate synthesis
Industrial uses of anaerobic cell respiration?
- yeast/bacteria respire anaerobically and are essential for production of foods, cheese, yogurt, bread, drinks, alcohol, biofuels, kimchi
What is different between anaerobic respiration of humans and yeast?
there is no difference. only the regeneration of NAD+ using pyruvate which result in differing products
What is linkage?
pyruvate enters mitochondrial matrix by facilitated diffusion and processed further.
What are the steps of linkage?
pyruvate –> acetate
OUT CO2
acetate –> acetyl-coenzyme A
IN coenzyme A
NAD + -> NADH + H+
acetyl CoA is transported into the matrix to participate in krebs cycleWhat
What is the krebs cycle?
oxidation and decarboxylation of acetyl groups with yield of ATP and NADH
What are the steps of the krebs cycle?
acetyl CoA –> citrate
BIND oxaloacetate
citrate –> alpha-ketoglutarate
OUT CO2, NAD+ -> NADH + H+
alpha-ketoglutarate –> succinate
OUT CO2, NAD+ -> NADH + H+
succinate –> fuminate
ADP -> ATP, FAD -> FADH
fuminate –> malate
IN H2O
malate –> oxaloacetate
NAD+ -> NADH + H+
What are the net products of the krebs cycle per 1 pyruvate?
3x NADH + H+
1 FADH2
1 ATP
2 CO2
What happens before the ETC and after krebs cycle?
electrons and H+ are transported to the cristae where they are offloaded by NADH and FADH.
What is ETC?
electron transport chain, reduced molecules of NADH and FADH2 from glycolysis and krebs cycle will become oxidized again in the ETC.
- energy released will be used to establish a proton gradient
- the proton gradient is used to phosphorylate ADP to ATP.
How is ETC established?
by inner mitochondrial membrane and carrier proteins that easily undergo redox reactions.
What is special about each carrier protein?
each has a slightly higher electronegativity and therefore a strong attraction for electrons than the previous carrier so electrons are passed own an energy gradient.
What are the steps of generation of a proton gradient by flow of electrons?
- NADH and FADH2 are oxidized to NAD+ and FAD, lose electrons and hydrogen ions
- carrier molecules embedded in the membrane of the cristae accept the protons, while pass along the chain from carrier to carrier.
- energy is released as the electrons fall from higher levels to lower ones.
- this energy is used to pump protons from the matrix into the inter membrane space against the concentration gradient.
What happens after the generation of proton gradient?
chemiosmosis and synthesis of ATP
Explain chemiosmosis and synthesis of ATP?
- transfer of H+ set up a concentration gradient across the membrane
- protons (H+) follow their nature concentration gradient as a result by moving through the ATP synthase
- energy releases used to phosphorylate ADP -> ATP
- once the H+ is back in matrix, it binds with an oxygen ad 2 electrons to form water.
What is ATP synthase?
a complex of integral proteins located in the mitochondrial inner membrane where it catalyzes the synthesis of ATP from ADP and phosphate. it is driven by the flow of protons
What is oxygen in the ETC?
the final electron acceptor in the mitochondrial ETC.
- the reduction of oxygen molecule involves both accepting electrons and forming a covalent bond with hydrogen to make water.
Are carbohydrates/lipids used in glycolysis and anaerobic respiration?
carbs: can be used as glucose or fructose
lipids: must be converted to glycerol or fatty acids and then into acetyl CoA to use in the krebs cycle. NOT glycolysis or anaerobic res.
Is hydrolysis of macromolecules required? carbs/lipids
carbs: only in complex carbs
lipids: into glycerol and fatty acids
What is the amount of energy produced per gram? carbs/lipids
carbs: half as much compared to lipids because less oxidation therefore less energy given out
lipids: twice as much energy because more oxidation needed
