Cellular respiration Flashcards
What is cellular respiration and the purpose
- Cellular respiration: the process by which food (glucose) is converted
into useable energy (ATP) - Purpose: to produce energy in the form of ATP
- The food/nutrients used for cellular respiration are the three major
biomolecules found in living organisms
What is ATP
Adenosine triphosphate (ATP) is the energy currency/energy molecule
for cells. ATP molecules store energy using a very high energy phosphate bond. This bond can be broken to provide energy
ATP 🡪 ADP
After the energy is given away, ATP becomes ADP (adenosine
diphosphate) and can return to the mitochondria to be recycled
What is ATP synthase
- The enzyme ATP synthase is responsible for the
production of ATP - ATP synthase is embedded in the inner
membrane (cristae) of the mitochondria - It uses H + ions as an energy source to
combine ADP molecules with phosphate ions
What is aerobic respiration
- Aerobic respiration: when glucose is broken down in the presence of
oxygen to form carbon dioxide, water, and ATP - Glucose + oxygen 🡪 carbon dioxide + water + ATP (36)
- Occurs in the cytoplasm AND mitochondria
What are the three enzyme controlled pathways for aerobic respiration
- Glycolysis
- Krebs cycle
- Electron transport chain
- Each glucose molecule fed into the aerobic respiration pathway
produces approximately 36 ATP
What is glycolysis
- Glycolysis: breakdown of glucose by
enzymes - Occurs in the cytoplasm
- One glucose molecule is broken down
into two molecules of pyruvate (with
three carbons each) - Glycolysis uses 2 ATP but produces 4
ATP… so overall (net) 2 ATP are made
What is Krebs Cycle
- Occurs in the fluid matrix of the
mitochondria - The pyruvate molecules produced
from glycolysis go through a complex
series of enzyme-controlled reactions - Pyruvate is attached to an enzyme to
form acetyl CoA - Acetyl CoA is used in the Krebs cycle to
produce the electron carrier NADH - 2 ATP are made
What is the electron transport chain
- This is where oxygen is needed for aerobic respiration
- Occurs on the cristae of the mitochondria
- NADH drops electrons off at the electron transport chain on the cristae
- These electrons “power” the enzyme ATP synthase which produces
huge amounts of ATP - 32 ATP are made
What is anaerobic respiration
- Anaerobic respiration: when glucose is broken down into lactic acid
and ATP (energy) - No oxygen is present, therefore less energy (2 ATP) is produced
compared to aerobic - Glucose 🡪 lactic acid + ATP (2)
- Occurs in the cytoplasm
What cycle does anaerobic respiration go through
Anaerobic respiration involves glycolysis too, but goes a different way
from there
- Glycolysis
- Fermentation (alcoholic or lactic acid)
- Each glucose molecule fed into the anaerobic respiration pathway
produces approximately 2 ATP
What is alcoholic fermentation
- Occurs in plants, bacteria, and fungi
- Pyruvate molecules produced in glycolysis cannot be sent to Krebs
cycle due to lack of oxygen - The fermentation process does not produce any energy; it only exists
to convert pyruvate and hydrogen molecules into the waste products
ethanol and CO2 - Ethanol produced is a toxic waste product that can only be removed
very slowly - This limits how much anaerobic respiration an organism or cell can
do, as they are limited by how quickly they can “process” the ethanol
into something less harmful
What is lactic acid fermentation
- Occurs in animals
- Anaerobic respiration is used during short, high-intensity exercise,
producing lactic acid (not ethanol) as a waste product - You breathe hard after intense exercise as oxygen is needed to convert
the lactic acid to other waste products such as carbon dioxide and water - Build up of lactic acid causes muscle fatigue, which is why you need
rest after an extreme workout
What are the advantages and disadvantages of aerobic respiration
Aerobic respiration makes lots of energy (36 ATP per glucose) BUT
takes lots of time, as we need to wait for oxygen to slowly diffuse into
the cells. The waste products of aerobic respiration are water and carbon
dioxide, which are not toxic and can be easily removed
What are the advantages and disadvantages of anaerobic respiration
Anaerobic respiration is very fast BUT makes very little energy (only 2
ATP per glucose) The waste products of anaerobic respiration are ethanol OR lactic acid
(and carbon dioxide) which are toxic and can harm/kill the organism
- This form of respiration is not sustainable
