2.3- ENERGY AND ATP Flashcards
What do all organisms require to remain alive?
energy
Where does energy initially come from?
the Sun
What do plants do during photosynthesis?
use solar energy to combine water and carbon dioxide into complex organic molecules
What do plants and animals do to the organic molecules produced from photosynthesis?
oxidise the organic molecules
What is made when the organic molecules is oxidised by plants and animals?
make adenosine triphosphate (ATP)
What is ATP used as?
main energy source to carry out processes within cells
What type of molecule is ATP?
phosphorylated macromolecule
How many parts does ATP have?
3
What are the 3 parts of ATP?
adenine
ribose
phosphates
What is adenine?
a nitrogen-containing organic base
What is a ribose?
a sugar molecule with a 5-carbon ring structure
What does the ribose of ATP act as?
backbone to which other parts attached
How many phosphate groups are there on ATP?
3
What is ATP?
nucleotide
What is key to how ATP stores energy?
the three phosphate groups
Why is the three phosphate groups key to how ATP stores energy?
bonds between phosphate groups unstable
What does it mean as the bonds between the phosphate groups are unstable?
they have a low activation energy
What does it mean as the phosphate groups bonds have a low activation energy?
they’re easily broken
How much energy is released when the bonds between the phosphate groups are broken?
considerable amount of energy
Usually in living cells what is removed in terms of ATP?
only the terminal phosphate removed
equation for ATP being broken down
ATP + (H20) = ADP + Pi + E
What is the reaction for the conversion of ATP to ADP known as? (2)
hydrolysis
reversible
Why is the conversion of ATP to ADP hydrolysis?
water is used
What is the conversion of ATP to ADP catalysed by?
enzyme ATP hydrolase (ATPase)
As the conversion of ATP to ADP is reversible what can happen?
energy can be used to add an inorganic phosphate to ADP to re-form ATP
When the ADP is converted back to ATP what is it catalysed by?
enzyme ATP synthase
What type of reaction is it when the ADP is reformed back to ATP?
condensation reaction
Why is it a condensation reaction when the ADP is reformed back to ATP?
water is removed
What does the synthesis of ATP from ADP involve?
addition of a phosphate molecule to ATP
In what ways can the ADP and phosphate molecule re-combine? (3)
photophosphorylation
oxidative phosphorylation
substrate-level phosphorylation
What is photophosphorylation?
in chlorophyll-containing plants during photosynthesis ADP and phosphate group re-combine
What is oxidative phosphorylation
in plant and animal cells during respiration ADP and phosphate group re-combine
What is substrate-level phosphorylation?
in plants and animal cells when phosphate groups are transferred from donor molecules to ADP so they re-combine
Why is ATP not a good long-term energy store?
instability of phosphate bonds
What serve the purpose of being a long-term energy store much better than ATP?
fats and carbohydrates i.e. glycogen
What type of source of energy is ATP to a cell?
immediate energy source
As ATP is not a good long-term energy store what do cells do?
do not store large quantities of ATP, but rather just maintain a few seconds’ supply
Why is it okay that only a few seconds’ supply of ATP in maintained within a cell?
ATP rapidly re-formed from ADP and inorganic phosphate so little goes a long way
Why is ATP a better immediate energy source than glucose? (2)
each ATP molecule releases less energy than each glucose molecules
so energy for reactions released in smaller, more manageable quantities rather than much greater, less manageable, release of energy from glucose molecules
hydrolysis of ATP to ADP is single reaction that releases immediate energy
breakdown of glucose is a long series of reactions and so energy release takes longer
Where is ATP made in the cell?
mitochondria
Examples of cells that require a lot of energy?
muscle fibres and epithelium of small intestines
Why do muscle fibres require a lot of energy?
for movement
Why do epithelium of the small intestine require a lot of energy?
for active transport
As some cells require a lot of energy what do they possess a lot of?
a lot of mitochondria
What process is ATP used in? (5)
metabolic processes movement active transport secretion activation of molecules
How is ATP used in metabolic processes?
ATP provides energy needed to build up macromolecules from their basic units
Example of how ATP used in metabolic processes?
making starch from glucose or polypeptides from amino acids
How is ATP used in movement?
ATP provides energy for muscle contraction
in muscle contraction, ATP provides energy for filaments of muscle to slide past one another and so shorten overall length of muscle fibre
How is ATP used in active transport?
ATP provides energy to change shape of carrier proteins in plasma membranes.
this allows molecules/ions to be moved against concentration gradient
How is ATP used in secretion?
ATP need to form lysosomes necessary for secretion of cell products
How is ATP used in activation of molecules?
inorganic phosphate released during hydrolysis of ATP can be used to phosphorylate other compounds to make them more reactive, so lowering activation energy in enzyme-catalysed reactions
Example of ATP being used in activation of molecules?
addition of phosphate to glucose molecules at start of glycolysis
