ATP, Water and inorganic ions Flashcards
What is the main energy source to carry out processes within cells
Adenosine Triphosphate (ATP)
What type of molecule is an ATP molecule
A phosphorylated macromolecule
What is the structure of ATP
Adenine - A nitrogen - containing organic base, Ribose - (pentose sugar) acts as backbone and phosphates - a chain of three phosphate groups
How does ATP store and release energy
ATP consists of 3 phosphate groups. The bonds between these phosphate groups are unstable and so have low activation energy, which means that they are easily broken. When they break they release a considerable amount of energy.
Which phosphate is usually removed in living cells
The terminal phosphate
What is the equation for the hydrolysis of ATP
ATP + (H2O) -> ADP (Adenosine diphosphate) + Pi (inorganic phosphate) + E (Free Energy)
What type of reaction is the conversion of ATP to ADP
Hydrolysis Reaction
What enzyme catalyses the conversion of ATP to ADP
ATP hydrolase (ATPase)
Is the conversion of ATP to ADP reversible?
Yes
How can ADP be converted to ATP
Energy can be used to add an inorganic phosphate to ADP to re-form ATP.
What enzyme is catalyses the conversion of ADP to ATP
ATP Synthase
What type of reaction is the conversion of ADP to ATP
Condensation Reaction
How does the synthesis of ATP from ADP occur
The addiction of a phosphate molecule to ADP.
What are the three ways the addiction of a phosphate molecule to ADP occurs
In chlorophyll containing plant cells during photosynthesis (photophosphorylation), In plant and animal cells during respiration (oxidative phosphorylation), In plant and animal cells when phosphate groups are transferred from donor molecules to ADP (substrate level phosphorylation)
Why is ATP not a good long term energy store
The instability of ATP’s bonds, mean it is a better immediate energy source of a cell.
How do cells store ATP
Cells do not store large quantities of ATP, but rather just maintain a few seconds of supply. This is not a problem as ATP is rapidly reformed from ADP and Pi.
Why is ATP a better immediate energy source than glucose
Each ATP molecule releases less energy than each glucose molecule. The energy for reactions is therefore released in smaller, more manageable quantities rather than the much greater, and therefore less manageable release of energy from Glucose.
The breakdown of glucose is a long series of reactions and therefore the energy release takes longer than the single reaction which is the hydrolysis of ATP to ADP, releasing immediate energy.
What has to happen for ATP to be sustained
ATP cannot be stored and so has to be made continuously within the mitochondria of cells that need it.
How is ATP used in metabolic processes
ATP provides the energy needed to build up macromolecules from their basic units. E.g. Starch from Glucose
How is ATP used in movement
ATP provides the energy for muscle contraction. In muscle contraction, ATP provides the energy for the filaments of muscle to slide past one another and therefore shorten the overall length of a muscle fibre.
How is ATP used in active transport
ATP provides the energy to change the shape of carrier proteins in plasma membranes. This allows molecules or ions to be moved against a concentration gradient.
How is ATP used in secretion
ATP is needed to form the lysosomes necessary for the secretion of cell products
How is ATP used in the activation of molecules
The inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate other compounds in order to make them more reactive, thus concerning the activation energy in enzyme - catalysed reactions. E.g. the addiction of phosphate to glucose molecules at the start of glycolysis.
In water which atom has the slight negative charge
Oxygen
In water which atom has the slight positive charge
Hydrogen
How does water being dipolar affect it
Different poles attract, the positive pole of one water molecule will attract the negative pole of another (Hydrogen bond)
Is hydrogen bond weak or strong
weak
What would water be if it weren’t for its hydrogen bonding
A gas
How does the hydrogen bonds in water affect the specific heat capacity
It takes more energy (heat) to separate water than would be needed if they didn’t bond
What does water act as a buffer against
Sudden temperature variations
How does hydrogen bonding between water molecules affect latent heat of vaporisation
It requires a lot of energy to evaporate 1 gram of water.
What is the tendency of molecules to stick together known as
Cohesion
Does water have large cohesive forces and why
Yes, due to its hydrogen bonding
What does waters large cohesive forces allow it to do
Allows it to be pulled through a tube e.g. xylem
What is the name of the force that pulls water molecules that meet the air back into the body of water
Surface tension
What % of mammals is made up water typically
65%
Importance of water in metabolism
Used to break down complex molecules by hydrolysis, Chemical reactions take place in aqueous medium, major raw material in photosynthesis
What substances does water readily dissolve
Gases - Oxygen and Carbon dioxide, Wastes - Ammonia and urea, Inorganic Ions and Small hydrophilic molecules - Amino acids, monosaccharides and ATP and enzymes who’s reactions take place in solution
How does waters evaporation support organisms
Cools them and allows them to control their temperature
Where are inorganic ions found
In organisms where they occur in solution, in the cytoplasm of cells and in body fluids as well as part of larger molecules
What determines an Inorganic ions function
The specific function a particular ion performs is related to its properties. E.g. Iron found in Haemoglobin has a role in transporting oxygen
Why is the copying of DNA known as semi - conservative replication
In each new DNA molecule being produced, one of the polynucleotide strands (half of the new DNA molecule) is from the original DNA molecule being copied. The other strand has to be newly created by the cell.
What does semi - conservative replication ensure
Genetic continuity between generations of cells
What catalyses the condensation reaction between the original DNA strand and the new DNA strand
DNA polymerase
What are the nucleotides within the nucleus known as
Nucleoside Triophosphates
What direction does DNA polymerase build the new strand
5’ to 3’
Who discovered semi conservative replication
Watson and Crick
How did Meselson and Stahlprove Watson and Crick’s theory correct
Bacteria containing heavy 15N nitrogen isotope in their DNA were spun in a centrifuge, the DNA settled to the bottom of the test tube. The bacteria containing only 15N was then taken out of its broth and added to the broth containing only 14N . One round of replication was allowed to occur and then the DNA was extracted and spun in the centrifuge again. The DNA from the second round of centrifugation settled in the middle of the tube showing each DNA molecule contained a mixture of the heavier and lighter nitrogen isotopes. Semi - conservative replication had occurred.
How much energy is released if all phosphate groups are removed from ATP
75.8kj/mol
How much energy is released if the first phosphate group of ATP is removed
30.8kj/mol
How much energy is released if the second phosphate group of ATP is removed
30.8kj/mol
How much energy is released if the third phosphate group of ATP is removed
14.2kj/mol
When is ATP made
During the reactions of respiration and photosynthesis
What are the two ways ATP can be made
Substrate - linked phosphorylation and Chemiosmosis
