Energy

Question 1

what is energy? brief definition

Answer 1

energy is the capacity to do work, which occurs when a force operates on an object over a distance. Therefore, it is the capacity to cause change

Question 1

types of energy and their examples in biology

Answer 1

chemical energy
- stored in bonds
- covalent bonds are broken during hydrolysis, releasing energy

electrical
- seperation of changes
- electrical gradient across cell membranes, helps to drive the movement of ions through channels

heat
- transfer due to temperature difference
- heat can be released by chemical reactions, and this can alter the internal temperature of an organism

light
- electromagnetic radiation stored as photons
- light energy is captured by pigments in the eye and plant pigments in photosynthesis

mechanical
- energy of motion
- mechanical energy is used in muscle movements and movements within cells

Question 2

what is potential energy?

Answer 2

potential energy is the energy of state or position. It is stored energy.

Question 3

what is kinetic energy?

Answer 3

The energy of movement. The type of energy that does work and makes things change

Question 4

what is thermodynamics and why is it relevant?

Answer 4

the study of energy transformations
It is important because biology is made up of chemical reactions, which all use and have a relationship with energy

Question 5

first law of thermodynamics

Answer 5

the energy of the universe is constant.

energy can be transformed and transferred, but not created or destroyed

principle of the conservation of energy

Question 6

second law of thermodynamics

Answer 6

every energy transfer or transformation increases the entropy (disorder) of the universe

during every energy transfer or transformation, some energy is unusable and is often lost as heat

Question 7

what is ATP and what does it do/how does it store energy?

Answer 7

ATP- Adenosinetriphosphate
captures and transfers free energy
ADP + Pi = ATP
can also phosphorylate (donate a phosphate group) to another molecule for them to gain energy

Question 8

what are redox reactions and their application in the body?

Answer 8

redox reactions facilitate the transfer of electrons and energy in chemical reactions

literally in every biochemical reaction
- electron carriers are currency fo rredox
- they actually carry hydrogen ions which causes the transfer of electrons
- glucose is the reducing agent
- oxygen is the oxidising agent

Question 9

what is entropy and how does it apply in biology?

Answer 9

measure of disorder in a system

e.g.
it requires energy to create/impose disorder in a system. If there is no energy the system will be randomly arranged; it will be disordered. Living cells unavoidably convert organised forms of energy into heat, for a process to occur without energy input, it must increase the entropy of the universe

Question 10

what is free energy?

Answer 10

• Gibbs free energy (g) = the amount of energy available to do work (i.e. usable energy)
• All chemical reactions affect G; change in G after a reaction is abbreviated as delta G
• free energy is measured the instability of a system. During spontaneous reactions, free energy decreases and the stability of a system increases. More free energy = more unstable = more capacity to do work

Question 11

what is the interaction between equilibrium and metabolism?

Answer 11

Reactions in a closed system eventually reach equilibrium and then do no work

cells are not in equilibrium because they are not in a closed system. Instead, they are in an open system as they are experiencing a constant flow of materials.

Question 12

spontaneous reactions

Answer 12

catabolic reactions are spontaneous and release free energy
breaks down ordered reactants into randomly distributed products
exergonic

Question 13

non-spontaneous reactions

Answer 13

anabolic reactions are non-spontaneous
make highly ordered substance out of smaller reactions
endergonic

Question 14

what is activation energy and how is it relevant to biological reactions?

Answer 14

Ea is the energy barrier required for a reaction to occur

Reaching the Ea puts the reactants in a reactive mode or transition state where it can either react or settle back into a stable state

Question 15

what are enzymes and how do they speed up biochemical reactions?

Answer 15

enzymes are proteins that lower Ea by transforming molecules into an unstable state with higher free energy, called transition state intermediates. They do this by bringing reactants together and positioning the substrates to resemble their transition states. Enzymes cause the bonds of the substrate to be less stable, so the bonds are easier to break and the substrate is therefore more likely to react

Question 16

how are enzyme substrate complexes held together?

Answer 16

substrate molecules bind to the active sites of teh enzymes. The 3D shape of the enzyme is complementary to the substrate molecule, and is therefore specific. When the substrate binds ot the active site, the two halves of the enzyme move together so that the reactioin can take place

Question 17

can enzymes change shape?

Answer 17

No, it doesn’t permanently change shape, however, it can change whilst it is bound to the substrate and will return to its original shape once it has finished being catalysed

Question 18

how do enzymes make substrates unstable?

Answer 18

enzymes can make substrates unstable through
- chaning the orientation of a substrate
- physically straning or putting pressure on the substrate’s bonds
- strain based on chemical changes- add or change charges or polarity of the bonds within the substrate

Question 19

what helps assist enzymes (4 possible things)?

Answer 19

prosthetic groups
non-amino acid groups
inorganic cofactors (metal-ions)
coenzymes

Question 20

Reaction rate and enzyme concentration relationship

Answer 20

rate of a catalysed reaction depends on substrate concentration
concentration of an enzyme is usually much lower than the substrate

Question 21

what is the induced fit model?

Answer 21

The substrates bond to the active site of an enzyme, and most enzymes then adopt the induced fit model. This is when conformational change alters the relative position of amino acids.