Week 3 Cellular Motabolism

Question 1

Energy is used to perform work.what kind of work?

Answer 1

Chemical work: making and breaking chemical bonds ex making new cells,protein,ECF
•amino acid -peptide-protein

Transport work:moving Ions and molecules across cell membranes (e.g. active transport uses ATP NA/K+ pump)
•moving 3Na out and taking in 2K+

Mechanical work: moving organelles around in a cell or contracting muscles-
•phagocytosis change shape to eat cell

Human body exchanges energy with the external environment

Energy cannot be created,destroyed
But it can be converted between forms
This is first law of thermodynamics

Question 2

Humans gain energy by eating food and lose energy to the environment through heat

Answer 2

Sun produces energy
•some is lost into the environment
•plants take in energy through photo synthesis
•energy is gained through food
1.Energy lost:heat
2.Energy used for work -Kenetic energy
3.Energy stored for later -potential energy

Question 3

Potential and kinetic energy

Answer 3

Potential energy any energy stored in body- Fat/carbohydrates stored in body, concentration gradient- low Na in cell and high outside
Can be conveyed to power work in body. Use to power exercise
Concentration gradient of sodium can be used to push sodium doen gradient.

Question 4

How energy can be converted using chemical reactions

Answer 4

When we need to store energy
1.build covalent bonds
-which
2. Transfer energy from one molecule to another
-energy conversion
3.increases potential energy
-called
ENDERGONJC REACTION
potential energy of products is higher than that of the reactants

We can also use chemical reactions to
1.Break down covalent bonds
-which
2.uses energy to produce work
-energy conversion
3.”decreases” potential energy
-called
EXERGONIC reaction potential energy of products is lower then the reactants

Question 5

Reactants and products in chemical reactions

Answer 5

Reactants and substrates
A+B
Products C+D

A+B -> C+D

Chemical reaction
EXERGONIC reaction at start it has higher potential energy and at the end lower
•potential energy reactants > Potential energy
Net free energy change
For example starting 10 and ending 2
Free energy that is released the body and cells Can use to perform work like running

Endergonic
Potential energy > reactants
So energy is stored
After eating we use endergonic reactions

Question 6

ATP breakdown

Answer 6

Is essential EXERGONIC reaction in body

ATP has 2 phosphate bonds that we call high energy bonds
When broken down there is free energy use energy to power sodium potassium pump ,contract muscles ect

ATP+H2O -> ADP + Pi + Free energy

Question 7

Activation energy determines the likely hood of a reaction

Answer 7

Activation energy: initial input of energy required to bring reactants in a position that allows them to react with one another

If low

Then reaction is spontaneous and likely to happen

If high reaction is unlikely to happen(enzymes can facilitate reactions) by bringing activation energy down

Enzyme: proteins that speed up chemical reactions by lowering their activation

•enzyme is specific to its substrate
Enzyme is the lock and substrate is the key

Enzyme bend the substrate and it makes it easier for chemical bonds to break and decrease the amount of energy for chemical reaction to happen

Question 8

Role of enzyme in chemical reactions

Answer 8

Some chemical reactions are irreversible due to their large activation energy

Most biological actions are reversible they can go in both directions when with large activation energy thanks to ACTIONS OF ENZYMES

Lower the activation energy

Question 9

Active site of enzymes is specific to the enzymes substrate (lock and key)

Answer 9

1.Substrate enters active site of enzyme

2.Enzyme/substrate complex -enzyme changes shape slightly as substrate bunds

3.Enzyme/products

4.products leaving active site of enzyme -

Proteins similar to Transporters
Enzymes are characterized by
1. Specificity: enzymes can
only bind specific substrates
so, they share
(or a group of closely related
similar characteristics substrates)
2. Competition: when
enzymes can bind more than
one substrate, these
substrates compete with one
another.
3. Saturation: when all
enzymes work at their
maximal capacity, reaction
rate can no longer increase

Question 10

Enzymatic activity

Answer 10

Enzymatic activity determines chemical reaction rate
Enzyme activity up arrow = reaction rate up arrow

It’s effected by

1.temperature most enzymes work best around 37°
2.pH-most enzymes work best at pH~7.4

Outside of temp and pH ranges,the enzymes lose their 3D shape(denaturation) -> results in loss of function

3D shape of hexokinase and enzyme specific to glucose

3.enzyme concentration-increase concentration of enzyme then increase activity

4.substrate concentration- increase of substrate = increase activity

If enzymes are full then adding more substrate(keys) will not speed up the activity

5.Cofactors
Are ions like magnesium or calcium
Enzymes that require cofactors the enzyme is responsible for the creation of the binding site

6.competitive inhibitors
Block the substrate binding at the binding site by taking shape of the substrate.enzymatic activity and reaction rate

7.Allosteric modulators
Allosteric activator- increase activity of enzyme.binds somwhere else on protein which allows the substrate to bind

Allosteric inhibitor work in the opposite they insert and the substrate release as enzyme changes shape