Biology 288-Lecture 4

Cell Biology

What is a neurotransmitter?

A molecule released by a neuron that has an effect on another cell

How is a complex molecule built up?

A precursor molecule takes part in a reaction to produce a secondary molecule which can then remain as it is or continue on into another reaction

Where do cells get their energy and building blocks from?

They breakdown the food we eat into usable materials

The conversion of food to molecules that form a cell produce two products, what are they?

1) Energy in the form of ATP

2)Heat

Explain how the saying “we are what we eat” is essentially true

The food we eat goes through a series of catabolic pathways to be broken down into its simplest forms. These forms are then taken and go through a series of anabolic pathways where they are built into molecules which can then be used to form cells

What are LDL and HDL?

Although often mistaken for forms of cholesterol, they are proteins that carry cholesterol

What do our cells use cholesterol for?

To generate useful cellular material

What makes biological order possible?

The release of heat energy

What is our main source of energy even for organisms that do not make their own energy?

The main source of energy is the sun

How do non-photosynthetic organisms use the sun as an energy form?

The photosynthetic organisms harvest the suns energy to produce their own energy, then they are consumed by other consumers and that energy is passed on

How do cells obtain energy from organic molecules?

They oxidize them

What state does the universe prefer?

The universe prefers a state of disorder

Why does the universe move from order to disorder?

The movement to order is energetically unfavorable and requires a lot of energy

Why can’t mammals properly breakdown plants?

Plants contain a rigid cellulose wall which is hard to breakdown

What is the purpose of carbon dating?

It allows us to examine the different carbon isotopes present and estimate the age of an organism

What is oxidation?

The loss of an electron

What is reduction

The gain of an electron

What kind of molecules are electrons attracted to?

Molecules with high electronegativities

What direction do chemical reactions proceed in?

The direction that causes a loss of free energy

What is the function of an enzyme?

An enzyme lowers the energy needed to initiate a spontaneous reaction while also remaining unchanged

What is determined by the free energy change?

Free energy change determines if a reaction will occur

If the change in free energy is very negative, will the reaction occur?

yes

What happens to a reaction if we change the concentration of its components?

The direction which the reaction proceeds in will change

What do enzyme-catalyzed reactions depend on?

Depends on rapid molecular collisions

What is the function of a catalyst?

It reduces the energy required for a reaction to occur and allows reactions to occur more easily

Draw a diagram representing an uncatalyzed reaction pathway and a catalyzed reaction pathway

If the change in free energy is positive, will the reaction occur?

The reaction will occur but it requires energy to initiate it

What is the 0th law of thermodynamics?

Two systems in equilibrium with a third system are also in equilibrium with each other

What is the 1st law of thermodynamics?

Energy can change forms but is not created or destroyed

What is the 2nd law of thermodynamics?

Entropy of an isolated system always increases

What is the 3rd law of thermodynamics?

Entropy of a system approaches a constant as the temperature approaches absolute 0

What is the purpose of reaction coupling?

Allows and energetically unfavorable reaction to take place

What are two possible ways that a reaction may cause disorder?

1) Changes the bond energy of the reacting molecules that can cause heat to be released

2) Decrease in the amount of order in the cell