Life on This Rock: Section 3 Flashcards
What is the main thing that drives biological processes?
Energy.
What is the scientific definition of energy?
The capacity to carry out work.
What is kinetic energy?
Energy that is currently performing work.
What is potential energy?
Energy that is being stored for later use.
Is the energy contained within the chemical bonds of molecules potential or kinetic energy?
Potential.
How does the potential energy stored inside the chemical bonds of molecules become kinetic energy?
It becomes kinetic energy when the bonds are broken.
True or false? It takes work to build up potential energy.
True.
We fight constantly to take in enough energy to _______.
Keep ourselves alive.
What are the laws of thermodynamics?
Physical principles that describe energy and its properties.
What is the first law of thermodynamics?
Energy is cannot be created nor destroyed, but changes form.
What is the second law of thermodynamics?
Energy cannot be changed from one form to another without a loss of usable energy. Also, systems become more disorganized over time.
Every engine loses some of its power as ____.
Heat.
What happens when we burn/metabolize a glucose molecule?
We capture some energy to do work and lose some as heat.
What is entropy?
A way to measure how disorganized a piece of energy is.
What do we use to measure energy?
Calories.
What is a calorie?
The amount of energy needed to raise the temperature of one gram of water 1 degree celcius.
What does “Calorie” (with a capital c) refer to?
A kilocalorie (1000 calories)
Molecules _____ until they are evenly spread out in a solution.
Diffuse.
Why do cells need to use energy?
To prevent themselves from diffusing.
When an organism consumes another organism, what is much of the energy lost as?
Heat and waste.
Where does the earth receive all of its energy from?
The sun.
What is the third law of thermodynamics?
The entropy of a system approaches a constant value as the temperature approaches absolute zero.
What is the Zeroth law of thermodynamics?
If two systems are in thermal equilibrium with a third system, they must be in equilibrium with each other.
What is thermal equilibrium?
A state in which heat is not transferred between systems that are connected by a path that is permeable by heat.
How do cells fight entropy?
They eject H+ ions through transmembrane proteins until they reach an equivalent concentration inside and outside the cell.
True or false? Most of the rays that the sun sends to the earth remain there.
False. Most of them bounce off.
Does entropy increase or decrease as light travels from the sun to us?
It increases.
Does it take energy to break down molecules?
Yes.
True or false? Since it takes energy to break down molecules, we always need to reserve a little bit of energy.
True.
Why do we always need to keep a little energy on reserve?
So that we can take advantage of any incoming food.
Where do organisms get the energy they have in their reserves?
From the previous metabolic activity.
What do animals use energy for?
Surviving, growing, reproducing, and starting the next reaction.
What is the term for reactions that release energy?
Exergonic reactions.
What is the term for reactions that assemble molecules?
Endergonic reactions.
What happens when a molecule like glycogen is broken down?
Energy is released.
What two things will happen to the energy from broken bonds?
Some of it will be used to create new bonds, some of it will be lost as heat.
What is the molecule that captures energy for reactions?
ATP
What is ATP short for?
Adenosine Tri-Phosphate
How is ATP made?
By adding a phosphate group to ADP using a standard dehydration reaction.
Is a dehydration reaction an exergonic or endergonic reaction?
Endergonic.
What are endergonic reactions powered by?
The energy released from exergonic reactions.
Why does it take energy to assemble a molecule of ATP?
The three phosphate groups are all negatively charged, so it takes energy to push them together.
Is ATP used immediately or saved for later?
Saved for later.
Which phosphate group in ATP holds the most energy?
The third one.
Why does the third phosphate group carry enough energy for a single reaction?
So that when some energy is lost as heat, there is not a lot of wasted energy.
What is meant when we say that cells “Couple reactions”?
They use the energy released from breaking down molecules to make ATP.
What is muscle contraction?
A process that converts chemical energy {stored in ATP} into physical energy.
What does muscle contraction rely on?
The hydrolysis of ATP (Removing the third phosphate group by adding a water molecule.
What are the cytoseleton fibers of a muscle cell made of?
Actin.
What do muscle cells organize their cytoskeleton fibers into?
A superstructure.
What kind of motor protein is found along our muscle’s actin fibers?
Myosin.
True or false? Myosin has head and tail ends.
True.
What does the tail end of myosin do?
Bind to some of the actin fibers.