unit 4

Question 1

Compare/contrast potential and kinetic energy?

Answer 1

Potential energy is energy based on position, whereas kinetic energy is energy based on motion.

Question 2

What are the laws of thermodynamics?

Answer 2

1st Law of Thermodynamics - Energy cannot be created or destroyed. 2nd Law of Thermodynamics - For a spontaneous process, the entropy of the universe increases. 3rd Law of Thermodynamics - A perfect crystal at zero Kelvin has zero entropy.

Question 3

What are exergonic and endergonic reactions?

Answer 3

In an exergonic reaction, energy is released to the surroundings. The bonds being formed are stronger than the bonds being broken. In an endergonic reaction, energy is absorbed from the surroundings.

Question 4

What molecule fuels cellular work (what is the energy currency that all living things use to do work)?

Answer 4

The cell has a special kind of molecule for storing that energy, and it’s called ATP. ATP (Adenosine tri-phosphate) is an important molecule found in all living things. Think of it as the “energy currency” of the cell.

Question 5

Describe the structure of ATP.

Answer 5

The structure of ATP is a nucleoside triphosphate, consisting of a nitrogenous base (adenine), a ribose sugar, and three serially bonded phosphate groups.

Question 6

Which phosphate group is removed from ATP when powering cellular work?

Answer 6

Usually only the outer phosphate is removed from ATP to yield energy; when this occurs ATP is converted to adenosine diphosphate (ADP), the form of the nucleotide having only two phosphates.

Question 7

what does ADP+P refer to and what does it look like? What are three types of work?

Answer 7

If a cell needs to spend energy to accomplish a task, the ATP molecule splits off one of its three phosphates, becoming ADP (Adenosine di-phosphate) + phosphate.

Question 8

Understand how enzymes function in chemical reactions

Answer 8

Enzymes act by reducing the activation energy, thereby increasing the rate of reaction.

Question 9

What is a substrate?

Answer 9

a substrate can be the surface on which an organism (eg: plant, fungus, or animal) lives or the substance on which an enzyme can act.

Question 10

What is an active site?

Answer 10

The active site refers to the specific region of an enzyme where a substrate binds and catalysis takes place or where chemical reaction occurs.

Question 11

What is an induced fit?

Answer 11

Proposes that the initial interaction between enzyme and substrate is relatively weak, but that these weak interactions rapidly induce conformational changes in the enzyme that strengthen binding. catalyze: Cause or accelerate (a reaction) by acting as a catalyst.

Question 12

What is activation energy?

Answer 12

Activation energy is the minimum energy required to cause a process (such as a chemical reaction) to occur.

Question 13

What are inhibitors and what do they do? How do they do it?

Answer 13

inhibitors are molecules that slow down or stop a chemical reaction from taking place. inhibitors are compounds which modify the catalytic properties of the enzyme and, therefore, slow down the reaction rate, or in some cases, even stop the catalysis. Such inhibitors work by blocking or distorting the active site.

Question 14

How do competitive and non competitive inhibitors differ?

Answer 14

A competitive inhibitor competes with the substrate for binding at the active site of the enzyme. A noncompetitive inhibitor binds at a site distinct from the active site.

Question 15

What is meant by “negative feedback” with respect to enzymes?

Answer 15

Results in the inhibition of an enzyme in a biochemical pathway, reducing the activity of earlier enzymes, and stopping the pathway.

Question 16

Understand membrane structure and function, and different types of transport across a membrane.

Answer 16

Cell membrane is a phospholipid bilayer that regulates the entry and exit of molecules. Diffusion, osmosis and active transport are some forms of transport seen across the cell membrane.

Question 17

What is osmoregulation?

Answer 17

Osmoregulation is a homeostatic mechanism that regulates the optimum temperature of water and salts in the tissues and body fluids. It maintains the internal environment of the body through water and ionic concentration.

Question 18

How do hypertonic, hypotonic, and isotonic solutions differ? What happens to cells when placed into these different solutions?

Answer 18

If a cell is placed in a hypertonic solution, water will leave the cell, and the cell will shrink. In an isotonic environment, there is no net water movement, so there is no change in the size of the cell. When a cell is placed in a hypotonic environment, water will enter the cell, and the cell will swell.

Question 19

Describe active and passive transport across a cell membrane- how do they differ?

Answer 19

Active transport requires energy for the movement of molecules whereas passive transport does not require energy for the movement of molecules. In active transport, the molecules move against the concentration gradient whereas in passive transport, the molecules move along the concentration gradient.

Question 20

What is simple diffusion?
What is faciliatated diffusion?

Answer 20

In simple diffusion, the substance passes between the phospholipids; in facilitated diffusion there are a specialized membrane channels. Charged or polar molecules that cannot fit between the phospholipids generally enter and leave cells through facilitated diffusion.

Question 21

What is osmosis?

Answer 21

Osmosis is the spontaneous net movement or diffusion of solvent molecules through a selectively-permeable membrane from a region of high water potential to a region of low water potential, in the direction that tends to equalize the solute concentrations on the two sides.

Question 22

What is concentration gradient?

Answer 22

Concentration gradient refers to the gradual change in the concentration of solutes in a solution as a function of distance through a solution. A solution, essentially, has two major components, the solvent (the dissolving component, e.g. water) and the solute (the particles that are dissolvable by the solvent).

Question 23

What is endo- and exocytosis?

Answer 23

In endocytosis, a large particle is moved into the cell by pinching off a section of the cell membrane to form a vesicle around the particle. In exocytosis, a vesicle or lysosome carries particles to the outer cell membrane, then fuses with the membrane to release the particles.