Chapter 5 - The Working Cell

Question 1

What is metabolism?

Answer 1

set of all chemical reactions that occur in a cell

Question 2

What are enzymes? What are the characteristics of an enzyme?

Answer 2

proteins that are catalysts (speed up rate of specific chemical reactions)

• reduce activation energy for a particular chemical reaction so it requires less energy/time to start reacting
• very selective
• can function over and over again
• often named for their substrates with “-ase” ending

Question 3

What is a substrate (reactant)?

Answer 3

molecule that is acted upon by an enzyme

Question 4

What is a product?

Answer 4

molecule made in a chemical reaction

Question 5

What is an active site?

Answer 5

binding region between substrate and enzyme

Question 6

What is induced fit?

Answer 6

the slight change in shape of an enzyme so that it better fits the substrate, however, the active site always fits the substrate exactly (reason for high selectivity)

Question 7

What is an enzyme inhibitor?

Answer 7

the prevention of a metabolic reaction by binding of some other material to the active site of an enzyme so that substrate no longer fits/has space to bind

Question 8

What is feedback regulation/inhibition?

Answer 8

when products of an chemical reaction reversibly inhibit the enzyme required for its production –> prevents cell from wasting resources

Question 9

Examples of drugs as enzyme inhibitors

Answer 9

1. Penicillin: blocks active site of enzyme that bacteria use in making cell walls
2. Ibuprofen: inhibits enzymes involved in sending pain signals
3. Cancer drugs: inhibit enzymes that promote cell division

Question 10

What are cofactors?

Answer 10

specific accessory molecules required for enzymes to function (ex. vitamin/mineral)

Question 11

What are the types of metabolic reactions

Answer 11

1. Catabolic: break down molecules into smaller units and may release energy (ex. digestion)
2. Anabolic: join molecular building blocks to form new molecules and may require energy (ex. construction of macromolecules using monomers as building blocks)

Question 12

ATP

Answer 12

• 3 phosphate groups, sugar base, and nitrogenous base
• stores energy between bonds –> breaking these bonds releases energy (loss of a phosphate)
• -> phosphate transfer results in 3 types of work (mechanical, chemical, and transport)

Question 13

What is chemical energy?

Answer 13

A type of potential energy, arises when the arrangements of atoms and can be released by a chemical reaction

Question 14

What is cellular respiration?

Answer 14

energy-releasing chemical breakdown of molecules and the storage of that energy in a form that the cell can use to perform work

Question 15

What are transport proteins?

Answer 15

membrane proteins that help move substances across a cell membrane

Question 16

What is diffusion?

Answer 16

movements of molecules spreading out evenly into the available space, from a region of high concentration to one of low concentration

Question 17

What is passive transport?

Answer 17

diffusion across a membrane, with no energy expenditure

-selectively permeable, only certain substances are allowed to pass through the membrane

Question 18

What is facilitated diffusion?

Answer 18

when a substance (ex. ions, large hydrophilic molecules) cannot cross a membrane spontaneously and must be transported via proteins
-target specific (glucose transporter will only transport glucose)

Question 19

What is osmosis?

Answer 19

diffusion of water across a selectively permeable membrane

Question 20

What is a solute?

Answer 20

a substance that is dissolved in a liquid solvent

Question 21

What does hypertonic mean?

Answer 21

having a higher concentration than another solution

Question 22

What does hypotonic mean?

Answer 22

having a lower concentration than another solution

Question 23

What does isotonic mean?

Answer 23

having solutions of equal solute concentration

Question 24

What is osmoregulation?

Answer 24

the control of water balance (ex. failure to do so –> dehydration/overhydration)

Question 25

What is active transport?

Answer 25

diffusion that requires a cell to expend energy to move molecules across a membrane
-ATP drives a transport protein that pumps a solute against the solute’s concentration gradient (opposite of natural flow)

Question 26

What is exocytosis?

Answer 26

secretory proteins exiting the cell by transport vesicles which fuse with plasma membrane and spill contents into cell

Question 27

What is endocytosis?

Answer 27

cell taking material in via vesicles that bud inward

Question 28

What is phagocytosis?

Answer 28

“cellular eating,” cell engulfing a particle and packaging it within a food vacuole

Question 29

What is the sodium-potassium pump?

Answer 29

pump that moved sodium ions from inside cell to outside of cell and potassium in opposite direction