3.1,2,3,4 Contd: Cells And Energy

Question 1

Living cells have a constant flow of _____ in an out of the cell membranes, meaning that they are not at _____.

Answer 1

• materials

- equilibrium

Question 2

What are the three types of work that cells perform?

Answer 2

Mechanical, transport and chemical

Question 3

What is mechanical work?

Answer 3

Movement ( such as beating cilia, movement of chromosomes, contraction of muscle cells)

Question 4

What is transport work?

Answer 4

Pumping substances across membranes against spontaneous movement

Question 5

What is chemical work?

Answer 5

Synthesis of molecules (ex, building polymers from monomer)

Question 6

What is ATP?

Answer 6

Molecules that organisms use as a source of energy to perform work

Question 7

How exactly does ATP power cellular work?

Answer 7

1. ATP couples exergonic rxn to endergonic rxn to power cellular work
2. Exergonic process then drives the endergonic process
3. Then organisms get energy by breaking the bond between the 2 and 3 phosphate in a hydrolysis reaction

Question 8

What occurs in phosphorylation?

Answer 8

The released phosphate moves to another molecule to give energy
Ex. ATP to ADP

Question 9

This was not in the notes, but why is cellular respiration exergonic, even though you need energy from the exergonic process to produce ATP?

Answer 9

• synthesis of ATP is endergonic, but cellular respiration as a whole is exergonic because more energy is released

Question 10

The Law of thermodynamics tells us a reaction is ____, but it does not describe what?

Answer 10

• spontaneous

- rate of reaction

Question 11

Some spontaneous reactions move slow that it would be impossible for cells to utilize them efficiently. An example is the hydrolysis of sucrose to glucose, which would take 1000 years. What speeds up these reactions, and why?

Answer 11

• enzymes are macromolecules that catalyzes reactions by lowering activation energy

Question 12

Are enzymes consumed by reactions?

Answer 12

No, they can be reused over and over

Question 13

Enzymes are a type of ___ that usually end in___.

Answer 13

• protein

- ase

Question 14

What is an enzyme’s reactant called?

Answer 14

Substrate

Question 15

What is an active site?

Answer 15

Area on enzyme for substrate to bind

Question 16

Substrates are held in active site by ____ interactions.

Answer 16

Weak

Question 17

What is an induced fit?

Answer 17

• enzymes will change shape of their active site to allow the substrate to bind better

Question 18

What is enzyme catabolism?

Answer 18

Enzyme helps breakdown complex molecules

Question 19

Enzyme anabolism

Answer 19

Enzyme helps build complex molecules

Question 20

Since enzymea are proteins, their 3D shape is affected by different factors. What is their efficientcy affecfes by?

Answer 20

• temperature
• pH
• Chemicals
  THUS A CHANGE IN SHAPE INDICATES A CHANGE IN FUNCTION

Question 21

What are optimal conditions?

Answer 21

• the condition (Temp and pH) that allow enzymes to function optimally (at their best)

Question 22

The rate of enzyme activity ____ with temperature (due to collision) up to a certain point. What happens after this?

Answer 22

• increases

After a certain point, enzyme will DENATURE

Question 23

What happens if an enzyme is out of their normal pH range?

Answer 23

• cause weak hydrogen bonds in the enzyme to break, changing the shape of the enzyme

Question 24

What are enzyme cofactors? (3)

Answer 24

• non-protein molecules that assist enzyme function
• inorganic cofactors consist of metals
  - can be bound loosely or tightly

Question 25

What is a holoenzyme?

Answer 25

Enzyme with the cofactor attached

Question 26

What are coenzymes?

Answer 26

Organic factors, such as vitamins

Question 27

What are enzyme inhibitors?

Answer 27

Reduce the activity of specific enzymes

Question 28

How can inhibition be permanent?

Answer 28

• inhibitor binds with covalent bonds

Ex. Toxins or poisons

Question 29

How can inhibition be reversible?

Answer 29

Inhibitor binds with weak interactions

Question 30

What do competitive inhibitors do? How can inhibition be reversed?

Answer 30

• they reduce the enzyme activity by blocking substrates from binding to the active site
• inhibition can be reversed with increased substrate concentration

Question 31

What do noncompetitive inhibitors do? What type of inhibition is this?

Answer 31

• bind to an area other than the active site (allosteric site) which changes shape of active site, preventinf substrates from binding
• type of allosteric inhibition

Question 32

How does a cell regulate its metabolic pathways? (2)

Answer 32

• Control where and when enzymes are active

- switch genes that code for enzymes on or off