Chapter 5: The Working Cell

Front 1

Energy

Back 1

The capacity to cause change or to perform work

Front 2

Kinetic Energy

Back 2

Energy that is actually doing the work (light and heat)

Ex: A bicycle in motion, water moving down river

Front 3

Potential Energy

Back 3

Stored energy (chemical)

Ex: A bicycle resting at top of hill, water behind a dam

Front 4

Thermodynamics

Back 4

The study of energy transformations that occur in a collection of matter

Front 5

1st Law of Thermodynamics

AKA: The Law of Energy Conservation

Back 5

The total amount of energy in the universe is constant. Energy can be transferred and transformed, but not created or destroyed

Front 6

2nd Law of Thermodynamics

Back 6

As energy is converted from one form to another, there is an increase in disorder or randomness

Front 7

Entropy

Back 7

The amount of disorder in a system

(More heat generated, the more entropy increases)

Front 8

How do living organisms maintain order despite entropy???

Back 8

Organisms take in energy from the surroundings to maintain internal order

Front 9

Endergonic Reactions

Back 9

"Energy Inward"

Requires a net input of energy - starts with reactant molecules of low potential energy & yields products with high potential energy

Ex: Photosynthesis

Front 10

Exergonic Reactions

Back 10

"Energy Outward"

Releases energy - starts with reactants whose covalent bonds contain more energy than those in the products

Ex: Burning, Cellular Respiration

Front 11

Burning vs Cellular Respiration

Back 11

Burning is a one-step process that release all energy at once, given off as heat. Cellular respiration has many steps. Some energy immediately lost as heat, but a substantial amount is converted to chemical energy of molecules, like ATP

Front 12

Cellular Metabolism

Back 12

The sum of all endergonic and exergonic reactions within the cell

Front 13

Energy Coupling

Back 13

Using energy released from exergonic reactions to drive endergonic reactions

Front 14

3 parts of an adenosine triphosphate (ATP) molecule

Back 14

* Adenine- a nitrogenous base

* Ribose- a 5 carbon sugar

* A chain of 3 phosphate groups

Front 15

Hydrolosis with ATP

Back 15

Removing a phosphate from ATP by hydrolosis (adding water) is an exogonic reaction that releases energy- coupled with and provides energy for endergonic reactions

Front 16

Dehydration Synthesis with ATP

Back 16

Adding the phosphate group to ADP to make ATP by dehydration synthesis (removing water) is an endergonic reaction that stores energy- coupled with and takes energy from exergonic reactions

Front 17

Phosphorylation

Back 17

The transfer of a phosphate group to another molecule

Front 18

Energy of Activation

Back 18

The amount of energy that reactants must absorb before a chemical reaction will start

Front 19

What type of molecule is an enzyme?

Back 19

Protein

Front 20

Enzymes and reaction rates

Back 20

Enzymes speed up reactions by lowering the Energy of Activation

Front 21

Enzymes = catalysts

Back 21

Enzymes are catalysts b/c they participate in reactions without being changed into different molecules

Front 22

Why can't an enzyme change an endergonic reaction into an exergonic one??

Back 22

It has no effect on the relative energy content of products versus reactants

Front 23

Substrate

Back 23

The substance that an enzyme acts on

(a reactant in a chemical reaction)

Front 24

Active Site

Back 24

The small part of an enzyme that binds to the substrate

Front 25

Induced Fit

Back 25

An enzymes active site's slight change in shape as it embraces it's substrate. In its new shape, the active site catalyzes the reaction

Front 26

3 factors that effect enzyme activity

Back 26

1. Temperature

2. Salt Concentration

3. pH level

Front 27

How temperature effects enzyme activity

Back 27

Affects molecular motion / warmer temps speed rate of contact / temp gets too high, it denatures enzyme: changing it's shape and destroying function

Front 28

How salt concentration effects enzyme activity

Back 28

Salt ions interfere with some of the chemical bonds that maintain protein structure

Front 29

How pH effects enzyme activity

Back 29

Too many hydrogen ions in an acid (or too many hydroxide in a base) can interfere w/some of the chemical bonds that maintain protein structure

Front 30

Cofactor

Back 30

An inorganic, non-protein substance that works with an enzyme in a reaction

Ex: zinc, iron, copper

Front 31

Coenzyme

Back 31

An organic molecule

Ex: vitamins

Front 32

Inhibitor

Back 32

A chemical that interferes with an enzymes activity

Front 33

Competitive Inhibitor

Back 33

Resembles normal substrate- will block substrate from entering active site

Front 34

Non-competitive Inhibitor

Back 34

Binds to enzyme somewhere other than active site, changing the shape of enzyme, so that the active site no longer fits substrate

Front 35

Irreversible Inhibition

Back 35

When covalent bonds form between inhibitor and enzyme

Front 36

Reversible Inhibitor

Back 36

When weak bonds (such as hydrogen bonds) form between inhibitor and enzyme

Front 37

Enzyme Inhibitors Negative Feedback

Back 37

Occurs when an enzyme's metabolic reaction is inhibited by the products of the reaction

Front 38

Inhibitor Poison

Back 38

When an irreversible inhibitor prevents an enzyme from catalyzing a crucial metabolic reaction

Front 39

Why is plasma membrane described as a fluid mosaic?

Back 39

Has diverse protein and phospholipid molecules embedded in it's fluid that can drift within membrane

Front 40

Membrane's Selective Permeability

Back 40

It allows some substances to cross more easily than others, and blocks some substances all together

Front 41

How do proteins in plasma membrane help hold membrane in place?

Back 41

Proteins may be linked to the cytoskeleton (inside cell) and to extracellular matrix (outside cell)

Front 42

Role of Cholesterol Molecules in Animal Cells

Back 42

Help stabilize the phospholipids at body temperature, but helps keep the membrane fluid at lower temperatures

Front 43

Glycoprotein

Back 43

A protein with attached sugars / a molecule with carbohydrate components found on outside surface of membrane / functions as cell ID tags that are recognized by other cells

Front 44

Glycolipid

Back 44

A lipid with attached sugars / a molecule with carbohydrate components found on outside surface of membrane / functions as cell ID tags that are recognized by other cells

Front 45

Functions of various membrane proteins

Back 45

- Attach membrane to cytoskeleton and external fibers

- Provide ID tags

- Form junctions between adjacent cells

- Are enzymes involved in catalytic reactions

- Receptors for chemical messengers from other cells

- Signal transduction

- Transports substances across membrane

Front 46

Main structural component of membranes

Back 46

Phospholipids: has a polar, hydrophilic head and a non-polar, hydrophobic tail

Front 47

Why do phospholipids form a bilayer in aqueous solutions?

Back 47

Shields hydrophobic tails from water, and exposed hydrophilic heads to water

Front 48

Ability of Polar Molecules to pass through membranes

Back 48

Dependent on the protein carriers that are present in the membrane

Front 49

Ability of Non-Polar Molecules to pass through membranes

Back 49

Are soluble in lipids, can easily pass through membrane

Front 50

Diffusion

Back 50

Tendency for particles of any kind to spread out evenly in an available space

Front 51

Concentration Gradient

Back 51

The change in concentration of molecules in an area / when a concentration gradient exists molecules will move from higher to lower by diffusion until equilibrium is reached

Front 52

Passive Transport

Back 52

Diffusion of a substance across membrane without use of energy

Front 53

2 molecules that move across membranes by passive transport

Back 53

- Oxygen

- Carbon Dioxide

Front 54

Osmosis

Back 54

Diffusion of water molecules across a selective permeable membrane

Front 55

Isotonic

Back 55

Solution outside cell has same solutes as the inside

Net movement of water is zero, cell's volume remains constant

Front 56

Hypotonic

Back 56

Solution outside cell has less solutes as the inside

Water moves into cell via osmosis, cell becomes larger

Front 57

Hypertonic

Back 57

Solution outside cell has more solutes as the inside

Water moves out of cell via osmosis, causing cell to shrivel

Front 58

Osmoregulation

Back 58

The control of water balance

Front 59

Plants in a hypotonic solution

Back 59

The net inflow of water keeps pressure exerted against the inside cell wall, making the cell turgid

Front 60

Facilitated Diffusion

Back 60

The passage of a substance across a membrane down it's concentration gradient, with aid of specific transport proteins

Front 61

Aquaporins

Back 61

Proteins with polar channels that allow water to move faster across membrane rather then if it had to pass through lipid bilayer through regular diffusion

Front 62

Active Transport

Back 62

The use of ATP to move molecules across a membrane against concentration gradient and requires specific transport proteins / an endergonic process

Front 63

Sodium-Potassium Pump

Back 63

The active transport system that helps nerve cells generate nerve signals

Front 64

Exocytosis

Back 64

Export of macromolecules out of cell

Front 65

Endocytosis

Back 65

Import of macromolecules into cell

Front 66

3 types of Endocytosis

Back 66

* Phagocytosis

* Pinocytosis

* Receptor-mediated Endocytocis

Front 67

Phagocytocis

Back 67

"Food Eating"

Front 68

Pinocytosis

Back 68

"Cellular Drinking"

Front 69

Receptor-mediated Endocytosis

Back 69

A receptor is located in pit on outside membrane. Receptor binds to specific molecules outside of cell