Energy And Life

CHAPTER 5

5.1 CELLS AND CHEMISTRYA. CHEMICAL REACTIONS IN LIVING

THINGS

1. Make or break chemical bonds

a. Dive all life activities in cells

b. METABOLISM refers to the

millions of chemical reactions

taking place in a living thing

at any given moment

2. Chemical Reactions store or release energya. EXERGONIC Release energy (OUT) Energy available to make

proteins and other

molecules

b. ENDERGONIC Store energy (IN) EX. Formation of glucose in

plants by photosynthesis

B. ACTIVATION ENERGY

1. Minimum amount of energy required to

start a chemical reaction

2. Cells must carry out specific reactions

at certain times at normal temperatures

a. High temperatures

trigger many reactions

different reactions at once

(Too Random)

b. High temperatures

destroy cells

C. ENZYMES

1. Protein molecules

2. Biological catalysts

a. Lower activation energy allowing

reactions to occur quickly at normal

temperatures

b. EX. Without digestive

enzymes a single meal

would take at least 50

years to digest

3. Enzymes are specific

a. Guide only one type of cell reaction

b. Named by adding the suffix “ase” to the

reactant

4. Cells contain 1000’s of different enzymes

a. Enzymes active at any given moment

control what is happening in the cell

b. Not all cells contain the same enzymes

ENZYME

Protease

Lipase

REACTANT

Protein

Lipid

D. ENZYME ACTION

1. Enzymes speed reactions by binding to

specific molecules (SUBSTRATES)

2. Substrates may be

a. Broken-up (hydrolysis)

b. Bonded (dehydration synthesis)

3. Enzymes are NOT used up

a. Remain unchanged

b. Ready to be used again

E. FACTORS AFFECTING ENZYMES

1. Temperature

a. Function in a certain temperature range

b. Enzymes shut down during high fever

44º C (112º F) enzymes destroyed and

death usually results

2. Acidity (pH)

a. Cease too function if too high or low

b. Pepsin in stomach is an exception

3. Concentration of Enzyme

a. High concentration accelerates activity

b. Body’s way of controlling development

F. COENZYMES

1. Composed of Vitamins

a. Only needed in small amounts

b. Reusable

2. Non-protein helpers

a. Temporarily join with enzyme to change

active site

b. Act as transfer agents

5.2 ENERGY FOR CELLS

A. CELLS USE ENERGY FOR ALL LIFE PROCESSES

1. Energy is stored in

chemical bonds of food

2. Photosynthesis:

CARBON DIOXIDE

WATER GLUCOSESimple Sugar

OXYGEN

6CO2 6H2O C6H12O6 6O2++

B. CELLS RELEASE ENERGY IN SMALL STEPS

1. Energy is released gradually by a series of

enzyme reactions (Biochemical Pathway)

2. Some given off as heat and the rest is stored

C. ENERGY IS STORED IN ATP

1. ATP (Adenosine Triphosphate)

a. Cell’s currency

Each ATP stores a small amount of energy Just enough for most cell reactions

b. Structure of ATP

ADENINE

RIBOSE

THREE PHOSPHATES

(Amino Acid)

(Sugar)

(Phosphoric Acid)

A P P P

STRUCTURAL FORMULA of ATP

2. Releasing Energy from ATP

a. Released when bonds between phosphate

groups are broken

b. Forms ADP (Adenosine Diphosphate)

c.

A P P

EXOTHERMIC

ATP H2O +ADP P + ENERGYENZYME

+

d. Structure of ADP

ADENINE

RIBOSE

TWO PHOSPHATES

(Amino Acid)

(Sugar)

(Phosphoric Acid)

A P P

STRUCTURAL FORMULA of ADP

3. ATP – ADP CYCLE

a. Reverse process reforms ATP

b. P is converted to high energy phosphate

and rejoins

c. Like

recharging

a battery

ENDOTHERMIC

ATP H2O+ADP P + ENERGY +

P

ATP

ADP + P

E E

ATP - ADP CYCLE

5.3 CELLULAR RESPIRATION Process of releasing energy from food Takes place in cytoplasm and mitochondria Results in the formation ATP Can be completed with or without oxygen

GLUCOSE

Glycolysis

ATP

Without O2

PYRUVATE With O2

ATP

Fermentation

Oxidative respiration

ANAEROBIC RESPIRATION

A. RESPIRATION WITHOUT OXYGEN Takes place in the cytoplasm Takes 2 ATP start

2 ATPC6H12O6

GLUCOSE1. GLYCOLYSIS

a. Breaks down glucose

b. Carried out by all living things

2C2H3OCOOH + 4HPYRUVATE (Pyruvic Acid)

2. FERMENTATION

Break down of organic molecules

without O2

Divided into two kinds

a. LACTIC ACID FERMENTATION

2CH3CHOHCOOH + 4 ATPLATIC ACID

Occurs during muscle fatigue

Bacteria ferment milk (flavor of yogurt,

buttermilk, cottage cheese, sour cream) Bact eria ferment cabbage to make

sauerkraut

b. ALCOHOLIC FERMENTATION

2C2H5OH + 2CO2 + 4 ATP

ETHYL ALCOHOL

Yeasts in baking and brewing

CARBON DIOXIDE

AEROBIC RESPIRATIONB. RESPIRATION WITH OXYGEN

Starts in the cytoplasm Takes 2 ATP start

2 ATPC6H12O6

GLUCOSE1. GLYCOLYSIS

a. Starts without oxygen

b. Forms 2 PYRUVATE (Pyruvic Acid)

2C2H3OCOOH + 4H

2. OXIDATIVE RESPIRATION

2C2H3OCOOH + 4H + 6O2 6CO2 + 6H2O + 38 ATP

a. Uses oxygen to break down Pyruvate

b. Occurs in mitochondria

Numerous in active cells

EX. Brain and Muscle cells

c. Complex organisms could

not have evolved

without O2

GLUCOSE

Glycolysis

ATP

Without O2

PYRUVATE With O2

ATP

Fermentation

Oxidative respiration

AEROBIC VS. ANAEROBIC

AEROBICRESPIRATION

ANAEROBICRESPIRATION

2 ATP

4 ATP38 ATP

2 ATP

+36 +2