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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