Transcript Features of Life and the Cell

Chapter 2
Chemistry of Life
Section 2.1 – Atoms, Ions and Molecules
Section 2.2 – Properties of water
Section 2.3 – Carbon-based Molecules
Section 2.4 – Chemical Reactions
Section 2.5 - Enzymes
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Atoms, Ions and Molecules
Living things and non-living things are
made of matter
- Matter – anything that occupies
space and has mass
- Mass – the amount of matter in an
object
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Matter is made up of atoms.
- Atom – smallest particle of matter that
can exist and still have the properties
of that particular kind of matter.
- 3 Parts make up an atom
1. proton – positive charged particle
Affects the IDENTITY of element
2. electron – negative charged particle
affects reactivity
3. neutron – neutral/ no charge
affects mass
- Atoms make up elements
3
Atoms make up elements
-
Element – substance consisting entirely of one type
of atom.
- Cannot be broken down into simpler
substances.
- Just 4 elements make up 96% of the human
body’s mass
-
-
Carbon (C)
Oxygen (O)
Nitrogen (N)
Hydrogen (H)
Elements are found on the periodic table.
4
Sodium, reacts violently with water
http://ruminatingdude.blogspot.com/2005/08/justifying-what-we-teach-in-hs.html
Video
Chlorine gas used in chemical warfare is
Deadly stuff!
5
But chemically combined…
NaCl = Table salt!
Compound – two or more elements that are
chemically combined
- Can be broken down into smaller
substances
Ex: water – made up of hydrogen and
oxygen = H2O
NaCl - table salt (sodium and chlorine)
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Ion - Is an atom that has gained or lost an
electron,
- Anion – The atom gains an electron
- Cation – the atom loses an electron
 Ex.
Li+
 Ex. F Ex. Ca+
 Ex. O-
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Compounds

Ionic bond: Metal + Non metal
(transferred electrons)
 Strongest

bond
Covalent bond: Nonmetal + nonmetal
(shared electrons)
 Second
strongest bond
 Molecule - The smallest part of a covalent
compound that still has all the properties of
the compound

Example: the smallest unit possible of water
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Checkpoint

What distinguished one element from another?

Describe how an ionic compound is formed and
how a covalent compound is formed.

What is the difference between and ionic bond
and a covalent bond?
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2.2 Properties of Water

KEY CONCEPT
Water’s unique properties allow life to exist on Earth.
Life depends on hydrogen bonds in water.
• Water is a polar molecule.
– Polar molecules have slightly charged regions.
+
H
O
H
+
– Nonpolar molecules do
not have charged regions.
_
+
H
O
H
_
- Hydrogen bonds form between slightly
positive hydrogen atoms and slightly
negative atoms.
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+
Properties of water
1. High Specific Heat- water resists changes
in temperature.
 Example:
Ocean Temp
2. Cohesion – Attraction of molecules of the
same substance.

1 molecule of water sticking to another molecule
of water (droplets)
3. Adhesion – Attraction of molecules of
different substances.
 Water
molecules sticking to other things.
 Water sticking to glass.
 Water sticking to the inside stem of a plant.
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• Hydrogen bonds are responsible for four
important properties of water.
1. Polarity
2. High specific heat
3. Cohesion
4. Adhesion
Two additional properties of water:
5. Capillary Action - the ability to move upward against
gravity. Due to the combined properties of adhesion and
cohesion.
6. Surface Tension - because water is polar and bonds with
other water molecules it creates hydrogen bonds that create
a small amount of tension on the surface.
Properties of water video
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Many compounds dissolve in water.
• A solution - when one
substance dissolves in
another.
– homogeneous mixture.
– Solvents dissolve other
substances.
– Solutes dissolve in a
solvent.
solution
• “Like dissolves like.”
– Polar solvents
dissolve polar solutes.
– Nonpolar solvents
dissolve nonpolar
solutes.
– Polar substances and
nonpolar substances
generally remain
separate.
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Some compounds form acids or bases.
• An acid releases a
hydrogen ion when it
dissolves in water.
– high H+ concentration
– pH less than 7
stomach acid pH between 1 and 3
more acidic
• A base removes
hydrogen ions from a
solution.
– low H+ concentration
– pH greater than 7
bile pH between 8 and 9
more basic
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• A neutral solution has a pH of 7.
pure water pH 7
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Check Point

How do polar molecules form hydrogen bonds?

What determines whether or not a compound
will dissolve in water?

Compare acids and bases
Name one example, from everyday life, of
adhesion and cohesion.
 Hank water video

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2-3 Carbon Based Molecules- Organic

Carbon atoms have unique bonding properties.
 Carbon
forms covalent bonds with up to four other
atoms, including other carbon atoms.
 Carbon-based molecules have three general types
of structures.
– Straight chain, branched or rings
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Carbon-Based Molecules
• Most Living things are made up of Carbon.
(Organic)
• Many carbon-based molecules are made of
many small subunits bonded together.
• Monomer = 1 molecule.
• Polymer = many monomers bonded together.
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Four Main types of carbon
based molecules

1. Carbohydrates


2. Lipids


Fats and oils
3. Nucleic Acids


Sugars and starches
DNA and RNA
4. Proteins

Amino acids
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1. Carbohydrates





Molecules made of C, H, O (1:2:1)
Broken down into usable chemical
energy that the body can use.
Include sugars and starches
Monosaccharides include simple
sugars (C6H12O6) – glucose, fructose,
galactose
Polysaccaharides
 Glycogen, starches, and cellulose
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Carbohydrates - Function
Carbohydrates can be broken down to
provide energy for cells.
 Some carbohydrates are part of cell
structure.

Polymer (starch)
Starch is a polymer of
glucose monomers that
often has a branched
structure.
Polymer (cellulose)
monomer
Cellulose is a polymer
of glucose monomers
that has a straight, rigid
structure
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Carbohydrates

Polysaccharides:
– storage in animals
(glucose/sugar)
 Starches – made and stored by plants.
 Cellulose – makes up the cell wall of a plant
- structure
 Glycogen
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Biochemical Reactions -
•
Dehydration Synthesis –anabolic reaction polymers are formed
monomer + monomer  polymer + water
•
Example:
•
•
monosaccharide + monosaccharide  disaccharide + water
Hydrolysis –large molecules ( polymers) broken
into simpler ones (monomers)
polymer + water  monomer + monomer
Example
disaccharide + water  monosaccharide +monosaccharide
2. Lipids
Molecules made of C, H, O no fixed ratio
 Store large amounts of chemical energy in
organisms.
 Include fats, oils, waxes and cholesterol
 Fats – found in foods such as meat and butter.
 Oil – olive oil, peanut oil
 Cholesterol – your body needs a certain
amount to function but
too much can cause
problems.

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Lipids

Lipids are nonpolar molecules
 -fats,
oils, and cholesterol.
– contain carbon chains called fatty acids.
– fatty acids bonded to glycerol.
Triglyceride
25
Lipids: structure
• Fats and oils have different types of fatty
acids.
– saturated fatty acids (single bonds)
– unsaturated fatty acids (at least one double bond
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Lipids: Functions
–
broken down as a source of energy
– make up cell membranes
– used to make hormones
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• Phospholipids make up all cell
membranes.
– Polar phosphate “head”
– Nonpolar fatty acid “tails”
Phospholipid
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3. Protein






Molecules made of C, H, O and N
A protein is a polymer made of monomers called
amino acids.
Organisms use 20 different amino acids to
build proteins.
Your body makes 12 of the 20 amino acids.
The rest come from foods you eat such as
meat, beans and nuts.
Proteins differ in the number and order of amino
acids.
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Proteins
– 20 different amino acids are used to
build proteins in organisms.
– differ in side groups, or R groups.
– linked by peptide bonds.
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Protein
Protein is required by the body for the growth,
maintenance and repair of all cells.
 Protein is a major component of all muscles,
tissues and organs.
 Needed for metabolism, digestion and the
transportation of nutrients and oxygen in the
blood.
 The main nutrient that keeps our hair shiny
and healthy, our nails strong, our skin fresh and
glowing and our bones strong and healthy.

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4. Nucleic Acids
Molecules made of C, H, O, N and P
 Nucleic acids are polymers of monomers
called nucleotides.
– Nucleotides are made of a sugar,
phosphate group, and a nitrogen
base.

A phosphate group
deoxyribose (sugar)
nitrogen-containing molecule,
called a base
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Nucleic Acids
There are 2 types
 DNA and RNA
 DNA - stores the information
for putting amino acids
together to make proteins.

 Deoxyribo

Nucleic Acid
RNA – helps to build
proteins.
 Ribo
Nucleic Acid
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Nucleic Acids
– DNA stores genetic information.
– RNA builds proteins.
DNA
RNA
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Check Point

What is the relationship between a monomer
and a polymer?

How are nucleic acids and proteins polymers?

How are carbohydrates and lipids similar?
Different?

How does the property of carbon account for
the variety of organic compounds?
35
2.4 Chemical Reactions
Bonds break and form during chemical reactions.
• Chemical reactions change substances into different ones by
breaking and forming chemical bonds.
– Reactants: changed during a chemical reaction.
– Products: made by a chemical reaction.
• Bond energy - the amount of energy that it takes to break a
bond.
– Energy is added to break bonds.
– Energy is released when bonds form.
• A reaction is at equilibrium when reactants and products form
at the same rate.
CO2 + H2O
H2CO3
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Chemical reactions release or absorb energy.
• Activation energy - amount of energy needed to
start a chemical reaction.
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• Exothermic reactions release more energy than
they absorb.
– Reactants have higher bond energies than products.
– Excess energy is released by the reaction.
38
• Endothermic reactions absorb more energy than
they release.
– Reactants have lower bond energies than products.
– Energy is absorbed by the reaction to make up the
difference.
39
Check point

Hydrogen peroxide breaks down into water and
hydrogen gas. Explain why this is a chemical
reaction. What are the reactants? What are the
products?

How do endothermic and exothermic reactions
differ?
40
2.5 Enzymes


A catalyst lowers activation energy.
Catalysts are substances that speed up chemical
reactions.
 decrease activation energy
 increase reaction rate
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Enzymes
Enzymes allow chemical reactions to occur under
tightly controlled conditions.
• Enzymes are catalysts in living things.
– Enzymes are needed for almost all processes.
– Most enzymes are proteins.
42
Enzymes
• An enzyme’s structure allows only certain reactants
to bind to the enzyme.
– Substrates - reactant
substrates
(reactants)
– active site
enzyme
Substrates bind to an
enzyme at certain places
called active sites.
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Enzymes
• The lock-and-key model helps show how
enzymes work.
– substrates brought together
– bonds in substrates weakened
Substrates bind to an
enzyme at certain
places called active
sites.
The enzyme brings
substrates together
and weakens their
bonds.
The catalyzed reaction forms
a product that is released
from the enzyme.
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Check Point

How does a catalyst affect the activation energy
of a chemical reaction?

Describe how the interaction between an
enzyme and a substrate changes a chemical
reaction

Some organisms live in very hot or acidic
environments. Would their enzymes work in a
person’s cells?
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