Transcript THE CHEMICAL CONTEXT OF LIFE

Chemistry of Life
CHAPTER 2
Sections 1-4
Bellringer Q
A butterfly is made of atoms. This flower is made
of atoms. Atoms make up the breakfast you ate
and the skin on your feet. Atoms make up the
pages of the book and the desk you are sitting
on.
• Soo… Why are all these things different?
Key Terms- Chapter 2, Section 1
• Atom- smallest unit of matter that can’t be broken
by chemicals. Made of nucleus and electron cloud.
• Nucleus- center of an atom
– Protons- positive charge
– Neutron- no charge
• Electron cloud- space surrounding nucleus
– Electron- negatively charged particle
Protons
and
Neutrons
are here
The Atom
Energy Levels in an Atom
• Electrons are found in Energy Levels
• 1st energy level holds max of 2 electrons
• 2nd energy levels holds max of 8 electrons
Foldable Periodic Table Activity
Elements
Q. Why do they call He, Cm, and Ba the
'medical elements'?
A. Because, if you can't helium or curium,
you barium!
Percents of Elements found
in the Human Body
Calcium Phosphorus
1%
2%
Other Elements
Nitrogen
1%
3%
Hydrogen
10%
Carbon
19%
Oxygen
64%
1. Which 4 elements are most common in the
human body?
2. What do you know about these 4 elements?
Very Important Elements
• Four elements, Hydrogen, Oxygen, Carbon, Nitrogen make up
96% of living matter
Nitrogen
normal
Nitrogen
deprived
About Periodic Table-Key info!
• Atomic # : number of protons
• Atomic mass: number of protons + neutrons
• Electrons are what are “traded”
• # of electrons in outside shell is determined by the
column number (get rid of leading “1’s”)
• Total # of electrons = Total # of protons = Atomic #
Electrons
• When an atom absorbs energy,
electrons get excited and “jump up”
to a higher energy level.
• When an atom loses energy,
electrons “fall back” to a lower
energy level. Energy is given off as
a form of light.
• Exciting and then giving off energy
as electrons “falling back” to a
lower energy level is what makes
neon signs glow.
Explore the Periodic Table
1. What do you notice about the atomic numbers of
the elements as you move across a row?
2. What do you notice about the mass numbers of
the elements as you move across a row?
3. What is the atomic mass and number of an atom
that has 6 protons, 8 neutrons, and 6 electrons?
What element is that?
Isotopes
• Isotopes- atoms of same element,
different numbers of
neutrons.
• Ex. Carbon-12 vs Carbon-14
(radioactive, decaying form used in
fossil dating)
• Ex. Nitrogen-14 vs. Nitrogen-15
(found more in marine sources)
• Ex. Cobalt-60 (used in treating
cancer patients and PET scans)
Atomic number & Mass practice
• Carbon-12
– How many protons?
– How many electrons?
– How many neutrons?
6
6
6
• Carbon-14.
– How many protons?
– How many electrons?
– How many neutrons?
6
6
8
Compounds
• Compound: substance that is composed of
two or more different elements
that are chemically combined
• Ex. NaCl, MgSO4, etc
• Compounds form by bonding, making the
compound more stable than individual
atoms.
Biology is based on Chemistry
• Nitric Oxide (NO) is a compound
• It is an important chemical for:
–
–
–
–
Ewe – Lamb (mom to baby) recognition
Mouse memory retention
Lowering of blood pressure in humans
Cell to cell Communication
Octet Rule
• Object of the game is to get a full energy
level
– Remember: 1st shell full with 2 e– Remember: 2nd shell full with 8 e-
• This makes the atom stable
• Unstable atoms react violently and bond in
order to get stable
http://theodoregray.com/PeriodicTable/Stories/011.2/Videos/
SodiumParty06.html
From a 145 gram total of sodium
Moral of bonding… It is good =)
+
sodium metal
chlorine gas
table salt
• Sodium reacts violently with water
• Chlorine is poisonous gas used as weapon in WWII
• Table salt is used in our bodies, as a preservative, and
in our food. So safe we use it everyday!
Bonding, pg 29
• Covalent Bond- shares electrons. Strongest bond.
– Ex. H2O (water), CO2 (carbon dioxide), O2
(oxygen)
Bonding, pg 30
• Ionic Bond- steals
electrons. Ex. NaCl
– Ion- charged particle.
Can be + or –
– Opposites attract!
Balloon Demo
Why it works…. The + charges of your hair are attracted to the –
charges in the balloon…. Cool!
Bonding Comic
Bonding, pg 29
• Hydrogen Bonds- attraction between
hydrogen atoms
• Ex. H2O
• Hydrogen bonds are NOT true bonds
Mixtures
• Mixture: a combination
of substances in which
you can spot individual
parts
• Ex. Italian salad
dressing, trail mix, etc.
Solution
Solute + Solvent = Solution
• Solute- solid particles that dissolve
• Solvent- what causes dissolving
• Solution- homogenous mixture made from solute
and solvent
– Concentrated: when there is more solute than solvent
– Diluted: when there is more solvent than solute
Soluble- “able to be dissolved”
A physicist, biologist and a chemist were going to the ocean
for the first time.
The physicist saw the ocean and was fascinated by the waves.
He said he wanted to do some research on the fluid
dynamics of the waves and walked into the ocean.
Obviously he drowned and never returned.
The biologist said she wanted to do research on the flora and
fauna inside the ocean and walked inside the ocean. She
too, never returned.
The chemist waited for a long time and afterwards, wrote the
observation, "The physicist and the biologist are soluble in
ocean water".
Water and Solutions- pg 31
How does water get to the tops of tall trees?
• Cohesion- attraction between the same
substance
• Adhesion- attraction between different
substances
Colored water drop demo
Polarity
• Polar molecules- have unequal sharing of
electrons in an atom
• Polar molecules dissolve easily in water
– Ex. salt, sugar, coco powder
• Nonpolar molecules do not dissolve well in
water
– Ex. oil, butter, lard, etc
pH Scale
• Based on logarithmic
scale
• pH of 3 is 10x
stronger than pH of 4
• pH of 3 is 100x
stronger than pH of 5
Acids and Bases-Differences- pg33
•
•
•
•
•
Acid
Tastes sour
pH < 7
Turn litmus paper red
More H+ (hydrogen)
Ex. Lemon juice,
tomatoes, vinegar
•
•
•
•
•
Bases
Tastes bitter
pH > 7
Turn litmus paper blue
More OH- (hydroxide)
Ex. Antacid, soap,
ammonia
Acids & Bases Similarities
• Acid & Bases conduct electricity
• Acids & Bases react with each other to produce salt
and water (this neutralizes the solution)
More about pH
• pH of 7 is “neutral”
• Most water (also rain/snow) has pH of 6.5
• “Acid rain” has pH less than 5
Acid rain demo
(chalk/limestone & vinegar)
Acid Rain
• Low pH kills fish eggs & some insects
• Soil enzymes are destroyed- decomposition
slows
• Most plants can’t grow in very acidic soil
• Ancient buildings, statues, gravestones erode
Chemistry of Cells- Chapter 2,
Section 3
1.
2.
3.
4.
4 Major Macromolecules
Carbohydrates
Lipids
Proteins
Nucleic Acids
Macromolecules= large molecule
• Macromolecules are made by stringing together of a bunch of “Monomers” together.
• These little molecules are joined together by dehydration synthesis (water is removed) to
make Macromolecules
• Polymers are large molecules consisting of many repeating subunits of monomers
(remember: Gak!)
• To break these macromolecules apart (disassemble) water is added and the molecule
separates.
Carbohydrates= “sugar or starch”
• Monosaccharides- “one sugar molecule”
– Glucose- made by green plants
– Galactose- found in milk
– Fructose- fruit sugar; VERY sweet!
Carbohydrates- Disaccharides
• Disaccharides- “two
sugar molecules”
– Sucrose- table sugar
– Maltose- malt
“Beer” sugar
– Lactose- milk sugar
Carbohydrates- Polysaccharides
• Storage Polysaccharides
– Starch in plants
– Glycogen in animals
• Structural Polysaccharides
– Cellulose- major plant cell wall part
– Chitin – major animal shell compound
Lipids= “fats, oils, wax, steroids”
• Made of 3 fatty acids + 1 glycerol
• Can be saturated (have single bond). Solid at
room temperature.
– Ex. Butter, lard, margarine
• Can be unsaturated (have double bond). Liquid at
room temperature.
– Ex. olive oil, vegetable oil, etc
Lipids important for cells
• Phospholipid bi-layer- surrounds cells
– Hydrophobic “water fearing”
• Fatty acid tail
– Hydrophilic “water loving”
• Phosphate head
Lipids important for cells
• Sex hormones
– Estrogen, testosterone, etc
Discussion: anabolic steroids
Discussion: fat-soluble vitamins
(Vitamins A, D, E and K )
Proteins= Enzymes
• Made of chains of amino acids
• Do basically “everything”
– Contract muscles, move oxygen, support cells,
insulin to break down sugar, protect against
disease, etc
• End in “-ase”
– Catalase, Amalase, Protease, Lactase, etc
How Proteins Work
• Enzymes bind to the substrate to break it apart
• Enzymes speed up reaction by LOWERING the
activation energy needed to start the reaction.
Nucleic Acids= DNA or RNA
• Made of strings of nucleotides
• Nucleotides are made of
– Sugar
– Phosphate
– Nitrogen Base (adenine, thymine, cytosine, or guanine)
• Stuck together by
hydrogen bonds