Transcript Biochemistry

Biochemistry
Unit 5 Part 2
Chemistry
 Most things in the universe are made of
matter
 Matter- Everything that has mass and
volume
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Mass- the quantity of matter an object has
Weight- the pull of gravity on an object
Volume- the amount of space an object
occupies
Atoms
 All matter consists of atoms
 Smallest unit of matter, cannot be broken
down further
 An atom consists of a positively charged
nucleus (protons and neutrons) and
negatively charged electrons that
surround the nucleus in an electron cloud
 The number of protons and neutrons
equal the mass of the atom
 As long as there are the same
number of protons (positive charges)
and electrons (negative charges)
than the overall charge of the atom is
zero
Ions
 When there are an unequal number of
protons (positive charges) and electrons
(negative charges) the atom will have a
charge
 A charged particle is known as an ion
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A negative ion is known as an anion
A positive ion is known as a cation
Elements
 Pure substance made of only one kind of
atom
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Important elements in biology:
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Carbon (C)
Oxygen (O)
Hydrogen (H)
Nitrogen (N)
Phosphorus (P)
Sodium (Na)
Potassium (K)
Chorine (Cl)
Elements
Compounds
 When two or more elements join together
chemically, they form a compound
 Compounds are represented by chemical
formulas that show the kind and ratio of
atoms of each element in the compound
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Ex: NaCl is a compound formed by sodium
and chlorine in a 1 to 1 ratio
Ex: H2O (water) is a compound formed by
hydrogen and oxygen in a 2 to 1 ratio (for
every 2 hydrogens there is 1 oxygen in the
compound)
Chemical Formula
 Subscript after a symbol tell the number of atoms
of each element
 H20 has 2 atoms of hydrogen & 1 atom of oxygen
 Coefficients before a formula tell the number of
molecules
 3O2 represents 3 molecules of oxygen or (3x2) or
6 atoms of oxygen
Molecules
 Molecules are the
simplest part of a
substance that
retains all of the
properties of the
substance and
exists in a free
state
Water
 A special bond is formed between water molecules
that give water its unique properties called a
hydrogen bond
 Water molecules are polar, meaning they have an
uneven distribution of electrons within the molecule.
This causes one end of the molecule to be more
positive and the other end to be more negative.
 Hydrogen bonds are formed between the water
molecules when the more positive end of one
molecule is attracted to the more negative end of
another molecule (opposites attract)
Hydrogen bonds forming between
water molecules
Properties of Water
 Water heats more slowly and retains heat
longer than many other substances
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Water has a high specific heat which means it
takes a lot of energy to raise or lower the
temperature of water 1 degree Celsius
Because of this water is resistant to
temperature change
Properties of Water
 Cohesion- the attraction between substances
of the same kind
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Because water molecules are polar, they are
attracted to one another
This results in surface tension (a measure of
the strength of water’s surface)
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Surface tension accounts for an insect’s ability to
walk on water and why a paperclip will float on
water even if it is more dense
Properties of Water
 Adhesion- attraction between
different substances
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Because water molecules are polar,
they are attracted to other polar
substances
This results in capillary action which
is when water molecules will move
UP a thin glass tube
In nature you see this when water
moves up the roots and stems of a
plant into the leaves
Properties of Water
 Water is less dense as a solid
than as a liquid
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In liquid water the hydrogen
bonds are constantly being
broken and reformed
In Ice, the water molecules
form a crystal-like lattice in
which the molecules are at a
fixed distance. This leaves
“holes” between the water
molecules making them more
spread out
Ice floats, insulating bodies of
water and keeping animals
alive through the winter
Liquid
Solid
Properties of Water
 Water is the Universal Solvent
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Because water is polar, it dissolves many
substances, including ions
Solution- a mixture in which one or more
substances are evenly distributed
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Solvent- the medium doing the dissolving (water)
Solute- what is being dissolved (salt)
Acids and Bases
 pH scale is based on the concentration of hydrogen
ions (H+) in a solution
 A pH of 7 is neutral
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Ex: Water
 An acid has a HIGH concentration of hydrogen ions
 Between 0-7 on the pH scale
 Ex: Lemon, Vinegar and Milk
 A base has a LOW concentration of hydrogen ions
 Between 7-14 on the pH scale
 Ex: Antacid, Hand soap and Ammonia
 Each pH unit represents a 10X change in
concentration of hydrogen ions
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Ex: pH of 3 is 10 x 10 x 10 (1000 times) stronger than
a pH of 6
Acids and Bases
Acids pH 0-7
Bases pH 7-14
Chemistry of Cells
 Organic compounds contain carbon atoms
covalently bonded to other elements
 There are 4 types of organic
macromolecules in cells
1)
2)
3)
4)
Carbohydrates (sugars)
Lipids (fats)
Proteins
Nucleic Acids (DNA)
Macromolecules
 Macromolecules are large organic molecules
 Also called polymers
 Poly means many
 Made up of smaller “building blocks” called monomers
 Mono means one
 Polymers are formed by combining monomers in a
reaction called dehydration synthesis (removing a
water molecule)
 Polymers are broken down to monomers in a reaction
called hydrolysis (adding water)
Carbohydrates
 Sugars (end in “ose”
 Made of carbon, hydrogen and oxygen
combined in a 1:2:1 ratio
 Key source of energy in most foods, primarily
fruits, vegetables and grains (producers)
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Monosaccharide (one sugar unit)
Disaccharides (two sugar units)
Polysaccharides (complex sugars)
Monosaccharide
 One Sugar Unit
 Examples:
 Glucose (product of photosynthesis)
 Deoxyribose (sugar in DNA)
 Ribose (sugar in RNA)
 Fructose (Sugar in honey and fruits)
 Galactose (sugar found in dairy products)
Disaccharides
 2 sugars joined together by dehydration synthesis
 Examples:
 Sucrose = glucose + fructose (table sugar)
 Lactose = glucose + galactose (milk sugar)
 Maltose = glucose + glucose (malt sugar)
Polysaccharides
 Complex sugars formed by the dehydration
synthesis of simple sugars
 Examples:
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Starch (bread and potatoes)
Glycogen (beef muscle)
Cellulose (lettuce and corn)
Chitin (exoskeleton of insects)
Cellulose
Chitin
Lipids
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Composed of hydrogen, carbon and oxygen
Energy storage molecules
Building blocks are fatty acids and glycerol
Phospholipids make up the cell membrane
Not soluble in water
Examples:
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Fats
Phospholipids
Oils
Waxes
Steroid hormones
Lipid Function
Six functions of lipids:
1. Long term energy storage
2. Protection against heat loss
(insulation)
3. Protection against physical shock
4. Protection against water loss
5. Chemical messengers (hormones)
6. Major component of membranes
(phospholipids)
Lipid Structure
 Triglyceride- 3 fatty acids bonded to a glycerol backbone
 Saturated Fatty Acid
All of the carbons are bonded to hydrogen atoms
(completely filled = saturated)
 Generally a solid at room temperature
 Bad fats
 Ex: butter, lard, grease from cooked meats
 Unsaturated Fatty Acid
 Some of the carbons are double bonded to each other
causing a kink in the chain and one less place for a
hydrogen to bond (not completely filled = unsaturated)
 Generally a liquid at room temperature
 Good Fats
 Ex: oils
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Lipid Structure
saturated
O
C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
O
unsaturated C-CH2-CH2-CH2-CH
Proteins
 Amino acids (20 different kinds of aa) bonded
together by peptide bonds (polypeptides).
 Six functions of proteins:
1.
2.
3.
4.
5.
6.
Storage:
Transport:
Regulatory:
Movement:
Structural:
Enzymes:
albumin (egg white)
hemoglobin
hormones
muscles
membranes, hair, nails
cellular reactions
Protein
Amino Acid
Amino Acids (aa)
aa1
aa2
aa3
Peptide Bonds
aa4
aa5
aa6
Nucleic Acids
 Two types:
1) Deoxyribonucleic acid (DNAdouble helix)
2) Ribonucleic acid (RNA-single
strand)
 Nucleic acids are composed of long chains of
nucleotides linked by dehydration synthesis.
 A Nucleotide is made up of a phosphate
group, sugar and nitrogenous base which
identifies the nucleotide (A,T-DNA only,G, C,
or U-RNA only)
Nucleic Acids
Nucleotide
DNA
Enzymes
Unit 5 Part 2
What is an enzyme?
 Enzymes are catalysts that speed up
reactions
 They are proteins
 They are not used up or permanently
changed in the reaction
Enzymes
 Enzymes are specific to the
chemical reaction they catalyze
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Their specificity depends on the
shape of the enzyme
 Because enzymes are not used up
in the reaction they can be used
over and over again
 Names of enzymes end in “ase”
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Ex: sucrase, maltase and lactase
How do enzymes work?
 Enzymes work because they
lower the energy needed for
the chemical reaction to take
place
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Chemical reactions take place
when chemical bonds are
broken and reformed. Energy
is needed to break those
bonds.
 This energy is known as the
activation energy
Enzyme Catalyzed Reaction
Without Enzyme
With Enzyme
Free
Energy
Free energy of activation
Reactants
Products
Progress of the reaction
Enzymes
 Substrate- (reactant) the substance an
enzyme acts on
 Active Site- the pocket of an enzyme
molecule that binds to the substrate
Active Site
Substrate
Joins
Enzyme
Enzymes
What factors affect enzyme activity?
 Enzymatic reactions are very specific. Reactions will
not occur if certain environmental factors are not
within a specific range.
 These factors include:
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Temperature
 Extreme temperatures, especially heat, will denature
an enzyme (cause it to unfold)
pH
 Most enzymes perform best at near neutral pH (pH of
6-8)
Ion concentration
 If the concentration of ions is too high or too low the
enzyme will not function properly