Upload
adela-short
View
219
Download
0
Embed Size (px)
Citation preview
Chemistry of Life
What is Chemistry?
Study of composition of matterWhat is matter?
anything that takes up space and has massWhy mass? Not weight?
B/c weight changes but mass is constantWhat is an element?
a substance consisting of only one type of atom
On Earth, 92 elements occur naturally, and 25 of them are essential to living organisms
Ex: C, H, O, N, Ca, P, K, S, Na, Cl, Mg
What are 4 elements that make up >96% of mass of a human?
Carbon, Hydrogen, Oxygen, Nitrogen
Trace elements
essential elements that present in living things in very small amount (less than 0.01%)
What is an atom?
Nucleus (+ proton & 0 neutron) in center and – electron cloud out side
Compoundsa substance that contains 2 or more
elements into a fixed ratioex: water (H2O), glucose (C6H12O6)
Compounds are made by bonding elementsIonic bond
by mutual attraction of 2 ions of opposite chargeex: Sodium Chloride (Na+Cl-)
Covalent bondby sharing electronsex: H2, CH4, H2O
Hydrogen bondby attraction of opposite charge b/w Hydrogen and OxygenIt holds and stabilize many large biological molecules such as proteins and DNA
How do the unique chemical and physical properties of water make life on earth possible?
Water Structure
Held together by covalent bond
Neutral in charge as a whole
PolarUnequal distribution
of charge Is the basis for
hydrogen bond
Hydrogen Bond
Formed by attraction of opposite charge b/w hydrogen and oxygen
Important to properties of water and to DNA replication
Properties of WaterStrong Cohesion
Tendency of molecules to stick togetherHigh Surface Tension
A measure of how difficult it is to stretch or break the surface of a liquid
High Specific HeatAmount of heat that must be absorbed or lost to
change its temperatureHigh Heat of vaporization
Quantity of heat a liquid must absorb to be converted from the liquid to the gaseous state
Universal solventDissolving agent of a solution
Strong Cohesion (and adhesion)
High Surface Tension
Evaporative cooling
Density of Water
Ice less dense than liquid water Ocean and lakes don’t
freeze solid because ice floats
Ice protects the liquid water below from colder air
If liquid water were less dense tan ice Ice will sink and all
ponds, lakes and ocean would freeze solid
Life on Earth would not be possible
pHa measure of how acidic or basic a solution is. Scale of pH is 0-14Acids
any substances that form hydrogen ion (H+) in water pH below 7
Basesany substances that form hydroxide ion (OH-) in water pH above 7
Bufferssubstances that resist change in pH by accepting or donating hydrogen ionprevent sharp change in pHcontrolling pH is important for maintaining homeostasis
Acid Rainrain or snow with a pH below 5.6causes: air-pollutants; sulfur oxide and
nitrogen oxide from burning of fossil fuelEffects: damages forest, other lands,
lakes, and streams (kills trees and fish)
Biologically important macromolecules
How do structure of biologically important molecules (Carbohydrates, lipids, proteins, and Nucleic Acids) account for their functions?
PROPERTIES OF ORGANIC COMPOUNDS
Contains Carbon 4 electron in the outer shell of carbon allow
it to form complex structuresHydrocarbon
compound composed of only carbon and hydrogen Ex: methane, ethane, propane, etc.
Isomerscompounds that have same simple
(molecular) formula but different 3-d structuresEx: glucose & fructose (simple formula C6H12O6)
PROPERTIES OF ORGANIC COMPOUNDS
MacromoleculesMonomers
The fundamental molecular unit; building block of polymers
PolymersA large molecule formed by bonding many
smaller molecules ; usually in long chains
Therefore, cells build macromolecules by forming a chainEx: DNA, RNA, Protein, Polysaccharides
HOW DO CELLS COMBINE MONOMERS TO MAKE POLYMERS?By Dehydration Synthesis
Cells link monomers together to form polymers by removing a water moleculeEx: Glucose to StarchEx: Amino Acids to Proteins
HOW DO CELLS BREAK DOWN POLYMERS INTO MONOMERS?
By Hydrolysis“Breaking (lyse) apart with water (hydro-)”Cells break down macromolecules into
monomersex: Starch to glucoseex: ATP to ADP
CarbohydratesLipidsProteinsNucleic Acids
4 organic compounds
CARBOHYDRATES
Composed of Carbon, Hydrogen, and Oxygen
Categorized by size(A) Monosaccharides(B) Disaccaharides(C) polysaccharides
(A) MONOSACCHARIDES
Simple sugarsC:H:O::1:2:1Glucose (plants)Fructose (fruits)Galactose (milk)Functions
Readily available energy
(B) DISACCHARIDES
Double sugarsMaltose (glucose + glucose)Sucrose (glucose + fructose)Lactose (glucose + galactose)Functions
Transport form of sugars in plantsAvailable to be break down for energy
How would we combine glucose and fructose to make sucrose?
Dehydration Synthesis
By removing a water molecule and bonding them together
How do we digest or break down lactose into glucose and galactose?
Hydrolysis
To break down a disaccharide, add the water back
(C) POLYSACCHARIDES
Many sugarsGlycogenStarch Cellulose ChitinFunctions
Storage forms of energyStructural molecules
LIPIDS
Composed of carbon, hydrogen, and oxygenC:H:O::1:2:1Subunits
triacylglycerol and 3 fatty acids Triacylglycerol- 3 carbon alcohol Fatty acids- chain of 16 or 18 carbons with a carboxyl group
Hydrophobic naturedue to nonpolar C-H bonds in the hydrocarbon chains of fatty acids
BIOLOGICALLY IMPORTANT LIPIDS
(A) Fats and oils(B) Waxes(C) Steroids(D) Phospholipids
(A) FATS AND OILS
Saturated fatty acids
Animal fats
single bond between the carbon atoms of hydrocarbon chain
Unsaturated fatty acids
Vegetable oils
one or more double bonds, formed by the removal of hydrogen atoms from the carbon skeleton
(A) FATS AND OILS
Formed by which process?
Dehydration Synthesis
Functions
1. Storage form of energy
2. insulation (fat)
3. Cushioning (fat)
(B) WAXES
Where are they naturally found? coats on leaves, fruits, animal skin,
feather, fur
Function
prevent water loss
(C) STEROIDS
Are based on cholesterolFunctions
1. Components of animal cell membrane and myelin sheaths
2. metabolic regulation
(a) makes hormones
(b) sex hormones are steroids
(D) PHOSPHOLIPIDS
Function
1. A major component of cell membrane
2. Affects transport across the membrane
Characteristics Hydrophilic heads
Hydrophobic tails
PROTEINS
Composed of carbon, hydrogen, oxygen, nitrogen, and sulfur
SubunitsAmino Acids
Formed by peptide bond between amino acids by dehydration synthesis
Involved in almost everything organisms do
TYPES OF PROTEINS
1. Structural proteins- collagen
2. Storage proteins- albumin
3. Transport proteins- hemoglobin
4. Defensive proteins- antibodies
5. Contractile proteins- actin, myosin
6. Receptor proteins- neuro-receptors
7. Hormonal proteins- insulin
8. Enzyme/Biocatalysts- gastrin
PROTEINS4 Levels of organization in proteins 1. Primary Structure
Linear sequence of amino acids
2. Secondary structureBased on hydrogen bonding betweenamino and carboxyl group
3. Tertiary structureBased on bonding between R group
4. Quaternary structure Results from intertwining 2 or more amino acid chains
PROTEINS
What determines Protein Conformation?
The sequence of the polypeptideDenaturaton
The loss of protein conformationWhat causes the denaturation?
Physical & Environmental alteration such as pH, temperature, salt concentration
How do enzymes regulate the rate of chemical reactions?
Enzyme is a catalyst; a protein that speeds up a chemical reaction
(without itself being changed into a different molecules in the process) by lowering the required activated energy
How does the specificity of an enzyme depend on its structure?
Enzymes are substrate-specific (Key-lock relationship)
How does the activity of an enzyme regulated?
Temperature, pH, and some chemicalsOptimal condition for Enzyme activity
Temperature 35-40 °C (close to our normal body temperature)
pH of 6-8Cofactor and coenzyme
Cofactor: non-protein helperex: magnesium is a cofactor that is essential for the
proper functioning of chlorophyllCoenzyme: organic cofactors (most Vitamins)
InhibitorsBlock substrate from entering active sitesEx: Penicillin
NUCLEIC ACIDS
Composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus
Subunit: Nucleotide3 components of nucleotidePentose (5-carbon sugar)Phosphate groupNitrogen base
2 typesDNA & RNA
DNA
Double Helix
Master copy of an organisms’s information (gene) code
DNA nucleotide
1. Deoxyribose2. Phosphate group3. Nitrogen base Purines
Adenine (A)Guanine (G)
PyrimidinesCytosine (C) Thymine (T)
RNA
Single Strand
Process genetic instructions to use in building proteins
RNA nucleotide1. Ribose2. Phosphate group3. Nitrogen base Purines
Adenine (A)Guanine (G)
PyrimidinesCytosine (C)Uracil (U)