chemistry of life unit when water, h2o, is created, hydrogen and oxygen share the electrons the...
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Chemistry of Life UnitWhen water, H2O, is created, hydrogen
and oxygen share the electrons
• The oxygen has a slightly negative charge
• The hydrogen’s have a slightly positive charge
This uneven pattern of charge creates a polar molecule = has a positive side and negative side
Water Molecule
Hydrogen Bonding
Hydrogen Bond = an attraction between a slightly positive hydrogen atom and a slightly negative atom, often oxygen or nitrogen
Hydrogen Bonding
Properties Related to Hydrogen Bonding
Life depends on hydrogen bonds in water
• High Specific Heat = water resists changes in temp.
- helps regulate cells
Properties Related to Hydrogen Bonding (cont)
• Cohesion = attractive forces between particles of the same kind
- example: surface tension of water
• Adhesion = the attractive forces between unlike substances- example: meniscus curve in a graduated cylinder
Surface Tension
Meniscus Curve
Properties Related to Hydrogen Bonding (cont)
• Capillarity = the ability of water to move up through narrow tubes against gravity
- due to cohesion and adhesion
- example: carnations turning a different color in colored water
Carnations in Colored Water
Carnations in Colored Water
SolutionsThe polarity of water makes it very
effective at dissolving many substances
Solvent + Solute = Solution
Concentration [ ] = amount of solute in a given amount of solvent
Saturated = no more solute will dissolve in the solvent
Solvent + Solute = Solution
Mosquito injects a solution into your body that prevents clotting
Solutions (cont)
Water is the universal solvent.
All processes necessary for life take place in water.
Acids and Bases
Acid = compound that releases a hydrogen ion (H+) when dissolved in water
- increases the H+ [ ]
Base = compound that remove H+ ions from a solution
- lowers the H+ [ ]
Acids and Bases (cont)
pH scale = amount of H+ ions in a solution
0 to 6 = acidic 7 = neutral 8 to 14 = basic
buffer = compound that regulates H+ [ ]- maintains homeostasis
pH Scale
Organic CompoundsCarbon is the building block of life
- can form multiple bonds (up to 4), including other carbon atoms
More than 90 % of the mass of all living things are composed of combinations of just 4 elements
1) Carbon ( C) 2) Hydrogen (H) 3) Oxygen (O) 4) Nitrogen (N)
1) CarbohydratesExamplessugars starchescelluloseglycogen
Specifics- contain C, H, and O- main source of usable chemical
energy for cells- major part of plant cell wall
(made of cellulose)- most basic are simple sugars =
monosaccharides (glucose)- bond to form polysaccharides
1) Carbohydrates
2) LipidsExamplesFatsOilsCholesterol
Specifics- contain C, H, and O- store large amounts of energy- cell membrane made up of
phospholipids- regulate body responses and
control sexual development- are nonpolar molecules (don’t
dissolve in water)
Saturated Fats (solid at room temp)
Unsaturated Fats (liquid at room temp)
3) ProteinsExamples Specifics
- contain C, H, O, and N
- made of monomers called amino acids
- 20 different amino acids build proteins
- specific sequence determines structure and function
Red Blood Cells and Sickle Cell Anemia(SEM 3500x)
4) Nucleic Acids- work together to make proteins
Functions:
– stores info to build proteins
– helps build proteins
Types:
1) DNA
2) RNA
Chemical Reactions
= change substances into different substances by breaking and forming chemical bonds
6O2 + C6H12O6 6CO2 + 6H2O
1. Reactants = substances changed during a chemical reaction (left side)
2. Direction
3. Products = substances made during a chemical reaction (right side)
Bond Energy = the amount of energy that will break a bond
Chemical Equilibrium = when both the reactants and products are made at the same rate
* Chemical reactions release or absorb energy
Types of Chemical Reactions
Activation Energy = the amount of energy needed to start a reaction
- is very high in most chemical reactions (especially in the body)
Activation Energy
Types of Chemical Reactions (cont)
Exothermic = chemical reaction that releases more energy than it absorbs
- gives off heat (hot)
- ex: cellular respiration
Exothermic Reaction
Types of Chemical Reactions (cont)
Endothermic = chemical reaction that absorbs more energy than it releases
- absorbs heat (cold)
- ex: photosynthesis
Endothermic Reaction
EnzymesCatalyst = substance that reduces the
amount of activation energy that is needed to start a chemical reaction
Catalysts are not changed during a chemical reaction
Enzymes = a type of catalyst in living things
Enzymes- almost all are proteins
- work best in normal body conditions (temp. and pH)
- specific shape allows only certain reactants to bind
- fit like a lock and key
Lock and Key Model - Enzymes
Enzymes (cont)
- functions:
1) help bring substrates together and chemical reactions occur
2) decrease the activation energy of the reaction
3) increase the rate of the reaction
Enzymes reduce Activation Energy
Enzymes (cont)
- Reaction 1 requires more activation energy than Reaction 2- Reaction 3 has less activation energy due to a catalyst being used