Biology Unit 4 - cabarrus.k12.nc.us
Transcript of Biology Unit 4 - cabarrus.k12.nc.us
Elements
• Everything in our universe that has a mass and a volume is made of matter.
• Matter in its purest form is an element.
• There are 118 elements on the periodic table, each of which is distinguished by its atomic number (number of protons)
Elements in Living Things
• There are 5 elements that make up about 96% of living things.
• They are:• Carbon• Hydrogen• Nitrogen• Oxygen • Phosphorus• Sulfur
• Remember them with “CHNOPS”
Atoms
• Elements are all made of the same type of atoms.
• Atoms have protons and neutrons in the nucleus.
• Orbited by negative electrons
• Electrons exist in energy levels around an atom.
Electron Energy Levels
• The first energy level can hold 2 electrons.
• The second can hold 8
• The third can hold 18
• In order to be stable, atoms want to have 8 electrons in their outer shells.
Isotopes
• Although every element has a specific number of protons, they can have different numbers of neutrons.
• Atoms of the same element with differing numbers of neutrons are called isotopes.
• Atomic mass from the periodic table is a decimal
because it is an average.
How to Find Subatomic Particles
• Protons=Atomic number on periodic table
• Neutrons= Rounded atomic mass- protons
• Electrons= Protons if atom is neutrally charged
• How many protons, neutrons, electrons in a neutral Helium atom?
Compounds and Bonding
• Multiple atoms of similar and different elements can bond together to form compounds.• Examples: H2O, CO2, NaCl
• Chemical bonds are formed and broken through chemical reactions.
Ionic vs. Covalent Bonds
• Covalent compounds are formed when atoms share electrons.• Most compounds in the body are formed this way
• Ionic compounds are formed when charged atoms transfer electrons.
• Charged atoms are called ions.
• Positive ions are called cations. “Cat Ion”
• Negative ions are called anions. “An Ion”
Number of Valence Electrons
• Valence electrons are electrons on the outermost energy level of an atom.
• Magic # is 8.
• You can find out how many valence electrons an element has by looking at group number on periodic table.
• IA has 1, IIA has 2, IIIA, has 3, etc.
How Ionic Compounds Form
• Charges need to balance to make 0.
• Ex: Na+Cl, Ca+F, K+O
• Named by leaving the cation as is and changing the ending on the anion to “ide”
• Ex: NaCl Sodium Chloride
Chemical Reactions
• Chemical reactions occur constantly in the body.
• These reactions are called metabolism.
Law of Conservation of Mass
• The law of conservation of mass says that mass can never be lost or gained during a chemical reaction.
• Because of this, we have to make sure we balance our chemical equations.
How to Balance an Equation
• You can balance a chemical equation by changing the coefficients (big numbers) that come before each product or reactant.
• It works like the distributive property in math. Each compound gets multiplied by the coefficient in front of it.
• YOU CAN NEVER CHANGE THE SUBSCRIPT!!!!!!!
The Molecules of Life
• Known as organic molecules
• Not the organic you see at the grocery store
• All organic molecules contain carbon
Carbon Bonding
• Carbon is special because it is so easy to bond with.
• Each carbon atom can form up to 4 bonds.
• Carbon can even bond more than once with the same atom.
• These are called double and triple bonds.
Polymers
• Many carbon based molecules can form polymers. Polymers are giant molecules that are made up of smaller molecules.
• The smaller molecules that make up polymers are called monomers.
Condensation vs. Hydrolysis
• Polymers are formed by a chemical reaction called condensation.
• Condensation causes 2 monomers to come together while a water molecule is released.
• Hydrolysis happens when a water molecule breaks apart a polymer and uses the H and OH from the water to fill in the gaps.
Carbohydrates (sugar and starch)
• Used by cells to provide energy.
• 4 calories per gram
• Monomers: Monosaccharides
• Multiple monomers can form polysaccharides.
• Polysaccharides form through condensation.
• 1:2:1 ratio of Carbon to hydrogen to oxygen
Carbohydrate Examples
• Examples of monosaccharides: Fructose and Glucose• Found in fruits, used for energy by both animals and plants
• Examples polysaccharides: Cellulose, glycogen• Very large molecules, take a long time to break down
• Animals store glycogen in their livers for back up energy.
• Plants use cellulose to help provide structure.
Lipids (fats)
• Large biomolecules made of mostly carbon and hydrogen with a little bit of oxygen.
• Non-Polar: Means they will not dissolve in water
• Monomer: Fatty acids
• 9 calories per gram
Lipids Examples/Uses
• Fats, oils, waxes, steroids
• Used for energy storage/insulation in many animals
• High in energy
• Major component in cell membranes
Proteins
• Made up of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur.
• Essential for all life
• Monomer: Amino Acids
• Come together to form proteins. Held together by peptide bonds.
• 4 calories per gram
Proteins Uses/Examples
• Come in a huge variety of shapes and sizes.
• Shape determines function.
• Building blocks of many structural components in living things.• Muscle tissue, assist with immunity, transport oxygen, carry out chemical
reactions.
• Used as enzymes!
Enzymes
• Life as we know it would not be possible without enzymes.
• Enzymes speed up reactions exponentially but do not get used up in the reaction.
• The activity of enzymes depends on pH and temperature.
• Every enzyme has an active site where a substrate must bind in order to speed up the reaction.
Nucleic Acids
• Made up of carbon, hydrogen, oxygen, nitrogen, and phosphorus atoms.
• These atoms are arranged into a nitrogenous base, a simple sugar, and a phosphate group.
• Monomer: Nucleotides
Nucleic Acids: Examples and Uses
• DNA and RNA
• DNA contains the instructions to form all of an organism’s enzymes for structural proteins.
• DNA determines how an organism looks and acts.
• RNA is used by the body to make a copy of DNA for use in making proteins.
Water is Polar
• Water is a covalently bonded molecule.
• Sometimes, covalently bonded molecules do not share electrons equally. This makes them polar.
• Polar molecules have both positive and negative parts.
• This allows them to make solutions very easily.
Hydrogen Bonds
• Water is attracted to itself through hydrogen bonds.
• This means that the negative oxygen is attracted to the positive hydrogen.
• Causes surface tension and capillary action.
High Specific Heat of Water
• Water is very resistant to temperature change.
• It takes more energy to change the temperature of water than it does to change most other liquids.
• Allows cells to maintain homeostasis.
• Why do you think coastal cities usually have milder temperatures than those inland?
Water Expands when it Freezes
• Water is one of the few substances that becomes less dense when it becomes a solid.
• It also expands when it becomes solid.
• This is helpful for breaking up rock and returning nutrients to the soil.
• What animals might benefit from this property of water?
Diffusion in Water
• Particles are in constant random motion.
• Diffusion is the net movement of particles from high concentration to low concentration.
• High temp can increase rate of diffusion.
• Eventually, concentration will be even. This is called dynamic equilibrium.
• Cells use diffusion to move substances in and out.
Water and Solutions
• The polarity of water makes it perfect for dissolving other compounds.
• Because it has both negative and positive charges, it can bond to both parts of other polar molecules, creating weak bonds that allow solutions to be made.
• See example on board:
Water and pH
• Acids are substances that release H+ ions in water. These substances have a pH below 7.
• More H+ = more acidic= lower pH
• Bases are solutions that release OH- ions in water. They have a pH above 7.
• More OH- = more basic= higher pH
Atoms that release fewer H+ ions that pure water would be classified as: