- Unit 1 Composition of living Things
Basic Biological Principles
Biology is the study of life.
Characteristics of living things:
- Made up of cells
- Cells are smallest unit of a living thing.
- Cells can grow, respond and reproduce.
- Organisms can be unicellular or multicellular.
- Multicellular organisms have different types of cells performing various functions.
- New organisms made via reproduction
- Sexual reproduction creates new individual from cells of 2 different individuals.
- Asexual reproduction creates new individual from splitting off of a parent.
- Makeup based on the genetic code
- Organisms are a product of inherited information.
- Growth and development
- Growth can occur in size and in cell differentiation of functions.
- Need for materials and energy
- Organisms use constant supply of materials and energy to grow, develop and reproduce. This life process is metabolism.
- Respond to the environment
- Living things detect and respond to stimuli. Examples can be light, temperature, chemicals, gravity.
- Maintain homeostasis
- Internal factors work to maintain a stable environment for chemical and physical reactions to continue life functions.
- Species evolves over time
- Process of evolution allows species to adapt to and thrive in ever-changing environments.
Smallest to largest:
Cells with organelles
Groups of cells form tissues
Groups of similar tissues form organs
Groups of similar organs form organ
- Made up of cells
- Chapter 2 Chemistry of Life
Nature of Matter
Atoms are the basic unit of all matter.
- Made up of subatomic particles
- Protons are positively charges and found in the nucleus
- Neutrons have no charge and found in the nucleus
- Protons and neutrons have about same mass
- Electrons travel around the positively charged nucleus and are equal to the number of protons
Elements consist of one kind of atom only.
- More than 100 known
- About 2 dozen found in living things
- Isotopes of an element have different numbers of neutrons
- All isotopes have the same chemical properties
- Some isotopes are radioactive because nuclei is unstable
- Used in medicine
- Analyze age of rocks and fossils
- Trace substances in organisms
A compound is a substance formed by the combination of 2 or more elements.
- Atoms are held together by bonds.
- Ionic bonds occur when electrons are transferred from one atom to another.
- Covalent bonds form when atoms share electrons resulting in a molecule.
- van der Waals forces occur when molecules with slight charges are attracted to one another.
Properties of Water
- Water is the most common compound found on Earth.
- Solid, liquid, gas
- High specific heat allows temperature moderation.
- When frozen, water is less dense therefore it floats.
- Good thing for fishesJ
- Makes ice skating a lot easierJ
- Polarity causes a bent molecule.
- Bending due to uneven distribution of electrons
- More electrons near oxygen than hydrogen
- Water molecules are attracted to one another.
- Attraction is called hydrogen bonding between water molecules.
- Cohesion forms between water molecules allowing such things as insects to walk on water.
- Adhesion between water molecules and other surfaces allows such things as capillary action which draws water up through roots of plants and out through leaves.
Solutions and Suspensions
Water is usually not pure, but part of a mixture. There are 2 types of mixtures:
- Solution occurs when solute is distributed evenly throughout the solvent (water). Examples would be ionic compound salt in water or polar molecule such as sugar in water.
- Suspensions occur when particles do not dissolve completely, but are so small they do not settle out. Example of a suspension and solution is blood.
Acids, Bases and pH
- Pure water dissociates evenly into hydrogen and hydroxide ions.
- Acids dissolved in water produce excess hydrogen ions.
- Bases dissolved in water produce excess hydroxide ions.
- pH scale indicates the numbers of hydrogen ions in a solution.
- Buffers are found in living things that help to control wild swings in pH. They are usually weak acids or bases.
- Versatile element
- 4 valence electrons that can join with other electrons to form covalent bonds
- Can bond with other elements or other carbon atoms
- Many molecules of living things
- Made via polymerization
- Smaller units, monomers, join to form polymers
- 4 classes of macromolecule organic compounds are carbohydrates, lipids, nucleic acids, proteins
- Made of carbon, hydrogen and oxygen in ratio of 1:2:1
- Used by all living things as a source of energy
- Used by some living things for structure
- Monosaccharides are single sugars…glucose, galactose, fructose
- Polysaccharides are made from joining monosaccharides
- Animals store excess sugar as glycogen
- Plants store excess sugar as starch and use to make cellulose
- Fats, oils, waxes
- Store energy, part of membranes, waterproofing
- Many lipids formed when glycerol molecule joins with fatty acids
- Saturated have hydrogens attached to every carbon, solid at room temperature
- Unsaturated (and polyunsaturated) have carbon to carbon double bond, they are liquid at room temperature
- Macromolecules containing carbon, hydrogen, oxygen, nitrogen, phosphorous
- Are polymers made of monomers known as nucleotides
- Consist of 5 carbon sugar, a phosphate group, nitrogenous base
- Store and transmit hereditary information
- DNA, RNA
- Contain carbon, hydrogen, nitrogen, oxygen
- Polymers made of amino acids
- Amino acids composed of amino group and carboxyl group
- Some control cell process, form muscle and bones, transport substances across cell membranes
- 4 levels of organization
- Sequence of amino acids,
- Amino acids within chain twisted and folded
- Chain is folded
- Combined with other chains and held together by van der Waals forces
Chemical Reactions and Enzymes
- Process that changes one set of chemicals into another
- Start with reactants, end with products
- Involves changes in chemical bonds
Energy in Reactions
- Chemical reactions either release or absorb energy.
- Some chemical reactions need a boost of energy called activation energy.
- Protein catalysts
- Speed up chemical reactions in cells
- Lowers the energy of activation needed to start a chemical reaction
- Very specific to chemical reactions
- Enzymes provide a place for reactants to meet
- Affected by pH range and temperatures
- Regulated by cells with proteins that turn enzymes on or off
- Made up of subatomic particles
- Topic 4
- Topic 5
- Topic 6
- Topic 7
- Topic 8
- Topic 9
- Topic 10