Unit One - Elements of Life

Module One

The carbon cycle is a link of processing between all organisms and the atmosphere.

• organic molecules are molecules made from carbon

• organisms exchange matter with other organisms (recycling)

• reproduction, growth, organization

Unlike matter, energy can’t be recycled.

• sustains community in order to survive

  • ex: plants require sun to create their own energy.

  • organisms transform energy, which is then converted into chemical forms

Atoms are the basic unit of matter.

• Contain a central system, the nucleus

  • Which is made up of positively charged protons, neutral particles named neutrons, and negatively charged electrons.

  • Proton number is also known as the atomic number, that specifies an element.

• Atomic mass is determined by the total number of protons and neutrons.

• Isotopes are atoms of the same element that carry a different amount of neutrons.

  • Subscript is written on the left of chemical symbol.

• Gaining or losing an electron results in ions.

Electrons serve as the foundation of energy transfers in biological reactions.

• Electron shell, or energy level, contains the electrons on an atom. They surround the nucleus.

• Remember: 2, 8, 8

  • 2 in the first, and the rest can hold 8 electrons.

• Electrons stability depends on their energy levels.

  • Gaining energy: less stable

  • ex: In Hydrogen, if an electron is lost, it forms an H+ ion.

• Valence electrons are elements outermost energy level.

  • vertical columns of the periodic table are named groups. members of groups share the same number of electrons in the outer shell.

When molecules form together, atoms interact creating a chemical bond.

• Chemical bonds form covalent bonds.

  • a bond in which two atoms share a pair of electrons.

  • Form a single bond, two atoms share two electrons covalently.

    • Shown with single line connecting atoms.

  • Form a double bond when two atoms share two pairs of electrons covalently.

    • Shown with double line connecting atoms.

• Reactions are based on the amount of energy required by an atom or molecule.

  • ex: Nitrogen gas requires a large amount of energy.

• Polar covalent bonds are formed by interactions of atoms unequal sharing electrons.

• Nonpolar covalent bonds share equal electrons between two atoms.

  • ex: H₂, O₂, and N₂

• Electronegativity, difference in ability of atoms to attract electrons, increases across rows in periodic table.

Ionic bond is formed when two ions with opposite charges associate with each other.

• ex: NaCl

Chemical reactions is a process by which atoms/molecules transform into different molecules.

• reactants are the atoms/molecules changing

• products are the molecules formed.

Carbon contains special properties which provide a variety of functions.

Four most common atoms in organic molecules are carbon, hydrogen, oxygen, and nitrogen.

• Proteins are organic molecules that provide structural support for the cell and speeds up chemical reactions.

  • composed of amino acids

• Nucleic acids encode and transmit genetic information.

  • Two types: RNA & DNA

  • The subunit of nucleic acids are nucleotides.

• Carbohydrates store energy in their chemical bonds.

  • sometimes attached to proteins on the surface layer of cells; red blood cells.

  • formed by repeating units of monosaccharides.

• Lipids are organic molecules that are hydrophobic, or “water fearing.”

  • interact with other lipids

  • effective barriers and are fats that store energy to make up our diet.

Module Two

The polarity of water molecules create interesting properties.

• Hydrogen bond is formed between the slight positive charge and electronegative atom.

  • Hydrogen bonds are weaker than covalent and ionic bonds

• Cohesion is the tendency of water molecules to stick to one another due to the hydrogen bonding.

  • ex: streams, puddles

• Adhesion is the tendency of water to stick to materials other than water.

  • ex: droplets of dew to stick to a leaf.

• Hydrogen bonds have high surface tension, the measure of the difficulty of breaking the surface of a liquid.

  • Allows for certain animals, and plants to float in water.

Hydrogen bonds’ structure varies depending on the state.

Module 3

Carbohydrates and lipids are referred to the fuel molecules because of the sources of energy contained in their bonds.

• examples include sucrose, glucose, fructose, galactose, and lactose

• Glucose and fructose are covalently bonded to hydroxly group —OH

Simplest form of carbohydrates are saccharides.

• contain five or six carbon atoms

• C₆H₁₂O₆

Functional groups are groups of one or more atoms that have particular chemical properties, regardless of what they are attached to.

• carbonyl group changes to be polar and hydrophillic

Monosaccharides form in two structures.

• linear or ring-like forms

Five carbon sugars are ribose, deoxyribose.

Carbs contain C, H, O, maybe N and P

Monosaccharides link creating different bonds

• Linking two simple sugars together by a covalent bond froms a dsiaccharide.

• Polysaccharides are many polymers of simple sugar

• Complex carboyhydrates are long branched chains of monosaccharides

Starch is an energy-storage molecule, while cellulose is a tough resilient molecule that gives strength to plan cell walls and stems.

Lipids are used to store energy, cell communication, and components of cell membranes

• Triacylglycerol. Hydrophobic

• Steroids

  • ex: cholesterol

• Phospholips