Biology 204 Quiz 1 Study Guide

Biological Definition of Life

-Made up of membrane-bound cells

-Process and encode information

-Can evolve

-Uses and acquires energy

-Can reproduce

Levels of Biological Organization

Atom → Molecule → Organelle → Cell

Atom

Smallest unit of matter that retains chemical properties

Cells

Smallest unit of life

-Life has to be made up of 1+ cells to be life

Element

A pure substance

Atom

Particles that make up an element

-Made up of protons, neutrons, electrons

Protons

Positively charged (+)

-Located in nucleus, has a mass, determines the element (atomic number)

Neutrons

Neutral charge, contributes to mass, determines isotope

Electrons

Negatively charged, NO mass, determines chemical behavior

Atomic Number

Number of protons/type of element

Atomic Mass

Average total number of neutrons and protons

Valence Shell

Electrons organized into electron shells/clouds that surround nucleus of atom

Shell 1: 2 electrons

Shell 2: 8 electrons

Shell 3: 8 electrons

Valence Electrons

Electrons in the outer electron shell

-Participate in chemical bonding (determines how it acts)

Stable Atom

All electron shells full

-Goal of an atom is to have a complete valence shell

Reactive Atom

Atom with an incomplete valence shell

# of electrons determines behavior

Periodic Table

Far left: Electron flush (Wants to lose electron)

Far right: electron happy (Noble gases)

Towards the right: Further to the right, the more electrons in the valence shell, want to steal electrons

Down a row: Same # of valence electrons, different # of valence shells (same row = similar properties)

Across a row: Same # of valence shells, different # of valence electrons

Electronegativity

How “electron hungry” an atom is; pull for electrons

-Higher electronegativity = greater pull for electrons

Ions

Atoms with a charge (+ or -)

-# of electrons lost or gained is determined by how many are required to fill shell

Ionic Bond

Bond formed when atoms transfer its electron(s) to another atom

• 1.8-3.3 electronegativity difference, Opposite sides of Periodic Table

-Electron flush + electron hungry

-Forms cation (+) and anion (-)

Covalent Bond

Sharing of electrons between two atoms to complete both valence shells

• <1.8 electronegativity, Similar electronegativity, not on opp. sides

-Hydrogen can lose or gain 1 electron - forms covalent bonds

-Some atoms have higher electronegativity (electrons spend more time nearby makes -) and some have lower electronegativity (electrons spend less time nearby makes +)

SHONCP (# of covalent bonds)

Sulfur - 2

Hydrogen - 1

Oxygen - 2

Nitrogen - 3

Carbon - 4

Phosphorus - 5

Polar Covalent

-Unequal electron sharing

• 0.5-1.7

-Partial charges

Nonpolar Covalent

-Equal electron sharing

• 0-0.4

-No partial charges

Electronegativity Rules

• Two of the same element; O2, H2, N2 = Nonpolar

• Carbon bound to Hydrogen = Nonpolar

• Oxygen or Nitrogen bound to Hydrogen; NH3, H2O = Polar

• Oxygen or Nitrogen bound to Carbon; CO2 = Polar

(1 polar covalent bond in small molecule with <10 atoms makes molecule polar)

Hydrogen Bond

Weak intermolecular force involving hydrogen due to partial charges

-Much weaker than covalent

Hydrophilic

Polar/Ionic molecules that can be dissolved in water

Hydrophobic

Nonpolar molecules that cannot be dissolved in water

Molecular Forces

-Intermolecular forces

-Intramolecular forces

Intramolecular Bonds

-Bonds within a molecule

Ex: Covalent Bonds <1.8 (Polar Covalent .5-1.7 -unequal sharing/partial charge & Nonpolar Covalent 0-0.4 - equal sharing of electrons) & Ionic Bonds 1.8-3.3 (Transfer of electrons)

Intermolecular Bonds

-Weak interactions between molecules because of opposite charges

Ex: Hydrogen bonds (Intermolecular force involving hydrogen due to partial charges)

Biomolecules

Carbohydrates: CH2O

Lipids: CH (some O)

Nucleic Acids: CHONP

Proteins: CHON

Monomer

Single building block

Dimer

Two monomers joined together

Polymer

Many monomers joined together

Dehydration Condensation/Polymerization Reaction

Joining together monomers with covalent bonds to form a polymer

-Input of energy to remove a water molecule → Makes polymer

2 monomers + energy → Polymer + water molecule

Hydrolysis (Depolymerization) Reaction

Breaking apart polymer into constituent monomers by breaking covalent bonds

-Input of water to break polymer → makes 2 monomers + releases energy

1 Polymer + water molecule → 2 monomers + energy

Carbohydrate

-Polar molecule

• Functions: Energy storage (sugars) & structural support (cellulose in plants)

• Chemical Formula: CH2O or (CH2O)n

• Monomer: Monosaccharide (Glucose, Fructose, Galactose)

• Dimer: Disaccharide (Sucrose & Lactose)

• Polymer: Polysaccharide (Cellulose, Starch, Glycogen)

-Different carbohydrates have different arrangements of atoms and numbers of carbons

-Have lots of O-C & O-H bonds so they are Polar

-Can be linear or in a ring

Lipids

-Nonpolar Molecule (Mostly C+H bonds), not water soluble (hydrophobic)

• Functions: Energy storage, cell membrane structure, hormone signaling (steroids)

• Elements: C + H + some Os

• “Monomer”: Fatty acid, single chain

• “Polymer”: Triglyceride, Glycerol + 3 fatty acid chains

• Sterol: Carbon chains with little oxygens

• Phospholipid: Hydrophilic Polar Head & Hydrophobic Nonpolar Tails (Amphipathic: both hydrophilic and hydrophobic)

-Shapes versatile (no true monomer)

-Saturated Fats: No double bonds in fatty acid

-Unsaturated Fats: One or more double bonds in fatty acid

Protein

-Polarity dependent on amino acid side chain (R group)

-Protein is a FOLDED polypeptide

• Functions: Running chemical reactions (enzymes), structural support, transport across cell membrane (proton pumps)

• Elements: CHON

• Identifying Characteristic: N-C-C backbone

• Monomer: Amino acid

• Dimer: Dipeptide

• Polymer: Polypeptide

  • Can fold into a protein

-Peptide bonds covalently bond amino acids through dehydration polymerization reactions

Amino Acid (Protein monomer)

-Variable R group + Amino Group + Carboxyl Acid Group + C bonded to H

-20 amino acids that make up proteins

-R group: Non-polar hydrophobic, Ionic + charge hydrophilic, Ionic - charge hydrophilic, Polar Hydrophilic

Polypeptide Folding

-Forms proteins

-R groups determine protein folding, allows for amino acids to interact

-Polypeptides fold into proteins

• Interaction types:

  • 2 polar amino acids: hydrogen bonds

  • 2 charged amino acids: ionic bonds

  • 2 nonpolar amino acids: Van der Waals interactions

  • 2 cysteine amino acids: disulfide bridge

Nucleic Acids

Types: deoxyribonucleic acid (DNA) & ribonucleic acid (RNA)

• Function: Information storage, some enzymatic activity (RNA)

• Monomer: Nucleotide (5’ phosphate group + 5-Carbon/Pentose sugar + 1’ nitrogenous base)

• Polymer: Nucleic acid

DNA Nucleotides

-Don’t contain 2’ OH (Hydroxyl)

• A (Adenine)

• T (Thymine)

• C (Cytosine)

• G (Guanine)

RNA Nucleotides

-Contains 2’ OH (Hydroxyl)

-A (Adenine)

-U (Uracil)

-C (Cytosine)

-G (Guanine)