BIOS1700
Chapter 1: Life: chemical, cellular, and evolutionary functions
What is science? Searching for answers to the unknown
Section 1.1: Scientific Method
Science operates by the scientific method
Observation-->Hypothesis-->Predictions-->Experiments or new observations--
>Theory
● Observation: detailed, clear description
● Hypothesis: what is going on? must be testable in an objective manner
● Prediction: what will happen if hypothesis is correct?
● Experiment: fair and repeatable
● Theory: consistent results over many experiments
Section 1.3: The Cell
Cell: the simplest self-replicating entity that exists as an independent unit of life.
● Unicellular organisms: bacteria, yeast, etc…
● Multicellular organisms: fruit fly, cheetah, humans, etc…
DNA: stores genetic info, double helix, unpacks genetic info for growth and function
Central Dogma of Molecular Biology: DNA-->RNA-->protein
● DNA: storage (replicates)
● Transcription- mRNA
● RNA: unpacking
● Translation- tRNA
● Protein: execution
Prokaryotic Both Eukaryotic
● No nucleus ● Enclosed by plasma ● Nucleus
● All single-celled membrane ● More complex
organisms ● Cytoplasm inside ● Organelles
● Transcription and ● Single celled or
translation in the multicellular
cytoplasm ● Transcription in nucleus,
translation in cytoplasm
Metabolism: a way of transforming energy from the environment for life
Chapter 2: The Molecules of Life
How does chemistry play a role in biology?
Section 2.1: Properties of Atoms
Atom: the basic unit of matter
Elements: smallest pure substance in chemistry
Atomic number: # of protons
Atomic mass: # of protons and neutrons
,Isotopes: different number of neutrons
Water (H2O): polar
Shell: energy level of orbital
Periodic table
● For the first three horizontal rows in the periodic table, elements in the same row have
the same number of shells (first row has 1 energy shell, second row has 2 energy shells,
third row has 3 energy shells)
● The elements in a vertical column are called a group/family. Members of a group all have
the same number of electrons in their outermost shell
● Electronegativity increases from left to right across the periodic table
○ Electronegativity is the power of protons to pull electrons closer to nucleus
(higher electronegativity has a stronger attraction of electrons)
● In the second row of the periodic table, the elements are ordered by number of electrons
in shell 2 (valence electrons)
○ The max number of valence electrons is 8 (most stable)
Section 2.2: Molecules and Chemical Bonds
Chemical Bonds:
Bonds with shared electrons: making atoms stable by filling a shell with electrons
● Covalent Bond: nonpolar or polar
● Ionic Bond: extreme cases of polar covalent bonds, unequal sharing of electrons
Bonds without shared electrons: bonds made by charges between molecules
● Hydrogen Bond
● Van der Waals Force
Strongest to weakest:
1. Covalent
2. Ionic
3. Hydrogen
4. Van der Waals
Covalent Bonds
● Share electrons
● When the outermost orbitals of two atoms come into proximity, two atomic orbitals each
containing one electron merge into a single orbital containing a full complement of two
electrons. The merged orbital is called a molecular orbital, and each shared pair of
electrons constitutes a covalent bond that holds the atoms together.
○ When electrons are shared unequally between two atoms, a polar covalent
bond results
○ When electrons are shared equally between two atoms (same electronegativity) a
, nonpolar covalent bond results
Hydrogen Bonds
● Occurs between polar molecules
● Positive charge attracts negative charge
● Hydrogen has a partial positive charge and oxygen has a partial negative charge
Ionic Bonds
● Ion: an atom in which the number of protons and electrons is different
● Elements on the right side (higher pulling power) steal electrons from elements on the
right side. Both become stable
○ Ex: Cl atom steals one electron from Na atom to become a stable configuration
(Cl- ion) and (Na+ion)
● Charged molecules are friends
○ Ex: NaCl dissolves easily in H2O because the two ions (Cl- and Na+) are pulled
Chapter 1: Life: chemical, cellular, and evolutionary functions
What is science? Searching for answers to the unknown
Section 1.1: Scientific Method
Science operates by the scientific method
Observation-->Hypothesis-->Predictions-->Experiments or new observations--
>Theory
● Observation: detailed, clear description
● Hypothesis: what is going on? must be testable in an objective manner
● Prediction: what will happen if hypothesis is correct?
● Experiment: fair and repeatable
● Theory: consistent results over many experiments
Section 1.3: The Cell
Cell: the simplest self-replicating entity that exists as an independent unit of life.
● Unicellular organisms: bacteria, yeast, etc…
● Multicellular organisms: fruit fly, cheetah, humans, etc…
DNA: stores genetic info, double helix, unpacks genetic info for growth and function
Central Dogma of Molecular Biology: DNA-->RNA-->protein
● DNA: storage (replicates)
● Transcription- mRNA
● RNA: unpacking
● Translation- tRNA
● Protein: execution
Prokaryotic Both Eukaryotic
● No nucleus ● Enclosed by plasma ● Nucleus
● All single-celled membrane ● More complex
organisms ● Cytoplasm inside ● Organelles
● Transcription and ● Single celled or
translation in the multicellular
cytoplasm ● Transcription in nucleus,
translation in cytoplasm
Metabolism: a way of transforming energy from the environment for life
Chapter 2: The Molecules of Life
How does chemistry play a role in biology?
Section 2.1: Properties of Atoms
Atom: the basic unit of matter
Elements: smallest pure substance in chemistry
Atomic number: # of protons
Atomic mass: # of protons and neutrons
,Isotopes: different number of neutrons
Water (H2O): polar
Shell: energy level of orbital
Periodic table
● For the first three horizontal rows in the periodic table, elements in the same row have
the same number of shells (first row has 1 energy shell, second row has 2 energy shells,
third row has 3 energy shells)
● The elements in a vertical column are called a group/family. Members of a group all have
the same number of electrons in their outermost shell
● Electronegativity increases from left to right across the periodic table
○ Electronegativity is the power of protons to pull electrons closer to nucleus
(higher electronegativity has a stronger attraction of electrons)
● In the second row of the periodic table, the elements are ordered by number of electrons
in shell 2 (valence electrons)
○ The max number of valence electrons is 8 (most stable)
Section 2.2: Molecules and Chemical Bonds
Chemical Bonds:
Bonds with shared electrons: making atoms stable by filling a shell with electrons
● Covalent Bond: nonpolar or polar
● Ionic Bond: extreme cases of polar covalent bonds, unequal sharing of electrons
Bonds without shared electrons: bonds made by charges between molecules
● Hydrogen Bond
● Van der Waals Force
Strongest to weakest:
1. Covalent
2. Ionic
3. Hydrogen
4. Van der Waals
Covalent Bonds
● Share electrons
● When the outermost orbitals of two atoms come into proximity, two atomic orbitals each
containing one electron merge into a single orbital containing a full complement of two
electrons. The merged orbital is called a molecular orbital, and each shared pair of
electrons constitutes a covalent bond that holds the atoms together.
○ When electrons are shared unequally between two atoms, a polar covalent
bond results
○ When electrons are shared equally between two atoms (same electronegativity) a
, nonpolar covalent bond results
Hydrogen Bonds
● Occurs between polar molecules
● Positive charge attracts negative charge
● Hydrogen has a partial positive charge and oxygen has a partial negative charge
Ionic Bonds
● Ion: an atom in which the number of protons and electrons is different
● Elements on the right side (higher pulling power) steal electrons from elements on the
right side. Both become stable
○ Ex: Cl atom steals one electron from Na atom to become a stable configuration
(Cl- ion) and (Na+ion)
● Charged molecules are friends
○ Ex: NaCl dissolves easily in H2O because the two ions (Cl- and Na+) are pulled
