Biology chapter 2
The smallest piece of an element that
retains the characteristics of the element
Atoms
Subatomic particles of atom. What is an atom composed of?
protons, neutrons, and electrons.
Surround the atomic nucleus.
They are very small and move very fast.
Electrons
Are close together in the atomic nucleus,
which is the center of the atom.
Protons and neutrons
positively charged
Protons
Neutral (none) charge
Neutrons
Negatively charged
Electrons
What determines the atomic number
Protons
What does an element’s atomic number indicates
It determines how many protons
are in each atom of that element.
What determines the mass number
Protons and neutrons
What is the total number of protons
and neutrons in its nucleus.
An atom’s mass number
What is same atomic number, different mass number called
Isotopes
The different structures of proteins
primary, secondary, tertiary and quaternary
Primary structure (sequence):
Amino acid sequence of a polypeptide
Localized areas of coils, sheets, and loops
within a polypeptide
Secondary structure (“substructure”)
Overall shape of one polypeptide
Tertiary structure (polypeptide shape):
Overall protein shape, arising from interaction
between the multiple polypeptides that make
up the functional protein. Only proteins with
multiple polypeptides have quaternary
structure.
Quaternary structure (protein shape):
properties of water
Cohesive, adhesive, cohesive & adhesive, excellent solvent, excellent solvent for salt (NaCl), only dissolves selected molecules, regulates temperature, expands when it freezes, and participates in chemical reactions needed for life.
Difference b/n hydrophobic and hydrophilic
Hydrophilic (“water-loving”) substances.
• Polar solutes
• Ions
Hydrophobic (“water-fearing”) solutes.
• The molecules in lipids, like the butter shown here, have
nonpolar covalent bonds.
A type of chemical reaction.
To “digest” or break down a polymer, enzymes break
bonds between the monomers.
A water molecule is required for the reaction to occur.
Hydrolysis
A type of chemical reaction.
To synthesize a polymer, enzymes form bonds between two
monomers.
As part of the reaction, a water molecule is released.
Dehydration synthesis
Difference b/n Hydrolysis and Dehydration
Hydrolysis: breaks polymers into monomers
Dehydration synthesis: joins monomers into polymers
Some examples of lipids
Triglycerides (fats), Phospholipids, Steroids, and waxes
Contains at least one double bond, which gives the
fatty acid a bent shape. (liquid at room temperature)
unsaturated
fatty acid
fatty acid are bonded to four other atoms.
This makes the fatty acid have a straight shape.
(solid at room temperature)
saturated
One atom donates one or more electrons to another atom;
electronegativity difference between atoms is very large (>1.7). The resulting oppositely charged ions attract each other.
(Ye quiz mels) an electrical attraction occurs between two atoms of different charge.
Ionic bond
Two atoms share pairs of electrons
Covalent bond
Electronegativity difference between atoms is small (<0.4).
Nonpolar
Electronegativity difference between atoms is moderate or large (0.4 to 1.7).
Polar
An atom with a partial negative charge attracts a hydrogen atom with a
partial positive charge. Hydrogen bonds form between adjacent
molecules or between different parts of a large molecule.
Hydrogen bond