Inquiry into Life – pg. 37-41
Today’s Objectives:
 Analyze the structure and function of biological molecules in living systems, including carbohydrates, lipids, proteins, nucleic acids
 List the major functions of proteins
 Draw a generalized amino acid and identify the amine, acid (carboxyl), and R-groups
 Identify the peptide bonds in dipeptides and polypeptides
 Differentiate among the different levels of protein organization with respect to structure and bond type, including: primary, secondary, tertiary, quaternary
 Name the four bases in DNA and describe the structure of DNA using the following terms: nucleotide (sugar, phosphate, base), complementary base pairing, double helix, hydrogen bonding
 Relate the general structure of the ATP molecule and its role as “energy currency”
2.7 Proteins
 Proteins have many functions:

Proteins such as ___________ and ______________ have structural roles.
 Proteins are also __________ that speed up the chemical reactions of ______________
 Proteins such as ________________ are responsible for the _____________ of substances within the body.

Proteins transport substances across cell _______________
 Proteins form the _______________ of the immune system that defend the body from
__________ and disease.

Proteins such as __________ are hormones that regulate cellular function.
 Contractile proteins such as _________ and __________ allow parts of cells to move and muscles to contract.
What are proteins?

Contain __________, ______________, ____________, and ____________
 Also often contain __________, and sometimes _____________ and _______
 The basic structure of a protein is a chain of __________ ________ (polypeptides)
 There are about ____ different amino acids
What are amino acids?
 Proteins are _____________ with amino acid _______________
 An amino acid has a central ________ atom bonded to a ____________ atom and
_________ groups:
 One of the three groups is an __________ group (-NH
2
),
 One of the groups is an __________ group (-COOH)
 The third group is called an ___ Group

Amino acids differ from one another by their R group

What are R groups?
 An R group is a _______ of atoms attached to amino acids
 R group = radical group or remainder group

An R group _______________ one amino acid from another
Formation of Proteins
 An amino acid can be referred to as a ____________
 Dehydration synthesis of amino acids result in the bonding of amino acids together and the release of water molecules
 When two amino acids bond together, they produce a _____________
 Example: amino acids __________ and __________ bond to form the dipeptide _______
 The bond that connects amino acids is called a _______________
 A __________ has one peptide bond holding together two amino acids

A __________ would have two peptide bonds holding together three amino acids
 A ______________ would have numerous peptide bonds holding together numerous amino acids
 A polypeptide is a single chain of amino acids

The _______ or combination of these amino acids determines which protein is produced
 This process when repeated form long _____________ of amino acids, or __________
 These sequences take on specific features and ________________ of the individual amino acids that are bonded together

Protein Structure
 There are three to four levels of protein structure

___________ structure – sequence of amino acids (polypeptide)
 ___________ structure – orientation of polypeptide

___________ structure – final 3-D shape of polypeptide
 ___________ structure* - arrangement of multiple polypeptides

*not all proteins have multiple polypeptides
Primary Structure
 Simply the _____________ of amino acids
 Because there are twenty amino acids, it is easy to see that there are literally
____________ of different possible amino acid sequences
 Consequently, there are millions of proteins
Secondary Structure
 As the amino acid chains (polypeptides) get longer, they begin to ________ or _______
 This is a result of _________ on the peptide bonds
 Two types of secondary structure:
 ________ ________ – like a spiral
 _______ ___________ __________ – like folded paper
 The alpha helix is most common
Secondary Structure – alpha helix

As the polypeptide bends into a spiral, ______________ _________ form between the hydrogen of one amino acid and an oxygen further down the chain
 This hydrogen bond helps the alpha helix hold its shape

An alpha helix contains _____ amino acids per spiral
Secondary Structure – Beta pleated sheet
 Hydrogen bonds can form between ___________ lengths of the polypeptide chain creating beta pleated sheets

Tertiary Structure

The third level of protein structure or tertiary structure is described as the ___________ and ____________ of the alpha helix
 As the helix gets longer there are some amino acids that cannot fit the configuration and therefore cause _________

New bonds will form to hold it into a _________________________ shape
 These bonds can be ________, ____________, and/or ____________ bonds
Quaternary Structure
 Only occurs in proteins with more than one _________________
 The quaternary structure is where ______________ 3-D (tertiary) configurations are associated with and function with ______ ________
 Imagine multiple kinked helixes tied up with each other in knots
 An example of a protein with quaternary structure is _______________ which transports substances through our body in our blood
More about Protein Functions
 ___________ proteins speed up chemical reactions in our body

Reactions that normally would take several hours will take only a fraction of a second
 Proteins such as hemoglobin _____________ nutrients and other substances through our body

_____________ proteins fight infections and attack viruses
 The protein __________ is the main structural component of fingernails and hair
 ____________ makes up the connective tissues in our muscles
 _______/__________ make up muscle fibers that allow for movement
2.8 Nucleic Acids
 ___________ _________ are polymers made up of monomers called ______________
 There are two types of nucleic acids:


______ –
 ______ –

Some functions of Nucleic Acids:
 They form ___________ material and are involved in the functioning of chromosomes and protein synthesis

_____ stores genetic information
 _____ codes for the order of amino acids in a protein
 _____ is an intermediary in the sequencing of amino acids into a protein
What are Nucleotides?
 Nucleotides are made from a ____________ _________, a _______________ group, and a _____________ _______________ ________
 There are five ________ nucleotides:
 A________ and G________

Double ring structure purines
 C__________, U________, and T__________
 single ring structure pyrimidines
 These bases are found in DNA and RNA
DNA contains ______________
RNA contains ______________
Nucleotides
 The bases found in DNA form ________________ _______ _________ (the same two bases always bond with each other)
 The structure of DNA is a _________ ______ (we will talk more about DNA later this year

Complementary Base Pairs in DNA
ATP (Adenosine Triphosphate)
 One particularly important nucleic acid is the modified nucleotide known as ______
 ATP is an ______ _______________ with an __________________ (adenine + ribose = adenosine) attached to __ _______________ _________
 ATP is a very ______ ___________ molecule
 When ATP undergoes ____________, large amounts of energy are released
ATP: The energy currency of cells
 ATP is a high energy molecule because the last two phosphate bonds are ___________ and easily broken
 A lot of energy is required to maintain these bonds
 If the bonds are broken, this energy is _____________
 When an ATP molecule loses a phosphate, it becomes the molecule ________
(adenosine diphosphate) and a _____________ molecule
 With the addition of energy, this process can be reversed, creating the ________
 __________ cells use the energy for muscle contraction
 Cells use the energy to synthesize _______________ and ____________