Download Proteins Chapter 3 pages 54-58

QUESTION 1
You are sitting by a lake, you drop a leaf on the
lake and notice that it floats on the top of the
water, which of the following properties of water
could help explain what you observe?
A) It is more dense when liquid than when frozen.
B) It can dissolve large quantities of solutes.
C) It has a high specific heat.
D) It has a strong surface tension.
E) None of these can explain what you observe.
QUESTION 2
The formation of large, repetitive organic
molecules from small monomers is a __________
reaction.
A) dehydration synthesis
B) reduction
C) dehydrogenation
D) hydrolysis
QUESTION 3
Carbon is such an important molecule for life
because:
A)it can form chemical bonds with a maximum of
four other atoms.
B) it is part of the water molecule.
C) it can hydrogen bond to so many molecules.
D) it can be bonded ionically.
E) it can form isomers.
QUESTION 4
Glycogen is a polysaccharide used for energy
storage by:
A)monera
B)fungi
C)plants
D)animals
QUESTION 5
Which of the following solutions has the greatest
concentration of hydrogen ions (H+)?
A) gastric juice at pH 2
B) black coffee at pH 5
C) vinegar at pH 3
D) tomato juice at pH 4
E) household bleach at pH 12
Proteins and Nucleic Acids
KEY WORDS:
Protein
Polypeptide
Amino Acid
Essential Amino Acid
Denature
1°, 2°, 3°, 4° Structure
Nucleic Acid
Nucleotide
DNA
RNA
Types of Proteins
See Table 5.1
Structural
Storage
Enzymes
Transport
Hormones
Antibodies
Receptor
Contractile
Proteins
Subunit = amino acid
Amino acids have three parts:
1. Amino group
2. R group
3. Carboxyl group
The 20 amino acids of proteins: nonpolar
The 20 amino acids of proteins: polar and electrically charged
Linking Amino Acids
Dehydration synthesis: forms a covalent bond –
A Peptide Bond
Creates a polypeptide
Making a polypeptide chain
How are proteins able to do so
many things?
20 different kinds amino acids - different R-groups
Non-polar
Polar
Charged
-O
Scrabble Analogy
Carbohydrates: Glucose
G1
G1
G1
G1
G1
G1
Proteins: 20 amino acids
• Glutamine
E1
• Isoleucine
I1
• Asparagine
• Serine
Hard to make more than
one word
• Threonine
• Lysine
• Arginine
N1
S1
T1
K5
R1
Proteins Fold into Active Shape
Protein function depends on shape
Four Levels of Structure:
Primary
Secondary
Tertiary
Quaternary
1°
2°
3°
4°
Primary (1°) Structure
Sequence of amino acids in polypeptide
The primary structure of a protein
Secondary (2°) Structure
Folds in part of amino acid chain: Hydrogen bonds
b- pleated sheet
a-helix
Tertiary (3°) Structure
3D Packing of Polypeptides: More hydrogen bonds
Examples of interactions contributing to the tertiary structure of a protein
Quaternary (4°) Structure
Interactions between 2+ polypeptides
The quaternary structure of proteins
Review: the four levels of protein structure
Conformation of a protein, the enzyme lysozyme
A chaperonin in action
Denatured Proteins
•Proteins can be unfolded = denatured
•Can affect the behavior of the protein
What can cause proteins to
denature?
Chemicals
pH
Heat
Shape is critical for protein
interactions
EXAMPLE:
Hemoglobin
•4 Polypeptides
•Binds Iron
•Oxygen transport
Protein Folding and Disease
Many diseases caused by incorrect protein folding
Mad Cow Disease
Alzheimers
Cystic Fibrosis
Parkinson’s Disease
Sickle Cell Anemia
Arthritis
Marfan Syndrome
ALS (Lou Gehrig’s Disease)
Cancer
Diabetes Insipidus
A single amino acid substitution in a protein causes sickle-cell disease
Sickled cells
Diet: Essential Amino Acids
• 20 different amino acids
• All living things have protein
• 8 Essential Amino Acids can not be
synthesized by our bodies - must be found
in diet
• All 8 essential amino acids are present in
animal protein and soy beans
Essential Amino Acids
QUESTION
Which of the following is contains all 8
essential amino acids?
1. Wheat
2. Soy beans
3. Brown rice
4. Corn
5. None of these
Lipoproteins & Glycoproteins
LIPOPROTEINS
-Lipid + Protein
-Used for transport of fats throughout the body
-Example: HDL and LDL Cholesterol
GLYCOPROTEINS
-Carbohydrate + Protein
-Receptors on the surface of cells
QUESTION
The myoglobin protein, which carries oxygen
in muscle cells, only has the first three
levels of protein structure (it lacks a
quaternary level). From this you can
conclude that myglobin:
a)Is made of nucleic acids
b)Is made of only one polypeptide chain
c)Lacks hydrogen bonds
d)Is not helical or pleated
e)Is a fiber
NUCLEIC ACIDS
• Nucleic acids include RNA and
DNA
• Polymers made up of repeating
monomers called nucleotides.
James Watson and Francis Crick
Rosalind Franklin
X-ray crystallography
NUCLEOTIDES
3 Main Components:
• 5-Carbon Sugar
(Pentose):
RNA ribose,
DNA deoxyribose
• Phosphate Group
• Nitrogen-containing
base
Nucleotides: Important Energy
Storage Molecules
• Adenosine Triphosphate (ATP): acts like
cell’s battery, providing energy for most
activities.
RNA and DNA
SIMILARITIES:
• 5-carbon sugar
• Phosphate group
DIFFERENCES:
• Nucleotides
– DNA: Adenine, Guanine, Cytosine, Thymine
– RNA: Adenine, Guanine, Cytosine, Uracil
• Sugar
– DNA: Deoxyribose
– RNA: Ribose
Nucleic Acid Synthesis
• Nucleotides joined by
dehydration synthesis
• Covalent bond forms
between PHOSPHATE
GROUP and SUGAR
Structure of DNA
The components of nucleic acids
The DNA double helix and its replication
Polypeptide Sequence as Evidence for Evolutionary Relationships
Nucleotides are to ____ as ____
are to proteins.
• Nucleic acids; amino acids
• Amino acids; polypeptides
• Glycosidic linkages; polypeptide
linkages
• Genes; enzymes
• Polymers; polypeptides
The structural level of a protein least
affected by a disruption in
hydrogen bonding is
• Primary
• Secondary
• Tertiary
• Quaternary
• All equally affected
Which of the following is not a
protein?
• Hemoglobin
• cholesterol
• An antibody
• An enzyme
• Insulin