Transcript Bio1A - Lec 3 slides File

Proteins
•Amino acids
•Synthesis & Degredation
•Structural Levels
•Factors for structure
•Domains
Reading
Lipids
•Parts of triglyceride
•Function of triglycerides
•Phospholipids
•Steroids
Homework
Carbohydrates
•Characteristics & Isomers
•Mono-, di-, & Poly-
Homework 1
Ch 4: Proteins
Ch 5: Lipids, Carbs,
Nucleic acids
Ch 6 Prequiz
Ch 7 Prequiz
Diffusion & Osmosis Prequiz
Study Groups!
Moodle email
Molecules of the body
Protein building block
monomer
Variable side chain
(R group)
What Kind of Molecule is this?
Notice different way of drawing = perspective
1000s exist
Only 20 in proteins
20 Amino Acids
Essential amino
acids
p78
Some have charged side chains
(depending on pH)
Notice different way of drawing = perspective
Some side chains are uncharged
But polar
Some R-groups are hydrophobic
Variations in side chains determine how the protein
will interact with other molecules or itself
Asparagine is:
a)Polar
b)Charged +
c)Charged d)hydrophobic
e)None of the above
Asparagine is a polar molecule and will likely
NOT interact with
a)H2O
b)Hydrophillic molecules
c)Charged molecules
d)Hydrophobic molecules
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When amino acids are polymerized
Polymerized  Chain
Added in order
aa #1
aa #2
Backbone
aa #1
aa #2
Condensation
/
Amino terminal
N-ter
= beginning
Amino acid, dipeptide, tripeptide, polypeptide
Carboxyl
Terminal
C-ter
= end
Peptide Bond
carboxyl
amino
amide
Proteins have shape: 3D
4 Levels of protein structure
Shape is required for
function
Native = functional
Biologically active
Primarily Hydrogen bonds
But also ionic
And covalent – disulfide bonds
Cysteine
Cysteine
Dimeric
form of
cysteine
When amino acids are polymerized
Polymerized  Chain
Added in order
aa #1
aa #2
Backbone
aa #1
aa #2
Condensation
/
Amino terminal
N-ter
= beginning
Amino acid, dipeptide, tripeptide, polypeptide
Carboxyl
Terminal
C-ter
= end
Proteins have shape: 3D
4 Levels of protein structure
Shape is required for
function
Native = functional
Biologically active
Primarily Hydrogen bonds
But also ionic
And covalent – disulfide bonds
Cysteine
Cysteine
Dimeric
form of
cysteine
Proteins have shape: 3D
4 Levels of protein structure
Primary (1°) - Sequence
Secondary (2°) – Features within the
overall chain
The sequence of amino acids in a
protein is: G-Y-T-T-Q. This is an example
of what level of protein structure?
a)Primary
b)Secondary
c)Tertiary
d)Quatenary
e)None of the above
Androgen Receptor is a protein that has a
helix shape which allows it to fit into DNA.
The helix is an example of what level of
protein structure?
a)Primary
b)Secondary
c)Tertiary
d)Quatenary
How does a protein fold? Unknown
Determined by Primary sequence
Mostly through hydrogen
bonding determined by side
chains and backbone
Shape is required for
function
Native = functional
Biologically active
Proof? Protein Denaturation
Essentially: build the chain and it will fold itself
Finds most thermodynamically stable form
• If you denature a protein it can renature
Native = functional
Biologically active
Non-functional
Structure = function
Interaction with H2O
Drives globular form, hydrophobic residues
inside, hydrophillic residues on outside
Classical example of structure = function
What kind of interaction is the
most influential in protein shape?
a)Covalent
b)Ionic
c)Hydrogen
d)Hydrophobic
e)Van der waals
Sequence not the whole story
Eggs can’t renature
1.
2.
Particular proteins
Presence of other proteins
Chaperones
prions
Globular
X-ray crystallography
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X-ray crystallography
Lysozyme
Myoglobin: 1st structure 1958 Kendrew
Ball and Stick
Ribbon (route of aa’s)
Patterns of structure & sequence
 domains
Regions that do something
Example region that interacts with Zn have similar
structure – now can identify through primary
sequence
DNA binding domain – helix loop helix
Fibrous and Globular Proteins
• Fibrous proteins
– Extended and strand-like proteins
– Water insoluble
– Examples: keratin, elastin, collagen, and certain
contractile fibers
• Globular proteins
– Compact, spherical proteins with tertiary and
quaternary structures
– Water soluble (more or less)
– Examples: antibodies, hormones, and enzymes
Phenylalanine is:
a)Polar
b)Charged +
c)Charged d)hydrophobic
e)None of the above
Many Globular proteins change shape
This structure is an example of ___
structure?
a)1°
b)2°
c)3°
d)4°
e)5°
Example of a transmembrane domain
Highly hydrophobic side chains
Binding of the red molecule gives an
alternative protein structure. What
level of protein structure is this?
a)1°
b)2°
c)3°
d)4°
e)5°
What is breaking and reforming to
allow this rearrangement?
a)Covalent
b)Ionic
c)Hydrogen
d)Hydrophobic
e)Van der waals
Shape changes
Mostly / usually alters
hydrogen bonding pattern
Different composition
means another more
thermodynamically stable
shape
When O2 binds to hemoglobin, the
protein changes shape. This is an
example of what level of protein
structure?
a)Primary
b)Secondary
c)Tertiary
d)Quatenary
How would you expect 2 proteins
to interact with each other?
Primarily through:
a)Covalent
b)Ionic
c)Hydrogen
d)Hydrophobic
e)Van der waals
How would you expect 2 proteins
to interact with each other?
Primarily through:
a)Covalent
b)Ionic
c)Hydrogen
d)Hydrophobic
e)Van der waals
Lipids
•Contain C, H, and O, but the proportion of oxygen
in lipids is less than in carbohydrates
therefore hydrophobic / Insoluble in water
Soluble in other lipids and organic solvents
Lipids are therefore a less cohesive / broad
category
Functional Groups –
a)Carboxyl
b)Amino
c)Ester
d)Methyl
e)phosphate
Lipids: Triglycerides
oils (liquid) & fats (solid)
For energy storage
Lipids: Triglycerides
oils (liquid) & fats (solid)
Joining is through?
a)Condensation
b)Hybridization
c)Hydrolysis
d)redox
Lipids: Triglycerides
oils (liquid) & fats (solid)
Esterify glycerol
Ester = derived from alcohol + carboxyl
Monoglyceride, diglyceride, tri-
NOT a polymer
2 Major categories of Fatty acids
Solids = Fats
Saturated with H’s
H-O
Liquids = oils
mono-UNsaturated
H-O
Trans vs Cis
Trans bad – determined empirically / statistical analysis
II . Phospholipids
Phospholids are
amphipathic
Phosphate
choline group
Can vary
Serine, etc.
Esterification
Alcohol + acid
 Phosphodiester bond
The Cell Membrane
In water/solution phospholipds will
spontanesouly form
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Membrane Lipids
• 75% phospholipids (lipid bilayer)
– Phosphate heads: polar and hydrophilic
– Fatty acid tails: nonpolar and hydrophobic
• 5% glycolipids
– Lipids with polar sugar groups on outer membrane surface
• 20% cholesterol
– Increases membrane stability and fluidity
Steroid hormones
Testosterone
Estradiol (Estrogen)
chenodeoxycholic acid
(bile salt)
Lipids Summary
Triglycerides
Function: food storage
composition:
1 glycerol (know structure)
3 Fatty acids (carboxyl on unbranched hydrocarbon)
Saturated vs unsaturated (Cis vs Trans)
Phospholipids
Function: membranes
due to amphipathic structure
Composition: 1 glycerol, 2 fatty acids, 1 phosphorous group
Cholesterol
Function: membranes & hormone precursor
Know general structure: 4 rings