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Structure of Protiens
Primary / Secondary / Tertiary / Quaternary
30
Biology
Undergraduate 1
09/28/2009

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Cards

Term
With respect to their structure, what are the most diverse class of molecules known?
Definition
Proteins.
Term
Proteins can serve diverse functions in cells because they are diverse in what?
Definition
Size and shape as well as in the chemical properties of their amino acids.
Term
A proteins underlying structure can be broken down into just four basic levels of organization, what are they? 
Definition
Primary, Seconday, Tertiary, Quarternary
Term
Who discovered that every protein has a unique sequence of amino acids?
Definition
Frederick Sanger - 1940's - 1950's
Term
The unique sequence of amino acids in a protein is called...
Definition
the primary structure
Term
The R-groups present on each amino acid affect...
Definition
its solubility and chemical reactivity.
Term
These structures are distinctively shaped by sections of proteins that are stabilized largely by hydrogen bonding that occurs between the carboxyl oxygen of one amino acid residue and the hydrogen on the amino group of another
Definition
Secondary Structures.
Term
Is secondary structure created between side chains or within the individual chain?
Definition

Individual chain! 

 

(look at page 54)!

Term
In secondary structure, hydrogen bonding between sections of the backbone is only possible when?
Definition
When different parts of the same polypeptide bend in a way that puts the carboxyl groups and the amino groups close together.
Term
When talking about Secondary Structure, what are two of the most important configuations that allow the formation of hydrogen bonds?
Definition

1.  α (Alpha) Helix

 

2.  β (Beta) pleated sheet

Term
What is an α-helix?
Definition
When the polypeptide's backbone is coiled
Term
What is a β-pleated sheet?
Definition
When segments of a peptide chain bend 180° and then fold in the same plane.
Term
When segments of a peptide chain bend 180° and then fold in the same plane.
Definition
a β-pleated sheet
Term
When the polypeptide's backbone is coiled
Definition
an α-helix
Term
The type of secondary structure that forms depends on what?
Definition
The protiens primary structure.
Term
Hydrogen bonds in an α-helix and a β- pleated sheet are very weak relative to covalent bonding, what then makes these structures so stable?
Definition
The large amount of Hydrogen bondings.
Term
The overall three-dimensional shape of a single polypeptide chain.
Definition
Tertiary Structure.
Term
The tertiary structure of a polypeptide results from what?
Definition
The interactions between R-groups or between R-groups and the peptide backbone.
Term
How many types of interactions that involve side chains are important in reguards to Tertiary Structure?
Definition
4
Term

1st important type of interaction...Hydrogen bonds form in several ways.  (In Tertiary Structure)

 

What are they?

Definition

Between hydrogen atoms and the carboxyl group in the peptide-bonded back bone

 

and

 

between hydrogen and atoms with partial negitive charges in side chains

 

Term

2nd important type of interaction... What is a van der Waals interaction? 

 

 

Definition
weak electrical attractions (weaker then hydrogen bonding)
Term

2nd important type of interaction... What is a van der Waals interaction?

 

Pt 2

 

How does this result in a significant increase in stability?

Definition
A large number of van der Waals interactions can occur in a polypeptide when many hydrophobic residues congregate.
Term
3rd important type of interaction... disulfide bonds can form.  What are these?
Definition

When 2 R-groups contain Sulfer, such as in cysteine, the sulfer atoms covalently bond. 

 

 

Term

In Tertiary Structure, what is frequently referred to as a bridge?

 

and why?

Definition

Disulfide Bonds. 

 

Because they create a strong link between distinct regions of the same polypeptide.

Term

4th important type of interaction... well you have had the other 3, what is the last one?

 

 

 

Definition

Ionic Bonding can occur between groups that have full and opposing charges.

 

 

(Ionic Bonding: metal and nonmetal through electrostatic attraction)

Term
The type of tertiary structure depends on what?
Definition
The primary and secondary structure!
Term
What is a Quarternary Structure?
Definition
The combination of polypeptide sub units.(Multiple Polypeptides)
Term
Proteins with two polypeptide sub units are called what?
Definition
Dimers (Two Parts)
Term
Proteins with four polypeptide sub units are called what?
Definition
tetramer (Four-Parts)
Term
remember the ten prefixes... not that you will need to know mono.
Definition

mono

di

tri

tetra

penta

hexa

hepta

octa

nona

deca

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