Asked Feb 9, 2019

What are four levels of protein structure, and explain how a protein's shape determines its function? Explain denaturation.


Expert Answer

Step 1

Proteins are bluiding blocks of an organisms structure.  These seve various functions such as formation of structure in form of muscles, provide immunity in form of antibodies, catalyze reactions in form of enzymes etc,  

Chemically, proteins are biomolecules containing carbon, nitrogen, hydrogen, oxygen and sulfur atoms in their structure. These are polymers formed of amino acids as their monomers. Amino acids contain both -COOH as well as -NH2 groups in their structure. These groups of two amino acids form condense with each other and form peptide bonds.

Step 2

Structurally, protiens are classified in four levels. 

  1. First level is primary structure which is  straight chain structure composed on amino acids bonded to each other by peptide bonds. The first amino acid with free -NH2 group is called N-terminal amino acid while one with free -COOH group is called C-terminal amino acid. This level has protein which is freshly translated from mRNA.  Protein is termed as simple polypeptide in this level.
  2. Second level is the secondary structure of protein in which primary structure forms hydrogen bonds with itself. Two types of secondary structures are alpha helix and beta sheets. 

Alpha helix is formed when primary structure forms helical shape, it is stabalized by hydrogen bonds formed between -NH and -CO of first and fourth amino acid. 

Beta sheets are formed when primary structure lines up and forms pleats. The amino acids, which occupy opposite position in these pleats, form hydrogen bonds between their CO and NH groups. 

So, secondary structure is stabalized by hydrogen bonds.

3. Third level or tertiary structure is that in which the polypeptide is coiled on itself to form 3-dimensional structure. Distant amino acids of polypeptide come closer in this structure. It is stabalized by four types of interactions i.e. hydrogen bonds, ionic interactions, disulfide linkages, hydrophobic interactions. 

4. Fourth level or quarternary structure is that in which protein is composed of two or more subunits. Each subunit is an idependent polypeptide. These subunits are coiled with each other and together form a functional protein. Example, hemoglobin has four polypeptides.  

Step 3

Shape of protein directly governs its function. Shape itself depends on the primary structure or more specifically to the amino acids present in protein. These amino acids decide which type of secondary or tertiary structure is possible for a protein and hence ...

Want to see the full answer?

See Solution

Check out a sample Q&A here.

Want to see this answer and more?

Solutions are written by subject experts who are available 24/7. Questions are typically answered within 1 hour.*

See Solution
*Response times may vary by subject and question.
Tagged in




Related Biology Q&A

Find answers to questions asked by student like you
Show more Q&A

Q: What makes hypervariable region I (HVRI) within mtDNA useful for researchers studying continental pa...

A: A hypervariable region (HVR) refers to a site within the D loop of mitochondrial DNA (mtDNA) or the ...


Q: How does non-compliance with antibiotic treatment regimens lead to the generation of drug resistant ...

A: Drug resistant bacteria, as the name suggests, are a special type of bacteria that are resistant to ...


Q: What is the function of the external nares, nasopharynx, oropharynx, laryngopharynx and the alveolar...

A: The lungs are one of the significant organs present in the human body. The lung consists of five lob...


Q: What do the adjectives obligate and facultative mean with regard to microbes?

A: The study of microbes or small living things is referred to as microbiology. Microbes are too small ...


Q: How do the antifungal drugs such as Polyenes, Griseofulvin, Azoles, and 5-flurocytosine affect funga...

A: Chemicals are used as antifungal agents. They affect the vital process of the fungal cell and affect...


Q: What advantages are associated with segmented bodies and appendages?

A: The term segmentation in biology means to duplicate the organs or body parts, like arms and legs. Se...


Q: What are van der waals attractions?

A: A chemical bond is a kind of attraction between two atoms, molecules, or ions. A chemical bond is a ...


Q: How does a blockage in a coronary artery cause a heart attack? What kind of dietary and lifestyle ch...

A: Coronary arteries are arteries that supply oxygen-rich blood and essential nutrients to the heart mu...


Q: The active coenzyme form of thiamin is 1. involved in glycolysis. 2. located in th...

A: Thiamine is also termed as vitamin B1, which is the derivative of pyrimidine and thiazole, linked to...