Amino Acids & Protein

Amino Acids & Protein

Advanced Animal Nutrition

Learning Objectives

• Identify the difference between essential and non-essential amino acids

• Explain the structure and features of amino acids and protein

• Summarise the roles of protein

• Simplify the process of how proteins are digested and absorbed

Open Ended

Provide a definition for an amino acid - be quick, you only have 3 minutes!

Amino Acids

• Organic compounds containing amine and carboxyl functional groups, along with a side chain specific to each amino acid.

Amine group

Carboxyl group

Important of Amino Acids

• Amino acids are the building blocks of Protein.

• 20% of the human body is made up of protein.

• A large proportion of our cells, muscles and tissue is made up of amino acids, meaning they carry out many important bodily functions, such as giving cells their structure. 

• They also play a key role in the transport and the storage of nutrients. 

Multiple Choice

Which sentence describes an essential amino acid?

• These are amino acids that cannot be made by the body, so they are gained through food.

• These are amino acids that can be produced by the body

Essential Amino Acids

• Must be obtained through foods

• Cannot be made by the body

• 9/20 are essential

• Body does not store them, so must have daily supply

Non-Essential Amino Acids

• Can be produced by the body

• Not classed as essential, however fulfil essential roles in the body

• When you’re sick or under significant stress, your body may not be able to produce enough of these amino acids to meet your needs

Amino Acids

• The 9 essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

• The 11 nonessential amino acids: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.

Structure

• All amino acids have a central carbon atom surrounded by a hydrogen atom, a carboxyl group, an amino group, and an R-group. 

• It is the R-group or side chain that differs between the 20 amino acids

• Each amino acid has unique characteristics arising from the size, shape, solubility, and ionization properties of its R group.

Open Ended

Define a Zwitterion. You may use research to help you. You have 5 minutes for this task.

Amino Acids as a Zwitterion

• Zwitterion = molecule or ion having separate positively and negatively charged groups.

• An amino acid has both a basic amine group and an acidic carboxylic acid group

Amino Acids as a Zwitterion

• Internal transfer of a hydrogen ion from the -COOH group to the -NH2 group

• Leaving an ion with both a negative charge and a positive charge.

Task

Scan the QR code and watch the video.

The next set of questions are related to this video!

Open Ended

What is a polymer?

Open Ended

What is a monomer?

Open Ended

What is an alpha carbon?

Protein

• Any of a class of nitrogenous organic compounds which have large molecules composed of one or more long chains of amino acids

Open Ended

Provide 5 examples of where protein can be sourced from.

Forming Proteins

• Peptide bonds are formed by a biochemical reaction that extracts a water molecule as it joins the amino group of one amino acid to the carboxyl group of a neighbouring amino acid. 

• If proteins are being broken down - hydrolysis reaction

Primary Structure

• Simplest level of protein structure

• Refers to sequence of amino acids in polypeptide chain

• Held together with peptide bonds

Secondary Structure

• Secondary structure is local interactions between stretches of a polypeptide chain and includes α-helix and β-pleated sheet structures

• Secondary structures arise as H bonds form between local groups of amino acids in a region of the polypeptide chain

Tertiary Structure

• 3-D shape formed through interactions within the polypeptide chain

• Cysteine side chains form disulfide linkages in the presence of oxygen, the only covalent bond forming during protein folding

• Hydrophobic R groups of nonpolar amino acids mostly lie in the interior of the protein, while the hydrophilic R groups lie mostly on the outside

Quaternary Structure

• How its subunits are oriented and arranged with respect to one another.

• Applies to multiple polypeptides proteins only

• Any proteins with a single polypeptide will not have a quaternary structure

Open Ended

Research task: How is protein absorbed?

Open Ended

Research the functions of proteins - provide at least 4 functions of proteins in the body.