Amino Acids and Proteins Biology Amino Acids and Proteins

Amino Acids and Proteins Biology Amino Acids and Proteins

The Big Picture Large whiteboard in groups: Each person in your group has to write one key point for each of water, ions, carbohydrates and lipids Find amino acids / proteins on your ‘biological molecules’ mindmap

The Big Picture Structure and role of amino acids and proteins. The peptide link between the amino acid monomers to make a protein polymer The structure of different types of proteins

Protein

Get an envelope of amino acid cards Get an envelope of amino acid cards. Make a table to show the ways that the amino acids are the same or different (see next slides for hints) Ways they are the same Ways they are different

Amino Acids Ways they are the same Ways they are different Timer

Amino Acids

Amino Acids

Amino Acids

Amino Acid (simple version)

Look at this interactive amino acid structure now! More help: Interactive animation showing the basics and then all of the ‘R’ groups (first 2 slides only!)

Candidates are not expected to recall names of amino acids but can be expected to identify them, given a structural formula and a suitable table showing -R groups

Make and draw the following amino acids: Glycine Alanine Aspartic acid Cysteine

Watch this reaction

Joining 2 amino acids together to make a dipeptide in a condensation reaction. They make a peptide bond

This is the primary structure of a protein Make a dipeptide from two of your amino acid models. Find another group and join both of your dipeptides together into a polypeptide (protein) Put 5 yellow cards in a line. Draw the polypeptide that would be made. Name the reaction. Identify and name the bonds formed This is the primary structure of a protein

Break up this polypeptide (protein primary structure) Break up this polypeptide (protein primary structure). Name the reaction, the other molecules that would be needed, and the general name for the products formed. (Or can you name the actual products?)

Primary structure Number, type and sequence of amino acids (determined by DNA triplet sequence)

Answer the practice questions below (1,2,3) as a team. Then copy out and complete the exam question (Q2, 8 marks) Ask the teacher or another student to mark your work and answer any queries

Well done! You now know about the primary structure of proteins!

Next part…building a full protein

Use sellotape/staples/glue to make a spiral with the paper Make a very long strip of paper. Write the names of many amino acids along the length Use sellotape/staples/glue to make a spiral with the paper Use sellotape/staples/glue to show extra folds of the whole spiral structure Use sellotape/staples/glue to attach your shape to another group’s Use the theory slides /books/notes to identify the different levels of protein structure, and the types of bonds that could be present at each level STAPLES = peptide bonds SELLOTAPE = Hydrogen, ionic, disulfide bonds

A protein is one or more polypeptide chains folded into a complex 3D shape It has a….. Primary structure Secondary structure Tertiary structure Quaternary structure

Primary structure Number, type and sequence of amino acids determined by DNA triplet sequence

Secondary structure Coiling of primary structure: Alpha Helix (α): Left handed spiral stabilized by hydrogen bonds between amino acids between –NH and -CO

Tertiary structure Projecting R groups of amino acids determine bonding/folding 3D Shape which eg. forms active site in enzymes (more) Hydrogen bonding Ionic bonding Disulfide bonding Hydrophobic interactions

Hydrogen bonding

Ionic bonding

Disulfide bonding

Hydrophobic interactions

Tertiary structure

Quaternary structure More than one polypeptide chain

This is insulin, a hormone This is insulin, a hormone. Identify the different levels of protein structure, and the types of bonds be present at each level

Proteins have a function linked to their structure Globular proteins are enzymes, antibodies, hormones and plasma proteins. They are folded or spherical, and soluble in water Fibrous proteins have structural functions and are strong and tough. They are made up of long chains with many crosslinks

Use the next slides and your notes to make simple models to show the general shapes of a globular protein (eg. Haemoglobin) and a fibrous protein (eg. Collagen) Show your models to the teacher and link the structures to the functions

Haemoglobin (Globular Protein) (detailed structure of haemoglobin not required).

Haemoglobin (Globular Protein) 4 x Polypeptide chains (2 x α, 2 x β) in the quaternary structure each with an iron group Folded spherical tertiary structure important for bonding Carries oxygen in the blood

Other globular proteins Enzymes Antibodies Hormones

Fibrous proteins Have alpha helices linked into strands Eg Collagen, Keratin

Collagen (Fibrous Protein) 3 polypeptide chains (each an α-helix) In a long rope-like structure with ends of molecules staggered so no weak points in the fibre Held together by hydrogen bonds between R groups keeping the chains tightly bound High tensile strength so used for structural tissues eg. tendons

Make a group spider diagram to plan out where you think the 15 marks are for this question. Reveal the mark scheme (next slide) and score yourself

Well done! Next step….do the task book and Moodle questions! Want a recap? Watch a video summary of protein structure