Protein structure and function

xtra carrds

What are proteins and how are they coded for?

Proteins are biomacromolecules coded for by genes in DNA.

What is a macromolecule and what are examples?

A macromolecule is a large molecule composed of monomers joined via bonds. Examples include proteins, carbohydrates, nucleic acids, and lipids.

What is the monomer of proteins?

Amino acids.

What are the monomers and polymers involved in forming proteins?

Amino acids are the monomers of proteins. When joined together, they form polypeptides (polymers), which fold into functional proteins.

What is a nucleic acid?

A macromolecule made of nucleotides linked in a long chain, such as DNA or RNA.

What nucleic acid is found in chloroplasts and what is its function?

Chloroplast DNA; it controls the production of proteins for photosynthesis or chloroplast replication.

What is the monomer of nucleic acids?

Nucleotides.

What is the monomer of carbohydrates?

Monosaccharides.

What is the monomer of lipids?

Glycerol.

What bonds are found in nucleic acids?

Hydrogen bonds between nitrogen bases and phosphodiester bonds between the sugar-phosphate backbone.

What type of bond joins amino acids in a protein?

Peptide bonds.

What are the structural components of an amino acid?

An amino group, a carboxyl group, and a variable R group (side chain).

What are the four levels of protein structure?

Primary, secondary, tertiary, and quaternary structure.

What is the primary structure of a protein, and what is its significance?

The linear sequence of amino acids of the polypeptide chain joined by peptide bonds (coded for by the DNA). The primary structure will determine the interactions that can occur between amino acids and consequently all subsequent structures.

What defines the secondary structure of a protein, and what is its significance?

Folding of the polypeptide chains into repeating elements such as alpha helices, beta pleated sheets, and random coils.

• caused by hydrogen bonds between amine and carboxyl groups between non-adjacent amino acids.,

• Basically multiple primary structures (polypeptides) bonded together. Alpha helix provides elasticity and stretch, beta pleated sheet is not elastic but strong. Random coils are any other shapes that can form due to the polypeptide chainls.

significance: the secondary structure will help form the tertiary/quatenary structure of the protein by allowing only some interactions between amino acids, based on the shape formed.

What defines the tertiary structure of a protein, and what is its significance?

overall folding (3D shape) of the polypeptide, so now it's a protein 😛.

A result of the secondary structure undergoing further folding held together by various bonds (disulfide, ionic, and hydrogen) between the R group side chains. All proteins are 3D.

significance: the 3D shape determines the overall function of the protein

What defines the quaternary structure of a protein, and what is its significance?

Two or more polypeptide chains joined to form a functional protein. not all all proteins have a quatenary structure.
significance: the quatenary structure will determine the function of the protein

(Hint: Look for the word chains when trying to work out if it is quaternary. If it has multiple chains it’s a quaternary structure.)

What are examples of proteins with quaternary structure?

Rubisco, DNA polymerase, and RNA polymerase.

What do all cellular structures and functions rely on?

Proteins.

What is the proteome?

The complete set of proteins produced by an organism, coded for by the genome.

What is the genome?

All of an organism’s genetic material.

What is the function of contractile proteins and an example?

They enable movement by contracting muscles; e.g., actin and myosin.

What is the function of regulatory proteins and an example?

they are hormones which regulate body processes, e.g. insulin regulates blood glucose levels.

What is the function of immunological proteins and an example?

They protect against pathogens; e.g., antibodies in immune responses.

What is the function of transport proteins and an example?

They transport substances; e.g., haemoglobin carries oxygen in blood.

What is the function of catalytic proteins and an example?

They speed up chemical reactions; e.g., rubisco catalyses reactions in photosynthesis.

What are fibrous proteins and examples?

• Long, strand-like shape

• Insoluble in water

• Strong and stable

• Structural function (not metabolic)

Fibrous proteins include contractile and structural proteins.

Examples: collagen, keratin, and elastin

What are globular proteins and examples?

Globular proteins are involved in metabolic processes and has a specific 3D shape.
Includes transport, catalytic, membrane, immunoglobulin, and regulatory, proteins.

• compact

• water-soluble

• function as enzymes, hormones, antibodies, and transport molecules.

What is the function of storage proteins and an example?

They store nutrients/minerals; e.g., ferritin stores iron.

What is the function of structural proteins and examples?

They provide support and strength; e.g., keratin (hair), collagen (skin), cytoskeleton.

What is the function of membrane or signal proteins and an example?

They detect/respond to signals; e.g., Rhodopsin in eye cells.

What factors affect protein structure?

Heat, pH, cofactors, and inhibitors.

Is protein denaturation reversible?

Usually not; the protein must be remade.

What happens if a mutation occurs in DNA?

It may change the amino acid sequence and produce a different, possibly non-functional, protein.

Draw the basic structure of a generalised amino acid

Draw the basic structure of a generalised dipeptide.

Identify how many different amino acids are present in nature and describe how they are distinctive.

• There are 20 amino acids

• Each amino acid has a different R/variable group.

• The properties of the R groups differ e.g. Polar vs non polar, acidic vs basic etc.