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A-level Biology - 3.1.1 Biological Molecules Part 4

Biology30 CardsCreated about 2 months ago

This deck covers key concepts related to proteins and their structures, including amino acids, peptide bonds, and the various structural levels of proteins.

What are the monomers in proteins?

Amino acids
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Key Terms

Term
Definition
What are the monomers in proteins?
Amino acids
What is formed when 2 amino acids join together?
Dipeptide
When is a polypeptide formed?
When more than 2 amino acids join together
Proteins are made up of one or more ____
polypeptides
What are 3 things all amino acids have? (structure wise)
Carboxyl group (-COOH) Amine group (NH2) R group (aka variable side group)
All living things share bank of ___ amino acids
20

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TermDefinition
What are the monomers in proteins?
Amino acids
What is formed when 2 amino acids join together?
Dipeptide
When is a polypeptide formed?
When more than 2 amino acids join together
Proteins are made up of one or more ____
polypeptides
What are 3 things all amino acids have? (structure wise)
Carboxyl group (-COOH) Amine group (NH2) R group (aka variable side group)
All living things share bank of ___ amino acids
20
What changes with each amino acid?
The R group
What is glycine's R group?
H

Draw an amino acid

How are polypeptides formed?
Formed by amino acids linking together by condensation reactions (molecule of water is released during reaction)

What is the name of the bond formed between amino acids?

Peptide bonds (Combines -OH from carboxyl group and -H from amino acid)

Draw a dipeptide

What is the primary structure in proteins?
Sequence of amino acids in polypeptide chain
What is the secondary structure in proteins?
Hydrogen bonds form between amino acids in chain = makes it coil into alpha helix or fold into beta pleated sheet
What is the tertiary structure in proteins?
Further folding of whole polypeptide chain More bonds form between different parts (R groups) of polypeptide chain: Hydrogen bonds Ionic bonds Hydrophobic interactions Disulphide bonds
Where do disulphide bonds form?
Between R-groups containing sulfur atoms
Where do ionic bonds form?
Form between R groups with charges
Describe hydrophobic interactions in proteins
When polypeptide chain folds: hydrophobic R-groups are in the interior of the folded chain whereas hydrophilic R-groups tend to be on the outside
What is the quaternary structure in proteins?
Arrangement of 2 or more polypeptide chains in a protein
For proteins made … the tertiary structure form their final 3D structure
proteins made from single polypeptide chain
For proteins made from … the quaternary structure is protein's final structure
proteins made from more than one polypeptide chain (e.g. haemoglobin, insulin, collagen)
Describe the structure of an enzyme and a property of them
Roughly spherical in shape due to tight folding of polypeptide chains Soluble (& often have roles in metabolism)
Describe the structure of antibodies
Made up of 2 light (short) polypeptide chains & 2 heavy (long) polypeptide chains bonded together Have variable regions: amino acid sequences in these regions vary greatly

Describe the structure of channel proteins (present in cell membranes) and its function

Contain hydrophobic and hydrophilic amino acids = cause protein to fold up & form a channel These proteins transport molecules and ions across membranes

Why are structural proteins physically strong?
Consist of long polypeptide chains lying parallel to each other with cross-link between them

Describe the biuret test for proteins

Test solution needs to alkaline ∴ add few drops of sodium hydroxide solution Then add some dilute copper(II) sulfate solution Protein present = turns purple No protein = solution stays blue (Colours are pale so look carefully)

Name the 2 types of proteins
Fibrous (strands) & Globular (spherical)
Give 3 examples of fibrous proteins
Structural: collagen, muscles (actin & myosin), keratin
Give 3 examples of globular proteins
haemoglobin, enzymes, hormones, antibodies
What bond/interaction helps in the tertiary structure helps to form the 3D shape of globular proteins?
Hydrophobic interactions (keep circular shape - hydrophobic centre and hydrophilic outside)