Back to AI Flashcard MakerBiology /A-level Biology - 3.1.1 Biological Molecules Part 4
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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| 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 |
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) |