Forensic biology- Proteins

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  • Created by: aarafa11
  • Created on: 23-05-20 17:41
Facts about proteins
Most abundant macromolecules; Structurally & functionally sophisticated macromolecules; Synthesised from 20 different types of Amino Acids (AA); Diverse properties among amino acids; mix ‘n’ match amino acids to produce proteins with function
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What are the size of
range in size from 50 to 4,636 amino acids residues in length*; There are 20 amino acids essential for life; 20 X great variety of chain length = Huge diversity of proteins
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Function of a protein
structure; protection; detoxification; transport; defence; regulation; movement; catalysis
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what is the difference between a catalyst and an enzyme
E) More specific (only catalyse reactions involving very similar compounds); Generally more efficient
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What is an amino acid structure
Amino group; carboxyl group; R- variable group
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How many amino acids are there
20
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How are proteins assembled
ribosome
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How is proteins formed from an amino acid
condensation reaction (H2O removed); Joined by a peptide bond; Carboxyl group of one amino acid reacts with the Amino group of the other
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What are the 3 structures of proteins
primary; secondary/tertiary; 3D/ conformation; Quaternary
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How to form disulphide linkage in protein
between two cysteine residues (covalent bond; very strong bond); Forms conformation of lowest energy, yielding thermodynamically most stable structure
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Strength of bonds in proteins (ascending)
Hydrophobic interaction; Van der Waal; hydrogen bonding; ionic bonding; covalent bonding
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Types of secondary structure
form α helices or β pleated sheets
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how do α helices or β pleated sheets from
Both conformations occur due to H bonds between the C=O of one peptide bond and the N-H of another
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How is a α helices (secondary structure) formed
the H bonds form between C=O and N-H 4 peptide bonds away
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How is a β sheets(secondary structure) formed
the polypeptide chain runs backwards and forwards in different direction
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Why would you want to modify a protein
To activate/inactivate the protein; to act as signal for transport of the protein and its intra-cellular location
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Which amino acid is frequently phosphorylated
Serine and Threonine
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Why is phosphorylation important for enzyme
activation of enzymes; Conformation changes on addition of phosphate group – enzyme becomes active;
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What is the similarities between Glutathione (GSH) and Metallothionein (MT)
contain cysteine amino acid residues; function in protecting cells from stress; Both have a particular role in metal regulation
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What is the structure difference between Glutathione (GSH) and Metallothionein (MT)
Glutathione (GSH) is the most abundant peptide in cells; Metallothionein (MT) is a protein
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reduce Glutathione (GSH) equation
GSH + .OH  —> .GS + H2O
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What are the Chalcophilic metals
Hg, Cu, Zn, Pb, Cd
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Why is the chalcophilic metals in Glutathione (GSH) important
metals have the tendency to bind to sulphur; thiol group of the cysteine residue is a powerful binder of these elements; Whilst the carboxyl group can bind Ni; This detoxifies these potentially toxic metal
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Where to find Metallothionein (MT)
They are localized to the membrane of the Golgi apparatus.
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What is the characteristic arrangement (primary structure) of Metallothionein (MT)
Cys-X-Cys (where X is an amino acid residue other than cysteine) - They have a lot of thiol groups
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How does Metallothionein (MT) work
Binds metals in 2 clusters; 1 cluster binds 4 metal atoms; Other 3 MTs bind atoms of more than 1 element in vivo; Connected to the protein backbone by cysteine thiolate ligands
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What is the Glutathione/ Metallothionein (GSH/MT) system
The MT gene expression results in MT synthesis; Time lag between the rise in metal conc & increased MT level in cell; GHS protects cell from harmful levels of metal by synthesising 2 enzyme; GHS send mental to MT so it can go to proteins
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how long is the Metallothionein (MT) synthesis time lag
18-24 hours
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What must Glutathione (GSH) need to synthesis 2 enzymes in the Glutathione/ Metallothionein (GSH/MT) system
cell has to have 3 amino acids available
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What are the essential metals that Metallothionein (MT) will send to the proteins
Cu, Zn
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What are the metals that Metallothionein (MT) will keep detoxified
non-essential metals e.g. Cd and Hg
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Why does Metallothionein (MT) keeps some metals detoxified and send some to proteins
Ensuring both a lack of toxicity and timely supply of metal to were it is needed
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Other cards in this set

Card 2

Front

What are the size of

Back

range in size from 50 to 4,636 amino acids residues in length*; There are 20 amino acids essential for life; 20 X great variety of chain length = Huge diversity of proteins

Card 3

Front

Function of a protein

Back

Preview of the front of card 3

Card 4

Front

what is the difference between a catalyst and an enzyme

Back

Preview of the front of card 4

Card 5

Front

What is an amino acid structure

Back

Preview of the front of card 5
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