Which of the following is not true about amino acids?
They act as buffers
They exist as zwitterions in solution
They are crystalline solids
At high pH the -NH3+ group is formed
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Amino acids, Proteins & DNA
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Amino acids, Proteins & DNA
Which of the following is not true about amino acids?
They act as buffers
They exist as zwitterions in solution
They are crystalline solids
At high pH the -NH3+ group is formed
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Proteins are made of chains of amino acids. One arrangement of proteins is in the shape of a helix.
Which interaction is responsible for holding the protein chain in the shape of a helix?
Covalent bonds
Ionic bonds
Hydrogen bonds
Sulfur-sulfur bridges
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What two bases pair up together when two separate strands of DNA form a double helix?
Cytosine and guanine
Cytosine and adenine
Guanine and adenine
Thymine and guanine
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Which of the following is true about enzymes?
Enzymes work on a variety of biological molecules
Enzymes are globular proteins
Enzymes can work on enantiomer substrate pairs
Enzymes work best at low pH
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Which of these statements is true about the anti-cancer drug cisplatin, Pt(NH3)2Cl2?
Cisplatin has a tetrahedral shape
Cisplatin prevents DNA replicating
Cisplatin destroys cancer cells
The platinum in cisplatin is in oxidation state +4
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The structure of the amino acid lysine is shown below:
The species present in a solution at low pH would be:
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A dipeptide molecule is shown below:
When the dipeptide is hydrolysed the two molecules formed are
H2NCH2CONH2 and H2NCH(CH3)COOH
H2NCH2COOH and H2NCH(CH3)COOH
H2NCH2COOH and H2NCOCH2COOH
H2NCOOH and H2NCH(CH3)CONH2
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Which ways can amino acids in a protein chain bond together?
| Hydrogen bonding | Ionic attractions | Sulfur-sulfur bonds |
A | ✓ | ✓ | ✓ |
B | ✓ | ✓ | ⨯ |
C | ⨯ | ✓ | ✓ |
D | ✓ | ⨯ | ⨯ |
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Which statement is not true about amino acids and DNA?
Hydrogen bonding holds together the double helix in DNA
Nucleotides are the monomers which make up DNA
DNA is made from twenty naturally occurring amino acids
Condensation polymerisation occurs when DNA monomers come together
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Which statement correctly describes the action of the anti-cancer drug cis-platin?
It breaks the hydrogen bonds between sections of DNA
It bonds to DNA preventing replication of cells
It bonds only to DNA in cancer cells and prevents them growing
It breaks the covalent bonds in the DNA chain of cancer cells
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The structures of four ∝-amino acids are shown below. Due to different R-groups, ∝-amino acids can be acidic, basic or neutral.
Which is the correct set of descriptions for these ∝-amino acids?
| Tyr | Asp | Lys | Asn |
A | Acidic | Neutral | Neutral | Neutral |
B | Neutral | Acidic | Basic | Neutral |
C | Neutral | Acidic | Basic | Basic |
D | Acidic | Neutral | Neutral | Basic |
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The structure of the amino acid cysteine is shown below:
Cysteines are important ∝-amino acids present in the formation of insulin from two protein chains, containing ‘R’ side groups that can interact with each other.
If these interactions do not occur correctly, which of the following will not be affected?
The number of ∝-helices that can be formed
The way that the insulin hormone forms bonds within the receptor site
The way the ∝-helices and ?-pleated sheets are arranged in the protein
The number of unfolded sections of the protein chains
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A tripeptide was hydrolysed and analysed using thin-layer chromatography. A diagram of the TLC plate is shown below:
Amino acid | Glycine | Threonine | Leucine | Aspartic acid | Alanine | Tryptophan |
Rf value | 0.26 | 0.34 | 0.73 | 0.24 | 0.38 | 0.65 |
Using this information, which of the following amino acids were present in the tripeptide?
Glycine, threonine and leucine
Aspartic acid, alanine and tryptophan
Aspartic acid, threonine and tryptophan
Glycine, alanine and leucine
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Drugs are developed from existing drugs to improve action or reduce side effects. Three anti-inflammatory drugs that act as COX-1 and COX-2 inhibitors are shown below:
Which of the following statements is not correct?
All of these drugs have an enantiomer that must be absent from the final product
Ionic bonds formed within the receptor site are likely to be essential to the drug action
A large planar section of the drug molecules is likely to be necessary
Forming hydrogen bonds to a hydroxyl group within the receptor site is likely to occur
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Adenine and thymine are two of the base pairs involved in the formation of DNA. The structures of these bases are shown on your data sheet.
Which statement is not correct about the hydrogen bonding between adenine and thymine?
Hydrogen bonds form between the two N-H groups of the two bases
Only one of the carbonyl (C=O) groups in thymine forms hydrogen bonds
The hydrogen bonds formed are on the inside of the DNA double helix
Two hydrogen bonds form between the bases
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