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MTM EXAM WITH QUESTIONS AND VERIFIED DETAILED CORRECT ANSWERS
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MTM EXAM WITH QUESTIONSAND VERIFIED DETAILED CORRECT WRITTEN BY EASTON
ANSWERS
, MTM EXAM WITH QUESTIONS AND VERIFIED
DETAILED CORRECT ANSWERS
What can pass through pores in the nuclear envelope?
proteins, RNA, and protein-RNA complexes
What does redundant mean in terms of the genetic code?
You can translate different combinations of amino acids and still get the same
protein.
Read More
DNA Basic structure
For the nucleotides in DNA, the sugar is deoxyribose attached to a single phosphate
group.
The nucleotides are covalently linked together in a chain through the sugars and
phosphates, which thus form a "backbone" of alternating sugar-phosphate-sugar-
phosphate.
The two ends of the chain can be easily distinguished, as one will have a hole (the 3
hydroxyl) and the other a knob (the 5 phosphate). This polarity in a DNA chain is
indicated by referring to one end as the 3 end and the other as the 5 end.
The two polynucleotide chains in the DNA double helix are held together by
hydrogen-bonding between the bases on the different strands.
How RNA differs to DNA in its structure
A) RNA contains the sugar ribose, which differs from deoxyribose, the sugar used in
DNA, by the presence of an additional -OH group.
(B) RNA contains the base uracil, which differs from thymine, the equivalent base in
DNA, by the absence of a -CH3 group. Uracil forms a base pair with adenine.
Despite the absence of a methyl group, uracil has the same base-pairing properties
as thymine.
(C) The chemical linkage between nucleotides in RNA is the same as that in DNA.
,Basic structure of carbohydrates
Carbohydrates (also called saccharides) are molecular compounds made from just
three elements: carbon, hydrogen and oxygen. Monosaccharides (e.g. glucose) and
disaccharides (e.g. sucrose) are relatively small molecules. They are often called
sugars. Other carbohydrate molecules are very large (polysaccharides such as
starch and cellulose).
Monosaccharides have the general molecular formula (CH2O)n
sucrose from α-glucose + α-fructose
maltose from α-glucose + α-glucose
α-lactose from α-glucose + β-galactose
What makes up the primary structure of a protein?
The sequence of amino acids, that form the polypeptide chain.
What makes up the secondary structure of a protein?
alpha helix pleated sheet held in place by local hydrogen bonds. Also ionic,
instantaneous dipoles, and hydrophobic
How do beta sheets form?
forces of attraction between different polypeptides
What makes up the tertiary structure?
final shape of a single protein molecule, held in place by non-local interactions ie
disulphide bonds The 3D conformation, they fold into the tertiary structure that has
the lowest energy.
How does a protein become quaternary?
More than one polypeptide chain (protein) present. Non-proteins can also associate.
Define a protein domain
Any segment of a protein that can fold independently to form a compact stable
structure
Improper folding
, When proteins fold improperly, they can form aggregates
• Accumulation of mis-folded proteins
• Prevents functioning
• Protein doesn't look like it should do
- Immune response directed at proteins
This can damage cells and tissues
• This is shown in Alzheimer's and Huntington's
Fibrous protein example
Collagen
Globular protein example
Secretory, can be enzymes, haemoglobin. Usually hydrophobic in, and hydrophilic
on the outside.
4 types of protein function
- Catalysis: Enzymes - have to be in right form and structure
- Receptors: Binding ligands(an ion/small molecule/macromolecule which binds to
protein)
- Switching: Signalling pathways - telling cell to differentiate or make enzymes from
the
message received from receptor
- Structural : Cytoskeletal element, gives cell shape, helps organelles move
Where does protein modification occur?
Proteins are modified in the endoplasmic reticulum
- Disulphide bonds (reinforce conformation) and glycosylation occurs (adding sugar)
• Has a major effect on function of protein - Further modification occurs in the golgi
• Resulting in a fully functional protein
Adding small molecules can add extra functions to proteins (e.g. Haemoglobin)
How are proteins controlled?
- This protein control is done by Phosphorylation
Activation and deactivation (dephosphorylation)
What are allosteric enzymes?
Enzymes that have two different binding sites that influence one another- often an
active site for the substrate and another active site for regulatory molecules.
What does phosphorylation of proteins trigger?
Conformational change as the phosphate has 2 negative charges so causes the
attraction of amino acid side chains, this affects ligand binding
CDK (Cyclin dependent kinase)
Catalytic protein is cyclin dependent kinase (cdK)
• Kinase, acting as an enzyme is only active when cyclin is present
- Cyclin is the regulatory molecule
- Substrate only binds to kniase when it is present.
- This allows for a change in conformation - cdK opens up to allow binding
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