Molecular & Cellular Flashcards
Name 2 commonly studied types of epigenetic modifications.
- DNA methylation
- Histone acetylation.
Define peptides.
Peptides are the foundations of polypeptides commonly referred to as proteins.
Define primary structure of a protein.
Linear sequence of amino acids.
Define secondary structure of a protein.
The type and position of the amino acid e.g. alpha helices and beta sheets.
Define tertiary structure of a protein.
Overall structure of a protein.
Define quartenary structure of a protein.
Proteins bound together.
Define microRNA.
(mir; 20-50base pairs). Nucleic acids that has the ability to function as ligands for proteins; mediate base pairing interactions to specific RNA or DNA sites.
Define long ncRNA.
(lncRNA; >200base pairs). Similar to microRNA; but can fold into complex secondary and higher order structures to provide versatility for protein and target sequence recognition.
What are the functions of lipids?
Storing energy (fats) and structural components of cell membranes (phospholipids, sterols).
Define monosacharides.
Basic building blocks of carbohydrates.
Define competitive modification of enzymes.
Caused by molecules that react directly with the active site of the enzyme; the binding can be reversed by displacement.
Define non-competitive modification of enzymes.
Molecules that bind to a region of the enzyme outside the active site causing a conformational change in enzyme structure.
Define allosteric molecules.
They bind to enzymes and alter their structure.
Define allosteric inhibitors.
They prevent enzyme activity.
What are the purine bases?
Adenine and guanine.
What are the pyrimidine bases?
Cytosine, thymine and uracil.
What base does cytosine pair with?
Guanine.
What base does thymine pair with?
Adenine.
What is a polynucleotide chain?
It consists of pentose residues that are linked by phosphodiester bonds.
Define rotavirus.
E.g. severe diarrhoea in infants or young children. Immunity develops with each infection.
What are DMNTs and what do they do?
DNA methyltransferase. Enzyme commonly used in many vertebrates to methylate DNA. Therefore methylating DNA is a one step process.
What are TETs and what do they do?
Ten eleven translocation enzyme. They do not remove methyl from DNA. Instead they initiate a conformational change that switches the structure of the methyl on the DNA and it is now recognised by other enzymes. So demethylating DNA occurs through a series of events.
DNA methylation + histone deacetylation =
Inhibited transcription.
DNA demethylation + histone acetylation =
Facilitates transcription.
Name two epigenetic mechanisms for regulating RNA expression.
- DNA methylation
2. Histone acetylation
Define peptide.
Made up of several amino acids, they are the foundations of polypeptides commonly referred to as proteins.
What is the central dogma?
DNA > RNA > Proteins.
What challenges the central dogma?
MicroRNA and long ncRNA do not translate into proteins yet they have a function - they go back and regulate a number of physiological processes within the cell. For every one coding RNA (that does become a protein), there is four non-coding RNA (does not become a protein) so they do a phenomenal amount of functional activity.
Define lipids.
Diverse group of water-insoluble molecules with relatively simple chemical structures.
What are the main functions of lipids?
Main biological functions include storing energy (fats) and structural components of cell membranes (phospholipids, sterols).
How are lipids usually stored?
In the form of adipose tissue.
Describe the structure of fatty acid molecules.
Carboxyl ‘head’ and a long hydrocarbon ‘tail’.
What is a triglyceride molecule?
A glycerol molecule that is attached to three fatty acids.
Give an example of a lipid sterol.
Cholesterol.
Name the two types of cholesterol and their function.
- LDL (low density lipid proteins) - facilitates plaque formation leading to atherosclerosis (cardiovascular disease).
- HDL (high density lipid proteins) -
transports LDL to the liver for degradation.
Define monosaccharide.
The basic building blocks of carbohydrates e.g. pentose, hexose.
Give examples of disaccharides and the two monosaccharides that they consist of.
- Sucrose - alpha glycosidic bond between glucose and fructose
- Lactose - beta glycosidic bond between glucose and galactose.
What is sucrase and lactase.
Enzymes which break down sucrose and lactose respectively.
Give examples of polysaccharides and where they are found.
- Glycogen found in the liver and muscles of animals
- Starch in plants.
Where does cellular respiration occur?
Mitochondria.
Define glycolysis.
Oxygen free; food molecules are oxidized incompletely to lactic acid (lactate) (produces 2 mol ATP).
Define respiration.
Require oxygen; food molecules are completely oxidized to carbon dioxide and water (produces 38 mol ATP).
Define competitive enzyme inhibition.
Caused by molecules that react directly with the active site of the enzyme; the binding can be reversed by displacement (e.g. letrozole inhibition of aromatase).
Define non-competitive enzyme inhibition.
Molecules that bind to a region of the enzyme outside the active site causing a conformational change in enzyme structure.
Define allosteric molecules in terms of activators and inhibitors.
Molecules bind to non-substrate locations.
Allosteric molecules bind to enzymes and alters the structure. Allosteric inhibitors will prevent enzyme activity; allosteric activators increase the efficiency of enzymes.
