Molecular & Cellular

Question 1

Name 2 commonly studied types of epigenetic modifications.

Answer 1

• DNA methylation

- Histone acetylation.

Question 2

Define peptides.

Answer 2

Peptides are the foundations of polypeptides commonly referred to as proteins.

Question 3

Define primary structure of a protein.

Answer 3

Linear sequence of amino acids.

Question 4

Define secondary structure of a protein.

Answer 4

The type and position of the amino acid e.g. alpha helices and beta sheets.

Question 5

Define tertiary structure of a protein.

Answer 5

Overall structure of a protein.

Question 6

Define quartenary structure of a protein.

Answer 6

Proteins bound together.

Question 7

Define microRNA.

Answer 7

(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.

Question 8

Define long ncRNA.

Answer 8

(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.

Question 9

What are the functions of lipids?

Answer 9

Storing energy (fats) and structural components of cell membranes (phospholipids, sterols).

Question 10

Define monosacharides.

Answer 10

Basic building blocks of carbohydrates.

Question 11

Define competitive modification of enzymes.

Answer 11

Caused by molecules that react directly with the active site of the enzyme; the binding can be reversed by displacement.

Question 12

Define non-competitive modification of enzymes.

Answer 12

Molecules that bind to a region of the enzyme outside the active site causing a conformational change in enzyme structure.

Question 13

Define allosteric molecules.

Answer 13

They bind to enzymes and alter their structure.

Question 14

Define allosteric inhibitors.

Answer 14

They prevent enzyme activity.

Question 15

What are the purine bases?

Answer 15

Adenine and guanine.

Question 16

What are the pyrimidine bases?

Answer 16

Cytosine, thymine and uracil.

Question 17

What base does cytosine pair with?

Answer 17

Guanine.

Question 18

What base does thymine pair with?

Answer 18

Adenine.

Question 19

What is a polynucleotide chain?

Answer 19

It consists of pentose residues that are linked by phosphodiester bonds.

Question 20

Define rotavirus.

Answer 20

E.g. severe diarrhoea in infants or young children. Immunity develops with each infection.

Question 21

What are DMNTs and what do they do?

Answer 21

DNA methyltransferase. Enzyme commonly used in many vertebrates to methylate DNA. Therefore methylating DNA is a one step process.

Question 22

What are TETs and what do they do?

Answer 22

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.

Question 23

DNA methylation + histone deacetylation =

Answer 23

Inhibited transcription.

Question 24

DNA demethylation + histone acetylation =

Answer 24

Facilitates transcription.

Question 25

Name two epigenetic mechanisms for regulating RNA expression.

Answer 25

1. DNA methylation

2. Histone acetylation

Question 26

Define peptide.

Answer 26

Made up of several amino acids, they are the foundations of polypeptides commonly referred to as proteins.

Question 27

What is the central dogma?

Answer 27

DNA > RNA > Proteins.

Question 28

What challenges the central dogma?

Answer 28

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.

Question 29

Define lipids.

Answer 29

Diverse group of water-insoluble molecules with relatively simple chemical structures.

Question 30

What are the main functions of lipids?

Answer 30

Main biological functions include storing energy (fats) and structural components of cell membranes (phospholipids, sterols).

Question 31

How are lipids usually stored?

Answer 31

In the form of adipose tissue.

Question 32

Describe the structure of fatty acid molecules.

Answer 32

Carboxyl ‘head’ and a long hydrocarbon ‘tail’.

Question 33

What is a triglyceride molecule?

Answer 33

A glycerol molecule that is attached to three fatty acids.

Question 34

Give an example of a lipid sterol.

Answer 34

Cholesterol.

Question 35

Name the two types of cholesterol and their function.

Answer 35

• 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.

Question 36

Define monosaccharide.

Answer 36

The basic building blocks of carbohydrates e.g. pentose, hexose.

Question 37

Give examples of disaccharides and the two monosaccharides that they consist of.

Answer 37

• Sucrose - alpha glycosidic bond between glucose and fructose
• Lactose - beta glycosidic bond between glucose and galactose.

Question 38

What is sucrase and lactase.

Answer 38

Enzymes which break down sucrose and lactose respectively.

Question 39

Give examples of polysaccharides and where they are found.

Answer 39

• Glycogen found in the liver and muscles of animals

- Starch in plants.

Question 40

Where does cellular respiration occur?

Answer 40

Mitochondria.

Question 41

Define glycolysis.

Answer 41

Oxygen free; food molecules are oxidized incompletely to lactic acid (lactate) (produces 2 mol ATP).

Question 42

Define respiration.

Answer 42

Require oxygen; food molecules are completely oxidized to carbon dioxide and water (produces 38 mol ATP).

Question 43

Define competitive enzyme inhibition.

Answer 43

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).

Question 44

Define non-competitive enzyme inhibition.

Answer 44

Molecules that bind to a region of the enzyme outside the active site causing a conformational change in enzyme structure.

Question 45

Define allosteric molecules in terms of activators and inhibitors.

Answer 45

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.