Enzymes in A Level Bio

Question 1

DNA Helicase

Answer 1

Involved in DNA replication and transcription: breaks the hydrogen bonds between the bases on the two DNA strands to form two single strands

Question 2

DNA Polymerase

Answer 2

Involved in DNA replication: joins the nucleotides together

Question 3

ATP Hydrolase

Answer 3

Involved in ATP production: catalyses the breaking of the phosphate bond (hydrolysis) to release energy

Question 4

ATP Synthase

Answer 4

Involved in ATP production: catalyses the re-synthesis of ATP in a condensation reaction between ADP and Pi

Question 5

Lysozyme

Answer 5

Involved in Phagocytosis: Digestive enzyme within lysosomes: digest invading cells/break down worn out components of cells

Question 6

Amylase

Answer 6

Involved in digestion: catalyses the conversion of starch into maltose by hydrolysing the glycosidic bonds in starch
Produced by salivary glands (released into mouth) and pancreas (released into small intestine)

Question 7

Membrane-Bound Disaccharides

Answer 7

Involved in digestion: attached to cell membranes of epithelial cells lining the ileum, and help break down disaccharides into monosaccharides through hydrolysis of glycosidic bonds

Question 8

Lipase

Answer 8

Involved in digestion: catalyses breakdown of lipids into monoglycerides and fatty acids by hydrolysing ester bonds in lipids
Produced in pancreas- works in small intestine

Question 9

Endopeptidase

Answer 9

Involved in digestion: hydrolyse peptide bonds within a protein
E.g: trypsin and chymotrypsin- synthesised in pancreas and secreted into small intestine
E.g: pepsin- released into stomach by cells in stomach lining

Question 10

Exopeptidase

Answer 10

Involved in digestion: hydrolyse peptide bonds at the ends of protein molecules and remove single amino acids from proteins.
E.g: dipeptidase- works specifically on dipeptides by hydrolysing peptide bond between the two amino acids and separating them. Located in cell-surface membrane of epithelial cells in small intestine.

Question 11

Maltase

Answer 11

Type of membrane-bound disaccharide involved in digestion: hydrolyses maltose (disaccharide) into alpha glucose

Question 12

Sucrase

Answer 12

Type of membrane-bound disaccharide involved in digestion: hydrolyses single glycosidic bond in sucrose to produce glucose and fructose (monosaccharides)

Question 13

Lactase

Answer 13

Type of membrane-bound disaccharide involved in digestion: hydrolyses single glycosidic bond in lactose to produce glucose and galactose (monosaccharides)

Question 14

RNA Polymerase

Answer 14

Involved in transcription: joins RNA nucleotides to form mRNA molecule

Question 15

ATP Synthase in Photosynthesis

Answer 15

Embedded in the thylakoid membrane. Protons move down their concentration gradient into the stroma via this enzyme

Question 16

Rubisco

Answer 16

Involved in the LIR: catalyses the reaction in which CO2 combines with RUBP