3) Energy Production: Carbs 1

Question 1

Stage one Catabolism

Answer 1

convert nutrients to usable forms,
takes energy,
breakage of C-N, C-O bonds, not C-C
then absorbed into blood from GI

Question 2

Stage Two Catabolism

Answer 2

Degradation of building blocks into small organic precursors.
C-C bonds broken
Some energy produced
OXIDATIVE
cytosolic and mitochondrial

Question 3

Stage Three Catabolism

Answer 3

Mitochondrial
TCA
OXIDATIVE
Some ATP produced

Question 4

Stage Four Catabolism

Answer 4

Mitochondrial
Electron Transport Chain
Lots of O2 required

Question 5

Enzymes in stage 1:
Amylase
lactase
sucrase
isomaltase

Answer 5

Amylase - salivary glands and pancreus
lactase - Lactose into
sucrase
isomaltase

Question 6

Types of Lactose intolerance

Answer 6

Primary- absence of lactase persistence allele. Highest in Nortwest Europe
Secondary- Caused by injury to digestive tract- coeliac, crohns etc
Congenital lactase deficiency - Very rare,** autosomal recessive defect**, cant digest breast milk

Question 7

Absorbtion of monosaccharides

Answer 7

Active Transport- sodium dependent glucose transporter SGLT-1 (cotransport)
passive transport- GLUT2 into blood supply

Question 8

The GLUTs and where are they found

Answer 8

GLUT 1- fetal tissues, erythrocytes, bloodbrain barrier.
GLUT 2 - Kidney Liver Pancreatic beta cells, small intestines
GLUT 3 - Neurones, placenta
GLUT 4- Adipose tissue, striated muscle - INSULIN REGULATED
GLUT 5- Spermatazoa, intestine

Question 9

How much ATP is produced in Glycolysis

Answer 9

2 Atp used before cleaving,
4 total ATP made in phase 2
net gain of 2 ATP (plus 5 from NADH after oxidative phosphorylation)
2 NADH produced too

Question 10

Why are stages 1,3,10 irreversible in glycolysis?

Answer 10

delta G is too negative.

Question 11

How is 2,3bisphospoglycerate (2,3BPG) made?

Answer 11

intermediate from glycolysis (after step 6) 1,3BPG becomes 2,3BPG, catalysed by BPG mutase

Question 12

How is Glycerol for triglycerol production made?

Answer 12

dihydroxyacetone-P (DHAP) from glycolysis forms Glycerol Phosphate with the enzyme glycerol-3-P dehydrogenase. This is reversible so can be used in gluconeogenesis

Question 13

How is Glycolysis used in cancer imaging

Answer 13

FDG, a radioactive modified hexokinase substrate can be used in a PET scan to show where most glycolysis occurs. glycolyss rate up to 200x greater in cancer, shows up in PET