GI Flashcards
2 types of cellular pathways?
- Catabolic.
- Anabolic.
What are carbohydrates?
- Organic molecules containing CHO.
- Monosaccharides: smallest like glucose cannot be further hydrolysed.
- Disaccharide: Two monosaccharides joined by glycosidic chain.
- Oligosaccharide: A few (3-10).
- Polysaccharide: More than 10.
Normal cells produce how many ATP in glycolysis?
38.
Cancer cells produce how many ATP in glycolysis?
2.
What happens in stomach?
Site of minimal digestion.
Amylase in saliva.
What happens in intestinal mucosa?
Carbs—-> Disaccharide or trisaccharide (amylases).
What happens in oral cavity?
Carbs—-> Disaccharide or trisaccharide (pancreatic amylases).
What happens in small intestine?
Di/trisaccharide to monosaccharide.
These are all absorbed into gut epithelial cells.
What happens to dietary glucose?
Glucose leaves intestine via hepatic portal vein and arrives first at the liver. Hepatocytes take up glucose where it is converted to pyruvate in the cytoplasm.
What does glycolysis mean?
The conversion of glucose to pyruvate in cytoplasm.
Glucolysis 10 step pathway?
- Conversion glucose to glucose 6 phosphate.
- Glucose 6 phosphate to fructose 6.
- Fructose 6 to fructose 1,6 biphosphate.
- Fructose 1,6 bi to glyceraldehyde 3 and dihydroxyacetone phosphate.
- Dihydro to gllyceraldgeyde 3.
- Glucealdehyde 4 to 1,3 bi.
- 1,3 bi to 3 phosphoglycertae.
- 3-phospho to 2 phospho.
- 2 phospho to phospho.
- Phospho to pyruvate.
Protein analysis technique is called?
X ray crystallography.
Can be used to generate quaternary structures.
Formation of acetylene coA.
Stage 1- Generation of an activated 2 carbon fragment.
Acetyl co A cell can use different fuels other than glucose (can use amino acids fatty acids).
Pyruvate oxidation first involves its movement across mitochondrial membrane by the pyruvate carrier.
Stomach stores and emulsifies?
Fatty food.
Gradually transferred to duodenum.
Minimal digestion by?
Lipases in saliva.
Small intestine?
Lipases break fat into free fatty acids that are absorbed by the gut epithelial cells where they resynthsised into triglycerils.
Bile salts?
Detergent substance.
Emulsify fat. Allows enzymes to digest fat.
Lipid and proteins become soluble. These are called?
Lipoproteins.
Products of lipid digestion?
Glycerol, free fatty acids, monoacylglycerols, diaclycerols.
Saturated fatty acids are?
Simplest form of lipid.
Saturated= no carbon double bonds.
Terminal carboxyl group?
Affinity to water when ionised.
Unsaturated fatty acids?
Some carbon double bonds present.
Examples of acids?
- Stearic acid- Saturated.
- Oleic acid- Mono unsaturated.
- Linoleic acid- Poly unsaturated fatty acid.
Major components of dietary fat are?
Triaclyglycerol ( Triglyceride).
Cholesterol.
Lipid digestion?
- Lipase in saliva and in small intestine break triaglycerol into glycerol and 3 fatty acids.
- Short are absorbed directly into blood stream form gut epithelial cells and transported to liver attached to albumin.
- Longer chain fatty acids and those still attached to glycerol taken up into ER.
Fatty acids ————> Acetyl coA.
B Oxidation
pathway
B oxidation of fatty acids?
Transport of long fatty acids into mitochondria.
B oxidation fatty acids with odd number carbon?
- Carboxylation- absolute requirement of biotin as co enzyme a.
- conversion of D isomer to L isomer.
- Syntheiss of succinyl COA.
- Succinyl CoA enters citric acid cycle directly.
Oxidation of 2 carbons in acetylene CoA.
In citric acid cycle to form 1 GTP and 2 CO2 and 4 pairs of electrons.
Electron transport chain?
Folded into projections called cristae.
Storage of excess glucose?
Glycogen stored mainly in liver.
Glycogen synthesis requires energy.
Fatty acid synthesis occurs in?
Cytosol.
Fatty acids synthesis from?
Acetyl CoA.
What’s produces as an end product?
Palmitate (C16).
Production of Acetyl CoA in matrix of mitochondrion is first stage of fatty acid biosynthesis.
Citrate translocated into cytosol when mitochondrial conc is too high.
Step 2: is
Carboxykation of Acetyl CoA to malonyl CoA.
Fatty acid synthase- a multifunctional enzyme.
Liver exports TAGs packaged with other lipids to form?
Very low density lipoproteins.
Fat more energy release than carbs.
Denser than carbs.
Most energy in fat released as oxidation of fatty acids for many tissues (except brain).
Lipolysis?
Achieved by lipases.
- Adipose triglyceride.
- Hormone sensitive.
- Monoacylglycerol.
Fate of glycerol?
Blood to liver, phosphorykated to glycerol 3 phosphate to form new TAGs.
Fate of fatty acids?
Bind to albumin, transported to tissues cells, activated into coA derivatives, oxidised in mitochondria.
