Carbohydrate Metabolism Lecture 1

<p>Poor health due to inadequate gut bulk. (A)</p> Signup and view all the answers

<p>They increase fecal bulk and decrease transit time. (D)</p> Signup and view all the answers

<p>Provide a major energy source (D)</p> Signup and view all the answers

<p>Pentose (A)</p> Signup and view all the answers

<p>Glycosidic bond (D)</p> Signup and view all the answers

<p>Starch (D)</p> Signup and view all the answers

<p>Reaction with a hydroxyl group (C)</p> Signup and view all the answers

<p>High liver glycogen levels (A)</p> Signup and view all the answers

<p>Regular carbohydrate feeding every 3-4 hours (C)</p> Signup and view all the answers

<p>Weakness and cramps in muscles (B)</p> Signup and view all the answers

<p>Reconversion of lactate to glucose in the liver (D)</p> Signup and view all the answers

<p>Individuals can manage symptoms by avoiding strenuous exercise. (C)</p> Signup and view all the answers

<p>Lactose (B)</p> Signup and view all the answers

<p>Sucrose has no free anomeric C-1 (B)</p> Signup and view all the answers

<p>Inability to convert glycogen to glucose (B)</p> Signup and view all the answers

<p>20-30 years (C)</p> Signup and view all the answers

<p>Amylopectin has α1→6 bonds (C)</p> Signup and view all the answers

<p>Glycogen has α1→4 and α1→6 linkages (A)</p> Signup and view all the answers

<p>No increase after exercise (B)</p> Signup and view all the answers

<p>It stabilizes the structure of glucose (A)</p> Signup and view all the answers

<p>Maltose is a breakdown product of starch (A)</p> Signup and view all the answers

<p>They may be homopolysaccharides or heteropolysaccharides (D)</p> Signup and view all the answers

<p>Liver (A)</p> Signup and view all the answers

<p>Allowing rapid synthesis and degradation (C)</p> Signup and view all the answers

<p>To communicate between cells and influence protein properties (A)</p> Signup and view all the answers

<p>From GAGs attaching to proteins (A)</p> Signup and view all the answers

<p>They are genetic disorders related to the breakdown of GAGs. (D)</p> Signup and view all the answers

<p>Severe developmental defects and early death (C)</p> Signup and view all the answers

<p>In the duodenum and jejunum (D)</p> Signup and view all the answers

<p>Cellulose and hemicellulose (C)</p> Signup and view all the answers

<p>Form part of mucus and synovial fluid (D)</p> Signup and view all the answers

<p>Glycogen (C)</p> Signup and view all the answers

<p>1-80% (B)</p> Signup and view all the answers

<p>Increased fiber intake (D)</p> Signup and view all the answers

<p>Abdominal distension (A)</p> Signup and view all the answers

<p>It is phosphorylated by glucokinase or hexokinase (D)</p> Signup and view all the answers

<p>Glucokinase (B)</p> Signup and view all the answers

<p>Skeletal muscle (B)</p> Signup and view all the answers

<p>It allows tissues to uptake glucose efficiently at low concentrations. (B)</p> Signup and view all the answers

<p>Glycogenin (A)</p> Signup and view all the answers

<p>Glucose 6-phosphate (B)</p> Signup and view all the answers

<p>Glycogen phosphorylase (B)</p> Signup and view all the answers

<p>It is released into the blood. (A)</p> Signup and view all the answers

<p>Urea cycle (C)</p> Signup and view all the answers

<p>High blood glucose concentration (B)</p> Signup and view all the answers

<p>It activates glycogen synthase. (C)</p> Signup and view all the answers

Simple sugars with 3 important hexoses (6-carbon sugars) including glucose, galactose, and fructose.

Sugars formed when monosaccharides bond via glycosidic bonds.

Carbohydrates provide energy, store energy (starch/glycogen), have structural roles (plant cell walls), and contribute to cell communication.

Covalent bonds connecting monosaccharides. They form when a hydroxyl group of one sugar reacts with the anomeric carbon of another.

The carbon atom in a monosaccharide that is involved in creating glycosidic bonds.

Mirror image forms of a molecule, specifically differing at carbon #1 in glucose.

Sugars with a free anomeric carbon that can be oxidized.

A disaccharide formed from two glucose molecules, often found as a breakdown product of starch.

A disaccharide consisting of galactose and glucose, primarily found in milk.

A common table sugar, formed from glucose and fructose; it's a non-reducing sugar.

Polysaccharides composed of only one type of monosaccharide.

A linear glucose polymer, part of starch, with (α1→4) linkages.

A highly branched glucose storage polymer in animal cells, with (α1→6) branches every 8-12 residues.

Breaks down (α1→6) bonds in starches, releasing glucose units.

Removes single glucose molecules from non-reducing ends of starch chains.

Glucose is absorbed through a process driven by the sodium gradient, moving against its concentration gradient when needed.

Fructose enters cells via GLUT5 down its concentration gradient.

These indigestible fibers increase stool bulk and speed up digestion, despite not providing energy.

Amylopectin and glycogen have many non-reducing ends, allowing for rapid synthesis and degradation of monomers. This makes them form hydrated gels.

Proteins with covalently attached carbohydrates, often found extracellularly in eukaryotes. They vary in carbohydrate content.

Unbranched polymers of hexuronic acid and amino sugars. They are found in mucus and synovial fluid.

Macromolecules with more carbohydrate than protein, composed of GAGs covalently attached to proteins, and found in the extracellular matrix.

Glycoproteins have more protein than carbohydrate, while proteoglycans have more carbohydrate than protein. Both are typically in the extracellular matrix, but glycoproteins can be in the blood, cells.

Genetic disorders where enzymes for breaking down glycosaminoglycans are missing or defective, causing a buildup which damages tissues.

A severe mucopolysaccharidosis with developmental delays, organ damage, and premature death (typically by age 10), due to buildup of undegraded GAGs.

Salivary amylase hydrolyzes α(1→4) bonds in starch in the mouth.

Pancreatic amylase hydrolyzes α(1→4) bonds in starch, continuing the chemical breakdown in the duodenum.

Mucosal cell-surface enzymes in the Jejunum complete the final breakdown of carbohydrates.

Inability to digest disaccharides due to a lack of specific enzymes like lactase, maltase, or sucrase. This can be genetic or acquired due to factors like intestinal infections, inflammation, medications, or surgery.

The most common disaccharidase deficiency where individuals lack the enzyme lactase, causing problems digesting lactose in milk products.

Undigested lactose is fermented by gut bacteria, producing gas and acids. Lactose also draws water into the gut, leading to diarrhea.

Glucose diffuses into the portal blood and travels to the liver. Hepatocytes rapidly phosphorylate glucose into glucose 6-phosphate.

GLUT transporters, responsible for glucose transport, don't recognize glucose 6-phosphate. This traps glucose within the cell.

Both enzymes phosphorylate glucose. Glucokinase in the liver has high Vmax and Km, while Hexokinase in other tissues has low Vmax and Km.

Liver's glucokinase efficiently 'grabs' glucose when blood levels are high, trapping it as glucose 6-phosphate.

Tissues with hexokinase can effectively 'grab' glucose even at low blood levels, but they are 'easily satisfied' due to low Vmax.

Glucose 6-phosphate has several fates: used for energy through glycolysis and the citric acid cycle, stored as glycogen, or used in the pentose phosphate pathway.

Glycogen is a storage form of glucose, primarily found in the liver and skeletal muscle. Liver glycogen is used to maintain blood glucose levels, while skeletal muscle glycogen provides energy for muscle contraction.

Glycogen synthase adds glucose units from UDP-glucose to a glycogen primer molecule called glycogenin, which is then extended into longer chains.

Glycogen-branching enzyme creates branches in the glycogen molecule by attaching chains via (α1→6) bonds.

Glycogen is a highly branched polymer of glucose molecules linked by (α1→4) and (α1→6) glycosidic bonds. The branches increase its surface area, allowing rapid glucose uptake.

Glycogen phosphorylase removes glucose units from the non-reducing ends of glycogen as glucose 1-phosphate.

In the liver, glucose 1-phosphate is converted to glucose and released into the blood. In skeletal muscle, it's used for energy production via glycolysis.

A genetic disorder where the liver lacks glucose 6-phosphatase, preventing glycogen breakdown into glucose. This leads to high liver glycogen, low blood glucose, and high blood lactate.

Fasting hypoglycemia (low blood sugar), high liver glycogen, and high blood lactate. This is due to the inability to use glycogen as an energy source.

Regular carbohydrate feeding to maintain blood glucose levels. This often means frequent small meals or continuous glucose infusion.

A genetic disorder where skeletal muscles lack glycogen phosphorylase, preventing glycogen breakdown into glucose. This leads to a build-up of muscle glycogen.

Weakness and cramps after exercise due to the inability to use glycogen as an energy source. Blood glucose levels also do not increase after exercise.

Avoid strenuous activity and utilize the 'second wind' phenomenon: briefly exercise anaerobically, rest until pain subsides, then continue aerobically using fat as fuel.

The process of converting lactate back to glucose, primarily in the liver. This cycle is disrupted in von Gierke's disease due to the lack of glucose 6-phosphatase.

The enzyme that breaks down glycogen into glucose 1-phosphate is missing in McArdle’s Disease. This prevents muscles from using glycogen for energy during exercise.