Biochem Lecture Week 5

Carbohydrates are classified as what?

polyhydroxy aldehyde or ketone derivatives

Which has a double bond oxygen on the first carbon?

Aldehyde

Which has a double bond oxygen on the second carbon?

ketone

Oligosaccarides have how many sugars?

3-10

Polysaccarides have how many sugars?

10+

Which has polymer of the same monosaccharides?

homopolysaccharides

ex. glycogen

Which has polymer of different monosaccharides?

heteropolysaccarides

ex. peptidoglycan

Cellulose is what type of polysaccaride? Branched or unbranched?

homopolysaccharide; unbranched

Starch is what type of polysaccaride? Branched or unbranched?

homopolysaccharide; branched

GAGs are what type of polysaccaride?

heteropolysaccaride

GAGs are found where?

hyaluronic acid in synovial fluid

Chondroitin sulfate is what type of polysaccharide?

heteropolysaccaride?

Chondroitin sulfate is found where?

in cartilage, tendons and ligaments

What causes the difference in taste between glucose and fructose?

location of double bond oxygen

Glucose, galactose, and fructose are all examples of what two things?

hexoses (6 sugar)

structural isomers

What are structural isomers?

have the same chemical formula but different arrangement of atoms

How are sugars attached to each other?

glycosidic linkages

What causes glycosidic bonds to form?

dehydration synthesis

α-1,4 are what type of linkage?

straight main chain

α-1,6 are what type of linkage?

branch point linkage

What do more branches mean in terms of digestion?

easier to digest

Is cellulose digested? Why or why not?

not digested; no branches (no α-1,6)

Starch amylose and starch amylopectin are what?

storage form of sugar in plants

Dietary carbohydrates consist of

Polysaccharides, disaccharides, monosaccharides

Polysaccharides are mainly what?

Plant starches and animal glycogen

What is sucrose made of?

Glucose and fructose

What is lactose made of?

Glucose and galactose

What is maltose made of?

Glucose and glucose

Glycosidases do what?

Hydrolyze glycosidic bonds between sugars (break them)

What is the first sight of carb digestion? What does it hydrolyze?

Salivary α amylase; α-1,4

Where does carb digestion occur after salivart α-amylase?

Pancreatic α-amylase;

Pancreatic α-amylase forms what? What does it hydrolyze?

Di-, tri-, and oligosaccarides

hydrolizes α-1,4

What does α-amylase not cleave?

α-1,6 glycosidic bonds

Hydrolysis of starch yields what?

di-, tri-, oligosaccharides

α-limit dextrin (α-1,6 branches)

What are the products from brush border glycosidase enzymes?

glucose, fructose, galactose (monosaccarides

What gets digested in brush border?

di-, tri-, oligosaccharides

How many transport enzymes are present in enterocyte absorption?

2 minimum

What utilizes a co-transporter to enter enterocyte?

Glucose and galactose

What drives the gradient transport of glucose and galactose? Via what?

Na+; via ATPase (3Na, 2K - active transport)

What kinda of transport does fructose use? Is ATP used?

facilitated diffusion transport channel (Na indepent)

no ATP used

Is simple diffusion fast or slow?

slow

Are all carbs digested completely?

no

What are some foods high in raffinose? Are they easy to digest?

beans, cabbage, brocolli; hard to digest

Starches that are high in amylose are what? What is an example?

less hydrated and not completely digested; dried beans

Where do undigested carbs go?

the colon

What does incomplete digestion increase?

water retention in colon → diarrhea

What do undigested carbs in colon form?

gases - H2, CO2, CH4

short chain fatty acids - acetic acids

What is lactose intolerance caused by? Due to what missing?

lactose not being hydrolyzed into monosaccharides

due to: lactase missing

What does lactose turn into when you have lactose intolerance?

lactid acid, CH4, H2

What is the osmotic effect of lactic acid and lactose?

diarrhea

What is congenital lactase deficiency?

reduced or absent lactase activity at birth

Lactase non-persistance (normal)

lactase activity from birth to 1month then 10% decrease

Lactase persistance phenotype?

lactase levels remain at infant levels through adulthood

When do you undergo gluconeogenesis?

during sleep or fasted state

What is the product of glycolysis?

2 pyruvate

Glycogenolysis occurs where? What happens?

at liver and skeletal muscles

glycogen → glucose

What are the key enzymes of glycolysis?

Hexokinase, phosphofructokinase, pyruvate kinase

What’s the activation step of glycolysis?

putting a phosphate on glucose

What’s the purpose of glycolysis? Where does it occur?

making ATP; occurs in cytosol

How many net ATP do you gain from glycolysis?

2

How many TOTAL atp is gained in glycolysis?

4

What enzyme of glycolysis creates ATP?

pyruvate kinase

What enzyme of glycolysis burns ATP?

hexokinase and phosphofructokinase

Aerobic glycolysis occurs in cells containing what?

mitochondria

What can NADH do in Aerobic glycolysis?

donate an electron to ETC to produce ATP

Anaerobic glycolysis occurs where?

in highly exercised muscles

• pyruvate production > breakdown

RBCs

• enzymes not present

Purpose of anaerobic glycolysis

refurbish NAD to continue glycolysis

What does anaerobic glycolysis yield?

lactate and ATP (less than aerobic)

Does glycolysis occur in all living cells?

yes

If DHAP is pushed over during glycolysis what occurs?

2x GA3P