L06: Biomolecules: Carbohydrates and Lipids Flashcards
Which elements comprise carbohydrates? What are examples of carbohydrates? What roles do carbohydrates play in biota?
Carbohydrates (C, H, O) = sugars, starch, glycogen,
cellulose, chitin, etc.
- energy to make ATP
- short-term energy storage
- cellular/molecular tags
- structural roles (some biota)
Which elements comprise lipids? What are examples of lipids? What roles do lipids play in biota?
Lipids (C, H, O) = Fats, oils, phospholipids, steroids, etc.
- energy to make ATP
- long-term energy storage
- cellular membrane structure
- hormones
- insulation
- cushion
What are saccharides?
Saccharides are sugars typically used for immediate energy or metabolized into larger biomolecules (e.g., DNA)
What are monosaccharides? How are monosaccharides classified?
Monosaccharides (monomer for carbs) (e.g., glucose) are sugars whose carbon skeletons routinely assume a single ring conformation (shape).
Monosaccharides are classified as aldoses or ketoses by their functional group (=O) (e.g., glucose is an aldose).
Monosaccharides are also classified by the number of sugars in their carbon skeleton (e.g., glucose is a hexose).
How is glucose classified? Can you give examples of aldose and ketose monosaccharides?
Glucose is an aldose (carbonyl is end of carbon skeleton) and a hexose.
Fructose is a ketone (carbonyl is in middle) and hexose.
What is the difference between a triose, pentose, and a hexose?
Trioses: 3-carbon sugars (C3H6O3)
Pentoses: 5-carbon sugars (C5H10O5)
Hexoses: 6-carbon sugars (C6H12O6)
based off carbon atoms
Monosaccharides routinely assume ring conformations. What does this allow them to do?
Monosaccharides now serve as a monomer.
Ring conformations permit monosaccharides to polymerize
via dehydration reactions into disaccharides (e.g., maltose,
sucrose) and polysaccharides (e.g., starch, glycogen).
What are disaccharides?
the sugar formed when two monosaccharides are joined by glycosidic linkage (covalent bond).
Which monomers form maltose and sucrose? Which enzymes hydrolyze these disaccharides? Do humans have these enzymes? Which suffix is used to indicate an enzyme?
Two glucose monomers polymerize into maltose whereas glucose and fructose form sucrose.
We hydrolyze maltose with maltase and sucrose with sucrase. (enzymes tend to end with -ase).
What is a polysaccharide?
a carbohydrate (e.g. starch, cellulose, or glycogen) whose molecules consist of a number of sugar molecules bonded together. (amylo prefix for polysaccharides starches)
Which polysaccharides do plants make and for what purpose?
Plants make/store starch for a source of glucose when photosynthesis rate is low and/or energy needs are high (e.g., reproduction).
Plant makes storage molecules (starch) to tap into when doesn’t have access to light or has large energy demands like reproduction
Which plant polysaccharide can humans digest/hydrolyze? Which enzyme hydrolyzes it? Do humans have cellulosases? What role does cellulose play in humans?
We eat starch (potatoes) and hydrolyze it with amylase (enzyme to break down starch) made from salivary glands and pancreas.
Plants also make cellulose to strengthen cell walls but animals DONT have cellulases.
We can absorb small amounts of cellulose that serve as insoluble fiber that stimulates mucus production and bulks feces.
What is glycogen? How is it made? Which group of biota make glycogen? Which human tissues make/store glycogen?
Glycogen is polysaccharide of glucose. Animals polymerize glucose into glycogen; larger and more branched than starch. Glycogen is stored in energy-demanding tissues; e.g., muscle and liver.
Which conditions favor glucose polymerization into glycogen and glycogen depolymerization into glucose? What do humans do with extra glucose when glycogen levels are maximized?
Glycogen is replenished when energy demands is low/glucose is high (sleeping, eating, relaxing). The liver breaks it down to maintain blood glucose levels and muscles break down glycogen to maintain energy for contractions.
Excess glucose gets shunted into fat production for long term storage. Glycogen is longer term storage than glucose but it really isn’t considered to be long term.
What are fatty acids? How do fatty acids vary?
Fatty acids are hydrocarbon chains with a terminal carbonyl group (lipid basic building blocks). They vary in carbon chain length.
What is glycerol?
(short helper molecule) Glycerol is a precursor for synthesis of triacylglycerols and of phospholipids in the liver and adipose tissue.
What are triglycerides (triacylglycerols)? How many fatty acids are found in triglycerides? Do they all have to be the same length? Which human cells make triglycerides? Which human cells store triglycerides? What roles do they play in humans? What can happen if one over-consumes triglycerides?
Fatty acids bond with glycerol to form triglycerides and phospholipids. Triglycerides are a type of fat (lipid) found in your blood.
triglycerides (triaclyglycerols) = 3 fatty acids + glycerol
They can vary in length.
They are made in liver cells and move through your blood to be stored in adipose cells where they insulate, cushion, and serve as long term storage.
High triglycerides may contribute to hardening of the arteries or thickening of the artery walls (arteriosclerosis) — which increases the risk of stroke, heart attack and heart disease.
How are fats classified?
Fats are classified by how saturated their hydrocarbon chains are with H atoms.
What is the relationship among hydrogen atom saturation of fatty acids, packing ability, and melting temperature?
Hydrogen saturation influences the melting point of fats.
Saturated fats have straight fatty acids that pack tightly.
They have high melting points and are solid at room temp.
Unsaturated fats have bent fatty acids that do not pack
tightly because of their cis double bonds. They have lower
melting points and are liquid at room temp.
What is different between saturated and unsaturated fatty acids? Which fatty acid is solid?
Saturated fats (e.g., butter, lard) only have single C-C bonds.
Unsaturated fats (e.g., olive oil) have at least one cis C=C bond.
Saturated fats have straight fatty acids that pack tightly.
They have high melting points and are solid at room temp.
How does a cis double carbon bond impact the overall shape of a fatty acid? Which fatty acids do trans fats most resemble and why?
Cis double bond makes it an unsaturated fatn
Trans fat most resemble saturated fats.
What is LDL-C and HDL-C? Over-consumption of which two fats increases LDL-C?
HDL-C (‘good’ cholesterol) is high-density lipoproteins + total cholesterol
Excessive saturated fats and trans fats increases LDL-C (low density lipoproteins + total cholesterol) in the blood
Unsaturated fats ↓ LDL-C (low density lipoproteins + total
cholesterol) in the blood ↓ risk of antherosclerosis/CV disease.
What happens to arteries when LDL-C are elevated in the blood? What are the likely consequences of maintaining high levels of LDL-C in the blood?
atherosclerosis (narrowing of arteries) & cardiovascular disease (heart attack and stroke)
How do monounsaturated and polyunsaturated fats impact LDL-C, and HDL-C? Is elevated blood HDL-C good or bad for you?
monounsaturated fats:
- lower total cholesterol
- lower LDL
- raise HDL (reduce risk of atherosclerosis/CV disease)
polysaturated fats:
- lower total cholesterol
- lower LDL
- lower HDL
