Biomolecules

Question 1

• organic molecules consisting of carbon, hydrogen, and oxygen
• general formula: Cn(H2O)n; (n=3-9)
• important cellular fuel stores
• critical molecules in control of metabolism (catabolism/anabolism)
• examples: starch (poly), sucrose (di), dietary fiber, and lactose (di)

Answer 1

dietary carbohydrates

Question 2

• the body’s inability to easily digest lactose due to genetic deficiency of lactase
• production of lactase decreases with age, especially when an infant starts weaning process
• sx: abd cramps, gas, bloating
• tx: avoid dairy products, use lactose-free products, take lactase supps
• regionally, gain of function in lactase genes can occur in populations with large dairy consumption

Answer 2

lactose intolerance

Question 3

• regulated by insulin and glucagon
• normal: fasting (70-100 mg/dL), post prandial (<140 mg/dL)
• hypoglycemia: <60 mg/dL; hunger, sweating, trembling
• <40 mg/dL: convulsions, coma, brain damage, death
• diabetes: fasting (>126 mg/dL), post prandial (>199 mg/dL)

Answer 3

blood glucose

Question 4

• the metabolism of glucose
• process by which most cells generate energy (2 net ATP molecules formed)
• breaks 6 C’s of glucose to 2x 3 C’s of pyruvate; energy production continues in mitochondria with O2
• aerobic conditions suppress this process (except cancers)
• used to help screen for cancers via PET scans

Answer 4

glycolysis

Question 5

What are the 4 forms of carbohydrates?

Answer 5

• monosaccharides
• disaccharides
• oligosaccharides (glycolipids and glycoproteins)
• polysaccharides

Question 6

• modified monosaccharide

- a component of DNA

Answer 6

deoxyaldose

Question 7

• modified monosaccharide

- components of glycoproteins and glycolipids (cell signaling, cell adhesion, immune response)

Answer 7

acetylated amino sugars

Question 8

• modified monosaccharide

- present in cell membrane and in the extracellular matrix

Answer 8

acidic sugars

Question 9

• modified monosaccharide

- constitute the gangliosides in oligodendrocyte of the nervous system

Answer 9

sugar esters

Question 10

• modified monosaccharide
• food additives, sweeteners
• significant in diabetes (cataracts and peripheral neuropathy)
• fewer calories per gram
• not as readily absorbed
• does not contribute to tooth decay

Answer 10

sugar alcohols

Question 11

What is the bond that links monosaccharides within disaccharides?

Answer 11

glycosidic bond

Question 12

What are the common types of disaccharides and what are their bonds?

Answer 12

• sucrose = glucose + fructose (alpha-1, beta-2 bond)
• lactose = galactose + glucose (beta-1>4 bond)
• maltose = glucose + glucose (alpha-1>4 bond)

Question 13

• carbohydrate stores: structural an mechanical cellular support
• in times of feeding, unused carbs in the form of glucose are shunted to glycogenesis pathway for formation of glycogen (storage)

Answer 13

polysaccharides

Question 14

• polysaccharide in humans
• sugar component: alpha-glucose
• linkage: alpha-1>4 and alpha-1>6
• function: food storage in animals
• branching: ~6-10 glucose

Answer 14

glycogen

Question 15

What are the different types of lipids (4)?

Answer 15

• fatty acids: saturated (single bonds) or unsaturated (double bonds)
• triacylglycerol: 3 fatty acids with glycerol backbone
• cholesterol esters: fatty acid esterfied to a cholesterol
• phospholipids: comprise cell membranes

Question 16

What are the lipid soluble vitamins?

Answer 16

A, D, E, K

Question 17

• long, unbranched hydrocarbon chains
• general formula: CH3(CH2)nCOOH
• saturated, monounsaturated, or polyunsaturated
• omega-3 and omega-6 are essential

Answer 17

fatty acids

Question 18

• essential fatty acids
• the “3” and “6” denote carbon location of terminal double bond
• linolenic acid is a common 3
• linoleic and arachidonic acids are common 6’s

Answer 18

omega-3 and omega-6 fatty acids

Question 19

• any of a class of organic compounds composed of two or more units of hydrocarbons, with each unit consisting of five carbon atoms arranged in a specific pattern
• synthesized from acetyl CoA via intermediate IPP (isopentenyl pyrophosphate)
• condensation of IPP = steroids, vitamins, and coenzyme Q
• steroids: characteristics ABCD ring system

Answer 19

isoprenoids

Question 20

• component of membranes
• precursor to:
  
  • steroid hormones: (progesterone, aldosterone, cortisol, testosterone, and estradiol)
  • bile acids
  • vitamin D

Answer 20

cholesterol

Question 21

• when the non ideal bile, including too much cholesterol and too little bile salts, cause formation of crystalline _______ in the gallbladder
• continued disturbances in metabolism can lead to malabsorption and fat soluble vitamin deficiencies
• tx: oral chenodeoxycholic acid can help dissolve

Answer 21

gallstones

Question 22

• fuel: amino acids generate ATP in TCA cycle
• structural: key components in connective tissue
• activity: enzymes, cell signaling, transport

Answer 22

proteins

Question 23

• amino acid sequence written from left to right starting with N-terminus (NH3) and terminating with C-terminus (COO)
• R-groups alternate above or below backbone
• peptide bonds (no rotation), rotation allowed between C-alpha, but restricted due to steric hindrance of R-groups and carboxyl

Answer 23

primary protein structure

Question 24

• helices: right hand curvature, stabilized by hydrogen bonds between nonadjacent amino acids
• beta sheet (parallel or antiparallel): two or more non-coiled strands that associate via hydrogen bond formation, alternating directions of carboxyls and alternating R-groups
• turns/loops: ~4 amino acids in length, one of which is proline; join antiparallel sheets or between sheets and helices

Answer 24

secondary structure or proteins

Question 25

• hydrophobic interactions, non polar amino acids fold into center, away from water forming a hydrophobic core
• disulfide bonds in cysteine, metal ion complexes, hydrogen bonding

Answer 25

tertiary structure of proteins

Question 26

• multiple protein subunits (pLGIC), hydrogen bonds, salt bridges, hydrophobic interactions

Answer 26

quaternary structure of proteins

Question 27

• an avg 155 lb person consumes ~100 g of protein qd
• protein is hydrolyzed to its component amino acids by proteolytic enzymes in stomach and duodenum prior to absorption
• further metabolism of amino acids occurs to provide energy or to create other important biomolecules
• ~400 g of protein is degraded qd in tissues, and ~400 g of new proteins are synthesized in the body qd
• nitrogen atoms contained in proteins are channeled into the urea cycle of the liver, nitrogen is excreted as urea in urine or sweat

Answer 27

protein turnover

Question 28

• oxidation of the sulfhydryl (-SH) group of cysteine residues in the lumen of the rough ER creates covalent _______ ______, usually in secreted proteins
• oxidizing environment is necessary for formation of these
• cytoplasm is not an oxidizing environment due to the high conc of the antioxidant, glutathione
• keratin (hair protein) has high cysteine content and tends to form disulfide bonds (manipulating these bonds is key to hair texture)

Answer 28

disulfide bonds