Chapter 5- Biological Macromolecules and Lipids (Done) Flashcards
Order of abundance of macromolecules in our body
water > protein > lipids > nucleic acid > carbohydrate
4 premises of macromolecules
1) Polymeric chain of limited kinds (< 100) of monomers
2) Formed by covalent bond through dehydration/condensation
3) Giant size
4) Immense diversity
Anabolic reaction
Build up from small to big molecules
(dehydration/condensation)
-endothermic
Catabolic reaction
Break down from big to small molecules
hydrolysis
- exothermic
Carbohydrate empirical formula
CnH2nOn or CnHn(OH)n
Role of carbohydrates
1) energy source (glycogen in animals, starch in plants)
2) molecular recognition in immune system
3) structural role (cellulose in plant cell wall, chitin in exoskeleton)
Aldehyde sugar
Aldose
- can form ring structure more easily due to COH at the end
- number of carbons and ring structure align (e.g. 6-carbon sugar glucose is a hexagon shape)
Ketone sugar
Ketose
-number of carbons and ring structure do not align (e.g. 6-carbon sugar fructose is a pentagon shape)
α-glucose
H (top), OH (bottom) on 1st carbon
-role: energy polysaccharides (glycogen, starch)
β-glucose
OH (top), H (bottom) on 1st carbon
-role: structural polysaccharides (cellulose, chitin)
Maltose
α-glucose (1-4) glucose
Sucrose
α-glucose (1-2) β-fructose
Lactose
β-galactose (1-4) glucose
1-6 glycosidic bond
branched structure
1-4 glycosidic bond
linear structure
Starch
- energy storing carbohydrate in plants
- α-glucose monomers
1) amylose: 1-4 glycosidic bonds
2) amylopectin: 1-4 and 1-6 glycosidic bonds - both form amyloplast - organelle that stores starch
- hydrophobic - don’t affect osmolarity
Amylose
- type of starch
- α-glucose monomers - energy storing carbohydrates in plants
- 1-4 glycosidic bonds
- 500-20,000 α-glucose monomers
- form amyloplast - organelle that stores starch
- hydrophobic - don’t affect osmolarity
Amylopectin
- type of starch
- α-glucose monomers
- energy storing carbohydrates in plants
- 1-4 and 1-6 glycosidic bonds (1-4 > 1-6)
- form amyloplast - organelle that stores starch
- hydrophobic - don’t affect osmolarity
Glycogen
- α-glucose monomers
- energy storing carbohydrates in animals
- forms 4kcal of energy per gram
- 1-4 and 1-6 glycosidic bonds (1-6 > 1-4)
- stored in liver, muscle, brain
- hydrophobic - don’t affect osmolarity
Cellulose
- β-glucose monomers
- structural carbohydrates in plant cell wall
- 1-4 bonds
- cross linked by H-bond
- make microfibrils
Chitin
- β-glucose monomers combined with nitrogen-containing appendages
- structural carbohydrates in exoskeletons (arthropods, cell wall of fungi)
- 1-4 bonds
- cross linked by H-bond
- make microfibrils
- strong and flexible - used in surgical threads
- digested ONLY by bacteria
3 types of lipids
1) Neutral fat (triacylglycerols)
2) Phospholipids
3) Steroids
Triacylglycerols
also called neutral fat (neutral pH)
- 1 glycerol + 3 fatty acids
- bonded by 3 ester bonds
Role:
1) efficient storage of excess energy (9kcal per gram)
2) thermal insulator (subcutaneous layer, stored as adipose cells)
Lipids
hydrophobic
insoluble in water
Fatty acid
- carboxyl group at the end (acidic properties)
1) saturated F.A - no double bond
- linear
- high density (solid)
2) unsaturated F.A - more than 1 double bond
- has kinks (bending)
- low density (plant and fish liquid oil)
Hydrogenation
Breaking double bonds into single bonds
(stirring oil makes butter)
-converts tasteless liquid oils into tasty solid fat
-also leads to trans double bond fat (unhealthy), causing atherosclerosis (lipid deposits in blood vessel)
Phospholipid
1 glycerol + 2 fatty acids + 1 phosphate group (PO4 2-)
(2 ester bonds)
-amphipathic (both hydrophobic and -philic) ‘
Role:
-form phospholipid bilayer (plasma membrane)
Steroids
- no glycerol, fatty acid or ester bonds
- four fused rings: 3 hexagonal ring + 1 pentagonal ring
- precursor = cholesterol
1) sex hormones: progesterone, testosterone, estradiol
2) corticoid hormones: mineralocorticoid and glucocorticoid
3) vitamin D: absorption of Ca2+ in small intestine
Cholesterol
- acts as fluidity buffer in membrane
- metabolized in liver and transported through blood
- HDL (more protein, healthy) and LDL (less protein, unhealthy)
- precursor of other steroids
Function of proteins
1) enzymes
2) structure to cells and tissues
e. g. keratin, elastin, collagen
3) energy storage
e. g. casein, albumin
4) immune protein - antibody
Draw amino acid structure
carboxyl group (acidic) amino group (basic) -amphoteric properties
Globular vs. fibrous shape of proteins
1) Globular
- water soluble
- charged or hydrophilic amino acids
e. g. enzyme, plasma protein
2) Fibrous
- water insoluble
- hydrophobic amino acids
e. g. keratin, collagen
4 hierarchical level of protein structure
1) Primary structure
-linear sequence of amino acids
-only changed by mutation
2) Secondary structure
-stabilized by H-bonds
-forms:
α-helix (coiled) - H-bond between every 4th amino acid
β-pleated (folds) - H-bond between 2 antiparallel polypeptide backbone
3) Tertiary structure
-chemical interaction between side chains
ionic, hydrogen, covalent bonds (S-S crosslinks), hydrophobic interactions
4) Quaternary structure
-more than 2 polypeptides
-biological functional protein
Nucleic acids
- phosphodiester bonds between phosphate group and pentose sugar on either side (5th C and 3rd C)
- N-glycosidic bond between 1st C in sugar and nitrogenous base
Pyrimidines
Cytosine, Thymine, Uracil
single rings
-one 6-membered ring
Purines
Adenine, Guanine
Double rings
-one 6-membered ring and 5-membered ring
A-T
2 hydrogen bonds
Nucleoside
ribose sugar + base
DNA double helix
- two strand of antiparallel DNA strands
- winds around as a right-handed coil
G-C
3 hydrogen bonds
Phosphate-phosphate bonding
phosphoanhydride bridge
Sickle cell anemia
- caused by change in 6th amino acid of beta-1 subunit of hemoglobin (glutamate to valine)
- reduces affinity and capacity for O2 transportation
