Water, Lipids, Carbohydrates, and Nucleotides Flashcards
Hydrogen Bonding
Intermolecular bonding between H and F, O, or N. Provides strong cohesive forces between water molecules
Responsible for elevation of boiling point of water
Hydrophilic
A characteristic referring to the tendency of molecules to congregate near and dissolve in water.
Ionic compounds’ negatively charged ends are attracted to partial positive charge of water’s hydrogen and positively charged ends are attracted to partial negative charge of water’s oxygen
Hydrolysis
Most macromolecules of living cells are broken apart by this process through the addition of water
Hydrolysis of ATP molecules provides the body’s major source of energy
Dehydration synthesis
Reverse reaction of hydrolysis. Two molecules are combined to form a larger molecule and water is formed as a byproduct
Allows formation of bonds that make up biological molecules (peptide, ester bonds)
ATP Hydrolysis reaction
Water serves as nucleophile and attacks the electrophilic phosphoanhydride bond between the beta and gamma phosphates of the ATP molecule.
Gamma phosphate is freed and can be used by a kinase enzyme
Lipids
Low solubility in water and high solubility in nonpolar organic solvents
Nonpolar and hydrophobic
Roles of lipids in an organism
- Energy storage: long carbon chains
- Cellular organization and structure: fats assemble into barriers separating aqueous environments (hydrophobic)
- Provision of precursor molecules for vitamins and hormones: can pass easily through cellular membranes
Fatty Acids
Lipids that are the building blocks for the most complex lipids
Act as fuel for body, components of cell membranes
Long chains of carbons truncated at one end by carboxylic acid (even Cs, max of 24)
Store more energy than any other molecule (9kcal)
Unsaturated Fatty Acid
Contain one or more Carbon-Carbon double bonds
Saturated Fatty Acid
Have only single Carbon-Carbon bonds
Triacylglycerol
AKA triglycerides or fats and oils
Constructed from 3C backbone called glycerol attached to three fatty acid chains
Function: to store energy, thermal insulation and padding to organism
Found in adipocytes
Sphingolipids
Have long chain fatty acid and polar head group, with amino alcohol (Sphingosine) backbone, rather than glycerol
Make up part of cell membrane
Sphingomyelin: phosphate group attached to sphingosine backbone (phospholipid)
Phosphatids
Simplest phosphoglycerides.
Glycerol backbone with a phosphate group attached
Steroids
Four-ringed structures
Include some hormones, vitamin D, and cholesterol
Cholesterol: maintains membrane stability and fluidity (precursor for steroid hormones)
Terpenes
Sixth class of lipids that are often part of pigments in the body
Includes vitamin A
Waxes
Formed by ester linkage between a long-chain alcohol and long-chain fatty acid
Water-repellant texture
Eicosanoids
12C structures, often considered a fatty acid
Released from cell membrane as local hormones that regulate blood pressure, body temperature, and smooth muscle contraction.
Includes prostaglandins, thromboxanes, and leukotrines.
Aspirin inhibits synthesis of prostaglandins
Lipoproteins
Contains a lipid core surrounded by phospholipids and apoproteins
Able to dissolve lipids in hydrophobic core
Move freely in aqueous solutions due to cell
Classified by density; greater ratio of lipid to protein, lower the density
Major classes of lipoproteins
Chylomicrons
Very low density lipoproteins (VLDL)
Low density lipoproteins (LDL)
High density lipoproteins (HDL)
Major functions of lipids
- Phospholipids serve as structural component of membranes
- Triacylglycerols store metabolic energy and provide thermal insulation and padding
- Steroids regulate metabolic activity
- Some fatty acids (eicosanoids) serve as local hormones
Phospholipids
Lipids with a phosphate group attached
E.g. phosphoglycerides
Glycerol backbone, with polar phosphate group at head and two fatty acids at tail
Amphipathic, suited for cell membrane
Glycoliopids
One or more carbohydrates attached to 3C glycerol backbone with two fatty acids at tail
Amphipathic
Found in membranes of myelinated cells in human nervous system
Adipocytes
Specialized cells whose cytoplasm contains almost nothing but triglycerides
Types of lipids
Fatty acids, Triacylglycerols, Phospholipids, Glycolipids, Sphingolipids, Steroids, Terpenes, and Waxes
Carbohydrates
Carbon and water fixed in a one-to-one ratio:
C_n (H_2O)_n
Useful for storing energy and providing easily accessible energy to the body
Store up to 4 kcal of energy in C-H bonds
Consistent structure allows stacking in cell
Polysaccharides
Long chains of carbohydrates formed from linkage of many monosaccharides
Useful for energy storage
Dehydration: forms polysaccharides
Hydrolysis: Breaks down polysaccharides to monosaccharides through addition of water
Glucose
Most commonly occurring six carbon carbohydrate (hexose)
Accounts for ~80% of carbohydrates absorbed by humans. Almost all digested C converted to glucose by liver or enterocytes (intestinal cells)
Glucose polymerized to polysaccharide, glycogen, or converted to fat when sufficient energy available
Glycogen
Branched glucose polymer with alpha linkages
Found in all animal cells, but large quantities in muscle and liver cells
Liver can break down glycogen to glucose when needed (regulate blood glucose level)
Absorption of glucose
Most cells absorb glucose via facilitated diffusion
- Insulin increases this ability
Epithelial cells in digestive tract and proximal tubule of kidney are capable of absorbing glucose against concentration gradient
- secondary active transport down gradient of sodium
What happens to glucose absorption without insulin?
As insulin increases rate of facilitated diffusion of glucose, affects the uptake of glucose and blood glucose level
Only neural and hepatic cells are capable of absorbing sufficient amounts of glucose via the facilitated transport system
Starch
Polysaccharides present in animals
Can be amylose or amylopectin
Amylose: branched or unbranched and has same alpha linkages as glycogen
Amylopectin: resembles glycogen, but has different branching structure
Cellulose
Structural material in plants (polysaccharide) formed from glucose
Composed of beta linkages, stable for plant cell walls
Humans have enzymes to digest alpha linkages, but not cellulose- fiber
Bacteria break beta linkages
Nucleotides
Important class of molecules, building blocks of genetic material, involved in cell’s usage of energy
Three components of Nucleotides
- Five carbon (pentose) sugar
- Nitrogenous base
- Phosphate group
Highly stable sugar with phosphate group can link together to form stable and organized backbone (polar and hydrophilic)
Nitrogenous bases form weak H bonds to stabilize double helix, but can be separated
Four Nitrogenous Bases
Adenosine, Thymine, Guanine, and Cytosine
Two H-bonds form between A and T
Three H-bonds form between C and G
Purines
Guanine (G), and Adenine (A)
Two ring nitrogenous base structure
Nucleoside
Pentose sugar attached to nitrogenous base
Form nucleotide with addition of one or more phosphate groups to nucleoside
Nucleic Acids
Polymers of nucleotides
Known as DNA or RNA
Specify production of proteins to allow for expression of genetic traits
Formed by phosphodiester bonds between phosphate group of one nucleotide and 3rd C of pentose sugar of next nucleotide
Sugar Phosphate Backbone
Formed by phosphodiester bonds between nucleotides
In what direction are strands of nucleotides synthesized?
Synthesized by DNA polymerase in 5’ to 3’ direction
Watson-Crick Model of DNA
B Form of DNA: Two strands of DNA lie side by side in opposite 3’ to 5’ direction (antiparallel) bound together by H-bonds between nitrogenous bases, forming double-stranded structure
One spiral for every 10 nitrogenous bases
Complementary Strands
DNA strands whose bases match up in the correct order
RNA
Ribonucleic Acid:
1. Carbon number 2 on pentose is not deoxygenated (hydroxyl attached)
2. Almost always single stranded
3. Contains pyrimidine uracil (U) instead of thymine (T)
Can move through nuclear pores
Three types of RNA
Messenger RNA (mRNA) Ribosomal RNA (rRNA) Transfer RNA (tRNA)
Important Nucleotides beside DNA
ATP (adenosine triphosphate) for energy
Cyclic AMP (cAMP) important component in secondary messenger systems
NADH, FADH are coenzymes involved in Krebs Cycle and electron transport chain
Pyrimidines
Cytosine (C) and Thimine (T)
One ring nitrogenous base structure
