2. molecules necessary for life Flashcards
important biomolecules
- organic and inorganic molecules
- water is the most important inorganic molecule
- salts and ions
organic and inorganic molecules
organic molecules include carbon
(carbohydrates, proteins, lipids, nucleic acids)
-important as cell building blocks, energy sources and info storage
-exceptions: CO, CO2, H2CO3 (inorganic but contain carbon)
water
most important inorganic molecule
-60% of the human body
-majority is intracellular
(2/3 intracellular, 1/3 extracellular)
-a polar solvent: hydrophilic
(like dissolves like)
-effectively dissolves sugars, amino acids and other polar compounds
-dissolves wastes and salts as well
-universal solvent
-cannot dissolve large non-polar molecules
( lipids such as oil and fatty acids, O2 gas and CO2 gas are small and non-polar they are able to dissolve in water)
salts and ions
sodium, potassium, chloride, calcium
-salts are ionic compounds (consist of cations and anions. NaCl, CaCO3, KCl, CaPO4)
-ions are electrolytes
(conduct electrical current in solution)
-sals will dissociated into component ions when added to water
(NaCL->Na+ + Cl-
polarity of water caters to the charges on each ion)
four major classes of organic macromolecules:
carbohydrates
lipids
nucleic acids
proteins
organic molecules
-serve as info storage DNA and RNA -Energy carbohydrates, lipids -membrane building blocks proteins and lipids
carbohydrates
-Hydrophilic
•Dissolve well in water provided they aren’t too large
•General formula: (CnH2nOn)
•Example: Glucose: C6H12O6,ribose C5H10O5
-Important energy source
•Easily catabolized to supply the cell with energy
-Found as structural molecules in fungal cells, plant cells, bacterial cells and some animal cells
-Can be attached to other lipids and proteins
•Glycoproteins and glycolipids
•Important for cell recognition
monosaccharides
- Single sugar units
- Predominate as cyclical molecules in solution
- Include deoxyribose and ribose as well as glucose, fructose and galactose
disaccharides
Two sugar units covalently attached via a dehydration reaction between 2 monosaccharides
• Include sucrose, maltose and lactose
• Maltose is produced from breakdown of
starch and glycogen
polysaccharides
• Polymers of many sugar units linked together
via dehydration reactions
• Include starch, glycogen and cellulose
why is glucose not freely stored inside the cell
b/c is it osmotically active
water will move into the cell causing the cell to rupture
glycogen is too large to be soluble in the cell cytoplasm
does not disrupt osmotic balance
preferred form of sugar storage inside of the cell
lipids
- Hydrophobic molecules
- Hydrates of carbon
- Enriched with carbon and hydrogen atoms attached to one another by non- polar covalent bonds
- Some are amphipathic
- Contain both hydrophilic (usually very small) and hydrophobic components
- Structurally very diverse
- Common thread is hydrophobicity
- Include:
- Phospholipids: form the plasma membrane
- Sphingolipids: membrane components
- Steroids: hormones
- Triglycerides: energy storage
fatty acids
- Carboxylic acid terminus
- Hydrophobic carbon tail
- Length varies from 8-28 carbon atoms
- Carbon atoms can be joined by single covalent bonds
- Saturated fatty acids
- ‘stiff’ molecules
- Carbon atoms can be joined by double covalent bonds
- Unsaturated fatty acids
- Molecules contain ’kinks’ where double bond is located
Lipids are important because:
• They form a hydrophobic cell barrier
• Inhibits the entry/escape of hydrophilic molecules and ions
• Unsaturated fatty acid tails attached to membrane phospholipids allow a semi-fluid
membrane
• Important for function
• They are an attractive candidate for energy storage
• One gram of fat stores 2x more energy than one gram carbohydrate
• Form many hormones and vitamins
• Important for enzyme activity
• Important for cell to cell communication
glycerides
- Monoglycerides: glycerol + 1 fatty acid
- Diglycerides: glycerol + 2 fatty acids
- Triglycerides: glycerol + 3 fatty acids
- Most common
- All form from dehydration reactions between fatty acids and glycerol (a three carbon sugar)
glycerol
three carbon sugar
phospholipids
• Form from the combination of a diglyceride, a phosphate group and a R
group which exists in variety of different forms
• Amphipathic molecules
• Contain both polar and non-polar segments
• Ideal for the formation of membrane structures
• Sphingolipids vs Phospholipids
Sphingolipids have sphingosine instead of glycerol
• Also have only one fatty acid tail and lack a phosphate group • Phospholipids have glycerol as the ‘neck’ of the structure
• Also have two fatty acid tails and a phosphate group • Both sphingolipids and phospholipids can carry a sugar
group on the head of the molecule
• Glycosphingolipid/glycophospholipid
Steroids
Composed of four fused ring structures
• Differences in attached functional groups translate into differences in function
• Example: testosterone vs estradiol vs cholesterol
• Important for cell to cell communication
• Testosterone, cortisol and other hormones
• Also plays an important role in the structure of animal cell membranes • Cholesterol
- Proteins
• Hydrophilic molecules
• Often contain hydrophobic parts
• Form from amino acids
• Amino acids are the monomers, protein is the polymer
• There are 20 different amino acids
• Each differs based on the identity of the R group
• The R group can be:
• Polar
• Non-polar • Acidic
• R group carries a negative charge at pH=7 • Basic
• R group carries a positive charge at pH=7
AMINO ACIDS
All amino acids have a carboxyl group (–COOH), an amino group (–NH2), and a hydrogen attached to the same carbon. The fourth bond of the carbon attaches to
• Essential amino acids must be consumed
Essential
Non-ess
• Non-essential amino acids are synthesized inside of the cell
• Proteins are considered the workhorse of the cell
form membrane channels, receptors, signaling molecules, anitobides, ligands/hormones, and enzymes
proteins form from
• Thousands of proteins are expressed in mammalian cells
dehydration rxns b/w amino acid monomers
• Covalent bonds between amino acids are called peptide bonds
• Short chains of amino acids are referred to as peptides
• Large chains are called protein
• The amino acids that form the protein sequence determine the final shape
• Important for the function of the protein
• Amino acid sequence of a protein is determined by the DNA
sequence of the gene
• Primary protein structure: amino acid sequence N • Secondary protein structure: folded protein, formed by Secondary structure ix ( > cids) s bonds between different areas of the protein backbone which have Essential Primary structure bonds between different R groups of the protein sequence Non-essential Tertiary structure Qua Fibrous pr Polypeptides (10–100 amino acids) • Tertiary protein structure: compact, globular protein formed by once its in secondary structure Primary structure Proteins ( >100 amino acids) which have Tertiary structure between different polypeptide units (each in tertiary structure) • Determines solubility • Globular protein-usually soluble, fibrous protein-usually insoluble Quaternary structure Multiple subunits Collag • Quaternary protein structure: forms from interaction Sequence of -helix -pleated sheets Fibrous proteins Globular proteins amino acids Sequence of amino acids Secondary structure P Oligopeptides (2–9 amino acids) Secondary structure Tertiary struct P r Sequence of amino acids rim ary s Essential ( > l Sequence of amino acids r rimary structure AMINO ACIDS tructure c ed a variable “R” group. et can be categorized as and can link together by peptide bonds to form Oligopeptides (2–9 amino acids) -helix -pleated sheets and can link toge ts All amino acids ha group (–COOH), an amino group (–NH2), and a hydrogen attached to the same carbon. The fourth bond of the carbon attaches to P s (10–100 amino acids) v e a ca r bo x y o l yp P -h teins r e e o l p ti Polypeptides (10–10 and can link together by peptide bonds t All amino acids have a carboxyl group (–COOH), an amino group (–NH2), and a h s d -h th m which have e l e e - o a l ix - r by pepti d p 1 le 0 a 0 am t ed s Collagen Hemoglobin O 00 a p i e bo n h l to the same carbon. The fourth bond of the carbon attaches to a variable “R” group. i S y structure Proteins a e te can be Polypeptides (10–100aminoa Tertia c go o r iz a n d a s ig y le e dr a o o te n p d g d s e st e p n a o fo t h e P id t t e r e a o c o t h n 1 e e - (2 e 0 i d 0 a n – s s (> 9 am s en m in t o a 1 in ia o ac cids
