Lecture 2 - Chemical Bonds & Macromolecules Flashcards
important concepts: the types of bonds and monomers that make-up macromolecules and the roles the macromolecules play in the cell
What elements make up DNA and proteins?
DNA: C, H, O, P, N
Protein: C, H, O, S, N
Why is water the solvent of life?
- polar
- oxygen has a high affinity for electrons (high electronegativity)
- water can associate with other water molecules
- water can associate with any molecule that is charged or has dipole-dipole bonds
What are organic macromolecules?
- contain C-H
- C is the backbone of organic molecules because it can bond to 4 other atoms, form C-C chains, and from double and triple bonds
- C is weakly electronegative
What are monomers and polymers?
monomer = single building block of a macromolecule polymer = chain of monomers composed of similar but not identical subunits (DNA)
Describe Synthesis (Condensation Rxn)
- add monomers to a growing chain (forms a covalent bond)
- water is a product
requires energy
Describe Breakdown (Hydrolysis Rxn)
- cleavage of covalent bonds between monomers in a polymer
- water is a reactant (added in)
- releases energy
- spontaneous but SLOW
What are carbohydrates?
- energy storage, cell structure, cell-cell recognition
- monomers (carbon chains, linear or ring-shaped)
ex) glucose
What are disaccharides?
- formed by a covalent bond between monosaccharides
- bond type: glycosidic
ex) sucrose
What are polysaccharides?
- polymers of monosaccharides
ex) starch, cellulose, glycogen, chitin
What are lipids/fats?
- not a true polymer
- classified as a lipid because they are hydrophobic, meaning they aggregate away from water
- made mostly of H-C
What is the difference between fatty acids and fats?
fatty acids = can attach to a glycerol backbone, usually about 16-18C long
fats = triacylglyceride (animal fat), energy storage, and insulation
What are phospholipids?
- structural comp. of biological membrane
- functions in the cell membrane
- amphipathic = have both hydrophilic and hydrophobic domains
What are steroids?
- class of lipids based on cholesterol
- characterized by a backbone of 4 fused HC rings, with a small polar functional group
functions: - 1) hormones - estrogen/testosterone
- 2) in animals, cholesterol sits in the plasma membrane to maintain fluidity and increase stiffness
What are proteins?
- involved in every biological task
- composition and structure of amino acids
- proteins are polymers of the monomer - amino acid
- 20 biologically relevant a.a
What are the different R groups?
1) non-polar - R = CH
2) polar uncharged - R = -OH or -SH
3) polar charged acidic (-) - R = COO -
4) polar charged basic (+) - R = NH3 +
What is the structure of proteins?
- function in 3D but are synthesized as linear polypeptides
- a.a are polymerized during translation
- a.a are covalently linked by peptide bonds
Describe primary structure
- polymerization of a.a
- determined by the sequence of DNA
- written and translated N –> C
- bond type = peptide
- primary structure dictates folding, folding dictates function
Describe secondary structure
- interaction between the backbones of the peptide chain
- local folding of a.a chain into an alpha helix and beta-sheets
- the R group is NOT involved in stabilizing the secondary structure
Describe tertiary structure
- 3D pattern of folding
- hydrophobic interactions of non-polar R groups drive away the a.a away from water into the middle of the protein
- forces that maintain the tertiary structure: interactions between R groups, covalent bonds, ionic bonds, hydrophobic interactions, hydrogen bonds
Describe quaternary structure
- some proteins form multisubunit complexes that create a functional protein
- ex) hemoglobin, collagen, ribosome
What are chaperones?
- proteins that assist in folding other proteins, this folding is essential for protein function
- there are many diseases of protein folding (misfolded proteins aggregate in the cell and cause death)
- ex) bacterial chaperone = “molecular folding chamber”
What are nucleic acids?
- DNA and RNA
- store and transmit hereditary info
Describe DNA
- transmits info between cell generations
- contains all info essential for life
- polymer of deoxynucleotides
- double-stranded and forms helix with the bases pointing inwards
- form complementary base pairing
- purine always pair with a pyrimidine
- antiparallel
Describe RNA
- polymer of ribonucleotides
- many functions: info, translation, regulation, splicing
- singled-stranded
- 2’OH makes the helix more open and more reactive
- free base-pair with itself
Be able to describe the basic structure of a nucleotides
refer to notes!!
What are pyrimidines and purines?
pyrimidines = single ringed bases (T,C,U) purines = double ringed bases (A,G)
