macromolecules

types of macromolecules

lipids, carbohydrates, proteins, nucleic acids

three types of carbohydrates

• monosaccarides

• disaccarides

• polysaccarides

monosaccaride

• general formula: (CH₂O)n

• end in ose (sugar)

• classified by number of carbons

  • ex. glucose

disaccarides

• formed by dehydration synthesis

  • ex. maltose (two glucoses)

functions of monosaccarides

• energy source

• structural building block for other molecules (glycosidic bonds)

  • ex. glucose

polysacarides & their function

• made from many monosaccarides

• polymers

• energy-storing compounds

  • ex. starch & glycogen

• structural compounds

  • ex. cellulose & chitin

starch

• energy storage in plants- made from glucose (alpha, helix)

• amylose = simplest structure (unbranched helix)

• stored in plastids — broken down through hydrolyzation

glycogen

• energy storage in animals (liver & muscles)

• highly branched

cellulose & functions

• polymer of glucose molecules (beta, straight & unbranched)

• aids in plants standing upright & cell walls

• forms microfibrils bc straight structure (H hydrogen bonds with OH)

why starch & cellulose different

structure

• starch = branched & helix (alpha)

• cellulose = straight & unbranched (beta)

digestion of cellulose

• cannot be hydrolyzed by same cells used for starch

• eliminated as insoluble fiber (humans)

• can be digested using enzyme cellulase

• some fungi can digest it

benefit of cellulose in digestive tract

abrades intestinal walls & stimulates secretion of mucus — helps passage of food

chitin

• formed by glucose monomers with nitrogen group

• exoskeletons & cell walls (fungi)

polymers

chain-like molecules formed by linking of identical molecules (monomers)

synthesis & breakdown of polymers

• synthesis: dehydration: hydroxyl & h release water molecule

• breakdown: hydrolysis: addition of water molecules

  • ex. food digestion: if too big to be absorbed it is broken down through hydrolysis

lipids

• hydrophobic — insoluble in water

• not polymers

  • do not repeat units

three types of lipids

• fats

• phospholipids

• steroids

what is a fat composed of

• glycerol

  • 3 C alcohol

• fatty acid

  • long hydrocarbon chain with carboxyl group

  • holds energy in C-H bonds

how are fats formed

• three fatty acids to glycerol

  • ester linkage

    • triglyceride

saturated vs unsaturated fats

• saturated: max hydrogen bonds, solid at room temp. (animals)

• unsaturated: c-c double bonds, oils: liquid at room temp

  • increased volume bc kinks

hydrogeneration

converting unsaturated fats to saturated ones by adding hydrogen

ratio of carbon-hydrogen in lipids

1C:2H —— less oxygen

phospholipids

• two fatty acids (hydrophobic tail)

• phosphate group (charged, hydrophilic head)

how does a phospholipid react in water

forms bilayer (sphere-ish - micelle) — heads pointing out towards water and tails inward

• bilayer makes up cell membrane

steriods 

• carbon skeleton — 4 joined carbon rings 

  • created by attached functional groups 

• everything built from cholesterol

  • can act as hormones

function of fat

• stores twice as much energy as starch 

• humans/animals use it as long term energy reserve (we mobile)

• plants use it (seed)

• adipose tissue cushions vital organs

• insulation 

what are proteins polymers of

amino acids (20 dif.) — peptide bonds

what do amino acids consist of

• alpha carbon

• amino group (NH2)

• carboxyl groups

• hydrogen

• r group

what can the r groups be

• non-polar: hydrophobic

• polar: hydrophilic

• acidic: negative charge

• basic: positive charge

  • influence amino acids & 3d structure of protein

proteins

one or more polypetptides folded or coiled into a specific shape, conformation

• structure determines function

how is a polypeptide chain formed

dehydration synthesis: carboxyl & amino groups

• amino end: n-terminus

• carboxyl end: c-terminus

*each polypeptide has specific amino acid sequence — unique function

four levels of protein structure

• primary

• secondary

• tertiary

• quaternary: two or more polypeptides

primary structure

unique sequence of amino acids — determined by inherited genetic info

• slight changes = effects (sickle cell disease)

secondary structure 

coiling & folding of polypeptide backbone — hydrogen bonds 

• alpha helix (coil)

• beta pleated sheet (fold)

tertiary structure

overall 3-D shape: determined by the interactions of r groups/sides chains

interactions of the r groups

• hydrogen bonds (polar & charged areas)

• ionic bonds (charged r groups)

• hydrophobic interactions (hydrophobic r groups)

• van der Waals interactions

• disulfide bridges: strong covalent bond (cysteine’s sulfur)

  • influence shape

what is the effect of the cell being a watery solution on protein structure

• amino acids with non-polar r groups go towards center (away from water)

• amino acids with polar r groups go to outside

quaternary structure

multiple polypeptides together

• ex. collagen

how to denature a protein (destroy its structure)

altering pH, temp, salt concentration, adding to organic solvent

• can disrupt hydrogen bonds, ionic bonds & disulfide bridges

why is it hard to predict protein shape

• over 875000 proteins

• have several stages before final form

  • aided by chaperonins

functions of proteins

• structure: fibers

• transport: hemoglobins

• contractile/motor: acting & myosin (muscles)

• hormone: insulin

• defense: antibodies

• catalysts: enzyme

nucleic acids

polymers of nucleotides — DNA (double stranded) or RNA (single stranded)

what do nucleotides consist of

• nitrogenous bases

• pentose sugar (5 carbon)

• phosphate group

what are nucleotides linked by & what do they form

phosphodiester bonds (dehydration synthesis) on 3’ to phosphate to 5’ — form phosphate-sugar backbone

types of nitrogenous bases

• pyrimidines

  • thymine

  • uracil (RNA)

  • cytosine

• purines

  • guanine

  • adenine

types of pentose sugars

• deoxyribose: DNA

• ribose: RNA

directionality of nuclecic acids

• one end has 5’ prime end (free phosphate group on 5th carbon)

• other end has 3’ (free OH on 3rd carbon)

two tasks of DNA

• to provide genetic code for protein creation

• to be replicated exactly

double helix of DNA

• two chains run opposite 5’ to 3’ directions — antiparallelism

• strands held tg by hydrogen bonds (between nitrogenous bases)

complimentary base pair

• a double bonded to t

• c triple bonded to g

• complimentary from nitrogenous bases

  • allows for DNA to be replicated & code for protein production

what is the flow of genetic information

dna — mRNA —protien

process of translation

dna synthesises itself into messagner rna (inside nucleus)

process of translation

mrna interacts with cell’s protein (ribosome) — synthesizing machinery to direct ordering of amino acids in polypeptide

genalogy & evolution

• genes (DNA) & products (proteins) created hereditary background

• siblings have great similarity

• can see relations among species