Chemical Composition of Cells Flashcards
covalent bond
bond in which electrons are shared between atoms. in biology, considered a strong bond.
macromolecule
large, complex organic macromolecules
monomer
small molecule used as a building block to make polymers
polymer
long molecules consisting of many identical or similar monomer “building blocks” linked by covalent bonds
dehydration reaction
H and OH removed from monomers so that they can be linked. requires enzymes and energy. produces water.
hydrolysis reaction
degradation of polymers. covalent bond within a polymer is broken, water is split into H and OH, which attach where the covalent bond used to be. Releases energy. requires enzymes.
amphipathic
having both hydrophilic and hydrophobic segments
major classes of biological macromolecules
- carbohydrates
- lipids
- nucleic acids
- proteins
carbohydrates (function)
energy storage:
Plants-sugars (mono and disaccharides) and starch (polysaccharide)
Animals-glycogen in liver and muscles (polysaccharide)
structure:
plants-cellulose in cell walls (polysaccharide)
animals-chitin in exoskeletons
carbohydrate monomer
monosaccharide:
5- or 6-carbon linear or cyclic molecule
one carbon has a carboxyl group (if linear) or hemiacetal/hemiketal (if ring shaped) and the remaining carbons have hydroxyl groups
-contain only C, H, O
glycosidic linkage
covalent bond that links monosaccharides
-water is removed by taking a H from one molecule and an OH from the other, leaving the CO of one molecule to join the C of the other (-C-O-C-)
lipids (function)
long term energy storage-fats and lipids (triacylglycerol)
structure-phospholipids in cellular membranes
modulate membrane fluidity-cholesterol
signaling-sterols
triacylglycerol
subset of lipids
glycerol (3Cs and 3 OHs) and fatty acids (carbohydrate chains with a carboxyl group on one end)
not polymers
-fatty acids attached to glycerol by ester linkage
-store energy long term
contain C, H, O
phospholipid
subset of lipids
-(charged or polar headgroup bonded to) phosphate group bonded to glycerol with two fatty acid tails
-structural function, make up cell membranes
contain C, H, O, P, and many headgroups contain N
sterols
subset of lipids
- exist only as monomeric compounds
- structure of 4 fused carbon rings with varying functional group attachments
cholesterol
sterol, a subset of lipids
- precursor to all other sterols
- component of animal cell membranes (modulates fluidity)
- synthesized in liver, consumed in animal fats
nucleic acids (function)
- DNA stores genetic material
- RNA uses and decodes genetic material
nucleotide
monomer of nucleic acids
- composed of pentose sugar, phosphate group and nitrogenous base
- composed of C, H, O, N, P
pentose sugar
-substituent of nucleotides (nucleic acid monomers)
5-membered carbon ring
in ribose (RNA), C2 has OH group
in deoxyribose (DNA), C2 has H only
Nitrogenous bases
pyrimidines: 6-membered C and N rings include cytosine, thymine (DNA) and uracil (RNA) purines: fused 5- and 6-membered C and N rings include adenine and guanine
nucleic acids
chain of nucleotides with sugar-phosphate backbone bound by phosphodiester linkage (-C-Pgroup-C-)
-link 3’-OH of one nucleotide to 5’-Pgroup of the next
proteins (function)
- accelerate chemical reactions (enzymes)
- transportation of materials across the cell membrane
- movement (contractile and motor proteins)
- structure
amino acid
protein monomer
-amino group and carboxyl group bonded to central alpha carbon
-side chain R-group also bonded to the central carbon
Contain C, H, O, N, and sometimes S (from the side chain, always check structure if given)
1 protein structure
amino acids linked by peptide bonds in a unique order determined by DNA
(stabilized by peptide bonds)
2 protein structure
stabilized by backbone interactions
- hydrogen bonding between amino groups and carboxyl groups in the polypeptide backbone
- alpha helix, the coiling of a single amino acid around itself
- beta pleated sheets, where amino acid chain segments fold side by side (can be a single amino acid or multiple)
3 protein structure
the overall shape of a single polypeptide
-stabilized by side chain interactions
(H-bonding, ionic bonding, disulfide covalent bonding, hydrophobic effect and VWD forces (all between side chains))
4 protein structure
structure of multiple polypeptides folded together
-stabilized by same side chain interactions as 3 structure (H-bonding, ionic bonding, disulfide covalent bonding, hydrophobic effect and VWD forces (all between side chains))
prions
a prion is an /infectious protein particle/
- cannot be degraded/denatured by heat or acid
- derived from a protein in our brains, PrP
- cause normal proteins, PrP^C to refold into abnormally into prion particles, PrP^Sc
