Chapter 1 - The Chemical Basis of Life (2) Flashcards
Carbohydrates
contain C, H, and O in the ratio 1:2:1
names generally end in “ose”
exceptions = glycogen, amylopectin
aldehydes or ketones with hydroxyls on most of the carbons
Functions of carbohydrates
structural components = ribose and deoxyribose are components of nucleic acids
cellulose is the primary structural component of cell walls
chitin is a structural component of insect exoskeletons
fuel =
glucose (blood sugar) is the principal fuel of cells
identity markers =
sugar molecules on the cell surface identify types of cells within your body
they also identify foreign cells to your immune system
Monosaccharides
2 to 8 carbons
linear form in dry crystals, but form rings when dissolved in water
ribose and deoxyribose are important 5-carbon sugars
fructose and galactose are important 6-carbon sugars
Two ring forms of glucose
alpha glucose has C1 hydroxyl pointing down
beta glucose has C1 hydroxyl pointing upwards
(A)lpha (B)elow (B)eta (A)bove
Disaccharides
a linkage of 2 monosaccharides hides sugars so they aren’t metabolized during transport sucrose = glucose and fructose lactose = glucose and galactose maltose = glucose and glucose
Polysaccharides
polymers of glucose
insoluble in water due to their large size
this makes them excellent for sugar storage in cells since they do not make the cytoplasm hypertonic (increased pressure)
can be branched or unbranched
Glycosidic bonds
condensation synthesis (dehydration synthesis)
formation of polymers by removing water from a pair of hydroxyl groups on adjacent monomers
this is how polysaccharides are formed
hydrolysis
the shortening of a polymer by inserting water between the monomers
Amylose (plant starch)
energy storage in plants
linear polymer of alpha glucose
digested by vertebrates due to our enzyme amylase that cleaves the linkage
no branching, alpha 1-4 linkage, weak intermolecular attractions
Amylopectin
shorter, branched version of amylose
found in sticky rice
Glycogen (animal starch)
an alpha glucose polymer with two levels of branching
a day’s worth of energy is stored in the liver and muscles to provide glucose between meals or during strenuous activity
carbo-loading builds up glycogen reserves before important competitions
Cellulose (wood)
polymer of beta glucose used in cell walls for strength
only digested by some fungi and bacteria
bacteria may be present in some specialized stomachs, such as cows and termites
Chitin
modified form of cellulose with added nitrogen groups
found in insect exoskeletons and fungus cell walls
Lipids
lipids are large molecules that are not polymers of repeating subunits
they have diverse chemical structures
they are all hydrophobic
Triglycerides
three fatty acids linked to a glycerol backbone using ester linkages
mostly used for energy storage and thermal insulation
Saturated fats
saturated fatty acids have no double bonds, and allow for strong LDF
solid at room temperature
animal fats
Unsaturated fats
unsaturated fatty acids have double bonds, which introduce kinks preventing LDF
liquid at room temperature
plant oils
Phospholipids
triglycerides with one of the fatty acids replaced by a phosphate group
this phosphate end is polar and dissolves in water, but the fatty acids are non-polar and will not dissolve
amphiphilic = loves both
they are the main structural component of cell membrane
Phospholipid bilayers
phospholipid bilayers
hydrophilic ends face extracellular fluid and cytoplasm
hydrophobic ends are repelled towards each other
Waxes
waxes consist of a long chain alcohol ester linked to a long chain fatty acid
around 50 carbons in total
primarily used for waterproofing
Steroids/sterols
steroids have a characteristic set of four interconnected carbon rings
3 hexagons, 1 pentagon
many animal hormones are steroids
Polyphenols
terpenes with numerous phenol rings in their structure
a wide variety of these serve many purposes in plants
they are antioxidants, the alternating double bonds provide easy electrons for oxidizing agents, protecting your DNA
largely key to the health benefits of fruits and vegetables
Terpenes
long chain hydrocarbons that don’t belong in any of the previous lipid categories
plant pigments such as chlorophyll and beta-carotene and fat-soluble vitamins (A, D, E, K)
easiest to classify by elimination
Nucleic acids
made up of monomers called nucleotides each nucleotide consist of a sugar, a nitrogenous base, and phosphate(s) deoxyribonucleic acid (DNA) nucleotides adenine, thymine, guanine, cysteine ribonucleic acid (RNA) nucleotides adenine, uracil, guanine, cysteine
Roles of nucleic acids
energy carriers
coenzymes
genetic information
Energy carriers
adenosine triphosphate (ATP) is an unstable molecule due to 3 negatively charged phosphate groups
hydrolysis of the third phosphate results in a net release of energy
conversely, adding the third phosphate to ADP stores energy
your body uses approximately your body weight of ATP daily
Coenzymes
these are required for enzyme catalyzed metabolic reactions to occur
NADH and FADH2 act as carriers of high energy electron pairs
NADH = Nicotinamide Adenine Dinucleotide
FADH2 = Flavin Adenine Dinucleotide
DNA
encodes the sequence of every polypeptide that your cells make
each gene in a chromosome codes for one polypeptide
consists of antiparallel polymers held together by hydrogen bonds
each polymer consists of alternating sugar-phosphate strands
the nitrogenous bases extend from the strands
the entire molecule is a ladder in a double-helix shape
DNA in each nucleus has a length of 2m
RNA
acts as a temporary copy of a gene that is read by ribosomes to assemble the polypeptide
only single stranded
types = messenger, ribosomal, transfer
much shorter than DNA strands
contains ribose as opposed to deoxyribose
