Topic 2 Flashcards
Water is the biological medium here on Earth, and is the most abundant substance in living systems, making up ____ of the weight of most organisms.
70% or more
What are the four emergent properties of water?
- Cohesion and Adhesion of Water Molecules
- Moderation of Temperature by Water
- Evaporative Cooling of Water
- Water as the Solvent of Life
Water molecules stay close to each other as a result of ___ and these bonds that hold the water together, is a phenomenon called ____.
hydrogen bonding; cohesion
Cohesion contributes to the _____ in plants.
transport of water and dissolved nutrients against gravity
Combined with cohesion is adhesion
which is the ____.
clinging of one substance to another
This ____ helps counter the downward pull of gravity.
adhesion of water to cell walls by hydrogen bonds
Water moderates air temperature by _____.
absorbing heat from air that is warmer and releasing the stored heat to air that is cooler
It relates to which ___ in order to break hydrogen bonds; by the same token, heat is released when ___.
heat must be absorbed; hydrogen bonds are formed
As a liquid evaporates, the surface of the liquid that remains behind cools down. This
evaporative cooling occurs because ____.
the “hottest” molecules, those with the greatest kinetic energy, are the most likely to leave as a gas
It is a sphere of water molecules around each dissolved ion.
hydration shell
4 Biomolecules
- Nucleic Acids
- Proteins
- Lipids
- Carbohydrates
The monomers of nucleic acids are ___.
nucleotides
A nucleotide is composed of three parts: (3)
- a nitrogenous base,
- a five-carbon sugar
- one or more phosphate groups.
The portion of the nucleotide without any phosphate groups is called a ___.
nucleoside
There are two families of nitrogenous bases:
- Pyrimidine - 6 membered ring (cytosine, thymine, uracil)
- Purine -6 membered ring fused to a 5 membered ring (adenine, guanine)
The complementary base pairing states that ____, while ____.
adenine always pairs with thymine in DNA or uracil in RNA; guanine always pairs with cytosine
In terms of sugar, in DNA, it is called ____and RNA has the sugar, ____.
deoxyribose; ribose
The two sugar phosphate backbones run in arrangement called “______”.
antiparallel
Monomers of proteins.
Amino acids
Many proteins are roughly spherical (____), while others are shaped like long fibers (____).
globular proteins
fibrous proteins
Folding of proteins are done by ____ and when proteins are transferred from an aqueous environment to a non-polar solvent, it unravels and loses its native shape by a process called ____.
chaperonins; denaturation
It is a linked series of amino acids with a unique sequence. It is determined not by the random linking of amino acids, but by
inherited genetic information.
primary structure of proteins
This is collectively referred to as coils and folds, which are the result of hydrogen bonds between the repeating constituents of the polypeptide backbone.
secondary structure of proteins
It is a delicate coil held together by hydrogen bonding between every fourth amino acid.
a-helix
Two or more strands of the polyopeptide chain lying side by side (called b strands) are connected by hydrogen bonds between parts of the two parallel polypeptide backbones.
b pleated sheet
It is the overall shape of a polypeptide resulting from interactions between the side chains (R groups) of the various amino acids.
tertiary structure of proteins
caused by the exclusion of nonpolar substances by the water molecules.
hydrophobic interaction
___ are between polar side chains and ____ are between positively and negatively charged side chains.
hydrogen bonds; ionic bonds
These further reinforce the shape of a protein. They are formed when two cysteine monomers which have sulfhydryl groups (-SH) on their side chains are brought closer together by the folding of protein.
disulfide bridges
It is the overall protein structure that results from the aggregation of these polypeptide subunits, the a and b subunits.
quaternary structure of proteins
how do proteins act as enzymes?
selectively accelerate chemical reactions,
e.g. digestive enzymes on hydrolyzing bonds inn food molecules
how do proteins act as storage of amino acids?
e.g. ovalbumin, the protein of the egg white serve as storage of amino acid for the developing embryo.
how do proteins act as the coordinator of an organism’s activities?
e.g. insulin regulating blood sugar concentration
how do proteins act as motor proteins?
for movement
e.g. actin and myosin for the contraction of muscles
proteins as protection against diseases
e.g. antibodies inactivating bacteria and viruses
proteins as transporter of nutrients
e.g. hemoglobin transports oxygen
as one function of proteins, to which do they respond?
chemical stimuli
proteins as support
e.g. collagen and elastin providing a fibrous framework in connective tissues
___ are the one class of biomolecules that does not include true polymers, and they
are generally not big enough to be considered as macromolecules.
Lipids
why are lipids grouped together?
they mix poorly with water
3 types of lipids:
- fats
- phospholipids
- steroids
A fat is constructed from two kinds of smaller molecules:
glycerol and fatty acids
___ is an alcohol; each of its three carbons bear a hydroxyl group.
glycerol
A ___ has a long carbon skeleton, having a carbon at one end which is a part of the carboxyl group.
fatty acid
Fatty acids are hydrophobic (away from water) due to the ____.
nonpolar C-H bonds
In making a fat or triacylglycerol, ____ by an ester linkage, a bond between a hydroxyl group and carboxyl group.
three fatty acid molecules are each joined to glycerol
The major function of fats is ____.
energy storage
These are formed if there are no double bonds between carbon atoms composing a chain, then as many hydrogen atoms as possible are bonded to the carbon skeleton. They lack double bonds, and their flexibility allows the fat molecules to pack together tightly.
saturated FAs
It has one or more double bonds , with one fewer hydrogen atom on each double-bonded carbon. Its double bonds are cis which has kinks to prevent the molecules from packing together closely enough to solidify at room temperature.
unsaturated FA
they are essential on making up the cell membranes
phospholipids
A phospholipid is similar to a fat molecule but has only ___ fatty acids attached to glycerol rather than three.
two
The two ends of phospholipids show
different behavior toward water. The hydrocarbon tails are ____ while its hydrophilic head has ___.
hydrophobic; an affinity for water
When phospholipids are added to water, they self-assemble into double-layered structures called “___”, shielding their hydrophobic portions from water.
bilayers
These are lipids characterized by a carbon skeleton consisting of four fused rings.
steroids
____, a steroid, is a crucial molecule in animals since it is a component of animal cell membranes and is also the precursor from which other steroids are synthesized, such as the sex hormones.
cholesterol
The simplest carbohydrates are the _____; these are the monomers from which more complex carbohydrates are constructed.
monosaccharides, or simple sugars
____ are double sugars, consisting of two monosaccharides joined by a covalent bond.
disaccharides
Carbohydrates also include
macromolecules called ____, polymers composed of many sugar building blocks.
polysaccharides
____, the most common monosaccharide, is of central importance in the chemistry of life.
glucose (C6H12O6)
Monosaccharides are classified by the ____. (2)
- location of the carbonyl group (C=O)
- the size of the carbon skeleton.
___ consist of two monosaccharides joined by a glycosidic linkage, a covalent bond formed by a dehydration reaction.
disaccharides
___ are macromolecules, polymers with a few thousand monosaccharides joined by linkages.
polysaccharides