acid - A substance that increases the relative hydrogen ion concentration
in a solution by: yielding hydrogen ions when dissolved in water; accepting
hydroxide ions and thus increasing the relative hydrogen ion concentration.
adenine - A purine base, C 5H 5N 5, that is one of the building blocks of
DNA and RNA, and is involved in base pairing with thymine in DNA and with
uracil in RNA.
adult stem cells – Stem cells occurring in mature tissues, able to
self replicate but difficult to harvest in cultures.
amino acid - An organic molecule that is the main building block of proteins
and contains both carboxyl and amino groups.
aminoacyl- tRNA(A site) - The site in protein synthesis that holds the amino
acid about to be added to the chain and its carrier tRNA molecule.
aminoacyl- tRNA synthetase - An enzyme involved in protein synthesis that
is links tRNA to an mRNA codon with its corresponding amino acid.
anticodon- A sequence of three bases on a strand of tRNA that are meant
to bind to an mRNA codon.
blastocyst- An embryo made up of a ball of out cells called the trophoblast,
enclosing within it stem cells.
carboxyl group - A functional four atom COOH group, a carbon atom double
bonded to an oxygen and also bonded to a hydroxyl group. A carboxyl group
denotes an acid, due to the tendency of the H in the hydroxyl group to
dissociate from the O in water.
catalysts – Something that speeds up a chemical reaction. The most
common biological example is an enzyme.
cellulose - A polysaccharide produce by plants, of glucoses bonded together.
Used for structure purposes, and digestible by only a few organisms.
chitin - A polysaccharide used by anthropods to build exoskeletons, composed
mainly of an amino sugar found in many fungi.
chromosome - A long strand of DNA coiled with some additional protein molecules
found in the nucleus.
codon - A three base sequence in DNA that codes for one amino acid in a polypeptide
chain.
collagen and elastin– Proteins which compose fibrous framework in connective
tissues.
condensation reaction - A chemical reaction where two molecules become covalently
bonded through the loss of a small molecule, usually water. See dehydration
reaction.
corticosteroids(steroids) - A subclass of lipids, characterized by a carbon
skeleton of four fused rings, with various functional groups off to the
various sides.
Crick, Francis - One of the developers of the double helix theory for the
structure of DNA, who worked with James Watson.
cytosine - A pyrimidine base, C 4H 5N 3O, that is one of the building blocks
of DNA and RNA, and is involved in base pairing with guanine.
Dalton - The unit of atomic weight, protons and neutrons have a weight of
roughly 1 Dalton, electrons have a negligible weight.
dehydration reaction - A type of condensation reaction, where two monomers
are joined together with a covalent bond and an OH group is removed from
one monomer, an H from the other monomer, together forming water, H 2O.
deoxyribonucleic acid(DNA) - a helical nucleic acid that consists of two
long chains of nucleotides twisted together into a double helix. The two
chains are joined together by hydrogen bonding between the bases adenine
and thymine,
and the bases guanine and cytosine. It determines the inherited characteristics
of an organism.
differentiation – The process by which undifferentiated cells, usually
embryonic material, becomes specialized to carry out a specific function.
disaccharide - A combination of two monosaccharides; a double sugar formed
by dehydration synthesis of two monosaccharides.
DNA chain - a backbone of the pentose sugars and the phosphate
groups in DNA that helps hold together the nucleotides and nitrogenous
bases.
DNA ligase - An enzyme involved in DNA replication that joins Okazaki fragments
together.
DNA polymerase - An enzyme involved in DNA replication that catalyzes the
elongation of DNA at a replication fork. It achieves this by adding nucleotides
to the existing chain.
DNA template strand - The strand in RNA transcription which RNA Polymerase
copies.
double helix - The coiled, helical structure of DNA consisting of two separate
chains running in opposite directions linked by hydrogen bonds.
electronegativity - The pull an atom has on the electrons involved in its
covalent bonds.
ectoderm – Developed from the blastocyst, the layer of cells in an
embryo that becomes the outer nerves and skin.
endoderm – Developed from the blastocyst, the layer of cells in an
embryo that becomes the inner organs.
enzyme - Proteins that speed up a chemical reaction and allow it to occur
with less activation energy, while not being used up in the reaction; with
function depending on the structure of the enzyme.
eukaryote(eukaryotic cell) - A type of cell with a membrane-enclosed nucleus
and defined organelles; found in animals, fungi, plants, and protists.
exit site(E site) - The site in protein synthesis that the tRNA molecule
exits from.
exons - The expressed regions of RNA.
fat - A subclass of lipids, organic compounds composed of
glycerol, fatty acids and their functional groups.
fatty acid - A long carbon chain with a carboxyl group on the end. Each carbon
on the chain usually is covalently bonded to two carbons and two hydrogen
atoms, though some are double bonded to one carbon, and single bonded to
another carbon and a hydrogen. The end of the chain is a carbon bonded
to three hydrogen
atoms.
gametes - The cells in humans used to produce offspring
gene - A hereditary unit consisting of a specific nucleotide sequence in
DNA. Genes are also in RNA and may be found in viruses.
glycogen - The storage mechanism for glucose in animals, a polysaccharide
consisting of almost solely glucose.
glycosidic link - A link between two monosaccharides by way of a dehydration
reaction with a covalent bond.
guanine - A purine base, C 5H 5ON 5, that is one of the building blocks of
DNA and RNA, and is involved in base pairing with cytosine.
guanine cap - A modified guanine cap that is added to the 5' end of mRNA
to protect the mRNA from degradation; also signal the ribosome to attach
to the mRNA.
helicase - An enzyme involved in DNA replication that causes DNA to unwind
from its helical shape.
hematopoietic stem cells – Blood stem cells, found in bone marrow.
hemoglobin – A transporter protein on blood that enables it to carry
oxygen from the lungs to cells.
hydrogen bond - A bond in which the positively charged hydrogen atom in one
group or molecule is attracted to a negatively charged atom in the other
base, these charges often being the result of polar bonds.
hydroxyl group - A univalent OH group, an oxygen attached to a hydrogen with
a polar covalent bond; molecules possessing this function group are called
alcohols and are soluble in water.
initial transcript - In mRNA translation, the initial form
of the mRNA before it is modified into its final form.
Inosine - A base modified by an enzymatic alteration of adenine after the
tRNA is synthesized.
introns(intervening sequences) - The non-encoding regions of RNA
in vitro – Embryos produced through in vitro procedures are produced
in an artificial environment, such as that of a test tube.
keratin - A protein that makes up hair in humans and various other skin appendages
in other organisms.
lagging strand - The new strand of DNA synthesized in sections
(Okazaki fragments) each moving away from the replication fork.
large subunit - One of two subunits that make up ribosomes.
leading strand - The new strand of DNA synthesized along the template strand
in the 5’->3’ direction.
lipids - A class of complex macromolecules, hydrophobic, including fats,
waxes, phospholipids, corticosteroids, and pigments as its major subclasses.
lock and key hypothesis - The theory that the enzyme’s activation site
is definitively shaped to accommodate certain reactants to catalyze their
reactions.
macromolecules – A large molecule usually made up of smaller subunits
held together by some kind of chemical bond.
membrane - A bilayer of phospholipids that act as a thin container too cells
or organelles inside cells, being selectively permeable, allowing certain
atoms and molecules in yet not allowing others in.
Mesenchymal stem cells – Stem cells found in adult bone marrow, able
to produce bone, cartilage, muscle, and fat cells.
mesoderm – Developed from the blastocyst, the layer of cells in an
embryo that becomes the muscle and bones.
messenger RNA (mRNA) - RNA that directs the synthesis or a polypeptide chain,
a protein.
Micelle - A structure of phospholipids, where phospholipids arrange themselves
in a sphere, with the hydrophilic heads facing outward, and the hydrophobic
tails facing inward. Sometimes used to protect something on the inside
from water or from something else on the outside.
monomers - A subunit, used for construction of polymers; the smallest units
of a known physical class, ex: monosaccharide for a carbohydrate, amino
acid for a protein.
monosaccharides - Simple sugars; the basic unit of carbohydrates; a molecule
serving as the monomers of carbohydrates or disaccharides and polysaccharides
with a molecule formula often a multiple of CH 2O.
multipotent stem cell – One of the three types of stem cells, able
to only produce certain types of specialized cells.
nucleic acid(polynucleotide) - A polymer composed of carbohydrates, phosphoric
acid, and nucleotide monomers: purines and pyrimidines. The two types are
DNA and RNA, which determine protein structure.
nucleolus - A specialized structure in the nucleus, active in the synthesis
of ribosomes, where rRNA is synthesized.
nucleoside - The nitrogenous base and a pentose sugar together are called
a nucleoside
nucleoside monophosphate - see nucleotide
nucleotide - Consists of one organic nitrogenous base, one five-carbon (5-C)
sugar, and one phosphate group.
Okazaki fragments - Small fragments of DNA which form during
replication since DNA polymerase
must work backwards on some strands. The Okazaki fragments are joined together
by the enzyme DNA ligase.
organelles - One or several bodies with special functions inside the cytoplasm
of eukaryotic cells.
origin of replication - The point at which DNA replication begins. This is
a specific sequence of base pairs that DNA polymerase recognizes and latches
on to, sparking the chain of events that copies DNA.
peptide bond – The bond between two amino acid in a protein.
peptidyl-tRNA site(P site) - The site involved in protein synthesis that
holds the newly formed polypeptide chain attached to a tRNA molecule.
phosphate group - A functional five-atom group, PO 4, bonded with a phosphorous
in the center, and bonded to three oxygens with a single bond and one oxygen
with a double bond. Two of the single bonded oxygens usually have a negative
charge, making that section of the molecule polar/negative.
phospholipids - A subclass of lipids, composed of a glycerol, two fatty acids,
and a phosphate group; Used in cell and organelle membranes.
pluripotent stem cell – One of the three types of stem cells, also
able to produce every type of cell found in an organism, but unable to
make up a living organism.
polar - A compound or section of a compound where the electrons are not shared
equally in the covalent bonds due to one atom or another having greater
electronegativity then its neighbors.
poly(A) tail - A strand of RNA 30 to 200 nucleotides long added to the initial
transcript on the 3' end to help with degradation and ribosomal attachment,
and to help the mRNA pass through the nuclear membrane.
polymer - A large molecule built up of many smaller molecules called monomers,
which are usually similar, usually millions of Daltons.
polypeptide - A polymer, containing many molecules of amino acids, typically
between 10 and 100, linked together by peptide bonds.
polysaccharide - A polymer consisting of up to over a thousand monomers of
carbohydrates, monosaccharides. Formed by dehydration synthesis.
primary structure – A chain of amino acids held together by peptide
bonds, the basic structure of polypeptides and proteins.
primase - An enzyme involved in DNA replication that puts together a primer,
from which DNA polymerase starts strands of DNA.
primer - A segment of DNA or RNA, roughly 10 nucleotides long, that is complementary
to a given DNA sequence and that is needed to initiate replication by DNA
polymerase.
promoter region - The location on the DNA template strand where RNA polymerase
is going to attach itself.
proteins – Large macromolecules made up of polypeptide chains, ultimately
made up of amino acids.
purines - A double-ringed, crystalline organic base, C 5H 4N 4 , that, depending
on the positioning of the atoms and the addition of several atoms, forms
guanine or adenine.
pyrimidine - A single-ringed, crystalline organic base, C 4H 4N 2, that,
depending on the positioning of the atoms and the addition of several atoms,
forms uracil, cytosine, or thymine.
quaternary structure – Occurring when many tertiary structures combine.
This is the final protein structure.
reactants – Chemicals that participate in a reaction
to create a product.
replication fork - A Y-shaped point on a replicating DNA molecule where new
strands are growing.
ribonucleic acid(RNA) - A polymeric ingredient of all living cells and many
viruses, consisting of a long, usually single-stranded chain of with the
bases adenine, guanine, cytosine, and uracil bonded to alternating phosphate
and
ribose units. The structure and base sequence of RNA are determinants of
protein synthesis and the transmission of genetic information.
Ribosomal RNA(rRNA) - RNA that forms the structure of ribosomes along with
proteins; the most plentiful form of RNA in the body.
ribosomes - A cell organelle constructed in the nucleolus composed of RNA
and protein that is found in the cytoplasm of living cells and functions
as the site of assembly for polypeptides encoded by messenger RNA
ribozyme - An RNA molecule that acts as a catalyst
RNA Polymerase - An enzyme involved in RNA transcription that separates the
two RNA strands and attaches to the one it is going to copy.
RNA splicing - a process used to cut out the non-coding pieces of RNA and
piece back together the remaining expressed regions.
saturated fat - A fat in which there all of the fatty acid chains are fully
saturated, meaning there are no double bonds between carbons.
secondary structure – Occurring when the primary structure twists,
usually into a spiral shape.
small nuclear ribonucleoprotein(snRNP) - A combination of RNA and protein
that is used to recognize introns in RNA.
small nuclear RNA(snRNA) - The RNA present in snRNPs, roughly 150 nucleotides
long.
small subunit - One of two subunits that make up ribosomes.
soluble - Capable of being dissolved in water.
somatic - Any part of a multi-cellular organism except a sperm or egg.
specialized cell – A cell that possess specialized traits to carry
out specific functions within an organism, (example: nerve cell, blood
cell).
spliceosome - A combination of multiple snRNPs that is designed to cut at
the points on an RNA strand to release the introns and then recombine the
exons to make one continuous RNA strand.
starch - A polysaccharide composed solely of the monosaccharide glucose,
used as a storage mechanism in plants.
telomerase- An enzyme that speeds up the addition of telomeres to the ends
of DNA strands.
telomeres - A protective structure at each end of eukaryotic chromosomes,
the repetitive sequence of bases that codes for nothing in particular.
terminator region - A region on a DNA strand where RNA polymerase is told
to stop during RNA transcription.
tertiary structure – Occurring when the secondary structure folds back
onto itself, usually into a spherical shape.
thymine - A pyrimidine base, C 5H 6N 2O 2 , that is one of the building blocks
of DNA, and is involved in base pairing with adenine.
totipotent stem cell – One of the three types of stem cells, able to
produce every type of cell found in an organism to produce a whole organism.
transcription - The synthesis of RNA from a DNA template resulting in the
transfer of information from DNA to the transfer RNA.
transcription factor - A collection of proteins involved in RNA transcription
that find the location on a DNA template where RNA polymerase is going
to attach itself.
transcription initiation complex - The beginning of the first stage of RNA
transcription, initiation; a complex consisting of RNA polymerase and a
collection of proteins called transcription factors.
transcription unit - A section of DNA from which an RNA strand is synthesized
in transcription.
transfer RNA(tRNA) - A type of RNA used in protein synthesis that is used
to transfer amino acids from there storage place in the cytoplasm to the
ribosome.
translation - The process in which mRNA directs the construction of a polypeptide
from amino acids using the genetic information encoded in the mRNA molecule.
triplet code - A set of three nucleotides that codes for the synthesis of
a specific amino acid in a polypeptide chain.
undifferentiated cell – A cell that has no special
function, forming a specialized cell later through development.
unsaturated fat - A fat in which in one of three fatty acid chains, there
is at least one double bond between two carbons.
uracil - A pyrimidine base, C 4H 4N 2O 2 , that is one of the building blocks
or RNA, and is involved in base pairing with adenine.
valence - A property of atoms, stating how many covalent bonds are needed
for the atom to fill its final energy shell, its valence shell; the number
of covalent bonds an atom can have.
Watson, James - One of the developers of the double helix theory for the
structure of DNA, who worked with Francis Crick
wobble - The exception to the base-pairing rule, where Inosine can bond with
uracil, cytosine, or adenine.