Sickle Cell DNA


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Glossary

Allele - one member of a pair of genes that is located at a specific point on a particular chromosome.

Alpha Chain - one quarter of a hemoglobin molecule. There are two alpha chains and two beta chains in each molecule.

Alpha Helices - when proteins fold, an alpha helix is a secondary structural unit. One of the hallmarks of an alpha helix is bonding between amino acids that are in units of four along the chain.

Amino Acids - the building blocks of proteins. Proteins are composed of chains of amino acids that occur in a very specific order.

Amniocentesis - the sampling of amniotic fluid using a needle inserted into the uterus, which is used to withdraw amniotic fluid. The fluid is then used to screen for developmental abnormalities in a fetus.

Beta Chains - one quarter of a hemoglobin molecule. There are two alpha chains and two beta chains in each molecule.

Beta Sheets - A secondary structure that occurs in many proteins and consists of two or more parallel adjacent polypeptide chains arranged in such a way that hydrogen bonds can form between the chains. In an alpha helix the amino acids form a coil, but in beta sheets the amino acids are arranged in a zigzag pattern that forms a straight chain.

Carrier - a person or organism which carries an allele without exhibiting its effects. Such an allele is usually recessive, but it may also be dominant and latent.

Charge-to-charge interactions - One of the amino acid interactions that causes proteins to fold. A charge-to-charge interaction, also known as a salt bridge, is easy to understand. The positive charge of one amino acid is attracted to the negative charge of another.

Chemical Engineer - applies and uses principles of chemical engineering in 1) design, manufacture, and operations in industrial chemical and related processes 2) development of new or adapted substances for products ranging from foods, cleaners, pharmaceutical ingredients, and many other products; 3) development of new technologies such as fuel cells, clean energy and nanotechnology, as well as materials science, polymer engineering, and biomedical engineering.

Chorionic Villi Testing - a prenatal test that can detect genetic and chromosomal abnormalities of an unborn baby. The chorionic membrane is the outer sac which surrounds the developing fetus. Chorionic villi are microscopic, finger-like projections that emerge from the chorionic membrane and eventually form the placenta.

Dimers - a molecule or molecular complex consisting of two identical molecules linked together. Example: when the hemoglobin molecule falls apart, it typically splits into two sections, each with an alpha and a beta chain. The alpha and beta chain half would be known as a dimer.

Disulfide Bridges - One of the amino acid interactions that causes proteins to fold. Some amino acids can form a strong covalent bond joining their sulfur atoms, which is known as a disulfide bridge.

DNA - deoxyribonucleic acid. It is the genetic code that is passed from parents to children.

Family History - part of a patient's medical history in which questions are asked in an attempt to find out whether the patient has hereditary disease.

Genetic Counselor - a licensed medical professional who offers guidance for prospective parents on the likelihood of genetic disorders in their future children and what can be done to ameliorate or prevent the situation.

Genetic disease - a disease that can be passed from generation to generation due to a mutation in the chromosomes.

Genogram - a pictorial display of a person's family relationships and medical history. It goes beyond a traditional family tree by allowing the user to visualize hereditary patterns and psychological factors. It can be used to identify repetitive patterns of behavior and to recognize hereditary tendencies.

Hairpin Loops - when two regions of the same strand of bases, usually nucleotide sequences that are the same when read in opposite directions, base-pair to form a double helix that ends in an unpaired loop. The resulting loop is a common secondary structure in proteins.

Hemoglobin - a red protein responsible for transporting various respiratory gasses through the blood stream.

Hydrogen Bonds - one of the amino acid interactions that causes proteins to fold. A hydrogen bond is formed when a hydrogen atom links two atoms in the amino acid chain, usually oxygen or nitrogen.

Hydrophobic Collapse - a step in the way a protein folds in which two hydrophobic regions pull together in the middle of a protein molecule.

Hydrophobic Interations - One of the amino acid interactions that causes proteins to fold. Some amino acids that contain “oily” groups like the benzene ring of phenylalanine and the double ring of tryptophan. Just like oil separates from water, these groups tend to fold to the interior of a protein, away from water.

Mutation - a change in the structure of a gene that can then be passed on to subsequent generations.

Nanotechnology - the manipulation of materials, devices and other structures on an atomic and molecular scale with at least one dimension sized from 1 to 100 nanometres.

Nucleic acid - One of a family of large molecules which includes deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

Nucleotides - A compound consisting of a nucleoside linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA.

Protein - A large molecule composed of one or more chains of amino acids in a specific order which is determined by the genetic code.

Punnett squares – a diagram that is used to predict an outcome of a particular cross or breeding experiment

Recessive - heritable characteristics controlled by genes that are expressed in offspring only when inherited from both parents. Recessive alleles produce little or no noticable effect when they are paired with a dominant allele from the other parent.

Salt Bridges - One of the amino acid interactions that causes proteins to fold. A salt bridge, also known as a charge-to-charge interaction, is easy to understand. The positive charge of one amino acid is attracted to the negative charge of another.

Sickle Cell Anemia - a hereditary form of anemia in which a mutated form of hemoglobin distorts the red blood cells into a crescent shape.

Triplet - three rungs of the DNA ladder that code for a specific amino acid in a protein chain.