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AP Biology
Chater 13- DNA structure and function
28
Biology
12th Grade
05/02/2011

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Term
Bacteriophages
Definition
a type of virus, mostly of which consist only of DNA and a coat (nomally made of protein.)
Term
Francis Crick and James Watson
Definition
two scientists who built the first successful model of the structure of a DNA molecule
Term
nucleotide
Definition
(in DNA) has a five-carbon sugar, a phosphate group, and either an adenine, guanine, thymine, or cytoine base.
Term
x-ray diffraction images
Definition
images that form after a beam of light from x-rays directed at a DNA molecule, an is used to calculate the positions of the molecule's atoms
Term
patterns of base pairing
Definition
DNA must consist of two strands of nucleotides, held together at their bases by hydrogen bonds. These bonds form when the two strands run in opposite directions, and twist to form a double helix. (Base pairs are A-T or G-C)
Term
DNA replication
Definition
how the molecule is duplicated before a cell divides. (This takes place in interphase of the cell cycle.) Enzymes break down the hydrogen bonds between the DNA strands, and one strand unwinds and its nucleotide bases stretch. Cells contain stockpiles of free bases to pair up with the now exposed bases. These new companion strands now twist together in a double helix.
Term
helicase
Definition
enzymes that "unzip" the weak hydrogen bonds.
Term
DNA poymerases
Definition
enzymes that catalyze the formation of two brand-new strands of DNA from free nucleotides. They also catalyze the hydrogen bonding of each new strand to the unwound region of one of the two parent DNA strands. (They can assemble new strands only in the 5'-3' direction.)
Term
DNA ligase
Definition
enzyme that seals together the short stretches of new nucleotides and breaks in a strand.
Term
DNA proofreading mechanisms
Definition
fix most errors in replication and most of the strand breaks, and can reverse catalytic additions by one base and correct a mismatch.
Term
repair enzymes
Definition
specialized sets of enzymes that can repair some changes. They recognize and snip out damaged sites or mismatches.
Term
embryo cloning
Definition
occurs constantly in nature; DNA is inherited from two parents, but are chosen for particularly valued traits that will benefit the production of the animal
Term
sexual reproduction process
Definition
maternal (from mother) and paternal (from father) DNA combine to fertilize egg, which leads to early embryo, and eventually an individual with a mix of parental traits.
Term
"wet" form of DNA
Definition
the DNA form that occurs in cells and maes it easier to see the image clearly, discovered by Rosalind Franklin
Term
Base pairing constancy
Definition
The constancy in DNA's bonding patterns AND the variation in base sequences is the basis for life's unity. Most patterns are unique for each species and vary among individuals of a species.
Term
nanometer
Definition
diameter overall; distance between each DNA base pairs
Term
nuclear transfer
Definition
another process of cloning: the nucleus of an unfertilized egg is replaced with one from a differentiated cell of an adult animal. If successful, clusters of embryonic cells form and can be implantd inside a surrogate mother.
Term
components of nucleotide monomers
Definition
(of DNA) have a 5 carbon sugar, a phosphate group, and one of four kinds of nitrogen-containing bases, (A,T,G, or C)
Term
DNA molecule
Definition
consists of two nucleotide strands coiled together into a double helix. The bases of one strand hydrogen-bonds with the base of the other. These bases pair together according to the following rule: A-T and G-C
Term
cloning
Definition
the process of copying DNA fragments in an object (embryo cloning, adult cloning, therapeutic cloning.)
Term
Rosalind Franklin
Definition
a woman scientist who deveoped a refined x-ray diffraction method, and built 3 dimensional models showing the structure of a DNA strand, (which was later "stolen" and used by Watson and Crick.)
Term
four bases
Definition
(A-T and G-C. Overall all 4 have the same bonding pattern.)Thmine and cytosine are pyrimidines, meaning they have a carbon backbone and nitrogen that forms into a single ring. Adenine and Guanine are purines, meaning they are larger and bulkier molecules, and have two rings.
Term
adenine
Definition
pairs with thymine. is a base with a double-ring structure that also contains a deoxyribose (sugar.)
Term
thymine
Definition
pairs with adenine. is a base with a single-ring structure
Term
cytosine
Definition
pairs with guanine. is a base with a single-ring structure
Term
guanine
Definition
pairs with cytosine. a base with a double-ring structure
Term
Dolly the sheep
Definition
the first ever cloned animal that marked an era of revolutionary ideas. Developed in Scotland in 1997 by a geneticist named Ian Wilmut.
Term
telomeres
Definition
(Found in animals,) they are short segments that cap the ends of chromosomes and stabilize them. They become shorte as an animal ages.
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