Chapter 14: DNA The Genetic Material Flashcards Preview

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Flashcards in Chapter 14: DNA The Genetic Material Deck (32):
1

DNA

Deoxyribonucleic acid. A molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses. Contains 5-carbon sugar, phosphate group, and nitrogen-containing base (purine or pyrimadine)

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pyrimidine

Produces RNA and DNA, proteins and starches, the regulation of enzymes and cell signaling.

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purine

Produces of RNA and DNA, proteins and starches, the regulation of enzymes and cell signaling.

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thymine dimer

UV light causes a covalent bond to form between adjacent thymine bases on the same strand, in the next round of replication will often cause incorrect base to be substituted in the new strand

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thymine

a pyrimidine base, C 5 H 6 N 2 O 2, that is one of the principal components of DNA, in which it is paired with adenine.

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base-pair

Two chemical bases bonded to one another forming a "rung of the DNA ladder." The DNA molecule consists of two strands that wind around each other like a twisted ladder. Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups.

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origins of replication

A particular sequence in a genome at which replication is initiated. This can either involve the replication of DNA in living organisms such as prokaryotes and eukaryotes, or that of DNA or RNA in viruses, such as double-stranded RNA viruses.

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topoisomerase

Enzyme that cuts and rejoins helix to prevent tangling.

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DNA ligase

An enzyme that eventually joins the sugar-phosphate backbones of the Okazaki fragments.

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replisome

Macromolecular assembly formed by enzymes involved in DNA replication; two main subcomponents: primosome (primase and helicase) and a complex of DNA Pol III enzymes.

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phosphate group

A functional group or radical comprised of phosphorus attached to four oxygen, and with a net negative charge, thus represented as PO4.

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adenine

One of the two purine nucleobases (the other being guanine) used in forming nucleotides of the nucleic acids. In DNA, adenine binds to thymine via two hydrogen bonds to assist in stabilizing the nucleic acid structures. In RNA, which is used for protein synthesis, adenine binds to uracil.

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uracil genetics

One of four chemical bases that are part of RNA. The other three bases are adenine (A), cytosine (C), and guanine (G). In DNA, the base thymine (T) is used in place of uracil.

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antiparallel

A single strand of DNA has an inherent polarity. 5' and 3' ends.

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DNA pol I

Acts on the lagging strand to remove primers and replace them with DNA

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DNA pol III

Main replication enzyme; it is responsible for the bulk of DNA synthesis

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primase

An enzyme involved in the replication of DNA. DNA primase is a type of RNA polymerase which creates a RNA primer (later this RNA piece is removed by a 5' to 3' exonuclease); next, DNA polymerase uses the RNA primer to replicate ssDNA.

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leading strand

Strand of DNA that is synthesized continuously.

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telomeres

Structures at the ends of eukaryotic chromosomes protecting the ends of chromosomes from nucleases and maintain the integrity of linear chromosomes; composed of specific DNA sequences.

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nitrogenous base

Main function of a nitrogenous base is to bond nucleic acids together. A nitrogenous, or nitrogen-containing, base is an organic molecule with a nitrogen atom that has the chemical properties of a base. A nitrogenous base owes its basic properties to the lone pair of electrons of a nitrogen atom.

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guanine

One of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine.

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phosphodiester bond

The type of bond that links the nucleotides in DNA or RNA. joins the phosphate group of one nucleotide to the hydroxyl group on the sugar of another nucleotide.

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semiconservative model

Model of DNA replication. When a doule helix replicates, each of two daughter molecules will have one old and one new strand.

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DNA gyrase

Topoisomerase involved in DNA replication.

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lagging strand

A discontinuously synthesized DNA strand that elongates in a direction away from the replication fork.

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telomerase

Uses internal RNA as a template and not the DNA itself; allows short stretches of DNA to be synthesized.

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cytosine

Cytosine is one of the four main bases found in DNA and RNA, along with adenine, guanine, and thymine.

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Chargaff's rule

The nucleotides C to G and A to T ratios were the same in all organisms.

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DNA polymerase

Add new bases to the 3' end of existing strands, extending in the 5' to 3' direction; DNA polymerase require a primer to begin synthesis; they cannot begin without a strand of RNA or DNA base-paired to the template (RNA polymerases do not have this requirement, so they usually synthesize the primers.

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helicase

Enzyme that uses energy from ATP to unwind the DNA template (strands are unstable because their hydrophobic bases are exposed to water).

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single strand binding protein (SSB)

A protein that coats exposed single strands in order to remain stable

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Okazaki fragments

Short fragments of DNA that are a result of the synthesis of the lagging strand during DNA replication.