Genetics Chapter 6 Vocab

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C-value paradox

Back 1

among eukaryotes, there is no consistent relationship between the dna content of the haploid genome and the metabolic developmental, or behavioral complexity of the organism

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purines

Back 2

double ring structured bases (Adenine and Guanine)

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pyrimidines

Back 3

single ring-ring structures bases (Thymine and Cytosine)

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nucleoside

Back 4

a base chemically linked to one molecule of sugar deoxydribose

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nucleotide

Back 5

phosphate group attached to a sugar molecule attached to the base

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polynucleotide chain

Back 6

phosphate attached to the 5' carbon of one sugar linked to the hydroxyl group attached to the 3' carbon of the next sugar in line (ncleotides joined together)

Front 7

phosphodiester bonds

Back 7

chemical bonds that bond the sugar components of the adjacent nucleotides that are linked through the phosphate groups

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5' end

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the end that terminates in a phosphate

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3' end

Back 9

the end that terminates in a hydroxyl

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hydrogen bond

Back 10

a weak bond in which two negatively charged atoms share a hydrogen atom

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antiparallel

Back 11

the orientation of the two strands of double stranded nucleic acid molecules;; (the 5' to 3' orientation)

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daughter strand

Back 12

the newly replicated complimentrary strand

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parental strand

Back 13

the strand being replicated

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template

Back 14

a strand of nucleic acid whose base sequence is copied in a polymerization reaction to produce either a complementrary DNA or an RNA strand

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semiconservative replication

Back 15

the usual form of replication in which one strand of dna serves as a template for another

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Mathew Meselson and Franklin Stahl in 1958

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the expiriment that showed DNA replication was semiconservative by using bacteria in a heavy N-containing medium and replicating their DNA several generations.

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theta replication

Back 17

bidirectional replicaion of a circular dna molecule, starting from a single origin of replication

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replication origin

Back 18

the position long a molecule at which DNA replication begins

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replication fork

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the region on dna molecule where the parental strands are separating and new strands are being sythesized

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initiation

Back 20

the process of generaing a new replication fork

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rolling-circle replication

Back 21

a mode of replication in which a circular parent molecule produces a linear branch of newly formed dna

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helicase

Back 22

protein that hydrolyzes ATP to drive the unwinding reaction

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single stranded DNA binding protein (SSB)

Back 23

binds single-stranded DNA tightly and cooperatively and it has an affinity for single stranded DNA at least 1000-fold greater than that for double stranded DNA

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gyrase

Back 24

a type of topoisomerase II that cleaves and rejoins both strands of a DNA duplex to relieve torsional stress

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ribose

Back 25

identical to deoxyribose of DNA except for the presence of an -OH group on the 2' carbon atom

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RNA polymerase

Back 26

An enzyme that makes RNA by copying the base sequence of a DNA strand

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primer

Back 27

in nucleic acids, a short RNA or single-stranded DNA segment that functions as a growing point in polymerization

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primosome

Back 28

the enzyme complex that forms the RNA primer for DNA replication. Multienzyme complex composed of 15 to 20 polypeptide chains

Front 29

DNA polymerase

Back 29

the enzyme that forms the sugar-phosphate bond between adjacent nucleotides in a new DNA acid chain.

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editing function or proofreading function

Back 30

The activity of DNA polymerases that removes incorrectly incorporated nucleotides

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precursor fragments (okazaki fragment)

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any of the short strands of DNA produced during discontinuous replication of the lagging strand

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leading strand

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DNA strand whose complement is synthesized as a continuous unit

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lagging strand

Back 33

the DNA strand whose complement is synthesized in short fragments that are ultimately joined together

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DNA ligase

Back 34

an enzyme that catalyzes formation of a covalent bond between adjacent 5' P and 3' OH termini in broken polynucleotide strand of double-stranded DNA

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Denaturation

Back 35

Separation of DNA strands (i.e. heating them up)

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Renaturation

Back 36

DNA strands coming together (i.e. when the heat is lowered in a solution)

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3 uses and methods of Denaturation and renaturation

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1. Small DNA fragment mixed with larger DNA fragments, which can help identify specific DNA fragments in a complex mixture.
2. DNA fragment of one gene can be renatured with other genes of the same genome; is used to identify genes that are smaller, but not identical in sequence and have related functions.
3. DNA fragment from one species can be renatured with sequences of other species. This allows the isolation of genes that have the same or related functions in multiple species and can be used to study molecular evolution.

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Nucleic acid hybridization

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The process of renaturing DNA strands from two different sources

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probe

Back 39

a radioactive DNA and RNA molecule used in DNA-RNA and DNA-DNA hybridization assays

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restriction enzymes

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Also called restriction endonucleases, are able to cleave DNA molecules at the poistions at which particular, short sequences of bases are present.

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restriction site

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the sequence recognized for cleavage by a restriction enzyme

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restriction fragment

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The fragments formed when a large DNA molecule is cut into many restriction fragments of different sizes.

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restriction map

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A diagram of a DNA molecule showing the positions of cleavage by one or more restriction endonucleases

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Southern Blot

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a nucleic acid hybridization method in which, from a gel to a membrane filter and then exposed to radioctive regions locate the homologous DNA fragments on the filter.

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Polymerase chain reaction (PCR)

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repeaated cycles of DNA denaturation, renaturation with primer oligonucleotide sequences, and replication, resulting in exponential growth in the number of copies of the DNA sequence located between the primers.

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dideoxy sequencing method

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procedure for DNA sequencing in which a template strand is replicated from a particular primer sequence and terminated by the incorporation of a nucleotide that contains dideoxyribose instead of deoxyribose; the resulting fragments are separated by size via eletrophoresis.

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dideoxyribose

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a deoxyribose sugar that lacks the 3' hydroxyl group; when incorporated into a polynucleotide chain, it blocks further chain elongation.

Front 48

Exonuclease activity

Back 48

The ability to break phosphodiester bonds in the sugar-phophate backbones of nucleic acid chains

Front 49

cohesive ends

Back 49

single-stranded regions at the ends of otherwise double-stranded DNA molecules that are complementary in base sequence

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blunt ends

Back 50

ends of a DNA molecule in which all terminal bases are paired; the term usually referes to termini formed by a restriction enzyme that does not produce single-stranded ends.