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46 Cards in this Set

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genetic transformation
DNA is required to do this
Griffith
studied genetic transformation; studied pneumococcus in mice; some “transforming principle” from the heat-killed S strain changed the R strain to make it deadly
Avery and colleagues
identified DNA as the “transforming principle” of Griffith's experiment
Hershey-Chase
concluded that phage injected DNA into bacteria to infect them
bacteriophages or phages
viruses that infect bacteria; viruses execute a “genetic takeover” of cells
purines
the bases adenine and guanine
pyrimidines
bases cytosine and thymine
phosphodiester linkage
link nucleotides together 3' to 5'
Chargaff and colleagues
found any one organism they tested had amounts of A ≈ T and C ≈ G
Rosalind Franklin and Maurice Wilkins
x-ray diffraction studies indicated a helical molecule
(double helix)
complementary
the sequence of one strant of DNA had to have an appropriate, complementary sequence on the other for the molecule to hold together
James Watson and Francis Crick
the accepted model for the structure of the DNA double helix was published by them
semiconservative replication
the model suggested that each strand could serve as a template for making a complementary strand; one strand old, one strand new
replication bubble
synthesis generally proceeds in both directions from an origin creating this
replication forks
both strands are replicated at the same time on both sides of the replication bubble, producing these Y-shaped things on both sides; they move as synthesis proceeds
DNA helicase
does the unwinding and opening of DNA
single-strand DNA binding proteins
keep the 2 strands open after the DNA helicase unwinds them
topoisomerases
break and rejoin strands, resolving knots and strains that occur
DNA polymerases
direct synthesis of new strands; synthesis can only proceed in the 5’ à 3’ direction
primase
starts the strand by making an RNA primer
the leading strand
has its 3’ end at the fork; thus, its synthesis can proceed continuously, in the direction that the fork moves
lagging strand
has its 5’ end at the fork; it must be synthesized in the “opposite direction” from the leading strand
Okazaki fragments
the lagging strand makes these when it synthesizes away from the replication fork
DNA ligase
joins the Okazaki fragments
telomeres
the ends of chromosomes
telomerase enzymes
can generate longer telomeres
nucleosomes
the main packaging mechanism for eukaryotic DNA
histones
the proteins of DNA; positively charged, and thus able to associate with the negatively charged phosphates of the DNA backbone
“linker DNA” regions
parts of the continuous DNA molecule that are not wound on histones; nucleosomes are linked together by these
H1 - histone
associates with the linker DNA regions; binding leads to packing of nucleosomes into a chromatin fiber that is 30nm wide
scaffolding proteins
fibers produced by H1 form loops that are often held together by these non-histone things
Beadle and Tatum
developed the “one gene, one enzyme” hypothesis; found mutant genes in the fungus Neurospora that each affected a single step in a metabolic pathway
Pauling
“one gene, one polypeptide” hypothesis
RNA (ribonucleic acid)
serves mainly as an intermediary between the information in DNA and the realization of that information in proteins; single-stranded
ribose
sugar
uracil(U)
functions in place of T in an RNA strand
mRNA
messenger RNA: copies the actual instructions from the gene
tRNA
transfer RNA: links with amino acids and bring them to the appropriate sites for incorporation in proteins
rRNA
ribosomal RNA: main structural and catalytic components of ribosomes, where proteins are actually produced
Central Dogma of Gene Expression
DNA to RNA to protein
transcription
making RNA using directions from a DNA template; transcribe = copy in the same language
translation
making a polypeptide chain using directions in mRNA; translate = copy into a different language; here the translation is from base sequence to amino acid sequence
RNA polymerases
RNA polymerase I is used in making rRNA; RNA polymerase II is used in making mRNA and some small RNA molecules; RNA polymerase III is used in making tRNA and some small RNA molecules
template strand
the DNA strand that is read during transcription
upstream
toward the 5’ end of the RNA strand, or toward the 3’ end of the template strand
downstream
toward the 3’ end of the RNA strand, or toward the 5’ end of the template strand