Chapter 08.2: Transcription: Rna Polymerase Synthesizes A Single-Stranded Rna Copy Of A Gene

Front 1

promoter

Back 1

DNA sequences near the beginning of genes that signal RNA polymerase where to begin transcription

Front 2

transcription bubble

Back 2

the region of DNA unwound by RNA polymerase

Front 3

terminators

Back 3

sequences in the RNA products that tell RNA polymerase where to stop transcription

Front 4

downstream

Back 4

the direction traveled by RNA polymerase as it moves from the promoter to the terminator

Front 5

upstream

Back 5

movement opposite the direction RNA follows when moving along a gene

Front 6

hairpin loops

Back 6

structures formed when a single strand of DNA or RNA can fold back on itself because of complementary base pairing between different regions in the same molecule

Front 7

RNA polymerase

Back 7

enzymes that transcribe a DNA sequence into an RNA transcript.

Eukaryotes have three types of RNA polymarases called pol I, pol II, pol III that are responsible for transcribing different classes of genes

Front 8

reverse transcriptase

Back 8

an RNA-dependent DNA polymerase that synthesizes DNA strands complementary to an RNA template. The product of reverse transcriptase is a cDNA molecule.

Front 9

primary transcript

Back 9

the single strand of RNA resulting from transcription

Front 10

methylated cap

Back 10

formed by the action of capping enzyme and methyl transferases at the 5' end of eukaryotic mRNA, critical for efficient translation of the mRNA into protein

Front 11

poly-A tail

Back 11

the 3' end of eukaryotic mRNA consisting of 100-200 As, believed to stabilize the mRNA and increase the efficiency of the initial steps of translation.

Front 12

exon

Back 12

sequences that are found both in a gene's DNA and in the corresponding mature messenger RNA

Front 13

intron

Back 13

the DNA base sequences of a gene that are spliced out of the primary transcript and are therefore not found in the mature mRNA

Front 14

RNA splicing

Back 14

a process that deletes introns and joins together adjacent exons to form a mature mRNA consisting of only exons

Front 15

splice donor

Back 15

nucleotide sequences in a primary transcript at the border between an intron and the upstream exon that precedes it; required for proper RNA splicing

Front 16

splice acceptor

Back 16

nucleotide sequences in a primary transcript at the border between an intron and the downstream exon that follows it; required for proper RNA splicing

Front 17

branch site

Back 17

special sequence of RNA nucleotideswithin an intron that helps form the "lariat" intermediate required for RNA splicing

Front 18

spliceosome

Back 18

a complicated intranuclear machine that ensures that all of the splicing reactions take place in concert

Front 19

ribozyme

Back 19

RNA molecules that can act as enzymes to catalyze specific chemical reactions

Front 20

alternative splicing

Back 20

production of different mature mRNAs from the same primary transcript by joining different combinations of exons

Front 21

trans-splicing

Back 21

a rare type of RNA splicing that joins together exons of the primary transcripts of two different genes