Ch. 17 Terms

Front 1

promoter

Back 1

site where RNA polymerase initially binds to DNA

Front 2

initiation

Back 2

first stage of transcription; requires a promoter

Front 3

transcription factors

Back 3

bind to the promoter during transcription; these proteins facilitate binding of RNA polymerase to the site

Front 4

transcription initiation complex

Back 4

completed assembly of transcription factors and RNA polymerase at the promoter region

Front 5

elongation

Back 5

RNA polymerase continues building the RNA strand ; the newly synthesized RNA strand easily separates from the DNA and the DNA molecule “zips up” behind RNA polymerase, reforming the double helix

Front 6

termination

Back 6

the end of RNA transcription

Front 7

codons

Back 7

sequences of three bases that instruct for the addition of a particular amino acid (or a stop) to a polypeptide chain;

Front 8

triplet code

Back 8

a 3-base code

Front 9

stop codons

Back 9

do not code for an amino acid but instead will end the protein chain

Front 10

coding region

Back 10

codes for protein synthesis

Front 11

leader sequence

Back 11

the mRNA strand prior to the start codon is called the 5’ untranslated region or this

Front 12

trailing sequence

Back 12

the mRNA strand after the stop codon is called the 3’ untranslated region or this

Front 13

Translation

Back 13

using information in mRNA to direct protein synthesis

Front 14

ribozyme

Back 14

catalyzes peptide bond formation

Front 15

anticodon

Back 15

each tRNA has this region that will form a proper complementary basepairing with a codon on an mRNA molecule

Front 16

aminoacyl-tRNA synthetases

Back 16

tRNA is linked to the appropriate amino acid by enzymes called these; the result is aminoacyl-tRNA.

Front 17

E site

Back 17

where uncharged tRNA molecules are moved and then released

Front 18

P site

Back 18

where the completed part of the polypeptide chain will be attached to tRNA

Front 19

A site

Back 19

where the new amino acid will enter on an aminoacyl-tRNA as a polypeptide is made

Front 20

initiation of translation

Back 20

start of polypeptide production

Front 21

initiator tRNA

Back 21

recognizes the codon AUG, which is the initiation start codon

Front 22

ribosome recognition sequence

Back 22

where small ribosomal subunit binds to an mRNA in a prokaryote

Front 23

initiation factors

Back 23

proteins that help the small subunit bind to the initiator tRNA and mRNA

Front 24

elongation in translation

Back 24

the addition of amino acids to the growing polypeptide chain

Front 25

elongation factors

Back 25

assist in getting the charged tRNA to bind

Front 26

translocation

Back 26

takes place after elongation in translation; moving amino acids and nucleotides from the A site to the P site to the E site.

Front 27

termination in translation

Back 27

last step of translation where a stop codon signals the end for translation

Front 28

termination factor

Back 28

the termination factor causes everything to dissociate, freeing the polypeptide, mRNA, last tRNA, and ribosomal subunits all from each other

Front 29

polyribosomes

Back 29

as many as 20 ribosomes may be synthesizing protein from the same message - these are called what?

Front 30

5’ cap

Back 30

required for binding to eukaryotic ribosomes; makes eukaryotic mRNAs less susceptible to degradation and to promote the transport of the mRNA out of the nucleus

Front 31

polyadenylation

Back 31

the 3’ tail in RNA

Front 32

polyadenylation signal

Back 32

signals for the addition of a “tail” on the 3’ end of the mRNA

Front 33

poly-A tail

Back 33

the mRNA tail is a series of adenines called this

Front 34

introns

Back 34

stretches of bases that “interrupt” the sequence and must be removed

Front 35

exons

Back 35

regions that will not be removed from the sequence because they do not "interrupt" it

Front 36

RNA splicing

Back 36

the process of removing introns

Front 37

snRNPs

Back 37

made of small RNA molecules and proteins; associate with the mRNA in a complex called the spliceosome

Front 38

spliceosome

Back 38

catalyzes cutting out and removing an intron and joining together the exons

Front 39

alternative RNA splicing

Back 39

allows one DNA sequence to direct synthesis of two or more different polypeptides

Front 40

domain

Back 40

a region within the protein that has a specific function

Front 41

exon shuffling

Back 41

proteins consist of such functional domains which can be readily shuffled around during evolution to produce new proteins with novel catalytic functions

Front 42

Mutations

Back 42

changes in the DNA sequence

Front 43

mutagens

Back 43

DNA-damage inducers

Front 44

carcinogens

Back 44

mutagens that increase the likelihood of cancer

Front 45

mutational hot spots

Back 45

DNA regions that are more prone to mutations

Front 46

point mutations

Back 46

base substitution mutations; mutations that result in the substitution of one base for another

Front 47

silent mutation

Back 47

if the point mutation does not actually cause a change in what amino acid is coded for, it is called this

Front 48

missense mutation

Back 48

if the point mutation causes a change in what amino acid is coded for, it is called this

Front 49

nonsense mutation

Back 49

if the point mutation results in the formation of a stop codon where an amino previously was coded for, it is called this

Front 50

transposon

Back 50

some mutations are caused by pieces of DNA that can jump around the genome; such jumping DNA is called this.

Front 51

constitutive genes (housekeeping genes)

Back 51

genes that are constantly transcribed, with little or no regulation

Front 52

repressors

Back 52

transcription factors that suppress or stop gene expression

Front 53

activators

Back 53

transcription factors that either activate ( “turn on”) gene expression, or to enhance gene expression

Front 54

enhancers

Back 54

DNA regions, often far from the promoter, where activators will bind either directly or indirectly