Chapter 17 Biology

Front 1

Gene Expression

Back 1

overall process by which DNA directs protein synthesis
(2 steps -- transcription and translation)

Front 2

Transcription

Back 2

RNA copy made from DNA template

Front 3

Translation

Back 3

protein synthesized from RNA template

Front 4

Genetic information in all cells flows from:

Back 4

DNA --> RNA --> protein

Front 5

Triplet Code

Back 5

a series of nonoverlapping, three nucleotide words. (ex. ATG CCG TAC AGC TTA)
*these triplets code for all the amino acids

Front 6

DNA to RNA

Back 6

*during transcription, the template strand provides the information for ordering the sequence of nucleotides in an RNA transcript
*mRNA transcript built 5' to 3'

Front 7

RNA to protein

Back 7

*during translation, the mRNA base triplets, called codons, are read in the 5' to 3' direction
*each codon specifies the amino acid to be placed along a polypeptide
*each codon specifies the addition of only ONE of the 20 amino acids

Front 8

Promoter

Back 8

the dna sequence where RNA polymerase attaches

Front 9

Three Stages of Transcription

Back 9

Initiation
Elongation
Termination

Front 10

Transcription Factors

Back 10

mediate the binding of RNA polymerase and the initiation of transcription

Front 11

Transcription Initiation Complex

Back 11

completed assembly of transcription factors and RNA polymerase II bound to a promoter

Front 12

TATA box

Back 12

a promotor
-- crucial in forming the initiation complex in eukaryotes

Front 13

Introns

Back 13

noncoding stretches of nucleotides that lie between coding regions --> intervening sequences

Front 14

Exons

Back 14

noncoding stretches of nucleotides that lie between coding regions --> expressed
*usually translated into amino acid sequences

Front 15

RNA splicing

Back 15

removes introns and joins exons, creating an mRNA molecule with a continuous coding sequence

Front 16

Transfer RNA (tRNA)

Back 16

a cell translates an mRNA message into protein
*each molecule of tRNA carries a specific amino acid on one end
*each has an anti-codon on one end; the anticodon base pairs with a complementary codon on mRNA

Front 17

Accurate translation requires two steps:

Back 17

first -- a correct match between a tRNA and its corresponding amino acid must be carried out by the enzyme aminoacyl-tRNA synthetase
second -- a correct match between the tRNA anticodon and the mRNA codon must take place

Front 18

Ribosomes

Back 18

facilitate specific coupling of tRNA anticodons with mRNA codons in protein synthesis
*two ribosomal subunits include: proteins and rRNA

Front 19

P Site

Back 19

holds the tRNA that carries the growing polypeptide chain

Front 20

A Site

Back 20

holds the tRNA that carries the next amino acid to be added to the chain

Front 21

E Site

Back 21

exit site, where discharged tRNAs leave the ribosome