Mvhs Ap Biology Vocab Ch. 17

Front 1

one gene-one polypeptide hypothesis

Back 1

the premise that a gene is a segment of DNA that codes for one polypeptide

Front 2

transcription

Back 2

the synthesis of RNA under the direction of DNA

Front 3

Translation

Back 3

the actual synthesis of a polypeptide, which occurs under the direction of mRNA

Front 4

RNA processing

Back 4

modification of RNA before it leaves the nucleus, a process unique to eukaryotes

Front 5

primary transcript

Back 5

an intial RNA transcript; also called pre-mRNA

Front 6

triplet code

Back 6

the genetic instructions for a polypeptide chain

Front 7

template strand

Back 7

the DNA strand that provides the template for ordering the sequence of nucleotides in an RNA transcript

Front 8

codons

Back 8

mRNA bases consisting of 3 amino acids

Front 9

reading frame

Back 9

the way a cell's mRNA-translating machinery groups the mRNA nucleotides into codons

Front 10

promoter

Back 10

the DNA sequence where RNA polymerase attaches and initiates transcription

Front 11

terminator

Back 11

the sequence that signals the end of transcription

Front 12

transcription unit

Back 12

the stretch of DNA that is transcribed into an RNA molecule

Front 13

transcription factors

Back 13

collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription

Front 14

transcription initiation complex

Back 14

the completed assembly of transcription factors and RNA polymerase bound to the promoter

Front 15

TATA box

Back 15

crucial promoter DNA sequence that helps form the initiation complex

Front 16

cap

Back 16

5' end; helps protect the mRNA from degradation by hydrolytic enzymes, and functions as part of an "attach here" sign for ribosomes

Front 17

poly(A) tail

Back 17

inhibits degradation of the RNA and probably helps ribosomes attach to it

Front 18

RNA splicing

Back 18

the removal of a large portion of the RNA molecule that is intially synthesized

Front 19

introns

Back 19

the noncoding segments of nucleic acid tjay lie btw coding regions

Front 20

exons

Back 20

a coding region of a eukaryotic gene; separated by introns

Front 21

spliceosome

Back 21

several different snRNPs join with additional proteins that form an even larger assembly

Front 22

ribozymes

Back 22

RNA molecules that function as enzymes

Front 23

alternative RNA splicing

Back 23

a number of genes are known to give rise to 2 or more different polypeptides, depending on which segments are treated as exons during RNA processing

Front 24

domains

Back 24

proteins that often have a modular architecture consisting of discrete structural and functional regions

Front 25

transfer RNA (tRNA)

Back 25

the interpreter in which a series of codons along an mRNA molecule messages for

Front 26

anticodon

Back 26

base-pairs with a complementary codon on mRNA

Front 27

wobble

Back 27

relaxation of the base-pairing rules

Front 28

aminoacyt-tRNA synthetase

Back 28

a specific enzyme in which each amino acis is joined to the correct mRNA

Front 29

ribosomal RNA (rRNA)

Back 29

thr ribosomal subunits that are constructed of proteins and RNA molecules

Front 30

P site

Back 30

holds the tRNA carrying the growing polypeptide chain

Front 31

A site

Back 31

holds the tRNA carrying the next amino acid to be added to the chain

Front 32

E site

Back 32

(exit site) discharged tRNAs leave the ribosome from this site

Front 33

initiation

Back 33

brings together mRNA, a tRNA bearing the first amino acid of the polypeptide, and the 2 subunits of a ribosome

Front 34

Elongation

Back 34

amino acids are added one by one to the preceding amino acid

Front 35

termination

Back 35

the endig stage of translation

Front 36

polyribosomes

Back 36

strings of ribosomes

Front 37

signal peptide

Back 37

tragets the protein to the ER

Front 38

signal-recognition particle (SRP)

Back 38

a protein-RNA complex that recognizes a signal peptide as it emerges from the ribosome

Front 39

mutations

Back 39

changes in the genetic material of a cell

Front 40

point mutation

Back 40

chemical changes in just one base pair of a gene

Front 41

base-pair substitution

Back 41

the replacement of one nucleotide and its partner in the complementary DNA strand with another pair of nucleotides

Front 42

missense mutations

Back 42

altered codons still code for an amino acid and thus makes sense, although not necessarily the right sense

Front 43

nonsense mutations

Back 43

lead to nonfunctional proteins; alterations tht change an amino acid codon to a stop signal

Front 44

insertions

Back 44

addition of nucleotide pairs in a gene

Front 45

deletions

Back 45

a loss of nucleotide pairs in a gene

Front 46

frameshift mutations

Back 46

occurs whenever the number of nucleotides inserted or deleted is not a multiple of three

Front 47

mutagens

Back 47

a number of physical and chemical agents that interact with DNA to cause mutations