Ap Bio C 17

Front 1

one gene-one polypeptide hypothesis

Back 1

discovered by Beadle and Tatum
-not all proteins are enzymes
- proteins are contructed from two ore more different polypeptide chains
-each polypeptide is specified by its own gene

Front 2

transcription

Back 2

synthesis of RNA under the direction of DNA

Front 3

mRNA

Back 3

messenger RNA
-carries a genetic message from DNA to the protein to be synthesized by the machinery of the cell

Front 4

translation

Back 4

synthesis of a polypeptide under the direction of mRNA

Front 5

where does translation occur?

Back 5

in the ribosomes

Front 6

synthesis in prokaryotes

Back 6

transcription and translation occur simulaneously

Front 7

synthesis eukaryotes

Back 7

nuclear envelopeps separates transcription from translation

Front 8

primary transcript

Back 8

initial RNA transcript

Front 9

triplet code

Back 9

the genetic insructions for polypeptide chain
- series of three nucleotides

Front 10

template strand

Back 10

- for each gene only one of the two DNA strands is transcribed

Front 11

codons

Back 11

mRNA base triplets that specify for an amino acid

Front 12

AUG

Back 12

methionine (Met)
initiation codon that signals the protein-synthesizing machine to begin translating the mRNA at the location

Front 13

termination codons

Back 13

signal the end of translation

Front 14

redundancy but no ambiguity

Back 14

-two codons may specify one amino acid
-neither of any two codons specifies any other amino acid

Front 15

reading frame

Back 15

reading the symbols in the correct sequence and groupings

Front 16

RNA polymerase

Back 16

pries the two strands of DNA apart and hooks together the RNA nucleotides as they base-[air along the DNA template

Front 17

direction that RNA molecule elongates?

Back 17

5'--> 3'

Front 18

RNA polymerase II

Back 18

type of RNA polymerase used for mRNA synthesis

Front 19

three stages of transcription

Back 19

initiation, elongation, and termination of the RNA chain

Front 20

promoter

Back 20

region of DNA where RNA polymerase attaches and initiates transcription

Front 21

what are two functions of the promoter?

Back 21

-determines where transcription starts.
- determines whihch of the two strands of the DNA helix is used as the template.

Front 22

other (nontemplate strand)

Back 22

provides the instructions for making a new template strand when the DNA replicates

Front 23

transcription factors

Back 23

collection of proteins in Eukaryotes which mediate the binding of RNA polymerase and the initiation of transcription

Front 24

transcription initiation complex

Back 24

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

Front 25

TATA box

Back 25

promoter DNA sequence
- crucial in forming the iniation complex

Front 26

RNA splicing

Back 26

cut and paste job

Front 27

introns

Back 27

noncoding segments of nucleic acid that lie between coding regions

Front 28

exons

Back 28

regions of nucleic acd that are eventually expressed

Front 29

snRPs

Back 29

( small nuclear ribonucleic proteins)
signal RNA splicing
-located in the nucleus
-composed or RNA and protein molecules
-

Front 30

snRNA

Back 30

(small nuclea RNA)
the RNA in a snRNP particle
- 150 nucleotides long

Front 31

spliceosome

Back 31

an assembly of several additional proteins ( almost as big a ribosome)
- cuts at specidic points to release the intron, then immediately joins together the two exons that flanked the intron

Front 32

ribozymes

Back 32

RNA molecules that function as enzymes

Front 33

structural domain

Back 33

- structure that is self-stabilizing and often folds independently of the rest of the protein chain.
- classified into "folds

Front 34

how are introns related to variety?

Back 34

introns increase the opportunity for crossing over between two alleles of a gene, raising the probability that a crossover will switch one version of an exon for another version found on the homologous chromosome

Front 35

tRNA

Back 35

( transfer RNA)
transfers amino acids from the cytoplasm's amino acid pool to a ribosome

Front 36

anticodon

Back 36

nucleic triplet which binds according to base-pair rules to a complementary codon on mRNA

Front 37

wobble

Back 37

relaxation of base pair rules
ex: the bae U of a tRNA anticodon can pair with either Aor G in the third posistion of an mRNA codon

Front 38

aminoacyl-tRNA

Back 38

enzyme that joins each amino acid to the correct tRNA
-20 in each cell

Front 39

number of amino acids in a cell

Back 39

20

Front 40

rRNA

Back 40

(ribosomal RNA)
type of RNA that is the central component of the ribosome

Front 41

P site

Back 41

binding site for tRNA
- holds the tRNA carrying the growing polypeptide chain

Front 42

A site

Back 42

binding site for tRNA
- hold the tRNA carrying the 2nd anmino aicd to be added to the chain

Front 43

E site

Back 43

( exit site)
-site where discharged tRNAs leave the ribosome

Front 44

initiation

Back 44

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

Front 45

mutations

Back 45

changes in the genetic information of a vell

Front 46

base-pair substitution

Back 46

replaces one nucelotide and it complementary partner with another pair of nucleotides

Front 47

missense mutation

Back 47

substitution that results in an incorrectly coded amino acid

Front 48

Nonsense mutations

Back 48

occur when the point mutation changes an amino acid codon into a stop codon
-halts translation early

Front 49

frameshift mutatitions

Back 49

-mutations that alter the reading frame

Front 50

SRP

Back 50

signal-recognition particle
-attaches the ribosome to a receptor protein

Front 51

signal peptide

Back 51

begins polypeptide chain destined to be for secretion