Transcription and Translation

Question 1

gene expression

Answer 1

the process by which DNA directs protein synthesis, includes two stages: transcription and translation

Question 2

transcription

Answer 2

the synthesis of RNA under the direction of DNA

Question 3

what produces messenger RNA
(mRNA)

Answer 3

transcription

Question 4

ribosomes

Answer 4

the sites of translation

Question 5

translation

Answer 5

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

Question 6

RNA processing

Answer 6

how eukaryotic RNA transcripts are modified

Question 7

primary transcript

Answer 7

the initial RNA transcript from any gene

Question 8

central dogma

Answer 8

the concept that cells are governed by a cellular chain of command: DNA
→ RNA → protein

Question 9

how many amino acids and nucleotide bases are there

Answer 9

20 amino acids, 4 bases

Question 10

triplet code

Answer 10

a series of nonoverlapping, three-nucleotide words

Question 11

template strand

Answer 11

one of the 2 DNA strands that provides a template for ordering the sequence of nucleotides in an RNA transcript

Question 12

codons

Answer 12

the mRNA base triplets that are read in the 5’ to 3’ direction

Question 13

what does each codon do

Answer 13

specifies the amino acid to be placed at the corresponding position along a
polypeptide

Question 14

what does each codon specify

Answer 14

the addition of one of 20
amino acids

Question 15

how do you read codons

Answer 15

in the correct reading frame (triplet groups)

Question 16

RNA polymerase

Answer 16

catalyzes RNA synthesis and pries the DNA strands apart and hooks together the RNA nucleotides

Question 17

promoter

Answer 17

the DNA sequence where RNA polymerase attaches

Question 18

terminator

Answer 18

the sequence signaling the end of transcription

Question 19

transcription unit

Answer 19

the stretch of DNA that is transcribed

Question 20

three stages of transcription

Answer 20

– Initiation

– Elongation

– Termination

Question 21

transcription factors

Answer 21

mediate the binding of RNA polymerase and the initiation of
transcription

Question 22

transcription initiation complex

Answer 22

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

Question 23

TATA box

Answer 23

a promoter that is crucial in forming the initiation complex in eukaryotes

Question 24

how does RNA polymerase work

Answer 24

moves along the DNA, it untwists the double helix, 10 to 20 bases at a time

Question 25

what does the 5' end receive during RNA processing

Answer 25

a modified nucleotide 5' cap

Question 26

what does the 3' end receive during RNA processing

Answer 26

a poly-A tail

Question 27

what do this modifications do

Answer 27

– They seem to facilitate the export of mRNA – They protect mRNA from hydrolytic enzymes – They help ribosomes attach to the 5' end

Question 28

introns(intervening sequences)

Answer 28

noncoding regions

Question 29

exons

Answer 29

regions that do code and are eventually expressed

Question 30

RNA splicing

Answer 30

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

Question 31

Spliceosomes

Answer 31

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

Question 32

ribosomes

Answer 32

catalytic RNA molecules that function as enzymes and can splice RNA

Question 33

3 properties of RNA that enable it to function as an enzyme

Answer 33

- it can form a three dimensional structure because of its ability to base pair with itself - some bases in RNA contain functional groups - RNA may hydrogen bond with other nucleic acid molecules

Question 34

alternative RNA splicing

Answer 34

segments that are treated as exons during RNA splicing

Question 35

domains

Answer 35

molecular architecture consisting of discrete regions in proteins

Question 36

are molecules of tRNA identical?

Answer 36

no

Question 37

transfer RNA (tRNA)

Answer 37

what helps a cell translate an mRNA message into protein

Question 38

anticodon

Answer 38

a sequence of nucleotides that correspond to a complementary codon on the mRNA

Question 39

2 steps of translation

Answer 39

- a correct match between a tRNA and an amino acid - a correct match between the tRNA anticodon and and an mRNA codon

Question 40

aminoacyl-tRNA synthetase

Answer 40

an enzyme that matches a tRNA and an amino acid

Question 41

wobble

Answer 41

flexible pairing at the third base of a codon which allows some tRNA to bind to more than one codon

Question 42

ribosomal RNA (rRNA)

Answer 42

make up 2 ribosomal subunits

Question 43

a ribosomes three binding sites of tRNA

Answer 43

- p site - a site - e site

Question 44

p site

Answer 44

holds the tRNA that carries the growing polypeptide chain

Question 45

a site

Answer 45

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

Question 46

e site

Answer 46

the exit site, where discharged tRNAs leave the ribosome

Question 47

3 stages of translation

Answer 47

- initiation - elongation - termination

Question 48

initiation

Answer 48

it brings together mRNA, a tRNA with the first amino acid, and the 2 ribosomal subunits - first a small ribosomal subunit binds with mRNA and a special initiator tRNA - then the small subunit moves along the mRNA until it reaches the start codon - proteins called initiation factors bring in the large subunit that completes the translation initiation complex

Question 49

start codon

Answer 49

AUG

Question 50

elongation

Answer 50

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

Question 51

3 steps of proteins called elongation factors

Answer 51

- codon recognition - peptide bond formation - translocation

Question 52

when does termination occur

Answer 52

when a stop codon in the mRNA reaches the A site of a ribosome

Question 53

muations

Answer 53

changes in the genetic material of a cell or virus

Question 54

point mutations

Answer 54

chemical changes in just one base pair of a gene

Question 55

2 categories of point mutation

Answer 55

- base pair substitutions - base pair insertions or deletions

Question 56

deletions

Answer 56

losses of nucleotide pairs in a gene

Question 56

frameshift mutation

Answer 56

what is produced when insertion or deletion of nucleotides alter the reading frame

Question 56

base pait substitutions

Answer 56

replaces one nucleotide and its parter with another pair of nucleotides

Question 56

missense mutations

Answer 56

code for an animo acid, but not necessarily the right amino acid

Question 57

nonsense muations

Answer 57

change an animo acids codon into a stop codon, nearly always leading to a nonfunctional protein

Question 57

insertions

Answer 57

additions of nucleotide pairs in a gene

Question 58

mutagenes

Answer 58

physical or chemical agents that can cause mutations