Lecture 14 - RNA structure and gene expression

Question 1

RNA world hypothesis steps

Answer 1

1. RNA forms
2. Ribozyme catalyzes RNA replication
3. RNA catalyzes protein synthesis
4. RNA encodes both DNA and protein
5. Proteins catalyze cell activities

Question 2

Reverse transcriptase is a

Answer 2

polymerase

Question 3

Information encoded in a DNA molecule is transcribed via

Answer 3

synthesis of an RNA molecule

Question 4

Polymerase

Answer 4

An enzyme that brings about the formation of a particular polymer, especially DNA or RNA

Question 5

Messenger RNA is a

Answer 5

copy (transcription) of DNA and the template for protein synthesis (translation)

Question 6

Cistronic gene expression

Answer 6

one mRNA molecule is usually produced for a whole group of genes (in prokaryotes)

Question 7

Alternative splicing

Answer 7

A single distinct mRNA is produced for each gene (in eukaryotes)

Question 8

mRNA adopts _________ structures such as stem-loops

Answer 8

secondary

Question 9

RNA chains are produced by

Answer 9

copying of template DNA strands

Question 10

The base sequence of mRNA is the complement of

Answer 10

the DNA template strand

Question 11

The strand besides the mRNA and DNA template strand is the

Answer 11

coding strand

Question 12

The coding strand has the

Answer 12

same sequence as RNA transcript except T is replaced by U

Question 13

mRNA in eukaryotes is modified after

Answer 13

transcription

Question 14

A nucleotide cap is added to the 5’ end and signals

Answer 14

the docking of ribosomes

Question 15

The docking of ribosomes initiates

Answer 15

protein synthesis

Question 16

A poly (A) tail is added to the 3’ end to

Answer 16

prevent digestion of mRNA by exonucleases in the cytosol

Question 17

The 5’ UTRs in mRNA typically contain

Answer 17

regions of RNA that determine translational control (initiation)

Question 18

Transfer RNA (tRNA) is

Answer 18

a ribonucleic acid that carries a specific amino acid to the site of protein synthesis in ribosomes.

Question 19

There is at least one kind of tRNA for

Answer 19

each of the 20 amino acids

Question 20

Transfer RNA adopts a specific secondary structure of loops resembling a

Answer 20

clover leaf

Question 21

The adaptors in protein synthesis are

Answer 21

transfer RNAs

Question 22

A mature tRNA is about ________ amino acids long

Answer 22

75

Question 23

tRNAs contain

Answer 23

an amino acid attachment site and a template-recognition site

Question 24

a tRNA molecule carries

Answer 24

one specific amino acid in an activated form to the ribosome (site of protein synthesis)

Question 25

The anticodon of tRNAs recognize

Answer 25

a complementary sequence of three bases on mRNA called a codon

Question 26

In tRNA, the amino acid is attached by

Answer 26

esterification of the carboxyl group of the amino acid to the 3’- or 2’-hydroxyl group of the ribose unit at the 3’ end of the tRNA chain

Question 27

Amino acids attaching to tRNA is catalyzed by the enzyme

Answer 27

aminoacyl-tRNA synthetase

Question 28

Amino acids attaching to tRNA is driven by the

Answer 28

hydrolysis of ATP

Question 29

A tRNA molecule attached to an amino acid is called

Answer 29

an aminoacyl-tRNA

Question 30

mRNAs carry ________ signals for protein synthesis

Answer 30

start and stop

Question 31

In prokaryotes, the initial N-terminal amino acid in translation is

Answer 31

N-formylmethionine (fmet)

Question 32

The initiator tRNA carries

Answer 32

fmet which recognizes the codon AUG (start)

Question 33

Ribosomal RNA (rRNA) is the major component of

Answer 33

ribosomes

Question 34

In prokaryotes, the three kinds of rRNA are named ____________

Answer 34

23s, 16s, and 5s due to their sedimentation

Question 35

In eukaryotes, the four kinds of rRNA are named _____________

Answer 35

28s, 18s, 5.8s, and 5s

Question 36

rRNA functions as the catalyst in

Answer 36

protein synthesis

Question 37

Ribosomes are referred to as ribozymes because

Answer 37

most catalytic reactions in cells are carried out by enzymes

Question 38

The ribosome from E. coli consists of what two subunits

Answer 38

50S and 30s (form 70s)

Question 39

The 30S subunit in E. coli contains

Answer 39

21 different proteins and one 16s RNA molecule

Question 40

The 50S subunit in E. coli contains

Answer 40

31 different proteins and two RNA molecules (23S and 5S)

Question 41

The ribosome has three tRNA binding sites called

Answer 41

A site (aminoacyl)
P site (peptidyl)
E site (exit)

Question 42

Small nuclear RNA (snRNA) is found in

Answer 42

the nucleus of eukaryotic cells

Question 43

snRNA complexes with proteins to form

Answer 43

small nuclear ribonculeoprotein particles (snRNPs)

Question 44

snRNPs help with

Answer 44

mRNA processing to splice introns from the precursor mRNA to yield mature mRNA

Question 45

Splicing is done by a large complex called the

Answer 45

spliceosome

Question 46

The spliceosome consists of

Answer 46

RNAs and proteins

Question 47

In eukaryotes, the vast majority of RNA is processed immediately after

Answer 47

transcription

Question 48

Primary transcripts (pre-mRNA) acquire a

Answer 48

5’ cap and a 3’ poly(A) tail

Question 49

Almost all pre-mRNAs are

Answer 49

spliced

Question 50

Introns are _______ and exons are _______ to form mature mRNAs

Answer 50

excised; joined

Question 51

The pattern of splicing is regulated to

Answer 51

match the requirements of the cell

Question 52

Alternative splicing enlarges

Answer 52

the repertoire of proteins in eukaryotes

Question 53

Which is more complex, the proteome, or the genome?

Answer 53

proteome

Question 54

Micro RNA (miRNA) is

Answer 54

a class of small 21-oligonucleotides that serve as an inhibitor for translation by binding to the complementary mRNA

Question 55

Small interfering RNA (siRNA) is

Answer 55

a class of small RNA molecules that bind to mRNA and facilitate its degradation