Transcription

Question 1

RNA is a polymer of _____ and ____ nucleotides linked by

Answer 1

purine and pyrimidine
phosphodiester bonds

Question 2

Distribution of RNA in different cellular locations:

Answer 2

Distribution of RNA in different cellular locations:
50% in ribosomes and endoplasmic reticulum
25% in cytoplasm
15% in mitochondria
10% in nucleus

Question 3

DNA replication occurs only during _____
Transcription occurs continuously, all the time.

Answer 3

cell division.

Question 4

Genetic information of DNA is transcribed (copied) to

Answer 4

mRNA

Question 5

During transcription, the message from the DNA is copied in the language of nucleotides (4-letter language).

Question 6

The mRNA then reaches the _____ where it is translated into functional proteins.

Answer 6

cytoplasm

Question 7

During translation, the nucleotide sequence is translated to the language of amino acid sequence (20-letter language).

Question 8

during the process of DNA replication, not the entire DNA molecule is copied. Instead, only specific regions or segments of the DNA, which are located on the sense strand of the double-stranded DNA molecule, are replicated or copied.

Question 9

RNA synthesis is carried out by large enzymes called .

Answer 9

RNA polymerases
This process is common to all living organisms

Question 10

Rna polymerase search for specific sites on the DNA called

Answer 10

promoters, which mark the beginning of a gene. In E. coli bacteria, there are about 2000 promoter sites in their DNA.

Question 11

How do RNA polymerases locate initiation sites or promoters on DNA?

Answer 11

RNA polymerases locate initiation sites or promoters on DNA by searching for specific sequences that mark the beginning of a gene. In the case of E. coli bacteria, there are approximately 2000 promoter sites in their DNA

Question 12

How does RNA polymerase unwind DNA during transcription?

Answer 12

RNA polymerase unwinds DNA during transcription by separating the two strands of the double helix in a localized region, creating a single-stranded DNA template that can be used as a blueprint for RNA synthesis

Question 13

What is the function of ribonucleoside triphosphates in transcription?

Answer 13

Ribonucleoside triphosphates are the building blocks of RNA. They provide the necessary nucleotide units that are added to the growing RNA chain during transcription.

Question 14

How does RNA polymerase catalyze the formation of a phosphodiester bond?

Answer 14

RNA polymerase catalyzes the formation of a phosphodiester bond during transcription. The 3’-hydroxyl group of the last nucleotide in the RNA chain attacks the α-phosphoryl group of the incoming ribonucleoside triphosphate, resulting in the formation of a bond between them.

Question 15

What is the processivity of RNA polymerase?

Answer 15

Processivity refers to the ability of RNA polymerase to synthesize the entire RNA strand in one continuous process without falling off the DNA template.

Question 16

How does RNA polymerase identify termination signals?

Answer 16

RNA polymerase identifies termination signals that specify where the transcript should end. These signals can be specific DNA sequences or structural features that cause the RNA polymerase to stop transcription and release the completed RNA molecule.

Question 17

How do activator and repressor proteins affect transcription initiation?

Answer 17

Activator and repressor proteins interact with RNA polymerase and modulate the rate of transcription initiation. Activator proteins enhance transcription, while repressor proteins suppress or inhibit transcription.

Question 18

gene expression controlled at the level of

Answer 18

Transcription

Question 19

What’s the main goal of RNA synthesis

Answer 19

is the formation of a phosphodiester bond. This reaction involves the 3’-hydroxyl group of the last nucleotide in the RNA chain attacking the α-phosphoryl group of the incoming ribonucleoside triphosphate, resulting in the formation of a bond between them

Question 20

What is the significance of the two metal ions in RNA polymerases?

Answer 20

The catalytic sites of RNA polymerases contain two metal ions, typically magnesium ions. These metal ions assist in facilitating the chemical reactions involved in transcription.

Question 21

What happens to the pyrophosphate molecule during RNA synthesis?

Question 22

Why is the formation of a phosphodiester bond

Answer 22

The formation of a phosphodiester bond is thermodynamically favorable because it releases energy and results in the production of a more stable molecule (RNA) compared to the individual reactants.

Question 23

What happens to the pyrophosphate molecule during RNA synthesis?

Answer 23

The pyrophosphate molecule, which is released during the formation of a phosphodiester bond, is further degraded to orthophosphate. This breakdown helps drive the reaction in the direction of RNA synthesis.

Question 24

What is the role of orthophosphate in RNA synthesis?

Answer 24

Orthophosphate, which is produced from the degradation of pyrophosphate, helps lock the reaction in the direction of RNA synthesis and further contributes to the overall stability of the RNA molecule.

Question 25

The template strand transcribed to give mRNA is called

Answer 25

(-), antisense strand It has complementary sequence to mRNA ie opposite

Question 26

The opposite strand has the same sequence as the mRNA, and is called

Answer 26

coding strand or antitemplate strand or nontemplate or (+) or sense strand.

Question 27

What's RNA transcription signals

Answer 27

RNA transcription signals are specific areas on DNA that act as starting signals for the initiation process of making RNA copies.

Question 28

______specific spot on the DNA where a molecule called RNAP attaches. RNA polymerase

Answer 28

Promoter

Question 29

Human DNA has approximately transcription initiation sites.

Answer 29

105

Question 30

Bacterial DNA has a specific sequence called ____', and _____located about ___ & _____base pairs upstream of the transcription start site.

Answer 30

5'-TGTTGACA-3 and 5'-TATAAT-3(known as the TATA box or Pribnow box) 35 & 10

Question 31

In mammals, the TATA box sequence is slightly different it's ____ and is called the The TATA box is located at position ____ to ____and serves as a signal for the start region of transcription.

Answer 31

(TATAAA) Golberg-Hogness box. -25 to -30

Question 32

Further upstream, between positions ___&____ there is another sequence called , known as the CAAT box.

Answer 32

-70 and -80, GGCCAATCT

Question 33

These recognition signals are cis-acting, meaning

Answer 33

they are located near the gene they regulate.

Question 34

Enhancers increase the rate of transcription, while silencers decrease the rate.

Question 35

Other regulatory signals for transcription include

Answer 35

hormone response elements (HRE), repressors, inducers, and derepressors.

Question 36

The starting point of transcription in bacteria is the The nucleotide next to the downstream of the starting point is numbered

Answer 36

5' nucleotide of the DNA, designated as +1. as -1.

Question 37

RNA polymerase (RNAP) binds to the ______ site on DNA with the help of a _________, forming the pre-initiation complex (PIC). Prokaryotes

Answer 37

RNA polymerase (RNAP) binds to the promoter site on DNA with the help of a sigma factor, forming the pre-initiation complex (PIC).

Question 38

The first nucleotide of the mRNA attaches to the initiation site on the RNAP when it reaches the appropriate site on the gene. This nucleotide becomes the _____' end of the mRNA and is complementary to the DNA base at that site.

Answer 38

5

Question 39

Transcription begins with the initiation of the mRNA, and______ is usually the first unit in the mRNA.

Answer 39

a purine ribonucleotide

Question 40

After about 10-20 nucleotides are polymerized, the RNAP undergoes a conformational change and moves away from the promoter region. This is called _____ and the sigma factor is released.

Answer 40

promoter clearance,

Question 41

Eukaryote

Question 42

In eukaryotes, the transcription process is more complex. It involves at least ___ transcription factors collectively referred to as ___.

Answer 42

7 Tf-II

Question 43

The TATA box, a specific DNA sequence, is recognized by a protein called TBP (TATA binding protein) in prokayotes. In eukaryotes, a different factor called ___ ensures that the RNAP can locate the start point.

Answer 43

SL1

Question 44

In humans, there are approximately 105 transcription initiation sites available .The human TATA box binds to a multi-subunit protein called __, and other proteins called ___ bind to TBP to form a complex called .

Answer 44

TBP TAFs TFIID

Question 45

______ is the first step in the transcription process in eukaryotes.

Answer 45

Binding of the TFIID complex to the TATA box

Question 46

mammals, there are general transcription factors (GTFs) that help with promoter-specific binding to form the pre-initiation complex

Question 47

______ classes of transcription factors are involved in the transcription of mammalian genes namelt

Answer 47

Three : basal components (e.g., TBP, TFIIA, B, E, F, and H), co-regulators (e.g., TAFs, TFIID, Meds, chromatin modifiers), and activators (e.g., SP1, ATF, AP1).

Question 48

Whats the base pairing rule.

Answer 48

The base pairing rule states that A in DNA is transcribed to U in mRNA, T to A, G to C, and C to G.

Question 49

The polarity of mRNA synthesis is analogous to the polarity in DNA synthesis meaning?

Question 50

As the RNAP moves on the DNA template, the DNA helix unwinds ____ and rewinds _____.

Answer 50

downstream upstream

Question 51

The RNAP has the property of unwinding the DNA, but topo-isomerase also assists in the unwinding process

Question 52

A transcription bubble is formed, which includes ____,____&___. The transcription bubble is about _____ base pairs in length

Answer 52

RNAP, DNA, and the nascent RNA molecule 20

Question 53

RNAP does not have nuclease activity, which means ____

Answer 53

there is no proofreading mechanism during transcription.

Question 54

The fidelity of mRNA transcription is lower compared to DNA replication, with a mistake rate approximately _____

Answer 54

10^4 to 10^5 times higher.

Question 55

However, the mistakes in mRNA transcription are not transmitted to daughter cells or the next generation, making them less significant.

Question 56

____ type of RNAP is responsible for mRNA rrna and trna

Answer 56

Type 2 Type 1 Type 3

Question 57

What's the base paring for rna

Answer 57

Thus A in DNA is transcribed to U in mRNA; T to A; G to C and C to G

Question 58

RNAP has no nuclease activity; so there is no proof reading But it is less serious, since these mistakes are not transmitted to the daughter cells or to the next generation.

Question 59

Function of RNAP

Answer 59

Stabilize Unwinds Read and synthsize

Question 60

TERMINATION

Question 61

Types of termination

Answer 61

Role dependent termination Rho proteins causes rnaP to break away from the DNA Rho independent termination Inverted repeat causes a hair pin loop due to its attraction releasing cleavage enzymes that stops it CCGG Eukaryotic cells A sequence of DNA AAUAAA a polyadenylation signal which activates enzymes to come cleavethe DNA anway from rnaP

Question 62

RnaP reads the _____strand

Answer 62

Template

Question 63

Rho independent termination is also described. In humans, the termination signals exist far downstream of the coding sequence, usually ____to_____bases away.

Answer 63

1000 to 2000 bases away

Question 64

There are _____ different types of RNAPS in higher organisms and all are DNA dependent. Mammalian rnaP

Answer 64

3

Question 65

 They have molecular weight of Mammalian rnaP

Answer 65

500 to 600 kDa

Question 66

RNAP type ____is the main enzyme synthesizing mRNAs. It is inhibited by Mammalian rnaP

Answer 66

II or B alpha amanitin, a toxin from the mushroom Amanita phalloides

Question 67

How does amanitin block rnaP Mammalian rnaP

Answer 67

Amanitin blocks the translocation of RNAP during mRNA synthesis.

Question 68

____&_____ are also synthesized by the same RNAP B. Mammalian rnaP

Answer 68

SnRNA and miRNA

Question 69

RNAP has ____ large and ___ smaller subunits, it is Activated by ____ Mammalian rnaP

Answer 69

2 and 12 phosphorylation

Question 70

RNAP type I or A is responsible for synthesis of rRNA (ribosomal); it is not inhibited by amanitin.Mammalian rnaP

Question 71

RNAP type III or C is responsible for production of tRNA; it is moderately sensitive to amanitin Mammalian rnaP

Question 72

Bacterial RNAP: The enzyme contains ____&____subunits ____ subunit, ____factor and _____ molecules

Answer 72

two alpha, two beta one omega subunit and one sigma factor and two zinc molecules

Question 73

Function of them beta and sigma factor

Answer 73

Beta subunit fixes at the initiation site. Sigma factor recognises the promoter site and increases the affinity of the holo-enzyme to the promoter site

Question 74

Types of rna and it's% of rna

Answer 74

Mrna- DNA is transcribed into mRNA Constitutes 2-5% of total rna Degraded quickly rRNA- constitutes about 80% of all RNA in the cell... They are involved in the protein biosynthesis and they are very stable tRNA- constitute about 15% of the total RNA... They are very stable Small RNA.- constitute about 1-2% of total RNA in the cell. There are about 30 different varities

Question 75

What are the major variety of rrna

Answer 75

28S, 18S and 5S are the major varieties

Question 76

_____ are a subgroup of small RNA

Answer 76

Small Nuclear RNAs (SnRNAs)

Question 77

Some important species of SnRNAs are

Answer 77

U1 (165 nucleotides), U2 (188 nucleotides), U3 (216),U4 (139), U5 (118), U6 (106)

Question 78

SnRNA sizes ranges from ____to____

Answer 78

size ranges from 90-300 nucleotides

Question 79

 They are named as U1, U2, U4, U5, U6 and U7 SnRNA The U stands for

Answer 79

Uracil rich nature of SnRNA

Question 80

SnRNA takes part in the formation of ____ And they are all located at

Answer 80

spliceosomes The nucleus

Question 81

It is pronounced as "Snurps". Production of autoantibodies against “Snurps” cause a fatal autoimmune disease called

Answer 81

systemic lupus erythematosis (SLE),

Question 82

SnRNA are involved in DNA splicing*

Question 83

miRNA alter the function of mRNA and ____ly stable

Answer 83

Moderately

Question 84

Heterogeneous mRNA is also called

Answer 84

Immature mrna

Question 85

The 5 prime end has_____ and 3____

Answer 85

Phosphate group has a triphosohate OH

Question 86

After tri phosphatase cleaves one phosphatate from the tri phosphate _____ is added to the remaining 2 by___

Answer 86

A gmp(guanocynene monophaphate) molecule is added by guanayly transferase

Question 87

After gmp is added ___ is later added by____ what

Answer 87

Methyl group is added by methyltransferase

Question 88

After adding all that it forms the 7 methyl guanosine group and the entire process is called capping And the function of capping is?

Answer 88

Helps interact with ribosome and undergo translation Helps prevent degradation by nucleases

Question 89

What aids methyltransferase in adding the methyl group to the 5 phosphate site

Answer 89

S Adenosyl methionine SAM

Question 90

On the 3 OH side the polyadenylation signal is located______adds AAAAAAA groups to it forming the ______

Answer 90

Poly A Polymerase Poly A tail

Question 91

Function of Poly A tail

Answer 91

Helps interact with ribosome and undergo translation Helps prevent degradation by nucleases Helps in transportating immature mrna

Question 92

In the premature hnrna ____ codes for amino acids ____ doesn't code for AA

Answer 92

Hexons Introns

Question 93

____ helps cleave the intron and adds the hexons together forming a functional mRNA

Answer 93

SNRPS small nucleus rna and proteins

Question 94

Retrovirus particles contain _____

Answer 94

two copies of a single-stranded RNA molecule.

Question 95

Retroviruses are a type of virus that have two copies of a single-stranded RNA molecule. When they enter a host cell, one copy of the RNA serves as a template for an unusual enzyme called

Answer 95

reverse transcriptase

Question 96

Function of reverse transcriptase

Answer 96

This enzyme makes a new DNA strand based on the RNA template.

Question 97

The resulting double-stranded DNA version of the viral genome becomes a part of the host cell's chromosomal DNA and is replicated along with the cell's own DNA. This means that the viral genetic material is integrated into the host cell's DNA.

Question 98

To complete this process, the RNA part of the RNA-DNA hybrid is broken down by a specific enzyme called .

Answer 98

RNAse-H

Question 99

Transcription inhibitor Some of them are of natural origin e.g. And others are

Answer 99

from fungus such as streptomyces which produces Rifamycin and Mitomycin Systemic & semi systemic

Question 100

What drugs are used as anticancer drugs & how? And they are from

Answer 100

Actinomycin D (antibiotics from streptomyces) by inserting phenoxazone ring between 2 G-C bp of DNA and Mitomycin intercalate with DNA strands, thus blocking transcription hence are used as anticancer drugs.

Question 101

____ drug is used to treat tuberculosis and leprosy P from ____ How?

Answer 101

Rigampicin Synthetic derivative of ryfamicin Binds to neta subunit of RNAP which is inactivated

Question 102

Alpha manitin A toxin from mushroom Inactivates RNAP2

Question 103

3 deoxy adenosine Synthetic analog Causes incorrect entry into chain causing chain termination