Gene expression

Question 1

Type of cells in multi cellular organism ?.

Answer 1

1- housekeeping
General
both brain and
liver cells transcribe genes that code for enzymes and other molecules essential to the survival of all cells

2- non general
liver cells transcribe liver-specific proteins,

brain cells transcribe brain-specific proteins

Question 2

difference in the protein production pattern is due to …..?.

Answer 2

differential transcription

Question 3

What is the major control point for the
Gene Expression
regulation of gene expression in eukaryotic cells

Answer 3

Transcriptional control

Question 4

Mechanism of Regulation of Gene Expression?.

Answer 4

1- Remodling of chromatin

2- transcriptional control

Question 5

How many proteins are involved in initiating transcription?

Answer 5

1600 TF

Question 6

Does all the regulation proline bind directly to

DNA ?

Answer 6

Many (but not all)

Question 7

The location of enhancer ?

Answer 7

Intron encoding region

only in specific cell types

Question 8

Meaning of activator proteins and Repressors?

Answer 8

Both regulatory proteins

Repressors act to turn
off transcription

activator stimulate transcription

Question 9

Mechanism of Repressors to turn of the transcription?

Answer 9

Competing with activators

masking activator activity

direct negative interaction
on the transcription complex
assembled at the promoter (silencers)

Question 10

Mechanism of proteins to binding with DNA?

Motifs For Protein–DNA Interactions ?

Answer 10

Proteins that directly bind DNA have a DNA-binding
region whose protein surface is partially “complementary” to the surface features of the DNA recognition site

✓ Helix-turn-helix
Regulate genes involved in development 
✓ Leucine (basic) zipper
Cell division genes 
✓ Zinc finger
Steroid hormone receptors 
✓ Helix-loop-helix
Immune sys genes

Question 11

Diners proteins increases or decrease or no change in regulatory options ?

Answer 11

increases

Question 12

Ways Regulation Of Activity Of Gene Regulatory Proteins?

Answer 12

• Protein synthesis
• Ligand binding
• Protein phosphorylation
• Addition of a second subunit
• Unmasking
• Stimulation of nuclear entry
• Release from membrane

Question 13

RNAs Involved In Regulating Gene Expression ?.

Answer 13

microRNAs

Negatively regulate gene expression through
sequence-specific base-pairing with mRNA targets

siRNAs

regulate activity of transposons
few protein coding genes
viral infection

piRNAs
development of germ cells
(sperm in mammals)
Slide 20

Question 14

Example of regions are constitutively silenced in chromatin ?

Answer 14

telomeres

Question 15

What is the chromatin loop

Answer 15

chromatin loops ‘isolate’ the ‘active’ chromatin within
• It is proposed that the base of
a chromatin loop functions as an insulator element –
protein binding

Question 16

Regulation of Chromatin Assembly and Structure

Involves:

Answer 16

• ATP-dependent chromatin remodelling

* Histone modifications

Question 17

Meaning of Epigenetic?

Answer 17

Stably heritable phenotype……….from change in the chromosome without alteration in DNA sequence

Question 18

Function of Remodeling proteins

Answer 18

Disaggregate of nucleosome

Question 19

Why we need energy of ATP

In Chromatin Re-modelling ?.

Answer 19

ATP

hydrolysis to bind DNA and move histone octomers of nucleosomes

Question 20

List of Modification Of Histones

.?

Answer 20

Acetylation lysine, arginine Methylation.lysine (3), arginine (2)
Phosphorylation serine, threonine Ubiquitination lysine
ADP-ribosylation
Glycosylation

Question 21

Histone Acetylation reversible ?

Answer 21

acetylate
(histone acetyltransferases; HATs),
or deacetylate (histone deacetylases; HDACs)

Question 22

Which base and carbine does the methyl add to ?

Answer 22

Cytosine

Carbon 5

Question 23

functions in mammals of DNA Methylation?

Answer 23

Control of gene expression
• Cellular differentiation and development (programs
of gene expression)
• Preservation of chromosomal integrity
• X-chromosome inactivation
• Implicated in brain function and development of the
immune system
• Alterations in genomic patterns contribute to human cancers

Question 24

Example of m mutation of MeCBP2

Answer 24

X-linked Rett Syndrome,
a progressive neuromuscular
disorder

Question 25

Linkage between DNA methylation and transcriptional

repression by ?

Answer 25

histone deacetylation

Question 26

Genomic Imprinting meaning ?

Answer 26

Physical basis is that the gene from one parent is
“silenced” by methylation

Phenomenon in which the expression of the gene determines by whether you inherited from father or mother ?

Question 27

When genes become all demethylated ?

Answer 27

Grem line cell

Question 28

Where Igf2 and H19 works ?

Answer 28

Igf2 father

H19 mother

Question 29

Example of imprinting genomic ?

Answer 29

Igf2 ,H19

Question 30

Example of Disease may result if:
The active parental copy is affected by
mutation

Answer 30

prader-willi and angelman syndromes)

And beck with wiedemann syndrome

Question 31

Method of Implications For Inherited Disease ?

Answer 31

Mutation occurs in genes controlling
imprinting

Imprinting control region if it is become methylated make two imprinting gene

If it is become unmethylated it will one imprinting gene

Question 32

In early embryo From pre-gastrulation onwards the extent of

methylation varies?

Answer 32

✓ Somatic cell lineages (heavy methylation)
✓ Trophoblast-derived lineages (giving rise to placenta,
yolk sac – less methylated)
✓ Primordial gene cells (largely unmethylated)

Question 33

Mechanism of X Chromosome Inactivation?

Answer 33

Xist gene on X chromosome

Xist transcribe to interference RNA

RNA binds to the same X chromosome

Methylation and Huston deacetylation attract chromosome proteins

Inactivation X chromosome

Question 34

What is Barr body ?

Answer 34

Condensed inactive X chromosome.