T3M3

Question 1

All embryonic stem cells are…

Answer 1

identical

Question 2

How many distinct cell types in adult human?

Answer 2

200

Question 3

Transcription factors are

Answer 3

proteins that bind to specific DNA sequences

Question 4

Controlling which gene is active along the chromosome leads to

Answer 4

vast array of cell types found throughout our bodies

Question 5

Both prokaryotes and eukaryotes have

Answer 5

proteins that are involved with activating and repressing transcription and utilize RNA polymerase to bind to promoters that are upstream of genes to initiate transcription

Question 6

In the prokaryotic genome

Answer 6

groups of related genes with similar functions can often be found clustered together into operons transcribed by a single promoter

Question 7

eukaryotic genome

Answer 7

each gene is controlled by its own promoters
and enhancers

Question 8

DNA in eukaryotes is organized into

Answer 8

highly compacted chromatin

Question 9

DNA in tightly wound chromatin fibers makes for

Answer 9

• fit all the DNA within the nucleus
• DNA to be moved around during cell division

Question 10

Winding of DNA in nucleosomes can affect

Answer 10

whether DNA is transcribed or not

Question 11

Genes within this tightly wound heterochromatin are usually

Answer 11

not expressed

Question 12

To be able to transcribe a specific gene product

Answer 12

Must unwind DNA

Question 13

DNA compaction regulates

Answer 13

gene expression

Question 14

In eukaryotes DNA is

Answer 14

around a complex of histone proteins, forming the nucleosome structure

Question 15

Each nucleosome contains

Answer 15

an octamer of 8 histone proteins around which approximately 150 DNA base pairs wrap around

Question 16

When DNA is tightly wound into chromatin

Answer 16

the DNA is not accessible due to the tight winding around the histone proteins

Question 17

For transcription to occur chromatin must be

Answer 17

unravelled

Question 18

chromatin unravelled through

Answer 18

chromatin remodelling

Question 19

chromatin remodeling begins when

Answer 19

an activator protein or transcription factor is
able to bind to an accessible enhancer site. This
leads to the further recruitment of other proteins that can lead to further chromatin remodeling

Question 20

Transcription requires changes to chromatin structure to enable

Answer 20

transcription factors to bind important DNA regions, recruit RNA polymerase, and facilitate the transcriptional process

Question 21

DNA is tightly wound around histone proteins due to

Answer 21

the interactions of the positively charged tails of histone proteins with the negatively charged phosphates in DNA

Question 22

During the chromatin remodeling process, activator proteins can

Answer 22

recruit the coactivator enzyme histone
acetyltransferase (or HAT)

Question 23

HAT can

Answer 23

attach acetyl groups to lysine amino acids along the positively charged tails of nucleosome histone proteins

Question 24

When tails are acetylated

Answer 24

positive charge is reduced, and the interaction between the histones and the wound DNA is weakened

Question 25

other chemical modifications

Answer 25

methylation of lysine and arginine and phosphorylation of serine and threonine amino acids along the histone protein tails

Question 26

Acetylation and methylation with a single methyl group allows for

Answer 26

transcriptional activation

Question 27

Methylation with 3 methyl groups leads to

Answer 27

repression of transcription

Question 28

Most transcription factors can be classified based on

Answer 28

structures of their distinct DNA binding motifs

Question 29

DNA binding motifs include

Answer 29

the basic helix-loop-helix, helix-turn- helix, zinc finger and leucine zipper regions

Question 30

To initiate transcription in eukaryotes

Answer 30

specific DNA sequences (or cis-sequences) are required

Question 31

The TATA box and transcriptional start sites form

Answer 31

part of the core promoter

Question 32

The core promoter is

Answer 32

the binding site that is required for binding of RNA polymerase and associated transcription factors

Question 33

The TATA box and BRE regions are generally situated

Answer 33

in close proximity to the transcription start site

Question 34

The enhancer regions are able to

Answer 34

bind cell or region-specific transcription factors

Question 35

Flexible nature of DNA allows for

Answer 35

assembled transcription factors and RNA polymerase to come to close proximity by looping of the DNA

Question 36

Adaptor or mediator proteins are able to

Answer 36

connect the proteins that are bound to the enhancer regions with proteins that are bound to the core promoter region

Question 37

When the silencer regions of the DNA are activated by a repressor protein

Answer 37

interference of the general transcription factor assembly and mediator activity which is needed for the binding of RNA polymerase and subsequent transcription

Question 38

Blood cell progenitors (or stem cells) differentiate into

Answer 38

functional red blood cells that contain haemoglobin

Question 39

Progenitor cell must

Answer 39

activate transcription of globin proteins that are appropriate for the fetus or the adul

Question 40

Fetus globin proteins

Answer 40

2 alpha-globin proteins making up half of their tetrameric hemoglobin protein, 2 gamma-globin proteins

Question 41

Adult globin proteins

Answer 41

2 alpha-globin proteins making up half of their tetrameric hemoglobin protein, beta-globin proteins making up the other half of the hemoglobin protein

Question 42

Gamma globin can bind

Answer 42

oxygen more strongly than beta globin

Question 43

In the fetal blood cell progenitors

Answer 43

chromatin is wound up around the beta-globin gene to inhibit transcription, while the chromatin around the gamma-globin gene is open to allow transcription

Question 44

In adult cells chromatin

Answer 44

reorganized to prevent transcription of the gamma-globin gene but allow transcription of the adult beta-globin gene

Question 45

histone modifications permit

Answer 45

Unwinding of DNA from the nucleosomes to allow DNA-binding transcription factors to associate with enhancer and promoter sequences on the DNA and start transcription

Question 46

DNA modifications, such as methylation of certain nucleotides, can still

Answer 46

inhibit transcription

Question 47

In eukaryotic systems, transcription is affected by

Answer 47

the chemical modification of cytosine bases in the DNA sequence

Question 48

Most common cytosine base modification is

Answer 48

addition of a methyl group

Question 49

addition of a methyl group occurs

Answer 49

within a string of cytosine and guanine bases called a “CpG” island

Question 50

When a CpG island contains many methylated cytosine bases

Answer 50

the shape of the DNA binding site for the proteins has changed and the proteins can no longer bind

Question 51

Heavily methylated promoters

Answer 51

are not transcriptionally active because the RNA polymerase cannot bind to the methylated sequences

Question 52

DNA methylation is an example of

Answer 52

epigenetic mechanism that controls gene expression