Factors Affecting Gene Expression

Question 1

What is cell differentiation?

Answer 1

The process by which cells become specialised

Question 2

What are transcription factors?

Answer 2

Proteins that bind to DNA in the nucleus and affect the process of transcription

Question 3

What are promoter sequences?

Answer 3

Specfific areas in DNA that transcription factors bind to and stimulate transcription

Question 4

What are enhancer sequences?

Answer 4

Areas of DNA that transcription factors bind to and regulate the activity of DNA by making it more or less avaliable to RNA polymerase so stimulating or preventing transcription

Question 5

What is premRNA?

Answer 5

MRNA that has been transcribed directly from DNA but still needs to be modifyed and introns removed

Question 6

What are spliceosomes?

Answer 6

Enzymes that join exons together after the introns have been removed in mRNA

Question 7

What is epigenetics?

Answer 7

The way gene expression is controlled

Question 8

What systems interact to control gene expression?

Answer 8

DNA methalation
Histone modification
non-coding RNA

Question 9

What is DNA methalation?

Answer 9

The addition of a methyl group to a C base which prevents the transcription of a gene

Question 10

Does DNA methalation turn a gene on or off?

Answer 10

Off

Question 11

What is DNA demethalation?

Answer 11

The removal of a methyl group from C which enables a gene to be expressed

Question 12

What are histones?

Answer 12

Positively charged proteins that DNA winds around to form chromatin

Question 13

What are heterochromatin?

Answer 13

When the DNA is coiled tightly around histones so unable to be transcribed

Question 14

How does the tightness of DNA coils around histones affect gene expression?

Answer 14

The tighter the DNA is coiled, the less the gene is expressed as the enzymes can’t bind to it to transcribe

Question 15

What is histone acetylation?

Answer 15

An acetyl group is added which losens the coil of DNA arund the histones and allows genes to be transcribed

Question 16

What is histone methylation?

Answer 16

When a methyl group is added which tightens the coil of DNA arund the histones and stops genes from being transcribed and expressed

Question 17

What is the first stage of embryonic stem cell development?

Answer 17

Cleavage

Question 18

What is cleavage?

Answer 18

The first stage of embryonic development where cells divide repeatedly by mitosis without normal interphase which results in a uniform, undifferentiated mass of cells known as a blastocyst

Question 19

What is a blastocyst?

Answer 19

A small mass of uniform, undifferentiated cells

Question 20

What is a totipotent cell?

Answer 20

An undifferentiated cell that can form into any of the cells needed to form an entirely new organism

Question 21

What is an embryonic stem cell?

Answer 21

Undifferentiated cells in the early human embryo that can develop into many different types of specialised tissues

Question 22

Are embryonic stem cells totipotent or pluripotent?

Answer 22

At first totipotent but later Pluripotent

Question 23

Are ambilical cord stem cells totipotent or pluripotent

Answer 23

Pluripotent

Question 24

What is another term for adult stem cells?

Answer 24

Stomatic stem cells

Question 25

What are stomatic stem cells?

Answer 25

Undifferntiated cells found in adults that can differentiate into any of the major types of cell in the body

Question 26

What are multipotent cells?

Answer 26

A cell that can form a limited number of differentiated cells Found in adults.

Question 27

Why has stem cell therapy had limited sucess?

Answer 27

It's difficult to control how the cells differentiate

Question 28

What is theraputic cloning?

Answer 28

An experimental technique where scientists hope to produce large quantities of healthy tissue to treat people with diseases caused by faulty cells

Question 29

What is the process of theraputic cloning?

Answer 29

The nucleus from a normal cell is removed and put in the empty ovum cell. An electric shock is given to trigger development. The cell divides to produce stem cells with the same DNA as the patient

Question 30

What are the criticizms of stem cell therapy?

Answer 30

We have limited understanding of differentiation | Could cause cancer

Question 31

What are the advantages of using stem cell therapy?

Answer 31

Can cure illness | Less change of people rejecting organs

Question 32

What are induced pluripotent stem cells?

Answer 32

Adult cells that have been reprogrammed by the introduction of new genes to become pluripotent again

Question 33

What are the advantages of using induced pluripotent stem cells?

Answer 33

Overcomes the ethical objections of embryonic stem cells

Question 34

In what ways can stem cell therapy help people?

Answer 34

Parkinsons Type 1 diabetes Damaged nerves Organ transplants