Gene expression and DNA technology

Question 1

What is a gene mutation?

Answer 1

changes in sequence of nucleotide bases in DNA

Question 2

What genes control the rate of cell division?

Answer 2

Proto-oncgenes

Tumour suppressor genes

Question 3

What is the function of a Proto-oncogene

Answer 3

genes that code for proteins that stimulate cell division

Question 4

What is the function of Tumour suppressor genes?

Answer 4

genes code for proteins that slow cell devision

Question 5

What can happen if mutations occur in proto-oncogenes and tumour suppressor genes?

Answer 5

mutations can lead to rapid uncontrolled cell division (by mitosis) leading to the development of a tumour

Question 6

How do mutations in proto-oncogenes occur?

Answer 6

a mutated version called a oncogene stimulates cells to divide too quickly

resulting in tapid uncontrollable cell division

Question 7

How do mutations in Tumour suppressor genes occur?

Answer 7

a mutation leads to the tumour suppressor protein not being made of being non functional*

results in rapid uncontrollable cell division

Question 8

What is cancer?

Answer 8

a group of diseases caused by alterations in the genes that regulate mitosis and the cell cycle

Question 9

What is a tumour?

Answer 9

masses of dividing cells

Question 10

What are the two types if tumours

Answer 10

Benign

Malignant

Question 11

Describe a benign tumour

Answer 11

• grow slower than malignant
• non cancerous, they dont spread to other tissues bc the tumour is enclosed by fibrous tissue
• cells remain differentiated (specialised)
• nucleus has a normal appearance

Question 12

Describe a Malignant Tumour

Answer 12

• grow faster than benign
• cancerous cells break off and spread to other parts of the body bc tumour isn’t enclosed
• cells become undifferentiated (not specialised)
• nucleus is larger and darker

Question 13

Describe a Malignant Tumour

Answer 13

• grow faster than benign
• cancerous cells break off and spread to other parts of the body bc tumour isn’t enclosed
• cells become undifferentiated (not specialised)
• nucleus is larger and darker

Question 14

What are stem cells?

Answer 14

undifferentiated cells that can divide by mitosis and differentiate into different types of cells

Question 15

What are Totipotent stem cells?

Answer 15

occur for a limited time in early manmalian embryos

can differentiate into any type of cell

Question 16

What are pluripotent stem cells?

Answer 16

• found in embryos and develop from totipotent stem cells
• can differentiate into almost any type of cell
• cant produce cells of embryonic tissue

Question 17

What ate the two embryonic stem cells

Answer 17

Totipotent

Pluripotent

Question 18

What are multi-potent stem cells?

Answer 18

adult stem cells

found in mature aminals

differentiate into few limited types of specialised cells

Question 19

What are unipotent stem cells?

Answer 19

found in mature animals

can only differentiate into one type of cell

Question 20

What are induced pluripotent stem cells (iPS)?

Answer 20

type of pluripotent cell produced from unipotent stem cells

appropriate transcription factors make the unipotent cell pluripotent

Question 21

What is the function of iPS cells?

Answer 21

develop into a wide range of different types of tissue which could be used to treat people with certain diseases

Question 22

What is the function of a transcription factors?

Answer 22

proteins that bring about expressions of some genes and inhibit other genes so that these cells differentiate a particular cell

Question 23

Describe the role of oestrogen and gene expression

Answer 23

• oestrogen is lipid soluble and diffuses across the cell membrane
• oestrogen specifically bind to a receptor protein that is part of a transcription factor
• transcription factor enters nucleus
• binding change of shape of TF and allows it to bind to promoter sequence of a gene
• allows RNA polymerase to attach to gene and catalyse transcription
• mRNA then subscribed then translated into a protein

Question 24

how can oestrogen lead to cancer?

Answer 24

In some tissues oestrogen increases the expressions of genes

so high concentrations can increase uncontrollable cell division

Question 25

How does Tamoxifen treat some breast cancer?

Answer 25

it is converted into endoxifen which is a molecule of a similar structure to oestrogen

It competes with oestrogen for biding to an oestrogen receptor

Question 26

what is siRNA?

Answer 26

short double stranded sections of RNA
Usually 20 to 25 base pairs long

Question 27

what is the function of siRNA?

Answer 27

Regulates gene expression by causing mRNA to be broken down after transcription thus prevent preventing translation

Question 28

How does siRNA prevent translation?

Answer 28

• double trended RNA is hydrolysed into short molecules
• RNA becomes single stranded siRNA
• siRNA binds to an enzyme that hydrolyses mRNA
• it then binds to a specific molecule of mRNA by complementary base pairing and guides to hydrolytic enzyme to a target molecule of mRNA
• The enzyme highlight is the mRNA this prevents the translation