3.8.2.1 cells dna thats not transcribed

Question 1

what are stem cells

Answer 1

undifferentiated / unspecialised cells
that can divide by mitosis to replace themselves indefinitely and can differentiate into other types of specialised cells

Question 2

how do stem cells become specialised during development

Answer 2

stimuli lead to activation of some genes due to transcription factors
so mRNA is transcribed only from these genes and then translated to form proteins
these proteins modify cells permanently and determine cell structure and function

Question 3

describe totipotent cells

Answer 3

occur for a limited time in early mammalian embryos
can divide and differentiate into any type of body cell including extra embryonic cells

Question 4

describe pluripotent cells

Answer 4

found in mammalian embryos
can divide and differentiate into most cell types

Question 5

describe multipotent cells

Answer 5

found in mature mammals
can divide and differentiate into a limited number of cell types

Question 6

describe unipotent cells using an example

Answer 6

found in mature mammals
can divide and differentiate just one cell type
ex unipotent cells in the heart can divide and differentiate into cardiomyocytes

Question 7

explain how stem cells can be used in treatment of human disorders

Answer 7

transplanted into patients to divide in unlimited numbers
differentiate into required healthy cells
replaces faulty cells

Question 8

Explain the two steps in bone marrow stem transplant
1. Destroy patients bone marrow before treatment
2. Transplant cells from healthy person

Answer 8

1. so no faulty cells are produced
2. divide and differentiate into healthy cells

Question 9

Explain how induced pluripotent cells are produced

Answer 9

obtain adult somatic cells from patient
add specific transcription factors associated with pluripotency to cells so they express genes associated with pluripotency
transcription factors attach to promoter regions of DNA to stimulate or inhibit transcription
culture cells to allow them to divide by mitosis

Question 10

pros of using stem cells in treating human disorders

Answer 10

1. can divide and differentiate into required healthy cells so could relieve human suffering by saving / improving quality of life
2. embryos left over from IVF would other wise be destroyed
3. iPS cells are unlikely to be rejected by patients own cells
4. iPS cells can be made without destruction of embryo and adults can give permission

Question 11

Cons of use of stem cells in treating human disorders

Answer 11

1. Ethical issues with embryonic stem cells as obtaining requires destruction of an embryo (cannot consent )
2. Immunosuppressant drugs are required, risk of rejection
3. Cells could divide out of control, leading to tumours or cancers