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a level biology > stem cells and totipotency > Flashcards

stem cells and totipotency Flashcards

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1
Q

define cell differentiation

A

the process by which cells develop into specialised cells

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2
Q

why does cell differentiation occur

A

no one cell can provide the best conditions for all functions. More efficient if they are adapted to their function

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3
Q

what role does cell differentiation have in gene expression

A

all cells derived from mitotic division of zygotes
contain all genes, therefore capable of making all proteins. Only certain genes are expressed (switched on) in any one cell at one time. Some genes are permanently expressed in all cells (like those that produce enzymes for respiration). Some genes permanently switched off in certain cells

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4
Q

once specialised can stem cells develop into other types of cells

A

most specialised cells can no longer develop into any type of cell

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5
Q

what is a stem cell

A

the only type of cells that can differentiate

self renewal - stem cells’ ability to divide and form an identical copy

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6
Q

define self renewal

A

stem cells’ ability to divide and form an identical copy

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7
Q

what are the 4 sources of stem cells in humans

A

embryonic stem cells

umbilical cord stem cells

placental stem cells

adult stem cells

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8
Q

what is an embryonic stem cell

A

from early stage of embryo development, can become any type of cell

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9
Q

what is an umbilical cord stem cell

A

from umbilical cord, similar to adult stem cells

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10
Q

what is an placental stem cell

A

in placenta, develop into specific types of cell

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11
Q

what is an adult stem cell

A

found in body tissues of all ages. Specific to particular tissue/organ and produce cells to maintain and repair tissue

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12
Q

what are totipotent cells

A

totipotent cells can develop into all types of cell

in early embryo (zygote) can develop into any type of cell
develops into a pluripotent cell

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13
Q

how do totipotent cells become specialised

A

during specialisation only some genes are expressed so the cell only makes the proteins it needs to carry out its specialised function. A variety of stimuli ensure that the genes that are not needed stay switched off.

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14
Q

how are genes prevented from being expressed in totipotent cells

A

prevent transcription and therefore production of mRNA

prevent translation

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15
Q

list the 4 types of stem cells

A

totipotent

pluripotent

multipotent

unipotent

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16
Q

describe what pluripotent cells are

A

in embryos

become almost any type of cell

e.g: embryonic and foetal stem cells

17
Q

give 2 examples of pluripotent cells

A

embryonic and foetal stem cells

18
Q

describe what multipotent cells are

A

in adults

differentiate into a limited number of specialised cells

e.g: bone marrow stem cells make blood cells, adult stem cells, umbilical cord stem cells

19
Q

give 3 examples of multipotent cells

A

e.g: bone marrow stem cells make blood cells, adult stem cells, umbilical cord stem cells

20
Q

describe what unipotent cells are

A

differentiate into a single type of cell

derived from multipotent cells and found in adult tissue

21
Q

where are unipotent cells found

A

in adult tissue

22
Q

explain the importance of iPS

A

type of pluripotent cell produced from unipotent cell (which could almost be any body cell). Body cell altered in lab to give it characteristics of an embryonic stem cell. Causes genes and transcriptional factors in the cell to be expressed that are normally switched off (shows the genes are still there just inactive). Same as embryonic in form and function, express same genes but not exact duplicates. Can self renew so limitless supply ideal for medical research and treatment and avoid ethical issues from use of embryonic stem cells

23
Q

what are the uses of iPS

A
  • disease pathophysiology
  • identifying novel drug targets
  • drug screening
24
Q

describe some evidence that all cells contain all genes but they are “switched off” in some cells

A

ips - unipotent cells can be altered to act like pluripotent cells and produce the proteins of an embryonic stem cell

25
Q

give examples of how pluripotent cells can be used in treating human disorders

A
  • cells can be used to regrow tissues that have been damaged
  • skin grafts for burns
  • heart muscle cells for heart damage
  • nerve cells for MS
  • blood cells for leukaemia
  • bone cells for osteoporosis

a level biology (62 decks)

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