B2.1 Supplying the Cell - Differentiation & Stem cells Flashcards

2.1.5 Differentiation 2.1.6 Stem cells

1
Q

What is differentiation?

A

Process by which stem cells become specialised into different types of cells

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2
Q

What is produced once a sperm cell enters an egg?

A

Zygote

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3
Q

By what process does a zygote divide?

A

Mitosis

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4
Q

The zygote is composed of what type of cells?

A

Stem cells

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5
Q

When does a zygote become an embryo?

A

3-5 days after fertilisation

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6
Q

How do the cells of a zygote differ from an organisms somatic cells?

A

They are unspecialised and can therefore differentiate into any type of specialised cell.

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7
Q

Where are stem cells found in animals?

A

Embryos - Embryonic stem cells Brain, bone marrow, skin, liver - Adult stem cells N.B Multipluripotent stem cells have also now been isolated in the umbilical cord

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8
Q

Where are stem cells found in plants?

A

The meristems - unspecialised cells found in the root tips, shoot tips and in rings around the stem

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9
Q

How do the cells in the meristem differ from normal plant cells?

A

Differentiated plant cells cannot divide as they have thick & rigid cell walls Meristem cells are much smaller, have thin walls, small vacuoles and no chloroplasts

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10
Q

State a key difference between specialised plant and animal cells?

A

Once differentiated animal cells can only divide to produce that specialised cells. Plant cells however, under the right conditions, can become unspecialised and then re-specialise in order to adapt to their environment.

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11
Q

Name 5 types of specialised cells that a stem cell could differentiate into.

A

Animal

  • Gamete e.g sperm cell, ovum
  • Muscle cell
  • Adipocyte cell
  • Osteoblast
  • Blood cell e.g erythrocyte, neutrophils
  • Nerve cell
  • Cilliate epithelial cell
  • Goblet cell

Plant

  • Palisade cells
  • Root hair cell
  • Guard cell
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12
Q

How is a red blood cell specialised for its role?

A
  • Biconcave discs - increases surface area
  • Haemoglobin - binds to and releases oxygen
  • Enucleated - more room for oxygen transport
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13
Q

How is sperm cell is specialised to transfer genetic material?

A
  • Flagellum - movement
  • Mitochondria - provide energy for movement
  • Acrosome - contains digestive enzymes to allow breakdown the outer membrane of ovum
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14
Q

How is an adipocyte specialised for its role?

A
  • Can expand to 1000 times original size
  • Small layer of cytoplasm
  • Fat reservoir.
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15
Q

What is the function of a goblet cell?

A

Produces mucus to trap dust mucus and bacteria which the cillia then waft back up the throat to be swallowed.

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16
Q

How are palisade cells adapted for their function?

A
  • regularly shaped - can be closely packed cells that form a continuous layer at the top of the leaf
  • Large surface area - able to absorb more light for photosynthesis
  • Packed with chloroplasts - for photosynthesis
17
Q

How are guard cells adapted for their function?

A
  • Surround the stoma and regulate the rate of transpiration and CO2 uptake.
  • Inner wall thicker causing the โ€˜bean-likeโ€™ shape and gap when turgid
  • Open to allow exchange
  • Close to prevent exchange
18
Q

What type of cells can adult stem cells differenetiate into?

A

Only into cells from the type of tissue where they are found.

19
Q

Why are adult stem cells not as useful for medical research?

A

They only differentiate into a narrow range of cell types

20
Q

What are embryonic stem cells and why are they more useful to stem cell research?

A
  • Cells taken from 3-5 day old zygotes
  • Thye can specialise into any type of specialised cells
  • Potential to cure and treat disease
21
Q

Why are embryonic stem cells controversial?

A

Embryos are killed to obtain the cells.

22
Q

What are induced-pluripotent stem cells and how may they be useful?

A
  • Adult somatic cells altered to have properties of embryonic stem cells
  • May allow use of reprogrammed cells instead of embryonic stem cells
  • Solution to immune system rejection of โ€˜foreignโ€™ stem cells
23
Q

How are root hair cells adapted for their function?

A