stem cells

Question 1

what is differentiation

Answer 1

the process of a cell becoming specialised

Question 2

what are stem cells

Answer 2

undifferentiated cells that are not adapted to any particular function and have the potential to differentiate to become any one of the range of specialised cell types in the organism

Question 3

what happens to stem cells once they become specialised

Answer 3

• they lose the ability to divide and enter the G0 phase of the cell cycle

Question 4

what is potency

Answer 4

a stem cell’s ability to differentiate into different cell types

Question 5

totipotent

Answer 5

• can differentiate into any type of cell (fertilised egg, first 8/16 cells from mitotic divisions)
• can differentiate into extra embryonic tissues

Question 6

pluripotent

Answer 6

• can form all tissue types but not whole organisms
• present in early embryos and are the origin of the different types of tissue in an organism

Question 7

multipotent

Answer 7

• can only form a range of cells within a certain type of tissue
• (e.g. haematopoetic stem cells in bone marrow differentiate into blood cells

Question 8

name for red blood cells

Answer 8

erythrocytes

Question 9

name for white blood cells

Answer 9

neutrophils

Question 10

where are all blood cells derived from

Answer 10

stem cells in the bone marrow

Question 11

role of erythrocytes

Answer 11

• transport of oxygen around the body
• maximise their oxygen carrying capacity by having few organelles to make room for haemoglobin
• biconcave disc shape provides large surface area for gas exchange
• no nucleus
• short lifespan of 120 days so replaced constantly

Question 12

role of neutrophils

Answer 12

• immune system
• live for 6 hours
• flexible shape allows them to engulf foreign particles
• many lysosomes contain digestive enzymes to break down the engulfed particles

Question 13

embryonic stem cells

Answer 13

• present in early stage of embryo development
• totipotent
• after 7 days, blastoclyst is formed which is pluripotent

Question 14

tissue (adult) stem cells

Answer 14

• present throughout life from birth
• found in bone marrow
• harvested from umbilical cord
• multipotent

Question 15

source of plant stem cells

Answer 15

• meristematic tissue
• found where growth occurs (tips of roots or shoots)
• found in vascular cambium in between xylem and phloem
• pluripotent

Question 16

uses of stem cells

Answer 16

• heart disease
• type 1 diabetes
• Parkinson’s disease
• Alzheimer’s disease
• macular degeneration
• birth defects
• spinal injuries
• treatment of burns
• drug trials
• developmental biology