1.1 Differentiation & Stem Cells Flashcards
What is cellular differentiation?
the process by which an unspecialised cell becomes altered and adapted to perform a specialised function as part of a permanent tissue.
When cells have differentiated what do they now have and what does that allow them to do?
a special shape or structure that allows them to carry out a specific function.
Once a cell becomes differentiated, what does it only express?
the genes that produce the proteins characteristic for that type of cell.
State how the cell structure of a ciliated epithelial cell relates to its function?
It has cilia which are like tiny hairs which beat rhythmically to sweep dirt and microorganisms upwards and away from the lungs.
In the trachea and Fallopian tubes/oviduct
State how the cell structure of a nerve cell relates to its function?
Long axons increase its surface area to allow electrical impulses to be passed onto other nerve cells.
Myelin sheath surrounds axons and insulates it which speed up electrical impulses.
State how the cell structure of a red blood cell relates to its function?
Biconcave disc shape gives it a larger surface area for transporting oxygen
It has no nucleus therefore there is more room for haemoglobin so more oxygen can be carried
It is small and flexible so it can fit through small blood vessels e.g. capillaries
State how the cell structure of a goblet cell relates to its function?
Secretes mucus to trap dirt and microorganisms
In the windpipe
What are tissues?
Groups of specialised cells which work together to perform a similar function
Give 4 examples of different tissues and their function?
Epithelial - forms a continuous sheet over body surfaces and inner body cavities
Connective - variety of functions - stores fat, fills spaces, provides support, forms blood cells - includes bone, blood and cartilage cells
Muscle - to produce force and cause movement, either locomotion or movement within internal organs
Nervous - Transmit messages in the form of electrical impulses
What are the levels of organisation in humans?
cells>tissues>organs>systems>organism
What are stem cells?
unspecialised cells that can divide to make copies of themselves (self-renew) and/or differentiate into specialised cells.
What are most of genes present in the DNA of stem cells?
they are still ‘‘switched on’’ so they can develop into different cell types
What are the 2 main types of stem cells?
embryonic stem cells
tissue (adult) stem cells
What are embryonic stem cells derived from?
an embryo that is about 4-5 days old, known as a blastocyst
What are embryonic stem cells called and what does this mean?
They are called pluripotent. This means the embryonic stem cells can develop into any of the 200 plus cell types of the adult body.
How is the use of embryonic stem cells very controversial?
Because research using embryonic stem cells involves the destruction of embryos.
What do those who support the use of embryonic stem cells say?
that it is left over embryos from fertility treatment which are used.
Once the time limit for keeping spare embryos is up, they are destroyed anyways, it is better not to waste them, but to use them in research that could benefit people.
What is the only specialised cells in which embryonic cannot become?
placental cells
What can adult tissue stem cells be used to do?
replace cells that die or restore tissue after injury
Give 4 examples of tissues which contain there own stem cells?
skin
muscle
intestine
bone marrow
What are adult tissue stem cells called and what does this mean?(3)
They are called multipotent. This means they have the ability to divide into only several distinct cell types, usually similar to the tissue which surrounds them. They give rise to a more limited range of cell types, compared to embryonic stem cells.
What is bone marrow?(2)
the tissue found in the centre of larger bones and is the place where new blood cells are produced.
What are the 3 types of blood cells produced from bone marrow?
red blood cells
white blood cells
platelets
