Unit 1.1 Division & differentiation in human cells Flashcards
Name to describe an organism that consists of many cells
Multicellular
What is a somatic cell
Any cell in the body other than cells involved in reproduction
What do somatic cells divide by & what does this produce
Mitosis to produce more somatic cells
What are somatic cells produced by
Cellular differentiation
2 examples of somatic cells
Muscle cells, red blood cells
What are germline cells
Gametes & the stem cells that divide to form gametes
What do germline cells divide by
Mitosis & meiosis
What does mitosis in germline cells produce
More germline cells (diploid)
What are diploid cells
Cells containing 23 pairs of homologous chromosomes
What are homologous chromosomes
Chromosomes of the same size, with the same genes in the same position
What does meiosis in germline cells produce
Haploid gametes
What are haploid gametes
Gametes (sex cells) containing 23 single chromosomes
Differences between mitosis & meiosis in germline cells
Mitosis - 1 stage of division to produce 2 diploid germline cells
Meiosis- 2 stages of division to produce 4 haploid gametes
What happens in the first division of meiosis
The first division separates the homologous chromosomes
What happens in the second division of meiosis
The second division separates the chromatids
What is cellular differentiation
The process by which a cell expresses certain genes to produce proteins characteristic for that type of cell
What does cellular differentiation allow
The cell to carry out specialised functions
What are stem cells
Unspecialised somatic cells with the ability to become specialised cells
The 2 types of stem cells
Embryonic & tissue
The 2 things stem cells can do
Reproduce & differentiate
What does it mean for a stem cell to reproduce
‘Self-renews’ by carrying out mitosis to produce new cells
What does it mean for a stem cell to differentiate
Change into specialised cells when required by the organism
Are embryonic stem cells pluripotent or multipotent
Pluripotent
What does pluripotent mean
Embryonic stem cells can differentiate into all cell types that make up the individual
Where are embryonic cells found
An embryo that is 4-5 days old (blastocyst stage- ball of cells)
Why are embryonic stem cells pluripotent
All the genes in embryonic stem cells can be switched on, so these cells can differentiate into any type of cell
What are tissue stem cells also known as
Adult stem cells
Are tissue stem cells pluripotent or multipotent
Multipotent
What does multipotent mean
They can only differentiate into cell types found in that specific tissue type
Give an example of a multipotent cell & what it can differentiate into
Blood stem cells (found in bone marrow) can give rise to red blood cells, platelets, phagocytes & lymphocytes
Where are tissue stem cells found
In specific areas of the body (eg bone marrow)
What do tissue stem cells do
They are involved in the growth, repair, & renewal of the cells found in that tissue
What happens once a cell becomes differentiated
It only expresses the genes that produce the proteins characteristic for that type of cell
What is the difference between pluripotent & multipotent stem cells
Pluripotent cells can differentiate into ALL cells in the INDIVIDUAL.
Multipotent cells can only differentiate into cells found in a PARTICULAR TISSUE type.
What does therapeutic uses of stem cells involve
the repair of damaged or diseased organs or tissues
Examples of therapeutic uses of stem cells
Corneal repair, skin grafts for burn victims, & bone marrow transplants for treatment in leukaemia
What is a cornea
The eyes outermost layer, which plays an important role in focussing your vision
How can the cornea become damaged
By chemical burning
How can cornea damage be treated
By stem cell therapy:
Stem cells located in the corner of the healthy cornea can be grafted onto the damaged cornea
Advantage of stem cell therapy in cornea repair
No risk that the transplanted tissue will be rejected as its the patients own stem cells
What are skin grafts used for
Treating burn victims
Explain the process of a traditional skin graft
It involves taking a large section of skin from a healthy region of a persons body & grafting it onto the injured site
What is a downside to traditional skin grafts
The person will have 2 areas of skin to heal
Why are using stem cells for skin grafts a good idea
Only a sample of skin is required to obtain stem cells
Explain the process of skin grafts using stem cells
Enzymes are used to isolate the stem cells from the skin.
The stem cells are then cultured in the lab.
Once a suspension of new stem cells are developed, they are sprayed over the damaged area to bring around regeneration of missing skin.
What do research uses of stem cells involve
Using them as model cells to study how diseases develop & drug testing.
Also provides info on how cell processes work (such as cell growth & differentiation)
Why are embryonic stem cells ideal for carrying out research on
They are pluripotent
Why is it controversial to use embryonic stem cells in research
They offer very effective treatment for diseases & injury. However, using them destroys embryos- which many people believe is a destruction of life
Where do the embryos used in stem cell research come from
They are spare embryos from IVF treatment
Why do cancer cells divide excessively
They do not respond to regulatory signals
What happens when cancer cells divide excessively
A mass of abnormal cells is formed (a tumour)
How can tumours spread
Cells within the tumour may fail to attach to each other, spreading through the body where they may form secondary tumours
