L26

Question 1

What are Somites?

Answer 1

Forms vertebral structures and back muscles –> move after some times because the cells have specialised

Question 2

What do the cells look like at the 8 cell stage?

Answer 2

Rough, all the cells are the same

Question 3

What would happen if you were to take a cell out from the 8 cells?

Answer 3

The cells can compensate for the loss because all the cells are the same at this point

Question 4

What happens if you split the 8 cells into 2 4cell halves

Answer 4

Formation of twins

Question 5

What happens during cell polarisation?

Answer 5

The cells form a distinct structure with a gap in the middle, adhesions of the cells alongside each either and formation of microvilli on the outside

Question 6

Compaction

Answer 6

The cells join together asymetrically and there is asymmetric division of cells that form an outer and inner layer

Goes from rough to smooth

Question 7

What are the apolar cells?

Answer 7

The inner cells that are cut off from the uterine surroundings and take a different developmental path i.e they form the blastocyst (embryo)

Question 8

Trophectoderm

Answer 8

The formerly polar layer, its the embryos contribution to the placenta

Question 9

Totipotent

Answer 9

Naive cells, found during the 8 stage development, can turn into any cell including trophectoderm

Question 10

Pluripotent

Answer 10

The inner embryonic cells, can transform into any cell EXCEPT trophec

Question 11

Terminally differentiated

Answer 11

When the cell is specialised
*Can only do 1 job
*When divides, daughter cells are identical

Question 12

Exception to differentiation

Answer 12

Need to keep some cells aside for passing on info and growth
*Germ cells don’t differentiate
*Stem cells, somewhat differentiated but not so much, can still form a few different cell types (found in renewal tissue and provides us with new cells)

Question 13

The more specialised a cell is

Answer 13

The less flexible

Question 14

Why don’t embryonic precursor cells not produce a specific protein

Answer 14

Its because the specific genes are turned off eg myoD
If gene is not being transcribed, no protein is formed

Question 15

What happens to precursor cells by chance?

Answer 15

By chance, forms a specific cell eg muscle cell
*Determined as it can change if we mess with it but otherwise it activates other muscle genes that it would work with

Question 16

What does the Master regulatory gene produce

Answer 16

Protein MyoD protein that is a transcription factor
*goes back into nucleus and binds on regulatory areas on genes and turns them on/off

Question 17

MyoD protein does…

Answer 17

Goes to its own gene and keeps the gene to produce myoD on
*Then more MyoD goes to other genes and turn them on, they produce their own transcription factors that bind to other regulatory genes –> myosin and cell-cycle blocking

Question 18

What is cell cycle blocking?

Answer 18

The cell stops dividing into different types and specialises due to the transcription factors turning on specific genes

Question 19

How do muscle fibres form?

Answer 19

Fuse into cincitia, no obstruction of the outer discs of cell

Question 20

Cloning experiments

Answer 20

*Pluripotent nuclei from a frog embryo taken an implanted in an Enucleated frog egg
- As pluripotent, was able to develpp into embryo

*intestinal nucleus implanted in Enucleated frog egg, most didn’t develop but some did, could be because the specialised cell couldnt revert back to embryonic stage

Question 21

How is the nucleus in a frog egg destroyed

Answer 21

Using UV light

Question 22

What did the cloning experiments prove?

Answer 22

That all DNA is retained in adult cells

Question 23

How are embryonic stem cells made?

Answer 23

*Harvested from blastocyst from mammalian embryos
*Cells are pluripotent and under the right conditions and cues + chem condition, it can be transformed into any tissue/cell that we want
*Identical to donor but can be tissue matched

Question 24

What are Induced Pluripotent Stem Cell (iPS)

Answer 24

*Turn on genes that make a cell embryonic
*Using adult stem cells –> make embryonic –> pluripotent using flibroblasts from skin or blood cells
*Removes the ethical dilemma
*Cell tissue matched to you and can be made into any cell type

Question 25

Adult STEM cells

Answer 25

*Renews tissue
*Divides without limit - dont live very long
*Undifferentiated multipotent cells - only divide into 2-3 different types based on their specialised area
*Divides asymmetrically to give rise to stem cells and cells that will go on to differentiate into specialised tissue

Question 26

Umbilical cord STEM cells

Answer 26

*Full of immature STEM cells
*Frozen with dry ice or Nitrogen
*Multipotent, less restricted
*Treat siblings and matched patients

Question 27

How do STEM cells divide?

Answer 27

*Divides to give one STEM and one progenitor, which divides until it forms fat/bone/blood cells
*Can divide to give only progenitor cells but thats the end of the STEM cell

Question 28

Blood STEM cells aka

Answer 28

Haematopoietic STEM cells in bone marrow
Blood replaced every 6 weeks

Question 29

What kind of gene therapy is usually used?

Answer 29

Plasmid - temporary

Question 30

Integrated gene therapy

Answer 30

*Monogenic diseases where both copies of the allele are broken
*Use a virus vector to inject a healthy copy of gene into the targeted cells which gets integrated with DNA and becomes healthy
*Random and can go wrong

Question 31

Regenerative medicine

Answer 31

*Pluripotent STEM cells can be used to repair or replace damaged tissue
*made from stem cells of patient, donor or embryo
*Grow the organ/tissue in a lab and