stem cells

Question 1

`Explain why the lac operon is not transcribed when lactose is absent.

Answer 1

lacI produces repressor protein

Repressor binds to operator

Blocks RNA polymerase binding/ movement

No transcription of lacZ, lacY, lacA

Question 2

State the role of β-galactosidase in lactose metabolism.

Answer 2

breaks lactose into galactose and glucose

Question 3

Describe what happens in the lac operon when lactose is present. (PPQ)

Answer 3

Lactose acts as an inducer

Binds to repressor → changes its shape

Repressor cannot bind operator

RNA polymerase binds to promoter

Transcription occurs

Question 4

what does poly genic mean

Answer 4

a characteristic showing continous variation caused by multiple genes at different loci

Question 5

whats the difference between tissue and organ

Answer 5

a tissue is a group of cells organ is a group different of tissues

Question 6

what are the arguments against stem cell reaserch

Answer 6

comes from non consenting donor an embryo

need more reaserch

source of embryonic cells has to be regulated

Question 7

what is a totipotent cell

Answer 7

a cell that has the ability to differentiate into all cell types

Question 8

how do cells become specialised

Answer 8

chemical signs are sent to cell that cause some cells to be turned on

only activated genes produce mRNA

mRNA leads to specific proteins that cause cell modification

Question 9

why cant stem cells from the heart be used to repair the cornea

Answer 9

stem cells in the heart are pluripotent

so some genes have already been activated or deactivated

there fore they will not be able to specialise into cornea cells

Question 10

why can chemicals from the eyes be used to produce corneal celld from a suitable source of stem cells

Answer 10

cells in the chemicals from the eye have genes that have been activated or deactivated

which means they can transcibe to produce specific mRNA

pecific mRNA is translated into specific proteins

that cause the cell to develop into a corneal cell

Question 11

what is a stem cell

Answer 11

an undifferentated cell that can give rise to specialised cells and that can divide to produce new stem cells

Question 11

why would a person have a greater height than there biological parents

Answer 11

height is effected by environment and geneotype

height is a polygenic characteristic

can be effected by diet

Question 12

whats a continuous gene

Answer 12

something that effected by environment

Question 13

what is a disocntinuous gene

Answer 13

some thing effected by the genotype of a eprson