Unit 8

Question 1

define epigenetics

Answer 1

-heritable changes in gene function
-without changes to base sequence of DNA

Question 2

Explain how increased methylation could lead to cancer

Answer 2

-methyl group could be added to a tumour suppressor gene
-the transcription of tumour suppressor genes is inhibited
-leading to uncontrollable cell division

Question 3

Describe how mutations may lead to cancer

Answer 3

-change in DNA base sequence
-of oncogene/tumour stressor gene
-non functional protein formed
-tumour supressor genes produce proteins that slow cell division
-uncontrollable cell decision forming cancer

Question 4

Evaluate the use of stem cells in treating human disorder

Answer 4

-benefits: stem cells could be used to grow organs to save lives, bone marrow stem cells are used to treat blood cancer
-issues: obtaining embryonic stem cells involves the destruction of embryo

Question 5

Define stem cells

Answer 5

-Stem cells are unspecialised cells that continually divide and can divide into other types of cells.

Question 6

what is translocation mutation

Answer 6

-a section of bases on one chromosome dettaches and attaches onto another chromosome

Question 7

totipotent stem cell

Answer 7

-can divide and produce any type of body cell
-occur in the very early stages of mammolian embryo

Question 8

pluripotent stem cell

Answer 8

-can divide and produce almost every cell - not placenta cell
-found in the embryo

Question 9

multipotent stem cell

Answer 9

-found in mature mammals - bone marrow
-can divide and produce a limited number of cells

Question 10

unipotent stem cell

Answer 10

-found in mature mammals
-can divide and produce a limited number of cells eg cardiomyocytes

Question 11

explain how oestrogen can initiate the transcription of target genes

Answer 11

-it diffuses through the membrane into the cell
-it binds to the transcription factor ERa oestrogen receptor in the cytoplasm which is being held in a protein complex, which now changes shape and releases it
-the ERa oestrogen enters the nucleus binding to the promoter region of it’s target gene - stimulating RNA polymerase to transcribe that target gene