The control of gene expression Flashcards
0Define gene expression
The process of converting genetic information into functional proteins
Define differentiation
Process by which cell becomes specialised for a particular function
Define stem cell
Cells that have the ability to differentiate into specialised cells
Define totipotent
Can differentiate into any type of cell
Define pluripotent
Can differentiate into most type of cells
Define multipotent
Can differentiate into a limited number of cell
Define unipotent
Can differentiate into a single type of cell
What are the stem cell characteristics in an embryonic stem cell
From embryos up to 16 cell stage they are totipotent. 16 cell stage to blastocyst are pluripotent
What are the stem cell characteristics of an umbilical stem cell
From umbilical cord blood and are multipotent
What are the stem cell characteristics of a placental stem cell
Found in the placental and developed into specific cells, multipotent
What are the stem cell characteristic of an adult stem cell
Found in tissues of foetus and adult. Specific to a particular tissue and maintain/ repair that tissue. Can be multipotent or unipotent
What is the key feature of the IPS cells that is important for medical research and treatment
They are capable to self-renew themselves so can make large quantities
List some of the ethical objections to use embryonic stem cells
- Using embryos undermines our respect for human life
- Could progress to the use of fetuses or newborn babies
- Could lead to cloning
List some of the arguments for using embryonic stem cells
- Wrong to allow human suffering to continue when there is a possibility of alleviating it
- Ball of cells doesn’t represent humans
- Laws have provided enough protection against cloning
Define transcription factor
A protein or molecule that moves from the cytoplasm to the DNA and binds to a specific base sequence of the DNA molecule
Define promotor
DNA sequence before gene allowing RNA polymerase to bind to initiate transcription
Describe how Oestrogen (hormone) effects transcription
1) Oestrogen binds to the receptor on TF as complementary in shape
2) Shape of the DNA binding site on TF changes
3) TF binds to the promotor on the DNA
4) Easier for RNA polymerase to bind to the promotor
5) Transcription occurs
Define epigenetics
Environmental factors can cause heritable changes in gene function without changing the base sequence of DNA
How does adding methyl groups to DNA ( specifically cytosine) change gene expression
. DNA more tightly packed
. Harder for genes to be transcribed
. Transcription factors cannot bind
. Genes switched off / not expressed
How does adding acetyl groups to histones change gene expression
. DNA more loosely packed
. Genes can be transcribed more easily
. Transcription factors can bind
. Genes switched on / expressed
Describe how gene expression can be inhibited by RNA interference ( RNAi) of translation
- Large double stranded RNA molecule are cut into smaller sections called small interfering RNA, by an enzyme. Lots of small interfering RNA around 21 nucleotides long
- One of the two small interfering RNA strands ( guide strand) combines with an enzyme
- The small interfering RNA strand guides the enzyme to the mRNA and the small interfering RNA guide strand pairs with complementary bases on mRNA strand
- The enzyme cuts the mRNA into smaller sections so it can no longer be translated
Define cancer
Diseases caused by damage to genes that regulate mitosis and the cell cycle leading to uncontrolled Mitosis. Forms abnormal mass of cells called a tumour
Define benign tumour
(Non cancerous), gorws slowly and does not spread. Mitosis occurs at the centre of tumour
Define Maligant tumour
(Cancerous), grows quickly and spread. Mitosis occurs at the edges of the tumour
Define metastasis
Movement of cancerous cells around the body
