Mutation And Gene Expression - 8A Flashcards
Mutation
- any change to the base sequence of DNA
Types
Substitution, deletion, addition, duplication, inversion, and translocation
translocation = one part of DNA move within the chromosome or to diff on
What does change in mutation cause
Order of DNA determines sequence of AA = change polypeptide made- change the tertiary stu (3D shape )
- frame shift
Hereditary mutation
If there is a mutation in gamete (sex cell)
Why not all mutation effect protein
Due to the denature nature of the AA
- diff bases code for the same amino acid
Why mutation effect the protein
- if mutation = cause frame shift
- change in the base triplets that’s read so diff AA
Mutagenic agents
- increases the rate of mutation
1 . Acting as a base =** chem** called base analog can substitute bases during DNA replication
2 . Altering bases = some chem delete / alter base
3 . Changing the stu of DNA = some can change the DNA structure and can be problematic during DNA Replication
Cancer
If mutation occur = cause uncontrollable cell division = tumour ( mass of abnormal cells )
- tumors that invade surrounding tissues = cancer
Tumour suppressor gene
- when functioning normally - slows down cell division - producing protein / cause them to self destruct
- mutation = gene inactive - uncontrollable cell division
Proto-oncogenes
when functioning normally - stimulate cell division
- if mutation - stimulate uncontrollable cell division
- mutated proto-oncogene = oncogene
Malignant tumor
- cancer
- grow rapidly , invade and destroy surrounding tissues
- cells can break off the tumours and spread to other parts of the body
Benign tumors
not cancerous
- not invade / destroy cells
- put pressure / block organ
features of tumor cell
- nuclesus is larger and darker
- irregular shape
- not respond to bodies growth regulating process
- have different antigens on their surface
- divide (by mitosis) more frequently than normal cells
Causes of tumour growth
abnormal methylation
- controls if gene is transcribed and translated or not
-
- hypermethylation = genes not trans - no protien
- hypomethylation = gene trans - inc protien - stimulate growth
Role of oestrogen in brest cancer
- ostrogen can stimulate certain brest cell to divide and replicate ( more division higher chances of mutation )
- oestrogen ability to stimulate division rapidly - if mutation, helps tumour growth more quickly
- oestrogen able to** intro mutation directly** into the DNA
Risk factor of cancer
- genetic factor
- environmental factor
what is stem cell
stem cell= undiffrenciated cell - can become any type of cell
Types of stem cell
- toripotent = can differneciate into any cells
- pluripotent = intop any cell except placenta
- multipotent = into few diff type of cell
- unipotent - only one
Becoming specialised
- all DNA = same
- during development -not all transcribed and translated - not expressed ( depends on conditions)
- gene expressed - mRNA transcribed and tranlated into protein
- protein modify the cell - cell becomes specialised for a particular function
- cell become specialised for a particular function
protein modify the cell = determines the cell stu and control cell processes
Stem cell therapy - bone marrow transplants
- become specialised to form type of blood cell
- use to replace faulty bone marror of pt
- use to treat leukaemia and lymphoma
- also treat sickle-cell anaemia
sources of stem cell
- adult stem cell = obtained by simple operation, only specialised into limited range of cells
- embroyonic stem cell = from IVF (in vitro )- once 4-5 days old = stem cell removed and rest = destyroyed ( pluruipotent )
- Induced pluripotent stem cells (iPS cells)
Induced pluripotent stem cells (iPS cells)
- process = reprogramming specialised adult body cells - become pluripotent
- specially odified virus - contains genetic code to produce transcriptional factors
- virus infect adult cell = pass genetic material
- adult cell able to produce TF
-TFv = helps turn on / off gene by binding to DNA
Controlling transcription
- transcription of gene - controlled by transcriptional factors
- TF = move from cyto to nuc - bind to DNA site ( promotor ) - found at the start of the target gene
- TF = control expression by controlling the rate of trans
- TF = activator and repressor
Type of transcription factor and it’s function
- activator = stimulate or inc rate of transcription ( help RNA polymerase bind to start of target gene )
- repressor = inhibits or decrease rate of transcripgtion ( bind to start oif gene and prevent RNA polymerase from binding )
Oestreogen
- steroid hormone - binds to TF called oestrogen receptor ( from oestrogen oestrogen receptor complex )
- complex move form cyto to nuc - find to specific DNA = act as activator - RNA polymerase bind
