Gene expression Flashcards
(51 cards)
1
Q
What are stem cells?
A
- Unspecialised cells
2
Q
What are totipotent cells?
A
- Stem cells that differentiate into any type of specialised cells
- Can form placental cells
- Exist for a limited time
3
Q
Where are totipotent cells found?
A
- Very early stages of embryos
4
Q
What are pluripotent cells?
A
- Stem cells that can differentiate into many types of specialised cells
- But can’t form placental cells
5
Q
Where are pluripotent cells found?
A
- Embryos
6
Q
What can pluripotent cells be used for?
A
-Treating different human disorders
7
Q
What are multipotent cells?
A
- Stem cells that differentiate into a few types of specialised cells
8
Q
Where a multipotent cells found?
A
- Bone marrow of mature mammals
9
Q
What are unipotent cells?
A
- Stem cells that differentiate into one type of specialised cell
10
Q
Where are unipotent cells found?
A
- Mature mammals
11
Q
What happens when a gene is expressed?
A
- It is transcribed into mRNA and translated into a protein
12
Q
3 main sources of stem cells
A
- Adult bone marrow
- Embryos
- iPS - induced pluripotent stem cells
13
Q
What are the benefits of using stem cells in disease?
A
- Reduce preventable deaths
- Used to treat conditions that decrease the quality of life
14
Q
What are the disadvantages of using stem cells?
A
- Obtaining them from embryos is controversial (ethical)
- Using embryo stem cells is depriving an embryo of life
15
Q
Where are iPS produced from?
A
- Specialised adult somatic cell
16
Q
How are iPS cells produced?
A
- Somatic cells are converted to iPS cells by activating genes using transcription factors
- Somatic cells then become unspecialised
17
Q
What are bone marrow transplants used for?
A
- To treat blood and immune disorders
18
Q
Name a benefit of development biology?
A
- Can inform us why organs fail or have abnormalities
19
Q
What is a frameshift?
A
- When bases are inserted, duplicated or removed into the genome
20
Q
Advantage of using iPS then transplanting bone marrow?
A
- As it is generated from the same patient, it will have the same molecular markers
- It will not be rejected by the immune system as it is not recognised as foreign
21
Q
What are transcription factors?
A
- A protein that control gene expression by stimulating or inhibiting the transcription of target gene
22
Q
Where are transcription factors produced?
A
- Cytoplasm before moving to the nucleus
23
Q
What are activators?
A
- Transcription factors that stimulate gene expression
- They interact with RNA polymerase and allowing it to bind to DNA
24
Q
What are repressors?
A
- Transcription factors that inhibit gene expression
- Stop RNA polymerase from binding to DNA
25
How does oestrogen react with DNA?
- Oestrogen enters the cytoplasm as it is lipid soluble
- It binds to receptors on transcription factors causing them to change shape
- Transcription factors form a receptor-hormone complex that enters the nucleus
- Receptor-hormone complex binds to promoter region of DNA
- This activates transcription, stimulating protein synthesis
26
What is chromatin?
- A combination of DNA and histones
27
What is an epigenome?
- A chemical layer that surrounds the chromatin
28
How does the epigenome affect the chromatin
- Makes it more condensed - preventing transcription factors from binding, inhibiting transcription
- Makes it less condensed - easier access for transcription factors, promoting transcription
29
What are epigenetic markers?
- A group that does not alter the base sequence but influences the chromatin's structure
- Eg, Methyl or Acetyl groups
30
How does increased methylation inhibit transcription?
- Methyl groups bind to CpG site on DNA causing the chromatids to condense
- So transcription factors can't reach DNA
31
How does decreased acetylation inhibit transcription?
- Acetyl groups are removed from histones
- Increasing the positive charge on histones, increasing attraction with phosphate groups in DNA
- Causing the chromatin's to condense
- So transcription factors cannot bind
32
What is abnormal methylation?
- When methylation is not regulated, leading to uncontrollable cell division
- Which can disease
33
What is a tumour suppressor gene?
- Prevent cell division
34
What happens is methylation is increased too much
- It can decrease the expression of the tumour suppressor gene
- So cells divide uncontrollably and tumours are produced
35
What happens if methylation is decreased too much?
- It can increase the expression of proto-oncogenes
| - So cells divide uncontrollably leading to the formation of a tumour
36
What is a proto-oncogene?
- It promotes cell division
37
What is translation?
- A process where proteins are synthesised using genetic code
38
What is RNAi?
- A small molecule of double-stranded RNA
| - It interferes with mRNA by breaking it down, so it cannot be translated
39
What is siRNA?
- A type of RNAi that is complementary to the mRNA sequence it inhibits
- It targets a specific region on the mRNA before breaking it down into smaller fragments which are degraded
40
What is miRNA?
- It is not fully complementary to the mRNA sequence
- It can target multiple sequences
- After it binds, the mRNA is either degraded or stored
41
How can gene expression be measured?
- Through microarrays
42
What are microarrays?
- A way of studying the extent in which certain genes are expressed in a cell
43
What is benign tumour?
- Not cancerous
- They divide uncontrollably but do not spread to other tissues
- But can develop into malignant tumours
44
What are malignant tumours?
- Cancerous
- Cells divide uncontrollably and spread to other tissues
- Can be life threatening and grow rapidly
45
What hormone is associated with breast cancer?
- High levels of oestrogen
46
What environmental factors are associated with cancer?
- Exposure to radiation
- Smoking
- Alcohol consumption
- Diet high in fat
47
What is correlation?
- A relationship between 2 different variables
48
What determines the intensity of treatment required?
- Type of mutation
49
What is an inversion mutation?
- Where the order of bases in the DNA sequence are reversed
50
What are translocation mutations?
- Where a section of the DNA sequence is moved to another section of the DNA sequence
51
What can cause mutation?
- Mutagenic agents
| - An error in DNA replication
