20- Gene expression

Question 1

What are the 6 types of mutation?

Answer 1

Addition
Deletion
Duplication
Inversion
Substitution
Translocation (ADDIST)

Question 2

What is the inversion mutation?

Answer 2

Inversion=Order of bases are inverted in DNA sequence.

e.g. ATCGTT> TTGCTA

Question 3

What is the translocation mutation?

Answer 3

Translocation= section of sequence is moved to ANOTHER section

-can be within & across chromosomes-

Question 4

What is the minimal effect of a mutation on amino acid sequence?

Answer 4

Substitution= Change to only ONE triplet codon

The new codon sometimes codes for the same amino acid and no change occurs in the protein

Question 5

Effect of addition, deletion, or duplication

Answer 5

ALL base triplets downstream from mutation change (frame shift).
This impacts many amino acids so very likely protein will not function as normal.

Question 6

Causes of mutation= (2)

Answer 6

1. DNA replication (spontaneous)

2. Mutagenic agents

Question 7

4 main types of stem cell

Answer 7

Totipotent
Pluripotent
Multipotent
Unipotent

Question 8

Features of totipotent cells

Answer 8

• Can divide & differentiate into ANY type of cell

- occur for LIMITED time in embryonic development

Question 9

Features of pluripotent cells=

Answer 9

• able to divide into UNLIMITED numbers & produce any type of cell
• TC’s develop into these in embryos
• PC can be used to treat human disorders

Question 10

Features of Multipotent cells=

Answer 10

• found in mature mammals
• can develop into LIMITED number
  of cell types

Question 11

Features of Unipotent cells=

Answer 11

• found in mature mammals

- can divide to produce only ONE type of cell (cardiomyocytes?)

Question 12

Which of the 4 types of stem cell is the most UNSPECIALISED

Answer 12

totipotent

Question 13

which 2 types of stem cell are found in embryos?

Answer 13

totipotent

pluripotent

Question 14

which 2 types of stem cell are found in mature mammals?

Answer 14

multipotent

unipotent

Question 15

How are IPS cells produced

Answer 15

somatic cells converted to IPS by activating genes using protein transcription factors
(they then become unspecialised)

Question 16

Benefits of IPS (2)

Answer 16

1. No ethical concerns (as made from patients own body cells)
2. Less risk of rejection during transplants (as made from patients own body cells)

Question 17

Stem cells can be taken from: (3)

Answer 17

1. Adult stem cells
2. Embryonic stem cells
3. Induced pluripotent stem cells (IPS)

Question 18

Benefits of stem cells use in treating human disorders

Answer 18

1. can reduce preventable deaths

2. Can treat conditions that decrease quality of life

Question 19

Disadvantages of using stem cells in treating human disorders

Answer 19

1. Ethical controversy surrounding embryo use (some believe you are depriving a life)

Question 20

Specific stem cell use= (3)

Answer 20

1. Bone marrow transplants
2. Drug research
3. Developmental biology

Question 21

What are Transcription factors?

Answer 21

proteins that control gene expression via STIMULATING or INHIBITING transcription.

Question 22

Transcription factors- ACTIVATORS

Answer 22

TF’s that STIMULATE gene expression

by interacting with enzyme RNA polymerase and allowing it to bind to DNA

Question 23

Transcription factors- REPRESSORS

Answer 23

TF’s that INHIBIT gene expression

they stop RNA polymerase from binding to DNA, preventing transcription

Question 24

Role of oestrogen in initiating transcription (4)

Answer 24

1. oestrogen is lipid-soluble, passes through PLBL > cytoplasm
2. binds to inactive TF which forms receptor-hormone complex & changes shape
3. enters and binds to promoter region of DNA
4. stimulates T of genes by helping RNA polymerase bind.

Question 25

How epigenetics controls gene expression

Answer 25

- epigenetic regulation interacts with DNA to control ACCESS to DNA - controlling access ALTERS gene expression without actually changing the DNA code

Question 26

Causes of heritable epigenetic changes in gene function= (2)

Answer 26

1. Increased methylation | 2. Decreased Acetylation

Question 27

Increased methylation process= (3)

Answer 27

- nucleosome more tightly packed - when more condensed TF's cant bind - genes not transcribed

Question 28

Decreased Acetylation process= (4)

Answer 28

- Decreased a increases + charge of histones - Histones bind to DNA (-charged) more TIGHTLY) - Prevents TF's binding - Genes not transcribed

Question 29

What is chromatin?

Answer 29

DNA & histone combination

Question 30

What happens if methylation is DECREASED too much?

Answer 30

- Can INCREASE expression of pro-oncogenes (which promotes cell division) - so cells divide uncontrollably & tumours produced

Question 31

Impact of RNA interference?

Answer 31

translation of the mRNA produced from target genes is inhibited ^ this prevents gene expression

Question 31

RNA interference process (2)

Answer 31

- RNAi interferes with mRNA by binding to mRNA molecule & breaking it down - this means mRNA cannot be translated into a protein

Question 32

Benign tumour features=

Answer 32

- Not cancerous - normal nuclei - Dividing cells cannot spread & invade other tissues

Question 33

Malignant tumour features= (4)

Answer 33

- Grow rapidly - Dividing cells can spread & invade other tissues & around the body - Can be life-threatening - irregular, enlarged nuclei

Question 34

Ways tumours can develop=

Answer 34

1. Increased methylation of TSGs: (this inhibits TSG's which usually inhibit CD so CD) 2. Oncogenes: (cause excessive cell division) 3. Oestrogen (causes increased expression of genes, which can lead to a tumour developing)

Question 35

Environmental and genetic factors that can increase likelihood of developing cancer= (4+1)

Answer 35

``` Environmental= - radiation exposure - smoking - alcohol consumption - diet high in fat Genetic= - Certain alleles (e.g. BRCA1) ```

Question 36

(e.g. Cancer) when interpreting correlations in graphs what other factors need to be considered?

Answer 36

- Age - Gender - Sample size - variation in lifestyle (e.g. exercise) - changes in lifestyle provision

Question 37

Proteome definition=

Answer 37

complete set of proteins expressed by an organism

Question 38

What are coding genes?

Answer 38

genes that contribute to the proteome (used to produce proteins)

Question 39

what can genome projects be used for? (3)

Answer 39

1. medical advances (identify genes responsible for inherited diseases & target for drug treatment) 2. biotechnology 3. discover evolutionary relationships

Question 39

what means that knowledge of the genome cannot easily be translated into the proteome

Answer 39

- Non-coding DNA | - Regulatory genes