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Biology Year 13 > Gene expression is controlled by a number of features (20) > Flashcards

Gene expression is controlled by a number of features (20) Flashcards

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1
Q

What are stem cells?

A

undifferentiated cells that can divide indefinitely and turn into other specific cell types

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2
Q

What happens to totipotent cells during embryonic development?

A

certain parts of the DNA are selectively translated so that only some genes are switched on, in order to differentiate the cell into a specific type and form the tissues that make up the foetus

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3
Q

What are the 4 types of stem cell?

A

totipotent
pluripotent
multipotent
unipotent

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4
Q

What can totipotent stem cells do?

A

mature into any cell type including the placenta and embryo

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5
Q

What can pluripotent stem cells do?

A

mature into any cell type excluding placenta and embryo

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6
Q

What can multipotent stem cells do?

A

can differentiate to a few different types of cell

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7
Q

What can unipotent stem cells do?

A

can only develop into one type of cell

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8
Q

What type of cell can unipotent stem cells develop into?

A

cardiomyocytes

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9
Q

What are cardiomycocytes?

A

heart cells

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10
Q

What is the advantage of pluripotent stem cells?

A

can divide in unlimited numbers so can be used to repair or replace damaged tissue

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11
Q

Where are totipotent and pluripotent stem cells found?

A

in embryos

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12
Q

Where are multipotent and unipotent stem cells found?

A

in mature mammals

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13
Q

Which types of stem cell are found in embryos?

A

totipotent
pluripotent

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14
Q

Which types of stem cells are only found in mature mammals?

A

multipotent
unipotent

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15
Q

What is oestrogen?

A

steroid hormone that affects transcription and is lipid soluble

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16
Q

What are 3 uses of stem cells?

A
  • medical therapies e.g. bone marrow transplants, treating blood disorders
  • drug testing on artificially grown tissues
  • research e.g. on formation of organs and embryos
17
Q

What is a transcription factor?

A

protein that controls transcription of genes so that only certain parts of DNA are expressed e.g. in order to allow a cell to specialise

18
Q

What are the 3 steps on how transcription factors work?

A

1) move from cytoplasm to nucleus
2) bind to promotor region upstream of the target genes
3) make it easier or more difficult for RNA polymerase to bind to gene which either increases or decreases the rate of transcription

19
Q

How are induced pluripotent stem cells produced?

A

from mature, fully specialised (somatic) cells, cell regains capacity to differentiate through the use of proteins, in particular transcription factors

20
Q

What is meant by epigenetics?

A

heritable change in gene function without change to base sequence of DNA

21
Q

What is the role of tumour-suppressor genes?

A

code for proteins that control cell division, in particular, stopping cell cycle when damage is detected, as well as being involved in programming apoptosis

22
Q

What is the role of proto-oncogenes?

A

control cell division, in particular, code for proteins that stimulate cell division

23
Q

What are the 4 steps on how oestrogen works?

A

1) lipid soluble so easily diffuses through phospholipid bilayer
2) in cytoplasm, binds to a transcription factor called oestrogen receptor
3) forms oestrogen-oestrogen receptor complex
4) complex enters nucleus and acts as transcription factor to facilitate binding of RNA polymerase

24
Q

How is oestrogen linked to cancer?

A

can be involved in the development of breast cancer as it activates RNA polymerase, so in areas with high oestrogen levels, cell division can become uncontrolled

25
Q

What is an example of a place with high oestrogen levels?

A

adipose tissue in the breasts

26
Q

What happens in RNA interference?

A

RNA molecules inhibit gene expression, usually be destroying mRNA so that it cannot be translated

27
Q

Where does RNA interference occur?

A

in eukaryotes and some prokaryotes

28
Q

What are the 3 steps on how tumour-suppressor genes can be involved in causing cancer?

A

1) mutation in gene could code for nonfunctional protein
2) hypermethylation and low acetylation could prevent transcription
3) cells divide uncontrollably resulting in a tumour

29
Q

What is the word for high methylation?

A

hypermethylation

30
Q

What is the word for low methylation?

A

hypomethylation

31
Q

What are the 3 steps on how proto-concogenes can be involved in causing cancer?

A

1) mutation in gene could turn into permanently activated oncogene
2) hypomethylation and high acetylation causes excess transcription
3) cells divide uncontrollably resulting in a tumour

32
Q

What are 5 characteristics of malignant tumours?

A
  • rapid, uncontrollable growth
  • ill-defined boundary
  • cells do not retain function and often die
  • spreads quickly and easily
  • difficult to treat
33
Q

What are the 2 types of tumour?

A

malignant tumours
benign tumours

34
Q

What are 5 characteristics of benign tumours?

A
  • slow growth
  • defined by clear boundary due to cell adhesion molecules
  • cells retain function and normal shape
  • don’t spread easily
  • easy to treat
35
Q

How do epigenetic changes affect humans?

A

can cause disease either by over activating a gene’s function (such as cancer) or suppressing it

36
Q

What are 2 uses of epigenetics?

A
  • treat various diseases
  • develop ways to reverse epigenetic changes
37
Q

What are the 3 steps on how hypermethylation of DNA affects gene transcription?

A

1) involves addition of a methyl group to cytosine bases which are next to guanine
2) prevents transcription factors from binding
3) therefore gene transcription is suppressed

38
Q

What is the consequence of abnormal methylation?

A

can cause cancer as hypermethylation of tumour suppressor genes and oncogenes can impair their function, causing cell to divide uncontrollably

Biology Year 13 (21 decks)

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