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Genes and Gene Technology > Mutations and Stem Cells > Flashcards

Mutations and Stem Cells Flashcards

1
Q

What is a mutation ?

A

a random change to the nucleotide base sequence of DNA.

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2
Q

Why can mutations be beneficial ?

A

increases genetic diversity
Increases Variation in a population

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3
Q

Give examples of mutagens

A

Ionising radiation
Tobacco Tar
Mustard gas
UV light

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4
Q

How can a mutation lead to the formation to the non functional form of a protein ?

A

The mutation causes a change in the sequence of bases in the DNA
This leads to a change in the base sequence of MRNA produced in transcription
This therefore leads to a change in the amino acid sequence in the polypeptide chain produced in translation.
The primary structure of the protein is changed
Therefore the tertiary structure of the protein is changed due to a change in the position of hydrogen, ionic and disulphide bonds.

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5
Q

What is an addition mutation ?

A

an extra nucleotide base is added

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6
Q

What 3 types of mutation result in a frame shift ?

A

Addition
Deletion
Duplication

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7
Q

What is a deletion mutation ?

A

a nucleotide base is removed

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8
Q

What is the effect of a frameshift ?

A

a greater number of changed amino acids

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9
Q

What is a nonsense mutation ?

A

the base change results in the formation of a stop codon which means the synthesis of the polypeptide stops prematurely.

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10
Q

What is a mis-sense mutation ?

A

a different amino acid is coded for

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11
Q

What is a silent mutation ?

A

the substituted base still codes for the same amino acid

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12
Q

What does degenerate mean ?

A

an amino acid can be coded for by more than one codon

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13
Q

What is a duplication mutation ?

A

1 or more nucleotide bases are repeated

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14
Q

What is a inversion mutation ?

A

the nucleotide base sequence is reversed

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15
Q

What is a translocation mutation ?

A

DNA bases separate from the sequence get inserted into a chromosome.
(can occur in or across chromosomes)

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16
Q

Explain why a mutation that is transcribed onto mRNA may not result in any change to the polypeptide it codes for

A

Silent mutation
Degenerate nature of DNA

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17
Q

What is the definition of cancer ?

A

a mass of undifferentiated cells that divide uncontrollably

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18
Q

What are the two different types of tumour ?

A

malignant
Benign

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19
Q

What are features of a Benign Tumour ?

A

do not invade neighbouring tissue
does not spread
can be large
Differentiated cells
Grow slowly
normal nucleus
COMPACT (surrounded by dense tissue)
Less life threatening but affect area of growth
Localised effects
removed by surgery
rarely reoccur

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20
Q

What are features of a Malignant Tumour ?

A

Spread to other areas / metastasise
Can be large
rapid growth
larger nucleus-lots of DNA
Unspecialised cells
No capsule surrounding- grow into surrounding tissue
more likely to be life threatening as can replace normal tissue
Systematic effects
surgery and radiotherapy/chemotherapy
More frequently reoccur

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21
Q

Describe two ways in which both types of tumour may cause harm to the body

A

direct damage to organs
pressure to vessels and organs

22
Q

suggest why people with a family history of cancer are at a greater risk of cancer than those with no family history of cancer

A

inherit the genes which contains the mutations which causes cancer.

23
Q

What are the two genes that control the rate of mitosis ?

A

Proto-oncogenes
Tumour-Suppressor genes

24
Q

What is the role of proto-oncogenes ?

A

Stimulate cell division when a growth factor attaches to the receptor.
This leads to DNA replication and division

25
Q

What is the name of the mutated version of proto-oncogenes ?

A

oncogenes

26
Q

How can a mutation in a proto-oncogene lead to cancer ?

A

proto-oncogene mutated to an oncogene
Mutation means that the Receptor remains active without the presence of growth factors.
This causes continual DNA replication and cell division. This causes uncontrolled cell division and therefore cancer.

27
Q

What is the role of Tumour-suppressor genes ?

A

they slow the rate of cell division
Promote programmed cell death or apoptosis in cells too damaged for repair

28
Q

How can a mutation in a Tumour-suppressor gene lead to cancer?

A

Mutation causes the gene to become inactive
This gene promotes programmed cell death.
Therefore cells that should die continue to divide leading to cancer as the rate of cell division increases uncontrollably

29
Q

What are the two ways in which genes can be prevented from expressing themselves ?

A

preventing transcription
Breaking down mRNA before the code is translated

30
Q

What is the definition of Differentiation/specialisation ?

A

The process in which cells develop into specialised cells suited to their functions

Differentiation increases the efficiency of cells, this happens in multicellular organisms. In single celled organisms the cell has to carry out all the functions.

31
Q

Specialised cells do not express of their genes. Which part of the DNA in a specialised cell will be expressed ?

A

Only part of the DNA will be translated into proteins that are beneficial to the cells function

32
Q

What is a Totipotent cell ?

A

unspecialised cell and is capable of expressing all of its genes

33
Q

During development how do totipotent cells result in cell specialisation ?

A

they translate only part of their DNA resulting in cell specialisation. The cell therefore only makes those proteins that it requires to carry out its specialised function.

34
Q

Only a few totipotent cells exist in mature adults. What is the name for these cells ?

A

Stem cells

35
Q

Where do totipotent cells occur in humans ?

A

they occur for a limited amount of time in early mammalian embryos

36
Q

What is a frameshift ?

A

Some gene mutations change the nature of all base triplets downstream from the mutation.

37
Q

What can totipotent plant cells be used to produce ?

A

clones

38
Q

What are stem cells ?

A

cells which retain the ability to divide and give rise to new tissues

39
Q

Where are stem cells obtained from in mammals ?

A

Embryonic stem cells
Umbilical cord blood
placental stem cells
Adult stem cells (bone marrow)

40
Q

What are the three general properties of stem cells ?

A

Self renewal
Unspecialised/undifferentiated
they can develop into other specialised cell types.

41
Q

What is the definition of specialisation ?

A

the process that occurs after cell division where the newly formed cells develop into specialised cells

42
Q

What are features of totipotent cells ?

A

can differentiate into any cell type in an organism
found in early embryos, a zygote is totipotent
a human totipotent stem cell can develop into any type of cell in the body.

More cells remain totipotent in plants

43
Q

What are features of multipotent cells ?

A

can develop into more than one cell type, but are more limited than pluripotent stem cells
found in mature mammals
adult stem cells and umbilical cord blood stem cells ae considered multipotent

44
Q

What are features of pluripotent cells ?

A

pluripotent cells can give rise to most types of cells that make up the body. Embryonic stem cells for example.
Pluripotent stem cells can divide in unlimited numbers and cab be used in treated human disorders.

45
Q

What are features of unipotent stem cells ?

A

differentiate into a single type of cells found in mature mammals.
Form cardiomyocytes

46
Q

What is the order of potency of stem cells ?

A

Totipotent
Pluripotent
Multipotent
Unipotent

47
Q

Explain how cardiomyocytes are formed.

A

Totipotent zygote in first few divisions
pluripotent embryonic stem cells
This will differentiate into mesoderm (the middle layer of cells or tissues of an embryo)which is multipotent
This will differentiate into cardiac mesoderm
This will differentiate into cardiomyocytes which are unipotent.

48
Q

What does iPSC stand for ?

A

Induced Pluripotent Stem Cells

49
Q

How are Induced Pluripotent Stem Cells produced ?

A

these are produced from unipotent cells in a lab to acquire the characteristics of embryonic stem cells that are pluripotent
This involves genes that are not expressed to be turned on- Reactivated.
(result similar to embryonic stem cells however not identical)
These cells may be useful as they avoid ethical issues of using embryos.

50
Q
A

Genes and Gene Technology (5 decks)

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