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biology a level year 2 > gene expression > Flashcards

gene expression Flashcards

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1
Q

what are mutations

A

mutations are changes in the sequence of nucleotides in DNA

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2
Q

what are the different types of mutations

A

the different types of mutations iclude:
-insertions/deletion

  • duplication
  • inversion
  • translocation
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3
Q

what is insertation/ deletion

A

it is where one or more nucleotide pairs are inserted or deleted from the sequence

This type of mutation alters the sequence of nucleotide after the insertions/deletion point known as a frameshift

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4
Q

what is duplication

A

this is when one or more bases are repeated and therefore produces a frameshift

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5
Q

what is translocation

A

This is when a sequence of bases is moved from one location in the genome to another

This could be movement within the same chromosome or movement to a different chromosome

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6
Q

what are the different causes of gene mutation

A

gene mutation can arise spontaneously during DNA replication, and can be caused by MUTAGENIC AGENTS that affect DNA, causes of gene mutations are:

  • Chemical mutagens
  • ionising radiation
  • spontaneous errors
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7
Q

what are chemical mutagens

A

these include alcohol, benzene and substances in asbestos and is tar in tobacco

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8
Q

what is ionising radiation

A

alpha, beta and also UV and X rays

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9
Q

what effects do mutations have on the body

A

mutations can either have neutral effects where the mutation causes no change to the organism, e.g. in a case where the mutation occurs in a non-coding region of DNA or is a silent mutation

A mutation can also be neutral when a change in the tertiary structure of the protein has no effect on the organisms

sometimes, mutations can be beneficial

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10
Q

what are stem cells

A

stem cells are undifferentiated cells which can keep dividing to give rise to other cell types

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11
Q

what are the different types of stem cells

A

types of stem cells include:

  • pluripotent
  • totipotent cells
  • multipotent
  • unipotent
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12
Q

pluripotent cells

A

pluripotent cells are cells that are able to five ride to many tupes of specialised cells apart from embryonic cells

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13
Q

what are totipotent cells

A

totipotent cells are cells that can five rise to all types of specialised cells including embryonic cells

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14
Q

what are multipotent cells

A

they are cells that cen differentiate into other cell types but are more limited e.g. the cells in the bone marrow and umbilical cord

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15
Q

what are unipotent cells

A

these are cells that can only differentiate into one type of cell

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16
Q

what are the uses of pluripotent cells

A

pluripotent cells also have a number of different uses in repairing damaged tissue

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17
Q

how can pluripotent stem cells be created

A

pluripotent stem cells can also be created from unipotent stem cells and are therefore known as induced pluripotent stem cells (iPS)

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18
Q

what is the role of the hormone oestogen

A

oestrogen has the ability to alter transcription through altering molecules called transcription molecules

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19
Q

what are transcription molecules

A

these are molecules that bind to a specific site on DNA to begin the process of transcription

20
Q

how does oestrogen control transcription

A
  1. the lipid soluble nature of oestrogen means that it can freely diffuse across the cell membrane where it binds to a receptor molecule on a transcription factor
  2. the binding alters the shape of the DNA binding site on the transcription factor and makes it able to bind to the DNA
  3. The transcription factor therefore enters the nucleus via the nuclear pore where it binds to DNA. This stimulates the transcription of the gene that makes up the DNA
21
Q

what is small interfering RNA

A

Small interfering RNA (siRNA) also called silencing RNA is used for short term switching off of genes

The siRNA binds to a complementary sequence of mRNA.
As mRNA is usually single stranded and the cell there frore detets the double stranded form on mRNA and views it as abnormal

Therefore the mRNA is broken down by enzymes preventing translation

22
Q

what are epigenetics

A

epigenetics involve heritable changes in gene function without changes to the bse sequence of DNA

It show that environmental factors can make changes to the function of genes which can be inherited

23
Q

what are two examples of epigenetic changes

A

DNA methylation

DNA acetylartion

24
Q

what is DNA methylation

A

it is the process by which methyl groups are added to DNAA

Methylation modifies the fuunction of DNA, typically acting to suppress gene transcription.

DNA methylation alters the expression of genes in cells as they divide and become specialised.
The change is permanent and prevents the cell from converting back into a stem cell or a different cell type

The methylation is through the addition of CH3 chemical group to cytosine bases, which both prevents binding of transcriptional factors to DNA and stimulated decreased acetylation of histones

25
Q

what is DNA acetylationn

A

DNA acetylation also changes DNA structure.
Histones are positively charged proteins closely associated with DNA, which is negatively charged

Decreased acetylation of histones increases their positive change, so they bind DNA more tightly.

When this happens transcriptional factors can no longer access the DNA, so the gene is switched

26
Q

how does cancer arise

A

it can arise as a result of muation

Uncontrolled cell division in cancer leads to the formation of a timour

There are two types of

27
Q

what are the two types of tumours

A

benign

malignant

28
Q

what are benign tumours

A

this means they do not tend to cause much harm about from mechanical damage caused by pressing against blood vessels or other cells

benign tumours grow slowly and do not spread

29
Q

what are malign\ant tumours

A

malignant tumours grow rapidly and can spread to the neighbouring cells via METASTASIS (through the bloodstream or lymphatic system) this causes damage by disrupting the running of important processes

Malignant tumours are difficult to treat in comparison to benign

30
Q

what plays a role in developing cancer

A

proto-oncogenes

oncogenes

tumour suppressor genes

abnormal methylation of tumour suppressor genes and oncogenes

increased oestrogen concentration

31
Q

proto- oncogenes

A

These stimulates cells to divide by producing proteins that stimulate cell division allow the checkpoints of the cell cycle to be passed and can cause cancer if mutated

32
Q

oncogenes

A

these are formed from mutated proto-oncogenes and result are permanently switched on resulting cell division that is uncontrolled. It does this by permanently activating a cell surface receptor or coding for a growth factor

33
Q

tumour suppressor genes

A

They control cell divison, this causes the cell cycle to stop when damage is detected. They also play a role in the programming of apoptosis (cell death). When these are switched off the cell cycle becomes unregulated

34
Q

abnormal methylation of tumour suppressor genes and oncogenes

A

increased methylation also called hyper-methylation plays an important role in controlling tumor suppressor genes and oncogenes. The hyper-methylation of a tumour suppressor gene called BRAC1

35
Q

increased oestrogen concentration

A

this is linked to breast cancer development. These elevated levels are found in fatty tissues called adipose tissue in the breast of post menopausal women. Oestrogen binds to the transcription factor which activates the gene promoting cell division, leading to tumour formation

36
Q

what are sequencing projects

A

sequencing projects have read the genome of a wide range of organisms, including humands the genome of simpler organisms allows the sequecnes of the proteins that derive dorm the genetic code of organisms to be determined

37
Q

what has been the appliaation of sequecning genomes

A

this allows:

the idenfircation of potential antigens for usein vaccine production

38
Q

why has the knowlege of the genome cannot be easily trasnlated for more complex organisms

A

the presence of non-coding DNA and of regulatory genes means that knowledge of the genome cannot be easily translated into the proteome

However, dude to selective gene expression not all of these proteins will be found in every cell in the body

39
Q

what is the proteome

A

it is all the proteins that the genome can code for

40
Q

why is gene sequencing importanst

A

it allows for genome wide comprarison between individuals and between species

Comparing genomes between species is significant as it allows evolutionary relationship between species to be determine and it is also is beneficial in medical research

it is also useful in the study of human disease

41
Q

why is gene sequencing useful in medical research

A

comparing the genome of individuals enables differences to be identified which can then be used for development of personalised medicine tailored to a particular genome as well

42
Q

what else has genome wide comparison made possible

A

it has allowed the sequencing of amino acids in polypeptides to be predicted and has allowed for the development of synthetic biology

43
Q

what is the genome projects

A

The Human Genome Project is an international scientific project which has successfully
determined the sequence of bases of a human genome

44
Q

what is the potential application of the genome wide project

A

screening for mutated sequences,

carriers

and pre-implantation screening as well as
screening for disorders such as Huntington’s disease before symtoms appear

45
Q

what are the ethical issues regarding the human genome project

A
  • people can become discriminated against due to their genetic disease
  • the misuse and ownership of the genetic information
46
Q

what is recombinant DNA technology

A

it involves the many ways in which we can manipulate DNA

biology a level year 2 (14 decks)

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