8.2.3 + 8.3- gene expression & cancer + genome projects

what is a genome?

what is a proteome?

all the genetic material in an organism

the set of proteins that a cell or organism can produce

what does a genome project aid with the understanding of?

how does a genome project work?

gene function and interaction

collecting DNA samples from many individuals of a species. These DNA samples are then sequenced and compared to create a reference genome

what can the genome of simpler organisms be used to obtain?

give an application for this?

the proteome

identifying potential antigens for use in vaccine production

what is the use of making comparisons of genomes with other organisms?

help to find the degree of similarity between organisms which then gives an indication of how closely related the organisms are and whether there are organisms that could be used in experiments as a model for humans

what do genes with high levels of variation suggest?

those genes are under strong selective pressure

These genes could code for the antigen proteins found on the parasites

what happens once the antigenic genes are identified?

why would the protein coded for by the specific gene be injected into people living in areas with malaria?

the antigen they code for can be used in vaccine production

see if they produce antibodies that provide immunity against the disease

why is it difficult to translate the genome of complex organisms into their proteome?

large amounts of non-coding DNA are present in human genomes

very hard to identify these sections of DNA from the coding DNA

what affects gene expression and the synthesis of proteins?

The presence of regulatory genes and the process of alternative splicing in human genomes

why is the proteome is larger than the genome?

Alternative splicing

Post-translational modification of proteins

what does DNA sequencing allow?

the base sequence of an organism's genetic material to be identified and recorded

what is mitosis?

what does cancer result from, and what does this cause?

what does that result in and what is this called?

controlled process

mutations in the genes that control cell division, causing rapid, uncontrolled growth and division of cells by mitosis

formation of mass of abnormal cells- tumours

what are benign tumours and where are they located?

what does this then mean?

how are they removed?

non cancerous + restricted to one part of body

don’t invade surrounding tissues

surgery- affected tissue is cut away

what are malignant tumours?

how are they removed?

uncontrollably dividing cell groups that may divide, or metastasise to other parts of the body, so therefore cancerous

surgery combined with other treatments e.g. chemotherapy (drugs that kill fast growing cancer cells) or radiation therapy (use ionising radiation to damage the DNA of the cancer tissue to kill the abnormal cells)

what is cell division controlled by?

two genes that play an important role in mitosis, and what do they do?

genes

proto-oncogenes- stimulate cell division

tumour suppressor genes- slow cell division

what happens when a proto-oncogene is mutated?

what do oncogenes cause?

how are these cancers acquired?

referred to as an oncogene + permanently activated- shape of gene product can change e.g. resulting in a hyperactive enzyme that continuously stimulates cell division

cause normal cells to divide too quickly and become cancer cells

can be inherited, mostly acquired during lifetime

what do tumour suppressor genes do and when?

what are two other functions?

what happens when they are mutated?

inhibit cell division, when it is no longer necessary or if the cell’s DNA is damaged

also repair errors in the DNA and instruct death of faulty cells (apoptosis)

become inactivated- allowing cells to divide uncontrollably

what does smoking do?

what happens if a tumour supressor gene is heavily methylated?

how does increased methylation of DNA lead to the gene being suppressed?

increase risk of abnormal DNA methylation patterns

gene is inactivated + no longer inhibits cell division

prevents TF binding to DNA, transcription inhibited + gene not expressed

how does decreased methylation of proto-oncogenes lead to the formation of cancer?

TF can bind- transcription is stimulated

gene permanently activated- cell divides rapidly, causing cancer

proto-oncogene becomes oncogene

what does increased oestrogen concentration result in?

how does that happen?

development of breast cancer

when oestrogen binds to oestrogen receptors on breast cancer cells, they send a signal to the cell to stimulate cell division

causes tumour to grow more rapidly

results in increased oestrogen production- increased development of tumour

how can cancer be prevented and give two specific examples?

avoiding mutagen e.g. vaccination to prevent cervical cancer, sunscreen to protect against UV radiation

what does earlier diagnosis increase?

what needs to be known in order to choose type of treatment?

how can treatment be more targeted?

chances of recovery + lower dose of chemotherapy and radiation

if cancer is fast growing or not- can determine whether dose of radiation of chemotherapy should be given

identifying which specific gene has mutated

how to prevent hereditary mutations?

how to diagnose?

pre-emptive surgery e.g. mastectomies

genetic screening for particular genes