Application and Flashcards
What is the intended purpose of the Human Genome Project and the 100K Genome Project?
improve knowledge and understanding of genetic disorders and improve their diagnosis and treatment.
When did the human genome project begin and complete?
began in 1990 and was completed in 2003
What did the human genome project discover?
•The order of DNA bases in genomes.
•The distribution and sequences of introns and exons.
•The loci of individual genes.
What did scientists do in the human genome project?
-used ‘Sanger Sequencing’, a DNA sequencing process that involved reading the base sequence of a length of DNA.
-This method sequenced relatively small sections of DNA at a time (usually <1,000 bps) and took a long time.
-For example, it took a year to sequence a million base pairs.
What are there now and what are these called?
many faster techniques in use that can sequence the entire genome (all of the genetic information of an organism) in a few hours.
These new rapid techniques, collectively known as Next Generation Sequencing (NGS), enable scientists to study variation within the human genome.
What is the 100k genome project?
was launched in 2012.
It used NGS to sequence 100,000 genomes from NHS patients with cancer or rare diseases.
What did the 100K genome project project enable us to do?
•Locate genes responsible for rare diseases and cancers
•Locate mutated genes
•Compare genomes of genetic disorder sufferers with the normal genome
•Develop treatments for genetic disorders
•Undergo effective prenatal diagnosis for genetic disorders
What has identification of allele sequences enabled scientists to do?
to scan a patient’s DNA sample for mutated sequences and to compare the sequence of DNA bases in a patient’s gene to a normal version of the gene
What can IVF embryos have done?
be screened for the presence of alleles which cause conditions including cystic fibrosis, Huntington’s disease and thalassaemia.
where else can genetic screening be useful?
in association with genetic counselling, allowing a couple to make informed decisions before having children
What has been produced by the projects and what does this mean?
A vast quantity of data has been produced
- We do not know how this information might be used in the future.
Society has yet to decide how it should be treated and where legal and moral responsibilities lie.
What are Ethical issues regarding the screening of DNA?
-Ownership of genetic information that could lead to potential discrimination e.g. health insurance, job applications, social stigmatisation and misuse of the data.
-There are a number of concerns regarding the possibility of routine screening for adult-onset disorders such as Alzheimer’s disease and some cancers. Some people do not want to learn this information about themselves, and it could cause anxiety.
-Concerns have arisen over embryo screening and the potential for choosing alleles to ensure specific characteristics: ‘designer babies’.
What is one of the case studies?
Screening of embryos for cystic fibrosis
What are sufferers with cystic fibrosis?
homozygous for an autosomal recessive allele and lack a functioning CFTR gene
What happens in cystic fibrosis?
Mucus blocks the airways and results in symptoms such as difficulty breathing, coughing and recurrent chest infections
What is the effect of inheriting cystic fibrosis?
•Cl- can’t be transported out of epithelial cells.
•Water potential outside cells doesn’t lower and so water doesn’t leave cells by osmosis.
•This means mucus is thick and sticky and accumulates.
What none humans have genome’s been sequenced for and what has this allowed?
-mosquito, Anopheles gambiae and the Plasmodium parasite, as well as chimpanzees and other primates. -This has allowed scientists to look at evolutionary relationships and to conserve species in the future.
What are two other methods that could be used to determine how closely related organisms are?
DNA hybridisation and amino acid sequence analysis
Where is malaria common and what have been used to control it?
-common in tropical and subtropical regions around the equator. -chemicals have been used to attack both the vector, Anopheles gambiae, and the parasite, Plasmodium sp. in an effort to control the spread of this disease.
What is hampering attempts to irradiate malaria (which is responsible for over one million deaths a year)? (control of the vector)
Rapid evolution of insecticide resistance in the Anopheles gambiae mosquito
What resistance is a problem and why?
Pyrethroid resistance is a problem as this is the only insecticide safe for use with the nets that people sleep under.
When was the DNA sequence of the Anopheles gambiae genome was completed and what is it allowing scientist to do?
allowing scientists to develop chemicals that could render the mosquito susceptible to insecticides again, preventing it from transmitting malaria.
What has plasmodium sp also developed?
multi-drug resistance
When was the genome of Plasmodium sp sequenced and what is hoped
-in 2002.
-It is hoped that a better understanding of genetic control of Plasmodium infection will allow the development of more effective drugs.
Give two advantages and two disadvantages of the chemical control (pesticide) of
mosquitoes.
ADY.quick and easy to apply chemicals; fast results; application does-not require a high level of skill
DIS - fear of resistance, can kill beneficial organisms
Using your knowledges of natural selection, describe how the mosquito population in africa became resistant to insecticides like thyroid?
-Selection pressure of insecticide meant individuals with the resistant
allele had a selective advantage
-These mosquitos survive and reproduce, passing on the resistance allele to’the next generation.
-Resistance allele increases in frequency within the population.
Synthesis of antibodies can protect mosquitoes against Plasmodium. Describe the structure of an antibody. (3)
-Antibodies are globular proteins, they have a quaternary structure which means they have a specific 3D shape.
-They contain peptide bonds between amino acids and ionic, disulphide and hydrogen bonds between R-groups.
1.Suggest how the synthesis of these antibodies in mosquitoes could help to reduce malaria outbreaks in humans in the future? (2)
•The mosquito is able to produce antibodies to combat the plasmodium parasite.
•The plasmodium could no longer survive in the mosquito.
•The mosquito would no longer spread infection when biting people in the future.
