Skills & Applications Ch 3 Flashcards
Findings & benefits of Human Genome Project
- humans share most of their DNA sequences
- number, location, size, & sequence of human genes was established
- medicine –> discovery of new proteins
- improved treatments
- ancestry –> origins, evolution, migratory patterns
- cooperation + collaboration
Causes & consequences of sickle cell anemia
- single nucleotide (base substitution) mutation
- GAG –> GTG
- mutation of the 6th gene of haemoglobin
- mRNA copies the mutation of DNA
- glutamic acid is substituted by valine
- distorted haemoglobin protein (HbS)
- sickling + blocks capillaries
- can give resistance to malaria
Genome size of:
- T2 phage = ?
- E coli - ?
- D melanogaster = ?
- Homo sapiens = ?
- Paris japonica = ?
- T2 phage = 0.18
- E coli - 5
- D melanogaster = 140
- Homo sapiens = 3,000
- Paris japonica = 150, 000
Chromosome numbers
- Homo sapiens =
- chimpanzee =
- dog =
- rice =
- horse threadworm =
- Homo sapiens = 46
- chimpanzee = 48
- dog = 78
- rice = 24
- horse threadworm = 4
Cairn’s Technique of Autoradiography
- measured lengths of DNA molecules
- grew E coli in medium containing radioactively labelled thymine, so DNA ONLY was labelled not RNA
- he placed cells on membrane & digested their walls –> DNA spilled out over the membrane
- coated membrane with photographic film & left it in the dark for 2 months
- lines of black dots appeared showing the position of DNA molecules
- DNA molecules were circular & 1,100 micrometers long
Explain how non-disjunction (Down syndrome) is caused
- non-separation of chromosomes can occur in anaphase I or II
- gametes with an abnormal number of chromosomes are produced
- at anaphase I –> 4 affected cells
- at anaphase II –> 2 affected cells
- can lead to zygotes/individuals with an extra chromosome / individual has 47 chromosomes;
- in Down syndrome this would be trisomy 21/extra chromosome 21;
- increased probability with increased age of mother/ages of parents;
CENTROMETES NOT DIVIDING / INCORRECT SPINDLE ATTACHMENT
Describe 2 examples of codominance.
- Inheritance of ABO blood groups (involves more than 2 alleles being expressed together, e.g. AB)
- inheritance of sickle-cell anemia (heterozygous individuals have milder symptoms due to the MODERATING INFLUENCE of normal allele (HbA HbS)
Identify two examples of X-linked recessive diseases.
- Red-green colour blindness –> caused by recessive allele of gene for one of the photoreceptor proteins
- Hemophilia –> inability to control blood clotting leads to bleeding
- inability to make Factor VII (protein)
Provide an example of an autosomal recessive disease.
Cystic Fibrosis
- autosomal recessive allele on CFTR gene, chromosome 7
- produces sticky mucus, clogs airways
- clogs secretory ducts of the digestive system
- respiratory failure
- pancreatic cysts
Provide an example of an autosomal dominant disorder.
Huntington’s disease
- mutation to the HTT gene, chromosome 4
- degenerative changes in the brain’s nerve cells
- changes to behaviour, cognition
- heart failure, pneuomonia, symptoms emerge b/w 40-50 years of age
GMO Benefits
- pest-resistance, less insecticides needed
- longer shelf-life
- less fuel for farming (reducing ploughing/spraying)
- increased nutritional value
- resistance to drought, cold, salinity, disease
- lack known allergens
- improved food supply in poor countries
- less need for land clearing –> reduced costs + carbon footprint
GMO Risks
- non-target organisms affected
- reduced biodiversity
- antibiotic resistance genes –> bacteria
- adverse health reactions
- cross pollination –> super weeds
- conflicting regulatory standards
DNA profiling
- DNA of person from a selection of short tandem repeat loci is copied by PCR
- DNA cut using restriction enzymes
- gel electrophoresis used to separate DNA fragments
- pattern of bands is produced in gel
- analysed for matches b/w child with mother & possible father
- about half of child’s bands will match father, half will match mother
- paternity + forensic investigations
Describe amniocentesis.
- sample of amniotic fluid removed from amniotic sac around fetus
- hypodermic needle inserted into wall of mother’s abdomen + uterus
- amniotic fluid drawn into syringe
Describe chorionic villus sampling.
- Cells removed from fetal tissues in placenta called chorionic villi
- higher risk of miscarriage
- both have risk of infections
