3.3, 3.4 and 3.5 Flashcards
Describe crossing over.
During prophase 1, the chromosomes are held in points called chiasmata. If the genetic material is exchanged in those chiasmata, the chromatids are “recombined” and that’s crossing-over. Then the chromosomes are condensed into bivalents.
What is non-disjunction?
The chromosomes fail to separate properly.
When could a trisonomy occur during meiosis? in which phases
In meiosis 1, both homologous chromosome pairs can be pulled to one side, or in meiosis 2 both sister chromatids could be pulled to one side.
What is chorionic villi sampling? Risks?
A sample of the chorionic villus/placental tissue is taken to be tested for chromosomal abnormalties. 1% risk of a miscarriage.
What is aminocentesis? Risks?
A extraction of a bit of amniotic fluid, to be tested for chromosomal abnormalties. 0.5% risk of a miscarriage.
What are Mendel’s 3 laws? Notice, they are not always true.
- Alleles separate, so that each gamete only gets one allele.
- Alleles get segregated independently of eachother.
- Recessive alleles will be masked by dominant alleles.
What does hemizygous mean?
there’s only one allele, so e.g. only one allele on the x chromosome, which doesn’t exist on the y chromosome yay
Who is the universal recepeint, who is the universal donor? AB or 0?
AB: universal recepeint, as it has no antibodies against A or B.
0: universal donor, as it has no A or B antigens on it’s red blood cells, so the antibodies from other types don’t mind it, but 0 itself has antibodies for both A and B.
How strongly do co-dominantly inherited diseases affect you if you only get one bad allele?
It still affects you but with milder symptoms.
What are symptoms of Huntington’s Disease? How does it come about?
- uncontrollable movements and dementia
If a specific gene sequence is repeated more than so and so many times, you have huntington’s disease.
What do radiation and mutagenic chemicals do in terms of cancer?
They induce mutations. Mutations can occur randomly, or be induced.
How were bacteria brought to produce insulin?
- The gene of interest was amplified with PCR.
- A plasmid is cut open at the recognition sites with restriction enzymes, leaving blunt ends (no overhang) or sticky ends (with overhang).
- The gene of interest is inserted and DNA ligase fuses the backbones together.
How are genetically modified bacteria tested, if they actually work?
The plasmid vector also contains a antibiotic resistance and then the bacterium is tested if it can survive with the antibiotic or not.
State 3 pros and 3 cons for GMOs.
Pro: crops can produce herbicides to kill pests, food supply could be improved, can improve nutrition standards
Cons: cross-pollination can lead to super-weeds, biotech companies could hold monopolies, unknown effects
What is the issue with monarch butterflies and Bt corn?
Bt corn is a genetically modified corn that produces a pesticide, which is transferred via bt-corn-pollen to another plant, on which the larva of monarch butterflies live, so it kills them too.
