Unit 6 #2 - Genetics Flashcards
what did nettie stevens discover
1. genes are located on the recently discovered CHROMOSOMES inside the cell nucleus. 2. in certain insects, the Y chromosome is only found in males.
Also, pioneered use of fruit fly as model organism
What is the SRY gene
carried by the y chromosome in mammals, causes gonad to develop as a testis (has the coding for the protein responsable to do this). If no SRY gene, then the embryo develops as female, by default.
What genes (3+) are on the y chromosome in humans
- SRY gene
- Gene that gives hairy ears
- other genes responsable for sperm+testis development
WHat is the difference between the X and Y chromosome?
X chromosome nothing to do with sex and it has many genes.
What is the fruit fly life cycle?
embryo, 1st instar larva, 2nd instar larva, 3rd instar larva, prepupa, pupa
What is particular about fruit fly chromosomes
4 pairs (2n=8) and they are giant chromosomes (eat a lot, make a lot of saliva and replicate a lot)
In fruit flies, what reabsorbs the nutrients from the old larval body to become parts of the adult fly?
Homologous imaginal discs
What is the purpose of a chi square and what needs to be looked at to determine if your suspicion is probable or not
Purpose: Quantifying your suspicion and the discrepancy between what you observe and expect
if probability greater than 0.05 = great probability that what you expect will occur/fail to reject null hypothesis
if chi square value calculated is smaller = small discrepancy between between what is observed and expected/fail to reject null hypothesis
When n=2, what is the size of the chromosmes relative to one another
2 sets of chromosomes, 1 big, 1 small
Are traits controlled by one gene
Often traits are controlled by more than one gene
What did mendel solve? (1866)
Darwin’s question about how traits were inherited.
Mendel realised that:
1. each trait is controlled by TWO « factors », one from
the mother and one from the father
2. One factor dominates the other – they do not blend
with each other. (dominate vs recessive)
whereas, darwin thought essence from mother anf father, for example, produced a child…no!
What is chromatin
DNA+protein
what are genes made of
DNA
Provide an example of self-fertilization and another type of pollination
Self-fertilizing (self-pollination): pea flower; produces pollen (male gamete), which is trapped in the flower because it is closed, and ovules (female gamete) so it self-fertilizes
Cross-pollination: remove male organs (so no pollen production) and use brush to collect and fertilizes ovules with the pollen from another plant.
What are pure lines
individuals that always give the same phenotype in the offspring
eg pp always gives white flowers for example (its a true-breeding) or PP
