Flashcards in Chromosomes, linkage and genetic maps Deck (26):
What does the chi-squared test show?
Whether or not the data are consistent with the hypothesis.
What is the statistical cut off point?
P = 0.05
Do we accept or reject the null hypothesis if the P value is less than 0.05?
Reject, the results are statistically significant and not due to chance.
What 3 things did Mendel not know about meiosis?
1. Meiosis generates haploid cells, enabling 2 members of a gene pair to segregate from each other in the formation of gametes.
2. Maternal and paternal chromosomes segregate independently of their origin
3. Crossing over between maternal and paternal chromosomes generates more genetic variation
What happens in early prophase?
- Centrioles move apart
- Chromosomes shorten and thicken
- Nucleolus becomes visible
What happens in middle prophase?
- Centrioles continue to move apart
- Mitotic spindle begins forming
- Replicated chromosomes become visible
What happens in metaphase?
- Nuclear envelope has disapeared
- Replicated chromosomes held together at centromere align on equator of spindle at the metaphase plate
What happens in early anaphase?
-Centromeres split and daughter chromosomes migrate to poles of cell
What happens in late anaphase?
- 2 sets of daughter chromosomes approach poles of cell
- Cytokinesis beings
What happens in telophase?
- Nuclear envelop begins to form
- Chromosomes extent and become invisible
- Nucleolus reforms
- Cytokinesis continues.
How will genes on different chromosomes segregate?
Independently of one another
How will genes on the same chromosome segregate?
They cannot assort independently by may recombine.
What are genes found on the same chromosome called?
How would you show two sets of genes on one chromosome?
In the example of aC/Ac what are alleles a and C known as?
In the example of aC/Ac what are alleles A and C known as?
Who discovered gene linkage?
Thomas Hunt Morgan in 1911 while working on Drosophila
What happens to the recombination frequency is two loci are close together?
What does a recombination frequency of 50% indicate?
Above what recombination frequency can recombination not occur?
When are genes known as parental?
If they originated on the same chromosome.
When are genes known as recombinant?
If they came together through crossing-over
In a test cross how would you know if the genes are linked or not?
1. If the genes are linked, parental phenotypes and recombinant phenotypes should be 1:1
2. If the genes are unlinked, each of the 4 phenotypes should occur in a 1:1:1:1 ratio.
How do you calculate the recombination frequency?
Number of recombinants/number of test cross progeny x 100
What does the recombination frequency show?
The relative distance apart on the chromosome of the two genes, can be used to map genes relative to one another.