Sexual reproduction requires the production of gametes containing half the chromosomes of the parent
Mitochondrial DNA comes from the...
Define Homologous Chromosomes
Chromosomes of the same length and centromere position with genes for the same characteristics
Chromosomes of the same length and centromere position with genes for complimentary characteristics
Chromosomes of the different length/ centromere position with genes for the same characteristics
What must sister chromatids have?
Two identical replications
Three identical replications
Of different chromosomes
Of the same chromosomes
How do you get from homologous chromosomes to sister chromatids?
What is the difference between Meiosis I and Meiosis II?
Meiosis I- Sister chromatids separate
Meiosis II- Homologous chromosomes separate
Meiosis I- Homologous Chromosomes separate
Meiosis II- Sister chromatids separate
In Meiosis I, name two changes to nuclear architecture that assist homologous chromosome pairing
Telomere clustering causes Rabl formations
Some organisms have elements that facilitate pairing i.e.
Synaptonemal complexes are found between homologous chromosomes and are thought to facilitate what?
Chromosome synapsis is the close lying of chromosomes next to each other
The separating of homologous chromosomes is mediated by what?
Other species have specilised linkages - name two examples
Cohesin only occurs between sister chromatids
What is the role of cohesin in Meiosis I?
Holds sister chromatids together
Allows chiasmata to occur
Counteracts microtubule pulling force until the crossover is complete
What is the role of chiasmata/crossing over in meiosos?
Increases genetic diversity
Prevents mistakes (i.e. incorrect separation)
Increases efficiency of microtubule separation
In Meiosis I, sister chromatids must go to separate poles
What is the 'Mono-orientation of sister kinetochores?'
Sister chromatids remaining together and travelling to the same pole
The exchange of DNA between homologous chromosomes
Sister chromatids separating and travelling to opposite poles
What is the budding/fission yeast version of 'Mono-orientation of sister kinetochores'?
We have no idea how Mono-orientation of sister kinetochores occurs in humans
How is Cohesin lost in Anaphase I and II
Microtubules attach and release separase
Separase is released during chiasmata
Separase is transcribed in the nucleus and diffuses to homologous chromosomes
During anaphase I, cohesin is lost where?
Between sister chromatids
At the centromere
According to Medel's first law of inheritance, what happens to the two alleles present during replication?
They are separated away from each other to opposite poles, so each gamete has only 1 allele, giving a ratio of 2:2 in the gametes
They are not separated and go to the same pole, so each gamete has two alleles, giving a ratio of 1:1 in the gametes
They are separated to the same poles, so each gamete has two alleles, giving a ratio of 2:2 in the gametes
What assumptions are made in the Hardy Weinburg Equilibrium Equation?
Only random mating and gene flow
No meiotic drive
Mendel's Second Law is The Law Of Segregation
State Mendel's Sencond Law
That alleles are separated from each other so each gamete will possess one allele
The order in which the homologous chromosomes line up at the equator is completely random with respect to each other
Linked genes are much more likely to be separated
Define Linkage Disequilibrium
Genes are found on the same chromosome
The clustering of telomeres prevents genes from separating
The occurrence in members of a population, combinations of linked genes in non-random proportions
What is the following showing?
A bouquet formation
What is the following highlighting