BIOSCI 202 Lecture Notes - Lecture 2: Gc-Content, Polytene Chromosome, Histone H2B

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ochregiraffe940

25 Sep 2013

School

University of Auckland

Department

Biological Sciences

Course

BIOSCI 202

Professor

Craig Miller

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Document Summary

The chromosome set presented in organisms from the same species has a characteristic chromosome number and appearance. Haploid number (n) most fungi and algae have only one set of chromosomes. Diploid number (2n) most plants and animals have two sets of chromosomes. There is no relationship between chromosome number and the complexity of a species, but. The more chromosome a species has, there are potentially more variations it can produce via independent assortment. Slender golden week can produces 22, whereas the fern can produce 2500 different kinds of gametes. However, there is a balance for the number of chromosome a species can have e. g. stalked adder"s tongue fern has a 2n of ~1000, but it reproduces asexually as its gametes are unviable. Very large number of chromosome does not segregate properly during meiosis. Number of chromosome is not related to genome size (total amount of dna in the nucleus)

Related Questions

Suppose you have two species of corn. One has sweet kernels and the other has large ears. Both have 20 chromosomes, each of which is homologous in both species. Suppose you want to create a hybrid that has both characteristics of sweet kernels and large ears, so you cross individuals from the two species. The initial hybrid you obtain has 20 chromosomes, but then you establish a viable tetraploid (4n) individual with 40 chromosomes. Which of the following could best explain this observation?

		Nondisjunction of a single chromosome caused the doubling of the genome.
		The initial F1 hybrid was unable to produce normal haploid gametes and instead produced diploid gametes. As a result, self-fertilization created progeny with 40 chromosomes.
		The original F1 hybrid was able to produce normal gametes, thus, the tetraploid was formed by fusing one normal haploid gametes with an abnormal diploid gamete.
		Nondisjunction of a random set of chromosomes produced abnormal gametes, and thus the 40 chromosomes represent a random assortment of chromosomes from the two parents.
		None of the above can explain the phenomenon.

emeraldwhale18

Genetics

I dont really understand this

Please explain your answer!

A		Nondisjunction of a single chromosome caused the doubling of the genome.
B		The initial F1 hybrid was unable to produce normal haploid gametes and instead produced diploid gametes. As a result, self-fertilization created progeny with 40 chromosomes.
C		The original F1 hybrid was able to produce normal gametes, thus, the tetraploid was formed by fusing one normal haploid gametes with an abnormal diploid gamete.
D		Nondisjunction of a random set of chromosomes produced abnormal gametes, and thus the 40 chromosomes represent a random assortment of chromosomes from the two parents.
E		None of the above can explain the phenomenon.

maroonzebra679

1).Which of the following demonstrates the importance of mutation?

A.Mutation is the ultimate source of genetic variation and thus is the foundation of why people are interested in genetics in the first place.

B.Mutation will remove variation from the population.

C.Mutations are always beneficial and thus allow organisms to adapt.

D.Mutation is detrimental to the population and thus is important only because we need to get rid of mechanisms that induce mutations.

E.Mutation is not important.

2).While the SOS repair pathway can repair devastating pyrimidine dimers, it comes at a cost. Which of the following best explains the cost of repairing DNA via the SOS repair pathway?

A.The other strand of DNA is used as a template to repair the damaged strand of DNA.

B.A nucleotide is removed so that DNA polymerase III can move past the pyrimidine dimer.

C.SOS will help DNA replication bypass pyrimidine dimers but will do so by using random nucleotides in place of the lesion.

D.The SOS repair pathway uses analogs in place of nucleotides when repairing damaged DNA.

3.Suppose you have two species of corn. One has sweet kernels and the other has large ears. Both have 20 chromosomes, each of which is homologous in both species. Suppose you want to create a hybrid that has both characteristics of sweet kernels and large ears, so you cross individuals from the two species. The initial hybrid you obtain has 20 chromosomes, but then you establish a viable tetraploid (4n) individual with 40 chromosomes. Which of the following could best explain this observation?

A.		Nondisjunction of a single chromosome caused the doubling of the genome.
		B.The initial F1 hybrid was unable to produce normal haploid gametes and instead produced diploid gametes. As a result, self-fertilization created progeny with 40 chromosomes.
		C.The original F1 hybrid was able to produce normal gametes, thus, the tetraploid was formed by fusing one normal haploid gametes with an abnormal diploid gamete.
		D.Nondisjunction of a random set of chromosomes produced abnormal gametes, and thus the 40 chromosomes represent a random assortment of chromosomes from the two parents.
		E.None of the above can explain the phenomenon.

E.There is no consequence to SOS repair and the damaged DNA is repaired precisely back to the wild-type allele.

tealmammoth916

BIOSCI 202 Lecture Notes - Lecture 2: Gc-Content, Polytene Chromosome, Histone H2B

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