genetics and evolution

Question 1

what is the difference between allopatric speciation and sympatric speciation. give examples

Answer 1

allopatric is due to geographical isolation of a species where as sympatric speciation occurs between species living in the same area.

ie allopatric
when two populations become separated by the ocean
sympatric
when the breeding seasons of two species do not coincide.

Question 2

what is the genetic drift and how can this lead to speciation.

Answer 2

when a small subpopulation becomes separated from the majority population of the same species. this leads to a change in allele frequency due to gene mutations and by chance different individuals will breed more frequently. As it is a small population size it means that the changes will spread through the population size quicker. the individuals become adapted to their environment and evolve quicker then the original population becoming genetically different this means they may not be able to interbreed to produce fertile offspring so they are not the same species.

Question 3

what is recombinant DNA technology

Answer 3

allows a gene from one organism to be transplanted into another using a vector to transfer the DNA into bacteria where it can be grown into colonies.

it can improve the quality of yield and crop growth so increased nutrition values and quality of produce. it is simple as the genetic code is universal. in vivo means that there will be no possible contamination. crops can be produced and used in plant pharming.

it is very expensive and the money may be better spent on other forms of research. traditional farmers may miss out. we do not know what the long term effects of this technology are.

Question 4

explain how transcription is regulated using the second messenger system of cell signalling

Answer 4

1. a steroid hormone (first messenger) binds to the receptor on the cell surface membrane activates a transmembrane protein which activates a G protein which activates adenylyl cyclase causing the formation of cyclic AMP from ATP molecules. this activates protein kinase A which phosphorylates proteins activating them so they can act as transcription factors in order to regulate transcription.