Genetics/Cell division/ Mutation
March 9, 2012 at 3:50 am #16198AyeshaaParticipant
Hey, I watched a few videos in class about genetic stuff, and I was able to write down answers to some of the questions, but I wasn’t able to understand some of the stuff shown in the video, so there are some questions I need help on, and if you guys can help me, will really really appreciate that. Thanks in advance =) Sorry guys some of the questions are probably so simple, but I really suck at biology:\
1. What type of cell division provides continuity without variation, and what does this mean?
^ I got mitosis. Though I’m not sure what it means.
2.What is a positive mutation?
^ Is that like species that have advantages and are able to survive.
3.What are 2 examples of short wave radiation that can cause mutation?
^ I only got UV radiation.
4.How are gene combinations reshuffled?
^ by mitosis and meosis?
5.How are new genes added to a population?
6.Whats the difference b/w gradualism and punctuated equilibrium theories of evolution?
^ Gradualism is a smooth change, occurs slowly but steadily and Punctuated equilibrium shows leaps and is a long and stable period and continous.
March 9, 2012 at 4:06 pm #110053LuxorienParticipant
1) Mitosis is correct. In this type of cell division, the resulting "daughter" cells are genetically identical to the parent cell. Mitosis happens all over your body all the time, replacing damaged or aged tissue. According to this Q&A, the cells lining your small intestine get replaced every week. So, mitosis provides continuity, because a parent cell gives rise to daughter cells, propagating the genetic information carried in that cell. However, it does not introduce any variation, because the DNA is copied exactly (barring the occasional mutation). Meiosis is another matter. 🙂
2) Sounds about right. A mutation is a copying error that occurs during DNA replication. Most of these errors do not affect the organism’s survival one way or the other. A small number are either harmful or beneficial.
3) This might help: http://en.wikipedia.org/wiki/Electromagnetic_spectrum
4) Remember, mitosis can only produce more cells like the first. Only in meiosis do we see the genetic deck getting reshuffled, introducing a great amount of genetic variation. Mitosis happens all over your body, in your normal, everyday cells. Any changes to those cells do not get passed on to your offspring. When sex cells (egg/sperm) are created, however, an event called crossing over occurs during meiosis. The chromosomes exchange big chunks with each other and create novel combinations of alleles.
5) Basically, yes.
6) I would jump on board with that.
March 9, 2012 at 4:31 pm #110054AyeshaaParticipant
Thanks very much Luxorien =)
March 10, 2012 at 8:26 pm #110074AstraSequiParticipant
For #5, I would mention that most mutations actually don’t produce new genes, but rather cause changes to existing genes. The most common way for a new gene to be created is a gene duplication, which leads to two or more identical copies of the gene. Natural selection will ensure that at least one of the genes retains its original function, but any others can mutate and take on new functions. This is why organisms have many paralogous genes (highly similar to each other, but which do completely different things).
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