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Random Mutations (Meiosis (Genetics: Variability and diversity among…
Random Mutations
Mutations can be spontaneous, which happens in nature by an accident. This is caused by DNA replication error during mitosis or meiosis
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Random mutations in organisms can neutral, which has no effect on the individual, beneficial, which increases reproductive success of the individual and makes them successful, or harmful, which decreases the chances of reproductive success of the individual
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Beneficial or neutral mutation, which effects the gametes or sex cells, are passed on to the next generation
Neutral mutations get passed on because it does not harm the individual on any level. Therefore, it does not effect the individual's reproductive success
Harmful mutations do not get passed on as they decrease the reproductive success of an individual. As a result, they are not favoured by nature
Beneficial mutations increase the reproductive success of an individual. This allows them to be more biologically successful than others as they survive longer and allow them to thrive in their natural environment. As a result, it is passed on to the next generation
Evolution: The process of biological change over time based on the relationships between species and their environments. Evolution starts with a random beneficial mutation
I did not know how natural selection worked before. I never though about how a species came to be and that they must have evolved from another species. I am now fascinated by the complex yet systematic way in which nature works
I did not know about the reproductive isolating mechanisms. I always assumed that species did not inetrbreed because they are different species, but I did not know what exactly caused such behaviour. I did not know about the different reasons, like temporal and behavioural. I also did not know that a zygote created from two different species might not survive after fertilization
I came to appreciate the philosophy behind Charles Darwin's theories. He was alive a long time ago when technology was not as advanced as today and he was still able to come to the conclusion about natural selection. Today's evolutionary biology depend on his theory of evolution and without it I don't know where we would be about our origin
Natural selection: The process through which nature favors the reproductive of organisms with certain physical and behavioural traits that allows them to thrive in their natural environment.
Variation in hereditary traits already exists among individuals of every species due to cross over during meiosis. These variations allow certain individuals to survive longer and reproduce more.
The individuals with the favoured traits are selected by nature. As a result, the traits of these individual's become predominant in that species as they are able to reproduce more and pass on their genes
The selected traits become predominant in the species as all the successful members possess these traits
Eventually, all the members of a species will have the same traits as they guarantee reproductive success, assuming that the environment and the climate will not change drastically
Because of the random mutation, organisms must adapt to their environment to survive and reproduce
Overtime, species evolve because of various random mutations and adaptations because of those mutations. These individuals become different from their ancestor species as they evolved to fit their environment
Gradually, a new species is created as these evolved organisms cannot interbreed with their ancestor species anymore due to various mutations and adaptations. This new species are reproductively isolated from other species, including their ancestors
In conclusion, evolution started with a random mutation. The random mutation must affect the gametes or sex cells in order to be passed on to the next generation. Because of that mutation, the organism had to adapt. Eventually, organisms evolved to form new species. This is how genetics and evolution are related to each other
Example: A species of birds originally have thick beaks. Some birds have thicker beaks than others in that same species as genetic variation exists due to cross over during meiosis. Some random mutation in the sex cells during cell replication causes the birds with comparatively thin beaks to have even thinner beaks. As a result, those birds are able to exploit more food sources and survive longer as they have less competition. They are favoured by nature. These birds are able to reproduce and pass on their genes. Over time, the birds adapt and evolve to become reproductively isolated from their ancestor species and create a whole new species
Meiosis
In males, 4 genetically unique sperm cells, which are all equally viable are created. In females, 3 small egg cells and one large egg cell are created. The 3 small ones support the larger one.
Each haploid cell contains 23 chromosomes, half of the 46 chromosomes that are in an average human being
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Cross over happens between a homologous pair of chromosomes where they exchange equal segments of their genetic information with each other. This ensures genetic variation in each of the haploid cells.
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Genetics: Variability and diversity among living things result from the distribution of genetic materials during the process of meoisis
I learned about the process of meiosis from this unit. I have always wondered how human beings had some features from each parent. Now, I know this is because of the gametes that are created during meiosis with 23 chromosome in each, which is half of what is in a human cell.
I did not know how GMOs were created. I never though about the fact that most of our foods have some genes in it that increases its reproductive success. After the genetics unit, I am more aware of the fact that most of our foods are GMOs and were created by inserting genes of something else. I also appreciate the technology behind GMOs as those allow various tropical food products to grow in Canada that were impossible to grow before
Both of the units, Genetics and Evolution, had the concept of random mutations in common, which is why it is the central topic
Mutations can be induced in organisms. This means that this is caused by exposure to a chemical or physical agent, like cigarette smoke, UV rays etc. for humans
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Traits that are naturally selected could be a hereditary variation that exists because of cross over during meiosis or it could be random mutation that effected the sex cells. In both cases, evolution by natural selection could occur.
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