Genetic Diversity
The definition of Genetic Diversity is when each individual species possesses genes which are the source of its own unique features: In human beings, for example, the huge variety of people's faces reflects each person's genetic individuality. The term genetic diversity also covers distinct populations of a single species, such as the thousands of breeds of different dogs or the numerous variety of roses.
The definition of Genetic Diversity is when each individual species possesses genes which are the source of its own unique features: In human beings, for example, the huge variety of people's faces reflects each person's genetic individuality. The term genetic diversity also covers distinct populations of a single species, such as the thousands of breeds of different dogs or the numerous variety of roses.
The Importance of Genetic Diversity
Most higher organisms (both plants and animals) reproduce sexually—that is, they produce offspring through the union of reproductive cells from two different parents. Think back to our example of the violet. Violets produce showy flowers that attract insects that carry pollen from one plant to the next. Offspring resulting from this cross-pollination are genetically distinct from either parent. Violets also produce flowers that never open, and are self-pollinated. The resulting offspring are genetically similar, though not identical, to the parent. And, finally, violets send out creeping stems. Plants sprouting from these runners are genetically identical to the parent plant. We’ve talked about genetic diversity—but why is it important, and how does it fit in with our general topic of plant sexual reproduction?
Sexual reproduction is critical for maintaining genetic diversity within a species because it combines the parents’ genetic material, resulting in offspring with unique genetic blueprints—different from either parent.
While some individuals might be able to tolerate an increased load of pollutants in their environment, others, carrying different genes, might suffer from infertility or even die under the exact same environmental conditions. Whilst the former will continue to live in the environment the latter will either have to leave it or die. This process is called natural selection and it leads to the loss of genetic diversity in certain habitats. However, the individuals that are no longer present might have carried genes for faster growth or for the ability to cope better with other stress factors.
Mutation
Mutation is a natural process that changes a DNA sequence. And it is more common than you may think. As a cell copies its DNA before dividing, a "typo" occurs every 100,000 or so nucleotides. That's about 120,000 types each time one of our cells divides.
The random changes a mutation potentially causes to an organisms genetic code causes either
1. A different protein to be produced
2. None at all Mutations can either have a positive, negative or neutral (the vast majority) effect on the organism. (many times whether they are harmful or helpful depends on the environment.)
When a mutation makes an organism better able to survive that organism is more likely to survive and pass the mutated gene onto the next generation. Shown below is a diagram of mutation.
Chromosomal Mutation
A chromosome mutation is an unpredictable change that occurs in a chromosome. These changes are most often brought on by problems that occur during meiosis (cell division process of gametes) or by mutagens (chemicals, radiation, etc.). Chromosome mutations can result in changes in the number of chromosomes in a cell or changes in the structure of a chromosome. Unlike a gene mutation which alters a single gene or larger segment of DNA on a chromosome, chromosome mutations change and impact the entire chromosome.
Chromosome structure changes are often harmful to an individual leading to developmental difficulties and even death. Some changes are not as harmful and may have no significant effect on an individual. There are several types of chromosome structure changes that can occur. Some of them includes
Trans-location: The joining of a fragmented chromosome to a non-homologous chromosome is a translocation. The piece of chromosome detaches from one chromosome and moves to a new position on another chromosome
Most higher organisms (both plants and animals) reproduce sexually—that is, they produce offspring through the union of reproductive cells from two different parents. Think back to our example of the violet. Violets produce showy flowers that attract insects that carry pollen from one plant to the next. Offspring resulting from this cross-pollination are genetically distinct from either parent. Violets also produce flowers that never open, and are self-pollinated. The resulting offspring are genetically similar, though not identical, to the parent. And, finally, violets send out creeping stems. Plants sprouting from these runners are genetically identical to the parent plant. We’ve talked about genetic diversity—but why is it important, and how does it fit in with our general topic of plant sexual reproduction?
Sexual reproduction is critical for maintaining genetic diversity within a species because it combines the parents’ genetic material, resulting in offspring with unique genetic blueprints—different from either parent.
While some individuals might be able to tolerate an increased load of pollutants in their environment, others, carrying different genes, might suffer from infertility or even die under the exact same environmental conditions. Whilst the former will continue to live in the environment the latter will either have to leave it or die. This process is called natural selection and it leads to the loss of genetic diversity in certain habitats. However, the individuals that are no longer present might have carried genes for faster growth or for the ability to cope better with other stress factors.
Mutation
Mutation is a natural process that changes a DNA sequence. And it is more common than you may think. As a cell copies its DNA before dividing, a "typo" occurs every 100,000 or so nucleotides. That's about 120,000 types each time one of our cells divides.
The random changes a mutation potentially causes to an organisms genetic code causes either
1. A different protein to be produced
2. None at all Mutations can either have a positive, negative or neutral (the vast majority) effect on the organism. (many times whether they are harmful or helpful depends on the environment.)
When a mutation makes an organism better able to survive that organism is more likely to survive and pass the mutated gene onto the next generation. Shown below is a diagram of mutation.
Chromosomal Mutation
A chromosome mutation is an unpredictable change that occurs in a chromosome. These changes are most often brought on by problems that occur during meiosis (cell division process of gametes) or by mutagens (chemicals, radiation, etc.). Chromosome mutations can result in changes in the number of chromosomes in a cell or changes in the structure of a chromosome. Unlike a gene mutation which alters a single gene or larger segment of DNA on a chromosome, chromosome mutations change and impact the entire chromosome.
Chromosome structure changes are often harmful to an individual leading to developmental difficulties and even death. Some changes are not as harmful and may have no significant effect on an individual. There are several types of chromosome structure changes that can occur. Some of them includes
Trans-location: The joining of a fragmented chromosome to a non-homologous chromosome is a translocation. The piece of chromosome detaches from one chromosome and moves to a new position on another chromosome
- Deletion: This mutation results from the breakage of a chromosome in which the genetic material becomes lost during cell division. The genetic material can break off from anywhere on the chromosome.
- Duplication: Duplication are produced when extra copies of genes are generated on a chromosome.
- Inversion: In an inversion, the broken chromosome segment is reversed and inserted back into the chromosome. If the inversion encompasses the centromere of the chromosome, it is called a pericentric inversion. If it involves the long or short arm of the chromosome and does not include the centro mere, it is called a parametric inversion.
- Reciprocal Trans-location This type of chromosome is produced by the improper division of the centromere. Reciprocal Trans=location contain either two short arms or two long arms. A typical chromosome contains one short arm and one long arm
Genetic Mutation
A gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people. Mutations range in size; they can affect anywhere from a single DNA building block (base pair) to a large segment of a chromosome that includes multiple genes.
Types of Changes in DNA
The DNA in any cell can be altered through environmental exposure to certain chemicals, ultraviolet radiation, other genetic insults, or even errors that occur during the process of replication. If a mutation occurs in a germ-line cell (one that will give rise to gametes, i.e., egg or sperm cells), then this mutation can be passed to an organism's offspring. This means that every cell in the developing embryo will carry the mutation. As opposed to germ-line mutations, somatic mutations occur in cells found elsewhere in an organism's body. Such mutations are passed to daughter cells during the process of mitosis (Figure 2), but they are not passed to offspring conceived via sexual reproduction.
A gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people. Mutations range in size; they can affect anywhere from a single DNA building block (base pair) to a large segment of a chromosome that includes multiple genes.
Types of Changes in DNA
The DNA in any cell can be altered through environmental exposure to certain chemicals, ultraviolet radiation, other genetic insults, or even errors that occur during the process of replication. If a mutation occurs in a germ-line cell (one that will give rise to gametes, i.e., egg or sperm cells), then this mutation can be passed to an organism's offspring. This means that every cell in the developing embryo will carry the mutation. As opposed to germ-line mutations, somatic mutations occur in cells found elsewhere in an organism's body. Such mutations are passed to daughter cells during the process of mitosis (Figure 2), but they are not passed to offspring conceived via sexual reproduction.