An Introduction to Reproduction
Reproduction is the key to survival of all animals. Reproductive success is defined by the passing of genes from one generation to the next, so the next generation can reproduce, or pass on its genes. This is summed up to a species can interbreed and produce a fertile offspring.
There are two major ways in which organisms can reproduce; asexual and sexual. Asexual creatures, such as bacteria, don't need a sexual partner to reproduce where as sexual creatures, like humans and animals, preform sexual reproduction. Asexual reproduction, only involving the process of Mitosis, needs only on full set of chromosomes that are passed down from one generation to the next. This means that each offspring is a clone with no genetic variability. Though sexual reproduction is different, an organism only receives half of its chromosomes from one parent, and the other half from another parent. This is due to meiosis, making the offspring genetical different and have a greater variability.
Though as amazing and simple asexual reproduction may sound, it is in fact very complex and comes with a lot of advantages and disadvantages. Bacteria preform binary fission, when DNA is doubled and the divide. Budding is another form of asexual reproduction. It is mainly preformed by hydras, this is when the offspring grows off of the parent,s and eventually branches off. Sea sponges and sea stars preform fragmentation. This is when a piece of the organism breaks off, then replaces its self with anew organism. Asexual reproduction does not need another mate to reproduce. Asexual creatures can live in isolation, and also produce a large amount of offsprings in a small time slot. Though asexual reproduction has no genetic variability, meaning all the offsprings will be exactly the same as their parents. This can also mean that one factor that can kill one organism, can kill the entire population of that one organism.
There are two major ways in which organisms can reproduce; asexual and sexual. Asexual creatures, such as bacteria, don't need a sexual partner to reproduce where as sexual creatures, like humans and animals, preform sexual reproduction. Asexual reproduction, only involving the process of Mitosis, needs only on full set of chromosomes that are passed down from one generation to the next. This means that each offspring is a clone with no genetic variability. Though sexual reproduction is different, an organism only receives half of its chromosomes from one parent, and the other half from another parent. This is due to meiosis, making the offspring genetical different and have a greater variability.
Though as amazing and simple asexual reproduction may sound, it is in fact very complex and comes with a lot of advantages and disadvantages. Bacteria preform binary fission, when DNA is doubled and the divide. Budding is another form of asexual reproduction. It is mainly preformed by hydras, this is when the offspring grows off of the parent,s and eventually branches off. Sea sponges and sea stars preform fragmentation. This is when a piece of the organism breaks off, then replaces its self with anew organism. Asexual reproduction does not need another mate to reproduce. Asexual creatures can live in isolation, and also produce a large amount of offsprings in a small time slot. Though asexual reproduction has no genetic variability, meaning all the offsprings will be exactly the same as their parents. This can also mean that one factor that can kill one organism, can kill the entire population of that one organism.
Mitosis and Meiosis
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Meiosis and Mitosis are two forms of cell division. Mitosis is the process of cell division in a-sexual reproduction. Mitosis usually has a result of two genetically identical child cells. The four stages of Mitosis are as following
- Prophase: The stage in the process when the chromosomes appear, the nucleus disappears and the spindle fibers form.
- Metaphase: This is the stage when the chromosomes line up in the middle.
- Anaphase: This is the stage when the sister chromatids divide.
- Telophase: This is the stage when two cells have formed.
Meiosis is the process of producing four daughter cells, each having half of the parents chromosomes from one cell with a full set of chromosomes. This is called a diploid cell. This gives organisms the ability to reproduce sexually, due to the haploid cell, the cell with the full set of chromosomes such as gametes, are produced. When two haploid cells from different genders combine, they become one, for example an egg and a sperm becoming one. Though Meiosis is the process of creating four cells, so they need to go through cell division twice. These two processes are known as Meiosis I and Meiosis II. The steps to meiosis are as following:
- Prophase I: Homologous chromosomes pair up and they cross over. When they cross over, this is the process of genetic informations being exchanged between homologous pairs. This is the main cause for genetic variability.
- Metaphase I: The chromosomes line up in the center of the cell.
- Anaphase I: The homologous chromosomes are separated and spindle fibers pull apart the chromosomes.
- Telophase I: The two haploid cells are formed.
- Prophase II: Sister chromatids show up, the nucleus then dissolves.
- Metaphase II: Chromotids line up in the center of the cell.
- Anaphase II: Spindle fibers pull the chromotids apart.
- Telophase II: The two haploid daughter cells divide into four cells.
Reproduction in the Emperor Penguin
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Emperor penguins have a specific time they choose to reproduce. Their timing is different than any other species alive. They are the only ones who choose to reproduce in the peak of the winter chills in the Antarctic. They tend to travel over 70 miles to reach a destination made for reproducing, or mating grounds. They will find themselves in a group of thousands of other birds, choose one mate and begin the mating process. They will choose one mate and stay monogamous to it the entire season. The male birds have a pair of testes, which grow in size during mating season to produce more sperm. The sperm they produce travels through the vas deferens and is stored inside the cloaca ( an internal body part that both male and female birds have). The cloaco serves as an excretion tube for urine and semen. Most male birds don't have a penis, so the way that birds reproduce is that they touch each others cloaca and rub it together, this then transfers the males sperm into the female body. Once this happens, the sperm travels to the female's sperm storage tubules. The sperm can stay inside there for about 100 days. The sperm fertilizes the eggs in the female and happens before the eggs in the shell hardens in the oviduct.