Introduction to reproduction and reproductive success
Reproduction is important because it prevents species from dying out. Individuals must reproduce to ensure the survival of their species. In order for survival, the individuals must achieve reproductive success, being that they must be able to pass down genes to the next generation or produce fertile offspring. With the process of reproductive success, species are able to survive for generations and generations. The two different types of reproduction are sexual and asexual reproduction. While they both result in offspring, there are many differences between the two. Asexual reproduction involves only one parent, and to make offspring it clones itself, passing all of it's genes down to the child. Asexual reproduction is the primary way for single-celled organisms to reproduce, and there are four different ways to do so. These are vegetative propagation, budding, binary fission and fragmentation. Unlike asexual reproduction, sexual reproduction involves two parents. The two parents combine genetic material to get offspring. The child then receives half of it's genes from one parent and half from the other. This process is preformed by humans as well as other eukaryotes.
Sexual Reproduction asexual reproduction
Mitosis vs. meiosis
Both meiosis and mitosis are forms of cell division that occur in species of all kind. Meiosis is a form of cell division where the result is four haploid gametes. Gametes are sex cells, and haploid cells are cells containing half of a full set of chromosomes. The general purpose of meiosis is to produce gametes which are used in fertilization. Mitosis is a form of cell division where a cell divides into two identical sister cells called diploid cells. Diploid cells are cells with a full set of chromosomes. In this process, chromosomes in the nucleus are separated into two identical sets, each then in its own nucleus. The general purpose for this process is for growth and repair of the body, as well as the making of cells such as the skin cell.
During mitosis, there are five key stages to creating the two identical sister cells. The first is interphase, which takes up a majority of the time. During this stage, the cell does not divide, but the DNA inside replicates. During the second step, prophase, the nucleus of the cell begins to slowly disappear and chromosomes begin appearing while spindle fibers form from centrioles. Centrioles are cell structures that work to make these fibers which ultimately help chromosomes line up in the center of the cell. The third stage is Metaphase, where the chromosomes are lined up parallel in the "equator" of the cell. The spindle fibers then attach themselves to the chromosomes. The fourth stage, Anaphase, is when the sister chromosomes begin to pull apart and separate due to the pulling of the fibers. Lastly, Telophase occurs as the two separate cells form as their own.
Meiosis is not a form of reproduction, rather a process that forms four genetically variable cells. There are two distinct stages in meiosis, Meiosis I and Meiosis II. In Meiosis I, the stages are the same as Mitosis. Being that DNA replication starts, then the nucleus disappears, followed by chromosomes being lined up and pulled away from the center of the cell. However in Meiosis II, the stages pick up after the two sister cells are formed. In Prophase II, spindle fibers appear, chromosomes begin to form and the nucleus disappears. Next, in Metaphase II, chromosomes line up in the center of the cells yet again. In Anaphase II, the sister chromatids move apart, and lastly in Telophase II, four individual haploid cells are formed.
During mitosis, there are five key stages to creating the two identical sister cells. The first is interphase, which takes up a majority of the time. During this stage, the cell does not divide, but the DNA inside replicates. During the second step, prophase, the nucleus of the cell begins to slowly disappear and chromosomes begin appearing while spindle fibers form from centrioles. Centrioles are cell structures that work to make these fibers which ultimately help chromosomes line up in the center of the cell. The third stage is Metaphase, where the chromosomes are lined up parallel in the "equator" of the cell. The spindle fibers then attach themselves to the chromosomes. The fourth stage, Anaphase, is when the sister chromosomes begin to pull apart and separate due to the pulling of the fibers. Lastly, Telophase occurs as the two separate cells form as their own.
Meiosis is not a form of reproduction, rather a process that forms four genetically variable cells. There are two distinct stages in meiosis, Meiosis I and Meiosis II. In Meiosis I, the stages are the same as Mitosis. Being that DNA replication starts, then the nucleus disappears, followed by chromosomes being lined up and pulled away from the center of the cell. However in Meiosis II, the stages pick up after the two sister cells are formed. In Prophase II, spindle fibers appear, chromosomes begin to form and the nucleus disappears. Next, in Metaphase II, chromosomes line up in the center of the cells yet again. In Anaphase II, the sister chromatids move apart, and lastly in Telophase II, four individual haploid cells are formed.
How does sally reproduce?
The Sally Lightfoot Crab has a very unique way of reproducing. Unlike other arthropods, they do not preform a mating dance for each other. Instead, these crabs can have more than one mating partner in a breeding season, which contributes to the complexity of how they mate. During crab intercourse, the male deposits sperm into the spermatheca of the female. In the male, the release of sperm is helped by secretions from the gonopod tegumental glands. These glands are specialized for secretions which leads to protection of the male's genetic investment, as well as the process of sperm competition and paternity assurance [1]. After receiving the sperm, females release their fertilized eggs and store the remainder of the sperm into their specialized spermathecae. Their eggs remain attached on their belly for protection until the hatching [2]. The only exception for females to mate again is when all stored sperm has been used, which is fully dependent on the amount of eggs that are produced at a time.