Sexual Reproduction

You do not have access to this lesson.

The following is a limited nonfunctional preview of the actual lesson.

bzoomImage
DEMO

With Meiosis

Preview mode...

Without Meiosis

Preview mode...

Sexual Reproduction

Sexual reproduction is the reproduction of two separate individuals through the merging of gametes to form a zygote. The zygote then develops into a new individual, genetically different from, but very similar to both parents.

Gametes

Gametes are created by a kind of cell division called meiosis. In humans, gametes are delivered in the male and female gonads. Gametes are haploid, meaning that it is a lone stand out among the arrangement of chromosomes, whereas the zygote is diploid, meaning that it contains two different arrangements of chromosomes. The male sex cell, called the spermatozoon, is moderately motile and more often than not has a flagellum. The female gamete, called the ovum, is non-motile and is generally much more robust when compared with the male gamete.

During sexual reproduction, gametes from the male and female unite with one another to form a zygote.  In the case of seed-bearing plants, dust serves as the male sperm creating gametophyte whereas female gametes (ovules) are contained inside the plant ovary. Within most living creatures, the gametes contained in the male’s gonads, commonly known as sperm, take the form of long tailed cells and attempt to make their way to fertilize the female’s ova, or egg, inside the female. In this case, the female gamete, the ova is particularly static, in vast contrast to the male gamete, and awaits penetration by the male gamete.

It is through the process of meiosis that gametes are conceived in a two stage process. During this process, the four smaller female cells that result are the haploids that contain only one set of chromosomes each. It’s only once this process is complete that the fertilization process can occur and create the zygote.

Patterns and Cycles

Reproduction involves a continual process, which re-occurs at specific intervals. These cycles can be affected by any number of natural phenomena which can either positively or negatively impact a population’s ability to reproduce as easily as intended. As an example of this, there are various animals that have estrous cycles that recur within designated time frames throughout the year with the expectation of conception resulting from it.

External Fertilization

External fertilization most often occurs in humid or wet climates. It requires both the female and male to discharge their individual gametes into their environment, which is most often water. During this process, countless gametes can be released by both the male and female resulting ultimately in many offspring. The one prevailing danger associated with this type of sexual reproduction involves potential threats posed by predators. This danger greatly diminishes the potential for the offspring to evolve into adulthood.

Internal Fertilization

Internal fertilization occurs, as the name suggests, inside the body. The female retains the egg inside itself. The male releases its sperm inside the female, and when the two meet, the egg is fertilized and a zygote is formed. In some animals, this zygote grows a protective shell and becomes an egg that the mother then discharges to be hatched later. In other animals, the zygote develops for a period, called gestation, inside the mother's uterus and is born live.

Summary

Sexual reproduction is the merging of two gametes from two parents to form an offspring. Gametes, or sex cells, are haploid cells containing only half the genetic material of the parent organism. When the female gamete, or egg, is fertilized by the male gamete, the sperm, a zygote forms. The zygote is a new, unique organism that has genetic material from both parents. sexual reproduction occurs in cycles, with each organism only being fertile during a certain part of the cycle. With external fertilization, the female lays the eggs and a male comes by later and fertilized them. With internal fertilization, the male and female mate and the sperm fertilized the egg inside the female's body. In the case of internal fertilization, the female will either lay the fertilized egg for it to hatch later, or will carry the developing zygote and give live birth to it.

Demonstration mode. Purchase course to view.

This is the default dialog which is useful for displaying information. The dialog window can be moved, resized and closed with the 'x' icon.