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How do we get more organisms?

Last updated 7 months ago
6 questions
We have learned how cells go through the Cell Cycle to make more cells. But how do we get more dogs? More birds? More bacteria?
Different organism have developed different ways of reproducing, but all of those different methods can fit into two categories: Sexual Reproduction or Asexual Reproduction.
Asexual Reproduction
During asexual reproduction, an organism inherits all of its chromosomes from a single parent.
Prokaryotic cells reproduce by a method called fission. Fission allows a prokaryotic cell to divide into two genetically identical cells. When prokaryotic DNA is duplicated, both copes attach to the plasma membrane. As the plasma membrane grows, the attached DNA molecules are pulled apart. The cell completes fission by producing two new prokaryotic cells that are genetically identical.
Some organisms are able to reproduce through budding. In this process a bud, or offspring, that is identical to its parent grows through mitosis on the body of its parent. When it becomes large enough its able to break off and live on its own, or sometimes remain attached a form a colony. Yeast, hydra, and cactus are all able to reproduce through budding.
The last type of asexual reproduction we'll discuss is vegetative propagation. Here, identical offspring grow from parts of a plant. Sometimes the parent plant send out runners, which are like long stems, and a new offspring grows at the end and is able to grow roots if it touches down to soil. Strawberries and potatoes are just two examples of the many plants that can do this.
There are advantages to asexual reproduction:
  • No time or energy is wasted to find a mate
  • usually able to reproduce rapidly
There are also some disadvantages:
  • There's no genetic variation meaning no organism would have a better chance for survival
  • any dangerous mutation a parent had would be passed on to all of their offspring and any "grand" offspring.
Sexual Reproduction
Sexual reproduction requires the combination of genetic material from two parent organisms, which results in the offspring receiving half of its DNA from each parent. This process requires the production of gametes (sperm/eggs) and chromosome numbers to be reduced and maintained by meiosis. New organisms created via sexual reproduction are genetically diverse.
Sexual reproduction has some advantages. First and most importantly, it creates genetically diverse offspring. Each offspring receives half their DNA from their Mother, and half from their Dad. Because of this genetic diversity, individuals within a population will be slightly different. These differences can lead to advantages like disease resistance in plants, or other traits that can be beneficial if a harsh shift in their environment occurs.

Humans have been able to figure out a way to use sexual reproduction to our advantage. Selective breeding is the idea that we breed two specific organisms together to get a desired trait. This has led to the development of plants and animals that help us, plants that grow better, larger animals, better temperament of animals, desirable pets, ect.

Sexual reproduction also has some disadvantages. Organisms have to put in time and energy into finding a mate. Many also have to put time into raising their young until they're old enough to sustain themselves and have their own offspring. While they're out searching for a mate they are at an increased risk of being exposed to predators, disease, or other detrimental circumstances.
1

What is a primary advantage of asexual reproduction?

1

Which organism typically reproduces asexually?

1

What type of division occurs during asexual reproduction?

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What is a key benefit of sexual reproduction?

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Which process occurs during sexual reproduction?

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What do gametes (sperm or egg) contribute to sexual reproduction?