Bacteria

 

          In a recent biology lab we tested many different locations of the college to see where bacteria is most commonly found, and the results were extremely disgusting and very shocking.

          I always knew there was bacteria on almost everything we touched but it really surprised me to see that so many bacterium’s live on a door handle that is barely touched. There are millions of bacteria in the world but not all can live in every environmental conditions, for example bacterium’s found in Antarctica wouldn’t be found in Africa do to the temperature differences.

          In certain foods we eat such as yogurt, cheese and other dairy products contain many different bacterium’s, obviously not the ones found under toilet seats but ones that are edible and can even be good for you. It is really important for these food products to have these kinds of bacterium’s to make them edible and even good to eat.

          The bacteria found in many dairy products are known as cultures and are harmless to the human body, because we eat them every day and rarely get sick. Other bacterium’s that can be very harmful and even deadly is e-coli and salmonella that is found in questionable foods or foods that were produced in dirty areas or infected by animals with viruses.

How do hermaphrodites reproduce?

 

          Throughout biology I have learned that many different species are hermaphrodites, meaning that an organism has both sets of sex organs and can produce eggs and sperm. I have always wondered though is how they reproduce to produce offspring.

          What I have recently learned is that hermaphrodites can fertilize their own eggs with their own sperm to produce offspring that is genetically identical to them so they don’t need a mate to do so. For example worms and snails to name a few are known to be hermaphroditical and that is the reason they look so similar to each other. Another way hermaphrodites can reproduce is by trading their sperm with the same species and then create offspring by using the new sperm to fertilize the eggs, just like sexual reproduction.

          There is no major problem with hermaphrodites reproducing but if they weren’t able to switch sperm with the same species and only reproduce with themselves and make genetically identical offspring, if environmental changes were to occur they would not be able to survive because they wouldn’t be able to reproduce with other species.

Mitosis/Cell Division.

 

          Mitosis is the process when a single eukaryotic cell divides resulting in two identical daughter cells with the same genetic information from the parent cell. Mitosis is also known as a type of cell division when the parent cell separates its nucleus and chromosomes to duplicate and create 2 new sets. Mitosis is divided up into 6 stages.

1)   Interphase: During interphase the DNA replicates inside the single cell and the chromosomes have not yet formed so they remain as chromatin (long fibers that are a result as 2 chromosomes splitting apart)

 

2)   Prophase: During prophase the DNA molecules that were just replicated get shorter and condense to form chromosomes. At this stage the nuclear envelope and nuclear membrane disappear.

 

3)   Metaphase: During metaphase the spindle apparatus that help the cell separate form and are visible at opposite ends of the cell. The fibers then attach themselves to the chromosomes and bring them to the center of the cell which forms a “plate.”

 

4)   Anaphase: During anaphase the chromosomes separate to become sister chromatids and then are pulled to opposite sides of the cell by the centrioles and get ready for the cell to actually split apart.

 

5)   Telophase: At each side of the cell 2 new nuclear envelopes form around the newly duplicated chromosomes, the spindle fibers disappear at this stage.

 

6)   Cytokinesis: this phase can be in conjunction with telophase, but it is the stage were the 2 daughter cells are pinched off from each other to create 2 new cells with the same number of chromosomes.

 

After all these stages are complete, “depending on the organism it can take 20 minutes to 24 hours to reproduce” and start growing as a single cell and once again reproduce to form more cells.

 

1. http://www.wisegeek.org/how-long–does-it-take-for-cells-to-divide.htm

Patau Syndrome (Extra 13th Chromosome)

 

          Patau syndrome also known as an extra 13^th chromosome is caused by extra genetic information found in the 13^th set of chromosomes in each cell. Because of this extra genetic information it causes extreme abnormalities and physical and organ defects, even someone with a minor case still can have some sort of disability or abnormality. Between “1 in 10,000 and 1 in 20,000 are affected.”

 

          Patau syndrome mainly affects the nervous system and physical features of the person affected. Some signs of patau syndrome that are most common are “mental retardation, deformed facial features, deformed feet and hands, and heart and kidney defects. Patau syndrome can be screened before the mother gives birth, unfortunately some parents choose to abort the pregnancy. In some extreme cases the fetus is not able to survive in the womb and the mother miscarries during the 1^st trimester, and sometimes the 2^nd.

 

          There are other syndromes that can affect the body when there’s an extra 13^th chromosome but the most common disease is patau syndrome. “80% of infants that are born with this unfortunate syndrome usually don’t live past the age of one year. Many infants who survive the first couple of years may receive surgeries to fix heart defects and physical abnormalities, but the life expectancy for someone with patau syndrome is very low.

 

1. http://en.wikipedia.org/wiki/Patau_syndrome

Reproductive Barriers

Reproductive barriers are physical processes that prevent 2 different species coming together to mate and produce offspring. Reproductive barriers have been classified into 2 separate ways either prezygotic barriers which are the barriers that the 2 different species face before, or if they even can reproduce and produce offspring postzygotic barriers are the barriers that the 2 species face after they produced offspring that usually is sterile. There are many different types of prezygotic barriers but the main ones include habitat, temporal, behavioral, mechanical, and gametic isolation.

Habitat Isolation is when the 2 different species that are similar live in 2 different habitats such as one may live in water and one may live on land. There is a possibility for reproduction but it is highly unlikely.

Temporal Isolation is when the 2 different species live in 2 different temporal areas meaning 2 different climates. Grizzly bears are found in warmer areas and polar bears are found in extremely cold areas that barely get any sun, they are both bears but live in different temporal zones of the world.

Behavioral isolation is when 2 similar species act completely different from each other and the other species doesn’t know how to react to it. Wood and leopard frogs are an example of behavioral isolation because they are both frogs but the wood frog has a mating call that only attracts the opposite sex from the wood frogs and the leopard frog has a mating call that only attracts the opposite sex of the leopard frog.

Mechanical isolation is when the 2 different species are extremely similar but their reproductive tracts don’t match up. An example of that would be snails because the bulkiness of their shells and different locations for their genitals make it a challenge for them to reproduce, also another challenge is that snails are hermaphrodites.

Gametic Isolation is when the 2 species are not able to reproduce because the sperm and egg are not compatible so there is no way of offspring being able to be produced, an example would be some sea creatures one species being a red color and only reproduce with the same color because the red colored sperm doesn’t match up with a purple sea creatures eggs.

 

Postzygotic barriers are when 2 different species are able to reproduce but their offspring is not able to reproduce making it sterile, a good example of that would be a donkey and horse coming together to make a mule but in the end the mule is sterile making it not be able to reproduce with any other species or even its own.