Question

2. Symbiosis, mutualism, parasitism, commensalism, myxotrophic, coencytic 1. What is a eukaryote in terms of how genetic information (DNA) is stored and cellular structures, especially those using filaments and tubules? 2. What evidence is there that mitochondria and chloroplasts have an endosymbiotic origin? 3. Look at the Eukaryote phylogeny in the text. Back in the day, you would have been taught that there were five kingdoms; Animals, (land) Plants, Fungi, Monera (Archaea and Eubacteria) and Protists – the single celled Eukaryotes. What kind of phylogenetic group would Protists be?

Answer 1

•Symbiosis: two or more organisms living in close contact with each other.

•Mutualism: refers to the interaction between two or more organisms,and where both organism may benefit from each other.

•parasitism: this is a form of symbiosis where one organism(parasite)lives on or in another organism(usually called host),in turn causing them harm.

•commensalism: a form of symbiosis where one organism benefit from another while the other remain unaffected from the interaction.

•mixotrophic: refers to organisms that uses a combination of different sources of energy and carbon.Examples; can use combination of phototrophy and chemotrophy,or a combination of autotrophy and heterotrophy.

•coencytic: refers to a multinucleated organism that results from multiple nuclear division without their accompanying cytokinesis.It has a continuous mass of protoplasm,and surrounded by a cell wall.

1)The eukaryotic cells/organisms contain a clearly defined nucleus and also contain the following:

•It is composed of a cytoskeleton(The cytoskeleton contains microfilaments and microtubules that supports the cell and allow it to manage change in shape,to transport material from one part of cell to other parts and to distribute daughter chromosomes).

•contain a flexible cell surface.

•The microtubules might evolved and developed into a flagellum in some cells.

•Chromosomes present inside a nuclear envelope.

•The securing of specific organelles by means of endosymbiosis

•The presence of digestive vacuoles.

2)The following evidence suggests that mitochondria and chloroplast have endosymbiotic(which states that some of the eukaryotic cells where once prokaryotic microbes) origin:

•Mitochondria and chloroplasts are of the same size as the prokaryotic cells and they both divide by binary fission.

• Mitochondria and chloroplast both have their own circular DNA.

•Mitochondria and chloroplast have their own 30s and 50s subunits ribosomes and not 40s and 60s.

3)The protists forms a paraphyletic group. Paraphyletic group is a group of organisms that consists of a recent,common ancestor and some,not all, of its descendants.