1a: The Theory of Endosymbiosis proposes the origin of both mitochondria and chloroplasts in modern photosynthesizing eukaryotic cells. What was proposed to have occurred in the evolution of these two organelles? Select all that apply. a. Mitochondria are part of the endomembrane system and as such created by infoldings of the plasma membrane. b. Photosynthetic cells were engulfed (ingested) by the host cell. c. Chloroplasts are part of the endomembrane system and as such created by infoldings of the plasma membrane. d. Aerobic bacteria were engulfed (ingested) by the host cell.
Structure and Composition of Cell Membrane
Despite differences in structure and function, all living cells in multicellular organisms are surrounded by a cell membrane. Just like the outer layer of the skin separates the body from its environment similarly, the cell membrane, also known as 'plasma membrane,' separates the inner content from its exterior environment.
Cell Membrane
The cell membrane is known by different names like plasma membrane or cytoplasmic membrane, or biological membrane. The term "cell membrane" was first introduced by C. Nageli and C. Cramer in the year 1855. Later on, in 1931, the term "plasmalemma" for cell membrane was given by J. Plowe. The cell membrane separates the cell's internal environment from the extracellular space. This separation allows the protection of cells from their environment.
Prokaryotes vs Eukaryotes
The cell is defined as the basic structural and functional unit of life. The cell membrane bounds it. It is capable of independent existence.
1a: The Theory of Endosymbiosis proposes the origin of both mitochondria and chloroplasts in modern photosynthesizing eukaryotic cells. What was proposed to have occurred in the evolution of these two organelles?
Select all that apply.
a. Mitochondria are part of the endomembrane system and as such created by infoldings of the plasma membrane.
b. Photosynthetic cells were engulfed (ingested) by the host cell.
c. Chloroplasts are part of the endomembrane system and as such created by infoldings of the plasma membrane.
d. Aerobic bacteria were engulfed (ingested) by the host cell.
1b: Which statement is not true of mitochondria and chloroplasts?
Select one:
a. Both mitochondria and chloroplasts contain DNA.
b. Mitochondria are only found in animal cells, and chloroplasts are only found in plant cells.
c. Ribosomes are present in both mitochondria and chloroplasts.
d. They grow and divide independently in the cell.
1c: Which if the following apply to lysosomes?
Select one or more:
a. Lysosomes are only found in plant and fungal cells. They are not found in animal cells.
b. The pH of the lysosome lumen is maintained via proton pumps in the membrane.
c. Lysosomes are produced from merging vesicles which bud from mitochrondria.
d. Lysosomes have a single membrane that is continuous with the nuclear membrane.
1d: What is an important role of the Golgi
Select one:
a. It is studded with ribosomes for protein synthesis. Proteins move into the lumen and are then sent to the smooth ER.
b. Receives vesicles from the ER containing protein destined for export from the cell
c. Lipid synthesis
d. Connects with the nuclear membrane to receive mRNA destined for ribosomes.
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