Week 11 Application Questions Flashcards
- Many bacterial cells contain plasmids.
a. These cells can survive a process called ‘curing’ where chemicals are used to remove the plasmid molecules from the cytoplasm of the cells.
Explain why bacterial cells can survive the loss of this plasmid DNA.
The plasmid is not necessary to the cell in the first place
Plasmids carry non-essential genes; all essential genes are found on the cell’s chromosome
- Many bacterial cells contain plasmids.
b. Several antibiotics, such as the antibiotic erythromycin, inhibit the function of the ribosomes of bacterial ribosomes.
Explain why these antibiotics cause the death of bacterial cells.
– Protein production is essential to the cell. Cells are constantly producing proteins for all kinds of functions. Preventing translation interferes with everything from cell transport to signaling to digestion to energy production.
– Because the ribosomes between pro-and eukaryotes are slightly different, this only affects bacterial ribosomes
- Imagine that the cell is like a house. What would be the function of each of the following organelles or structures in the house? Make and explain an analogy for each structure listed below:
a. Nucleus, ribosome, endoplasmic reticulum, Golgi apparatus, lysosome, mitochondria, chloroplast, vesicle, central vacuole, cell wall, plasma membrane
- Imagine that the cell is like a house. What would be the function of each of the following organelles or structures in the house? Make and explain an analogy for each structure listed below:
b. Example: The nucleus is like the office space/nook of the house because it stores all the files (DNA) and directs all the activities of the cell (where the “smart house” processor is (modem WIFI?) .
- The lysosomes are an important organelle in the cell, involved in the processes of autophagy and digestion of food particles brought into the cell by phagocytosis.
a. Explain how the acidic pH would be established in these cells.
Proton pumps
- The lysosomes are an important organelle in the cell, involved in the processes of autophagy and digestion of food particles brought into the cell by phagocytosis.
b. If the lysosome membrane ruptured and the enzymes found inside were released into the cytoplasm, describe what would happen to the cell.
– Recall: enzymes need very specific pH to function properly
– Lysosomal enzymes are optimized to work at acidic pH
– Cytosol pH is neutral, so lysosomal enzymes won’t work efficiently – More a waste of enzymes than a problem for the cell
– One burst lysosome will not really change the pH of the whole cell (a table spoon of salt in a swimming pool will not make the water salty)
- The lysosomes are an important organelle in the cell, involved in the processes of autophagy and digestion of food particles brought into the cell by phagocytosis.
c. Some people have dysfunctional lysosomes (lysosomal disorders). Based on what was covered in this topic, what would be the direct result of this?
E.G. Lysosomal storage disorder, is considered contributing to Parkinson’s disease
Build up of parts of fats, carbohydrates, cell organelles that do not function any more, recycling stops…. Degradation of macromolecules would not occur
Spleen and liver enlargement, blood issues, bone issues, ….
- One focus was the synthesis and export of proteins by the endomembrane system, but this group of organelles is also involved in the synthesis and targeting of membrane phospholipids.
The main difference is that newly made phospholipids must be part of a membrane as they are modified and moved around the cell.
Based on the knowledge you have gained in previous topics, propose a process that would allow a cell to make phospholipids destined to become part of the plasma membrane of the cell.
Membrane flow/vesicle traffic in the cytoplasm —> Can use the same export pathway as the proteins.
Lipids synthesized into the SER membrane (not visible here)
SER and RER are continuous – share a membrane
During exocytosis, vesicle membrane fuses with cell membrane
- The endosymbiotic theory explains, in part, the evolution of eukaryotic cells.
a. Explain how the endosymbiotic theory explains the origin of mitochondria and chloroplasts.
First event: Aerobic prokaryote engulfed, survives, develops relationship with host
Now Mitochondria
Second event leads to chloroplasts
- The endosymbiotic theory explains, in part, the evolution of eukaryotic cells.
b. Describe any 2 pieces of evidence that support the endosymbiotic theory.
– Shape and size of mitochondria/chloroplasts
– Binary fission (vs. eukaryotic mitosis)
– Mitochondria and chloroplasts have their own DNA…
– … which is circular, in contrast to eukaryotic linear chromosomes
– Mitochondria, along with the DNA, have their own replication machinery (ribosomes are similar to bacteria’s)
– Mitochondria can produce their own proteins
– rRNA of mitochondria and chloroplasts most closely related to bacteria
– Outer membrane of chloroplasts and mitochondria is similar to “host” cell membrane, but inner membranes look like bacterial membranes
- The endosymbiotic theory explains, in part, the evolution of eukaryotic cells.
c. Does this theory explain the origin of the nuclear envelope, which also has a double membrane structure? Explain your answer.
No.
– Going theory is that infoldings of the plasma membrane pinched off and fused forming the nuclear membrane, the ER, the Golgi, etc.
– Similarly the endosymbiotic theory does not explain how linear chromosomes formed
