MCAT Biology : Bacteria and Types of Prokaryotes
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Example Question #1 : Bacteria And Types Of Prokaryotes
All of the following are characteristics of prokaryotic cells except for __________.
unicellularity
lack of membrane-bound organelles
lack of a nucleus
a cell wall
they are usually found in protists and fungi
they are usually found in protists and fungi
Protists, fungi, plants, and animals are eukaryotic, while bacteria are prokaryotic. The rest of the answer choices are characteristic of prokaryotic cells.
Example Question #2 : Bacteria And Types Of Prokaryotes
The presence of which of the following feature would best indicate a eukaryotic cell?
Cilia
Plasma membrane
Ribosomes
Homeostasis
Organelles
Organelles
Organelles are only found in eukaryotic cells which set them apart from prokaryotic cells.
Example Question #2 : Bacteria And Types Of Prokaryotes
Which of the following components of an animal cell would NOT also be observed in a bacterial cell?
Nucleus
DNA
Ribosomes
Phospholipid cell membrane
Nucleus
This question is asking about one of the differences between eukaryotes and prokaryotes. While both eukaryotes and prokaryotes use DNA to encode their genetic information, making "DNA" incorrect, remember that prokaryotes lack membrane-bound organelles. \This makes both "ribosomes" and "phospholipid cell membrane" incorrect, because neither of them are membrane-bound organelles. We are left with "nucleus," which is the correct answer.
Example Question #3 : Bacteria And Types Of Prokaryotes
Which of the following would not be found in a prokaryotic cell?
RNA
Mitochondria
Ribosomes
DNA polymerase
Plasma membrane
Mitochondria
One of the key differences between prokaryotes and eukaryotes is that prokaryotes have no membrane bound organelles, therefore, prokaryotes would not have mitochondria. Prokaryotes have a plasma membrane for protection, ribosomes for protein production, RNA in the form of mRNA, tRNA, and rRNA, and DNA polymerase to replicate their DNA.
Example Question #4 : Bacteria And Types Of Prokaryotes
A scientist studying a culture of bacteria finds an organism he hadn't seen before. He thinks it might be some kind of single-celled eukaryote. What observed characteristic would support the scientists prediction?
An electron transport chain
A membrane bound organelle
The presence of both DNA and RNA
A cell wall
The presence of ribosomes
A membrane bound organelle
The characteristic that defines a eukaryote is the presence of membrane bound organelles, such as the nucleus, mitochondria, Golgi body, and chloroplasts. Both eukaryotes and prokaryotes have ribosomes, DNA and RNA, and and electron trasnsport chain. Bacteria and plants have cell walls but not all eukaryotes do, so it is not a defining characteristic.
Example Question #6 : Bacteria And Types Of Prokaryotes
Which of the following is not a characteristic of prokaryotes?
Presence of ribosomes
Circular chromosome
Presence of mitochondria
Presence of a cell wall
Presence of mitochondria
Prokaryotes do not have membrane-bound organelles, such as the nucleus or mitochondria. In fact, endosymbiotic theory suggests that mitochondria evolved from symbiotic prokaryotic relationships. Prokaryotes are often associated with all of the other characteristics listed.
Example Question #5 : Bacteria And Types Of Prokaryotes
Which of the following would not help determine whether a cell was eukaryotic or prokaryotic?
Rough endoplasmic reticulum
Double-stranded DNA
Membrane bound organelles
Circular DNA
Double-stranded DNA
Membrane bound organelles are specific only to eukaryotes. Circular DNA is only present in prokaryotes. Rough endoplasmic reticulum is only present in eukaryotes, as all prokaryotic ribosomes are cytoplasmic. Although prokaryotes have circular DNA, both eukaryotes and prokaryotes have double-stranded DNA.
Example Question #6 : Bacteria And Types Of Prokaryotes
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
What is a key difference between human cells and Neisseria?
Human cells undergo anaerobic metabolism, while Neisseria does not
Human cells produce their own sialyltransferase enzyme, while Neisseria does not
Human cells naturally have sialyc acid on their surface, while Neisseria does not
Human cells have mitochondria, while Neisseria does not
Human cells have ribosomes, while Neisseria does not
Human cells have mitochondria, while Neisseria does not
Prokaryotes like Neisseria do not have mitochondria, while eukaryotic human cells do. In fact, prokaryotes probably gave rise to the first mitochondria via the theory of endosymbiosis.
Example Question #7 : Bacteria And Types Of Prokaryotes
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
The same scientist continues to explore Neisseria under a microscope, and makes a surprising finding for a bacterium. He wonders if the sample was mislabeled. Which of the following is likely to surprise this scientist if it were found in a sample that was labeled Neisseria?
Peptidoglycan
Cytosol
A nucleus
DNA
Ribosomes
A nucleus
Prokaryotes like Neisseria do not have mebrane bound organelles, including nuclei. Their DNA is stored in the cytosol without the benefit of extensive sequestration.
Example Question #10 : Bacteria And Types Of Prokaryotes
Which of the statements below describes eukaryotic, but not prokaryotic cells?
The cell lacks membrane-bound organelles and a nuclear membrane.
The cell contains ribosomes.
After transcription, introns are spliced out of mRNA. Other modifications, such as addition of a 5' cap and a poly-A tail, also take place.
Transcription and translation occur simultaneously in the cytoplasm; in other words, the processes are coupled.
Genetic material is present in both a nucleoid region and one or more external plasmids.
After transcription, introns are spliced out of mRNA. Other modifications, such as addition of a 5' cap and a poly-A tail, also take place.
Post-transcriptional modifications, such as the splicing out of introns, only occur in eukaryotic cells. They cannot occur in prokaryotes because in those cells, trancription and translation happen concurrently in the cytoplasm.
Both types of cell contain ribosomes, so this answer does not fulfill the question criteria. Cells that lack membrane-bound organelles and a nuclear membrane are prokaryotes, not eukaryotes. Similarly, only prokaryotes are capable of coupled transcription and translation mechanisms. Finally, the choice that references external plasmids also describes prokaryotes.
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