Which molecules or structures may be found in eukaryotic cells but not in bacteria?

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Which of the following cellular structures is not seen in both prokaryotes and eukaryotes?

Possible Answers:

A cell wall

Ribosomes

Mitochondria

DNA

Correct answer:

Mitochondria

Explanation:

Prokaryotes do have organelles, but not complex, membrane-bound organelles. As a result, the membrane-bound mitochondria would not be seen in prokaryotes. Remember that plants are eukaryotes, and have cell walls just like prokaryotes. In addition, prokaryotes have ribosomes as well as DNA.

Prokaryotes, but not eukaryotes, lack which of the following structures?

Possible Answers:

Flagella

Mitochondria

Ribosomes

DNA

Correct answer:

Mitochondria

Explanation:

Prokaryotes do not have membrane-bound organelles, such as mitochondria or an endoplasmic reticulum.

Flagella are hair-like structures that allow the cell to move, and are present in both prokaryotes and eukaryotes. Although prokaryotes don't have multiple chromosomes like eukaryotes, they do still have DNA in the form of a cyclic chromosome. Ribosomes are not bound by a membrane, and are essential to the process of translation, which creates proteins in the cell. Prokaryotes and eukaryotes possess ribosomes in order to form functional proteins.

Where does the electron transport chain occur in prokaryotic cells and eukaryotic cells, respectively?

Possible Answers:

The chloroplasts; the cellular membrane

The mitochondria; the mitochondria

The cellular membrane; the mitochondria

The chloroplasts; the mitochondria

The mitochondria; the cellular membrane

Correct answer:

The cellular membrane; the mitochondria

Explanation:

Prokaryotes, such as bacteria, do not contain membrane-bound organelles such as the nucleus, mitochondria, and chloroplasts that we might find in a eukaryotic cell. Since we know the electron transport chain (ETC) is important in providing cellular energy, prokaryotes must still perform some form of this process. The complexes of the ETC are found in the actual cellular membrane that separates the cell from the environment in prokaryotes, while they are found in the inner mitochondrial membrane in eukaryotes. Eukaryotes are then able to generate a proton gradient between the two mitochondrial membranes within the intermembrane space, while prokaryotes can generate a gradient between the cell membrane and cell wall.

Prokaryotes and eukaryotes are defined by a series of differences. Which of the following structures is found in one class of cell, but not the other?

Possible Answers:

Cell wall

Mitochondria

Plasma membrane

Ribosomes

Correct answer:

Mitochondria

Explanation:

Prokaryotes do not have membrane-bound organelles, so they would not have mitochondria.

Cell walls and plasma membranes are found in both bacteria (prokaryotes) and plants (eukaryotes). Ribosomes are not bound by a membrane, and are mainly composed of rRNA; they are used for protein synthesis in both prokaryotes and eukaryotes.

Which structure is present in prokaryotic cells, but not eukaryotic cells?

Possible Answers:

A circular, double-stranded molecule of DNA as its main genetic material

A nuclear envelope

80S ribosomes composed of one 60S and one 40S subunit

A cell membrane

Numerous organelles like mitochondria and lysosomes

Correct answer:

A circular, double-stranded molecule of DNA as its main genetic material

Explanation:

In general, prokaryotic cells are smaller and less complex than eukaryotic cells. They lack membrane-bound organelles (such as mitochondria) and contain a nucleoid region instead of a membrane-bound nucleus. They do have ribosomes, but those are small (70S) and composed of one 30S and one 50S subunit. Only eukaryotic ribosomes are 80S. Finally, both prokaryotes and eukaryotes are encased in cell membranes.

One difference between prokaryotic and eukaryotic cells is the organization and storage of genetic material. Both use DNA in the double-helix structure. In eukaryotes, this DNA is stored as chromatin or chromosomes within the nucleus, but in prokaryotes it is stored in a circular bundle known as the nucleoid in the cytoplasm.

Prokaryotic cells have __________.

Possible Answers:

a nucleoid region, but no plasma membrane encasing the cell

a membrane-bound nucleus, but no lysosomes

a plasma membrane encasing the cell, but no membrane-bound organelles

mitochondria, but no nucleus

a Golgi apparatus, but no membrane-bound nucleus

Correct answer:

a plasma membrane encasing the cell, but no membrane-bound organelles

Explanation:

When comparing prokaryotes to eukaryotes, the main fact to remember is that prokaryotes do not contain membrane-bound organelles. This means they have no mitochondria, Golgi apparatus, or endoplasmic reticulum. They also lack a membrane-bound nucleus, although they do have genetic material located in a nucleoid region. Prokaryotic cells are surrounded by a plasma membrane, and some types of bacteria have cell walls as well.

Which structure could be found in a prokaryotic cell?

Possible Answers:

Rough endoplasmic reticulum

Peroxisomes

Plasma membrane

Centrioles

Mitochondria

Correct answer:

Plasma membrane

Explanation:

Prokaryotic cells differ from eukaryotic cells in that they lack any membrane-bound organelles, including a nucleus. Instead, prokaryotic cells simply have an outer plasma membrane, DNA nucleoid structure, and ribosomes.

Rough endoplasmic reticulum, peroxisomes, and mitochondria are all bound by their own plasma membranes, and are only found in eukaryotic cells. Centrioles are a component of the cytoskeleton of eukaryotic cells, but are not found in prokaryotes.

A group of researchers in a laboratory have found what they believe to be an unknown organism. They notice that this organism lacks a nuclear membrane and mitochondria. Using this information, which of the following structures would this organism most likely possess?

Possible Answers:

Endoplasmic reticulum

Chloroplasts

Lysosomes

Ribosomes

Cilia

Explanation:

The organism is likely a prokaryotic organism, since it lacks a nuclear membrane and mitochondria. Prokaryotes lack all membrane-bound organelles, including nuclei, mitochondria, endoplasmic reticulum, chloroplasts, and lysosomes.

Both prokaryotes and eukaryotes contain ribosomes. Ribosomes are not membrane-bound, and are primarily composed of rRNA. Prokaryotes require ribosomes in order to synthesize proteins.

Cilia are composed of microtubules. While many prokaryotes have cilia, we cannot draw any conclusions without knowing more about the identity of the organism.

A prokaryotic cell contains which of the following? 

Possible Answers:

Microtubules 

Endoplasmic reticulum 

Nucleus 

Golgi apparatus 

Ribosomes

Explanation:

Prokaryotic cells are simple cells that lack membrane-bound nuclei and complex organelles. Endoplasmic reticulum, microtubules, and the Golgi apparatus are unique to eukaryotic cells, and will not be found in prokaryotes. Prokaryotes do, however, contain ribosomes, though smaller than the ribosomes in eukaryotic cells. Prokaryotes and eukaryotes are both capable of the main processes of the central dogma: DNA replication, transcription, and translation. For this to be possible, prokaryotes must contain DNA, transcription proteins, RNA, and ribosomes.

What structure can be found in all living cells?

Possible Answers:

Cell wall

Nucleolus 

Mitochondria

Nucleus

Ribosomes

Explanation:

Unlike eukaryotes, prokaryotes have no membrane-bound organelles. This means that they lack a nucleus, mitochondria, and other advanced cell structures.

All cells rely on protein components in order to function. Protein synthesis takes place on ribosomes, which can be found in all cell types. In prokaryotes, ribosomes are free floating the cytoplasm; in eukaryotes, ribosomes can be free floating in the cytoplasm, bound to the rough endoplasmic reticulum, in mitochondria, or in chloroplasts.

All AP Biology Resources

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