Multiple Choice
Which of the following structures is unique to prokaryotic cells and is responsible for maintaining cell shape and protecting against osmotic pressure?
7. Prokaryotic Cell Structures & Functions
Overview of Prokaryotic Cell Structure
2:19 minutesProblem 1
Textbook Question
Which of the following is not a distinguishing characteristic of prokaryotic cells?
a. They usually have a single, circular chromosome.
b. They have 70S ribosomes.
c. They have cell walls containing peptidoglycan.
d. Their DNA is not associated with histones.
e. They lack a plasma membrane.
Verified step by step guidance1
Step 1: Understand the defining characteristics of prokaryotic cells. Prokaryotes typically have a single, circular chromosome, 70S ribosomes, cell walls containing peptidoglycan, and DNA that is not associated with histones.
Step 2: Review each option carefully to see if it matches these known characteristics of prokaryotes.
Step 3: Analyze option (a): Prokaryotes usually have a single, circular chromosome, so this is a distinguishing characteristic.
Step 4: Analyze option (b): Prokaryotes have 70S ribosomes, which is different from the 80S ribosomes found in eukaryotes, so this is a distinguishing characteristic.
Step 5: Analyze option (e): Prokaryotic cells do have a plasma membrane, so stating they lack one is incorrect and not a distinguishing characteristic of prokaryotes.
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Video duration:
2mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Prokaryotic Cell Structure
Prokaryotic cells are simple, unicellular organisms without a nucleus. They typically have a single, circular chromosome located in the nucleoid region, and their DNA is not wrapped around histone proteins, unlike eukaryotes.
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Overview of Prokaryotic Cell Structure
Ribosomes and Protein Synthesis in Prokaryotes
Prokaryotic cells contain 70S ribosomes, which are smaller than the 80S ribosomes found in eukaryotic cells. These ribosomes are essential for protein synthesis and are a key feature distinguishing prokaryotes from eukaryotes.
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Cell Membrane and Cell Wall Composition
Prokaryotes have a plasma membrane that controls substance movement in and out of the cell. Many have cell walls containing peptidoglycan, a unique polymer that provides structural support and protection, distinguishing them from eukaryotic cells.
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