Edexcel A (SNAB) A Level Biology:复习笔记3.1.3 Prokaryotic Cells
Prokaryotic Cells: Structure
- Animal and plant cells are types of?eukaryotic?cells, whereas bacteria are a type of?prokaryote
- Prokaryotic cells are much?smaller?than eukaryotic cells
- They also differ from eukaryotic cells in having
- A?cytoplasm?that?lacks membrane-bound organelles
- Ribosomes?that are?smaller (70 S) than those found in eukaryotic cells (80 S)
- No nucleus,?instead having a?single circular?bacterial chromosome?that is free in the cytoplasm and is?not associated with proteins
- A cell wall that contains the glycoprotein?murein
- Murein is sometimes known as?peptidoglycan
- In addition, many prokaryotic cells also have the following structures
- Loops of DNA known as?plasmids
- Capsules
- Flagella (singular flagellum)
- Pili (singular pilus)
- A cell membrane that contains folds known as?mesosomes
Additional Prokaryotic Structures Table
Bacteria are prokaryotic cells
Prokaryotes vs eukaryotes
- There are a number of important structural and physiological differences between prokaryotic and eukaryotic cells
- These differences affect their metabolic processes and how they reproduce
Comparison of Prokaryotic and Eukaryotic Cells Table
Exam Tip
You will need to know all the?differences?between prokaryotic and eukaryotic cells; remember that not all of the structures mentioned here are present in?all?prokaryotic cells
Remember that?size is not a structural feature?so if you are asked for a structural difference between a prokaryotic and eukaryotic cell don't include size in your answer.
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