Cell Biology Chapter: ER, Golgi, and Membrane

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Questions and Answers

What is a key characteristic of the cytoplasmic membrane in eukaryotic cells?

It is rigid and inflexible.

It is a fluid phospholipid bilayer containing sterols. (correct)

It is incapable of endocytosis.

It lacks carbohydrates.

Which of the following statements correctly describes the cytoplasmic membrane of prokaryotic cells?

It is capable of exocytosis.

It is a fluid phospholipid bilayer usually lacking sterols. (correct)

It contains carbohydrates and sterols.

It has a rigid structure preventing fluidity.

Which process is not possible in prokaryotic cells?

Phagocytosis. (correct)

Pinocytosis. (correct)

Cell division.

Exocytosis. (correct)

What differentiates the ribosomes found in rough endoplasmic reticulum of eukaryotic cells from those in prokaryotic cells?

Eukaryotic ribosomes are larger. Signup and view all the answers

Which of the following structures is involved in packaging polypeptides for transport in eukaryotic cells?

Golgi apparatus. Signup and view all the answers

What is primarily responsible for the rapid nutrient absorption in smaller prokaryotic cells?

High surface-to-volume ratio Signup and view all the answers

Why do eukaryotic cells require specialized internal organelles?

Nutrients cannot rapidly diffuse to all parts of the cell. Signup and view all the answers

What type of cell generally exhibits a high metabolic rate?

Prokaryotic cell Signup and view all the answers

Which of the following statements about viruses is correct?

Viruses are considered genetic parasites. Signup and view all the answers

What structural feature differentiates bacterial cells from eukaryotic cells?

Nucleoid region Signup and view all the answers

What role do flagella and cilia play in eukaryotic cells?

They function in locomotion. Signup and view all the answers

Which organelle is involved in energy production in eukaryotic cells?

Mitochondrion Signup and view all the answers

Which structure is NOT found in prokaryotic cells?

Nucleus Signup and view all the answers

What is a key structural difference between eukaryotic and prokaryotic cells?

Eukaryotic cells have a nuclear membrane. Signup and view all the answers

Which statement accurately describes the genetic material in prokaryotic cells?

It consists of one circular chromosome associated with histone proteins. Signup and view all the answers

How do eukaryotic and prokaryotic cells differ in terms of cell division?

Eukaryotic cells undergo mitosis, while prokaryotic cells typically divide by binary fission. Signup and view all the answers

Which component is absent in prokaryotic cells compared to eukaryotic cells?

Nucleus. Signup and view all the answers

What is the primary structural feature of flagella in prokaryotic cells?

They are composed of a single rotating fibril. Signup and view all the answers

In what way do DNA and RNA differ structurally?

RNA contains ribose while DNA contains deoxyribose. Signup and view all the answers

What is the nuclear body called in prokaryotic cells?

Nucleoid. Signup and view all the answers

Which component is found in eukaryotic cells but not in prokaryotic cells?

Mitochondria. Signup and view all the answers

Study Notes

Endoplasmic Reticulum (ER)

The ER is a network of membranes that extends throughout the cytoplasm of eukaryotic cells.
There are two types of ER:
- Smooth ER: Involved in lipid synthesis, detoxification, and calcium storage.
- Rough ER: Studded with ribosomes, responsible for protein synthesis, folding, and modification.

Golgi Apparatus

The Golgi apparatus is a stack of flattened membrane-bound sacs called cisternae.
Its role is to further modify, sort, and package proteins and lipids received from the ER.
It is also involved in the synthesis of certain polysaccharides.

Plasma Membrane (Cell Membrane)

The plasma membrane is a selectively permeable barrier that encloses the cell and regulates what enters and exits.
Consists of a phospholipid bilayer with embedded proteins.
Eukaryotic cells:
- Contain sterols (like cholesterol) for structural integrity and fluidity.
- Capable of endocytosis (phagocytosis and pinocytosis) and exocytosis, important for transport processes.
Prokaryotic cells:
- Lack sterols, usually, but may contain hopanoids, which are sterol-like molecules.
- Incapable of endocytosis and exocytosis.

Size Comparison of Cellular Components

There is a substantial size difference between various cellular components.
This size variation affects the efficiency of nutrient transport and metabolic processes within cells.

Comparing Eukaryotic and Prokaryotic Cells

Major Differences:
- Size: Eukaryotes are larger than prokaryotes.
- Internal Organization: Eukaryotic cells have a more complex internal structure with membrane-bound organelles.
- Nucleus: Eukaryotic cells have a well-defined nucleus, while prokaryotic cells lack a true nucleus (contain a nucleoid).
- Chromosomes: Eukaryotic chromosomes are linear and histone associated. Prokaryotic chromosomes are circular and associated with histone-like proteins.
- Cell Division: Eukaryotes divide by mitosis and meiosis. Prokaryotes divide by binary fission.
- Flagella: Eukaryotic flagella are more complex, surrounded by membranes and arranged in a 9+2 microtubule pattern. Prokaryotic flagella are simpler, single fibrils, not surrounded by membranes.

Nucleic Acids: DNA and RNA

DNA and RNA are nucleic acids that carry genetic information.
DNA (deoxyribonucleic acid): Contains the sugar deoxyribose, the base thymine, and is typically double-stranded.
RNA (ribonucleic acid): Contains the sugar ribose, the base uracil, instead of thymine, and is typically single-stranded.

Surface-to-Volume Ratio

Cells with a high metabolic rate tend to be small, maximizing their surface area to volume ratio.
This allows for efficient nutrient transport and waste removal.

Viruses

Viruses are not cells but rather genetic parasites. They consist of a nucleic acid core surrounded by a protein coat.
They rely on host cells to replicate.
Bacteriophages: Special viruses that infect bacteria. Can be used in genetic engineering to introduce foreign genetic material into bacteria.

Prokaryotic Cell Structure

Bacterial Cell: Primarily focus on the structure of bacteria.
- Nucleoid: The region in the cytoplasm containing the bacterial chromosome.
- Bacterial Spores: Dormant, resistant forms of bacteria that can survive harsh conditions.

Flagellar Types in Bacteria

Monotrichous: A single flagellum at one end of the cell.
Lophotrichous: A tuft of flagella at one end of the cell.
Amphitrichous: A single flagellum at each end of the cell.
Peritrichous: Flagella distributed over the entire cell surface.

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Description

Explore the fundamental components of eukaryotic cells with this quiz on the Endoplasmic Reticulum, Golgi Apparatus, and Plasma Membrane. Test your knowledge on their structures, functions, and roles in cellular processes. Perfect for students of cell biology!