Biology Chapter: Plasma Membrane & Cell Types

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Questions and Answers

What is the primary difference between eukaryotic and prokaryotic cells?

The presence of ribosomes

The presence of a cell wall

The presence of a nucleus (correct)

The presence of DNA

What is the function of the phospholipid bilayer in the plasma membrane?

To provide structural support for the cell

To regulate the flow of water into and out of the cell

To facilitate the movement of large molecules across the membrane

To act as a barrier between the cell's interior and exterior (correct)

Which of the following is NOT a characteristic of prokaryotic cells?

They have a complex internal structure with many organelles (correct)

They have cytoplasm

They lack a nucleus

They have a small size

What is the significance of the hydrophobic and hydrophilic regions of phospholipids in the plasma membrane?

They create a selectively permeable barrier that regulates the passage of molecules (A) Signup and view all the answers

What is the significance of carbohydrate side chains attached to proteins or lipids on the outer surface of the plasma membrane?

To act as receptors for cell signaling (C) Signup and view all the answers

What is the term used to describe the region between the nucleus and the plasma membrane in a eukaryotic cell?

Cytosol (B) Signup and view all the answers

What is a primary function of the internal membranes within a eukaryotic cell?

To create compartments for specialized metabolic processes. (C) Signup and view all the answers

Which statement best explains why prokaryotic cells are generally smaller than eukaryotic cells?

Prokaryotic cells have a simpler structure and therefore require less space (D) Signup and view all the answers

What is the primary component of the basic fabric of most biological membranes?

Phospholipids (B) Signup and view all the answers

What is the primary difference between the plasma membrane of a eukaryotic cell and the membrane of an organelle?

The plasma membrane encloses the entire cell, while organelle membranes enclose only specific compartments (B) Signup and view all the answers

What is the primary function of microvilli, a surface feature found on some eukaryotic cells?

To increase the cell's surface area. (D) Signup and view all the answers

Which of the following statements accurately describes the role of proteins in cell membranes?

Proteins play a diverse role in membrane function, including enzymatic activity and signal transduction. (D) Signup and view all the answers

Which of the following components of the eukaryotic cell is NOT considered an organelle?

Plasma membrane (A) Signup and view all the answers

What is the primary function of the mitochondria in eukaryotic cells?

Cellular respiration (C) Signup and view all the answers

What is the primary difference between animal and plant cells, as discussed in the text?

Plant cells have chloroplasts, while animal cells do not. (B) Signup and view all the answers

Based on the text, how are membrane composition and function related?

Membrane composition varies depending on the specific function of the membrane. (C) Signup and view all the answers

What is the primary function of messenger RNA (mRNA) in the cell?

To carry information from DNA to ribosomes (B) Signup and view all the answers

Which structure is responsible for regulating the entry and exit of molecules in and out of the nucleus?

Pore complex (D) Signup and view all the answers

What is the main role of the nuclear lamina?

To mechanically support the nuclear envelope (B) Signup and view all the answers

What is the composition of ribosomes?

Ribosomal RNA and proteins (B) Signup and view all the answers

What might the nuclear matrix help with within the nucleus?

Organizing genetic material (B) Signup and view all the answers

What is the diameter of the pores in the nuclear envelope?

100 nm (B) Signup and view all the answers

Which structure is NOT considered an organelle according to the content?

Ribosomes (D) Signup and view all the answers

The primary structure of a specific polypeptide is produced by which cellular process?

Translation (A) Signup and view all the answers

What is the relationship between surface area and volume in cells?

A high surface area-to-volume ratio facilitates material exchange. (D) Signup and view all the answers

Why are most cells microscopically small?

To maintain a sufficient surface area for their volume. (B) Signup and view all the answers

Which type of cell typically has a high surface area-to-volume ratio?

Intestinal cells. (B) Signup and view all the answers

What helps explain the shape of some cells like nerve cells?

Their surface area must accommodate their volume. (C) Signup and view all the answers

How do larger organisms manage their cellular structure compared to smaller organisms?

They have a greater number of smaller cells. (B) Signup and view all the answers

What aspect of cells is important for those that need to exchange materials frequently?

They should have long, thin projections. (D) Signup and view all the answers

Which calculation is essential for understanding a cell's ability to interact with its environment?

Total surface area-to-volume ratio. (D) Signup and view all the answers

What calculation would you perform to determine the surface area of a cubic cell?

6 × Side Length. (B) Signup and view all the answers

What role do enzymes built into the ER membrane play in the formation of glycoproteins?

They attach carbohydrates to proteins. (C) Signup and view all the answers

What is the primary function of the rough ER related to secretory proteins?

It synthesizes and modifies secretory proteins. (C) Signup and view all the answers

How are new polypeptides processed as they are synthesized in the rough ER?

They are threaded into the ER lumen and folded there. (B) Signup and view all the answers

What are vesicles that transport proteins from the ER referred to as?

Transport vesicles. (D) Signup and view all the answers

What distinguishes glycoproteins from regular proteins?

Glycoproteins contain carbohydrates covalently bonded. (D) Signup and view all the answers

What happens to secretory proteins once they are formed in the rough ER?

They are wrapped in vesicles for transport. (A) Signup and view all the answers

What is a key function of the transitional ER?

It is a specialized region where vesicles bud off. (C) Signup and view all the answers

How does the rough ER contribute to membrane formation in the cell?

It adds membrane proteins and phospholipids to itself. (C) Signup and view all the answers

If the radius of the mature parent cell is 1.5 micrometers, what is its surface area?

113.04 square micrometers (A) Signup and view all the answers

What is the formula for calculating the volume of a sphere?

V = 4/3πr³ (B) Signup and view all the answers

If the diameter of the budding cell is 0.5 micrometers, what is its volume?

0.0654 cubic micrometers (A) Signup and view all the answers

Why does the plasma membrane of the new cell need to expand as it grows?

To enclose the increasing volume of cytoplasm (B) Signup and view all the answers

What is the approximate surface area of the new cell when it matures?

28.26 square micrometers (A) Signup and view all the answers

What is the approximate volume of the new cell when it matures?

0.5236 cubic micrometers (B) Signup and view all the answers

The experiment described in the excerpt focuses on what biological process?

Cell division (C) Signup and view all the answers

What is the significance of the septin ring mentioned in the excerpt?

It plays a role in the asymmetric localization of proteins during cell division. (B) Signup and view all the answers

Study Notes

Plasma Membrane Structure and Function

Plasma membranes are a double layer (bilayer) of phospholipids with proteins embedded.
Hydrophobic parts of phospholipids and proteins are in the membrane interior.
Hydrophilic parts are exposed to the aqueous solutions.
Carbohydrate chains are attached to proteins or lipids on the outer surface.
The plasma membrane appears as a pair of dark bands separated by a gold band in transmission electron micrographs.
High surface area-to-volume ratio is crucial for material exchange.
Cell size and shape (narrow and elongated) are solutions for maintaining high surface area-to-volume ratios.
Larger organisms have more cells, not larger cells.
Cells with high material exchange needs (like intestinal cells) may have projections (microvilli).

Prokaryotic vs. Eukaryotic Cells

Prokaryotic cells lack membrane-bound organelles.
Prokaryotic cytoplasm is not formless; it has protein-bound regions for specific reactions.
Eukaryotic cells are generally much larger than prokaryotic cells.
Eukaryotic cytoplasm is the region between the plasma membrane and the nucleus.
Organelles are suspended in the cytosol within the eukaryotic cytoplasm.
Compartments provide different local environments for metabolism.

Cell Size and Surface Area

Cell size is limited by the logistics of carrying out metabolism.
High surface area-to-volume ratios facilitate material exchange.
The surface area-to-volume ratio of smaller cells is higher and aids in exchange efficiency

Nucleus Structure and Function

The nucleus is surrounded by a nuclear envelope.
The nuclear envelope is perforated by pores (100 nm diameter).
A pore complex regulates protein and RNA passage.
The nuclear lamina in animal cells maintains nuclear shape.
The nuclear matrix or framework helps organize genetic material.
The nucleus contains chromosomes (DNA and proteins) and nucleoli (ribosome synthesis).

Endoplasmic Reticulum (ER) Structure and Function

Rough ER has ribosomes attached, synthesizing secretory proteins.
The ER membrane threads polypeptides into the lumen.
Secretory proteins are often glycoproteins (proteins with sugars).
Sugars are added in the ER lumen by ER enzymes.
Proteins are kept separate from the cytoplasm.
Transport vesicles carry proteins from the ER.
Smooth ER is a membrane factory, growing by producing membrane proteins and phospholipids.

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Description

Explore the intricate structure and function of plasma membranes, including their role in cellular exchange. Understand the differences between prokaryotic and eukaryotic cells and how these structures adapt for efficiency at various scales.