Cell Structure and Membranes

Questions and Answers

What are the three basic structures of a cell?

Cytoplasm, Ribosomes, Cell wall

Rough ER, Smooth ER, Cell membrane

Cell membrane, Cytoplasm, Organelles (correct)

Nucleus, Ribosomes, Cytoplasm

Which type of membranes line the body cavities that are connected to the external environment?

Cutaneous membranes

Mucous membranes (correct)

Serous membranes

Synovial membranes

What type of epithelium makes up serous membranes?

Stratified squamous epithelium

Simple squamous epithelium (correct)

Cuboidal epithelium

Pseudostratified columnar epithelium

Which of the following statements about synovial membranes is correct?

They contain adipose tissue elements. Signup and view all the answers

What is the role of special cells in mucous membranes?

To secrete mucus Signup and view all the answers

What are the two types of membranes mentioned?

Epithelial and connective tissue membranes Signup and view all the answers

Which of the following structures is NOT a part of the cellular architecture?

Synovial fluid Signup and view all the answers

Which term refers to the outer surfaces of organs that are lined with serous membranes?

Lamina visceralis Signup and view all the answers

Which of the following statements about the structure of biological membranes is TRUE?

The hydrophilic head groups of phospholipids face the aqueous environment inside and outside the cell. Signup and view all the answers

What is the primary function of transmembrane proteins in biological membranes?

To form channels for the transport of substances across the membrane. Signup and view all the answers

Which of the following is NOT a characteristic of peripheral membrane proteins?

They extend across the lipid bilayer. Signup and view all the answers

Which of the following statements accurately describes the movement of membrane proteins?

Membrane proteins can rotate around their own axis and move laterally within the membrane. Signup and view all the answers

What is the role of ATP hydrolysis in membrane transport?

ATP hydrolysis is required for the active transport of molecules against their concentration gradient. Signup and view all the answers

How do the hydrophobic tails of phospholipids contribute to the structure of the cell membrane?

They create a barrier that prevents the passage of water-soluble substances. Signup and view all the answers

Which of the following molecules would be most likely to diffuse freely across the lipid bilayer of a cell membrane?

Carbon dioxide (CO2) Signup and view all the answers

How do integral membrane proteins contribute to the diversity of membrane functions?

All of the above. Signup and view all the answers

Which of these functions is NOT associated with membrane proteins?

They act as a barrier to prevent the passage of all molecules through the membrane. Signup and view all the answers

What is the primary function of the lipid layer in the cell membrane?

To provide structural support and maintain the integrity of the cell and organelles. Signup and view all the answers

Which of the following statements is TRUE about the cell membrane's selective permeability?

It allows specific molecules to pass through based on their size and charge. Signup and view all the answers

Which of the following is NOT a function of proteoglycans in the cell membrane?

Acting as catalysts for chemical reactions within the cell. Signup and view all the answers

What is the role of transmembrane proteins in cell-cell binding?

They form special connections between adjacent cells, contributing to cell-cell binding. Signup and view all the answers

What is the main function of carrier proteins in the cell membrane?

To facilitate the transport of molecules across the membrane. Signup and view all the answers

Which of the following is a function of glycoproteins in the cell membrane?

To enable cells to recognize each other. Signup and view all the answers

Which of the following is NOT a characteristic of the cell membrane?

It is a rigid structure that maintains the cell's shape. Signup and view all the answers

Which of the following statements is NOT true about ribosomes?

Ribosomes are found only in the cytoplasm. Signup and view all the answers

Which of the following is NOT a function of the Golgi apparatus?

Synthesis of lipids. Signup and view all the answers

What is the primary function of lysosomes?

Cellular digestion and breakdown. Signup and view all the answers

What type of enzymes are found within lysosomes?

All of the above. Signup and view all the answers

Which of the following is NOT a component of the Golgi apparatus?

Microtubules. Signup and view all the answers

What is the role of ribosomes in protein synthesis?

Ribosomes assemble amino acids into polypeptide chains. Signup and view all the answers

Which of the following is a function of the Golgi apparatus in relation to the cell membrane?

The Golgi apparatus modifies and packages proteins for the cell membrane. Signup and view all the answers

What is the role of lysosomes in the breakdown of degenerated cell organelles?

Lysosomes break down the degraded organelles into reusable components. Signup and view all the answers

Which of the following statements accurately describes the relationship between the cisternal space and the cytosol?

The cisternal space is separate from the cytosol, but connected to the perinuclear space. Signup and view all the answers

Which of these functions is NOT directly associated with the rough endoplasmic reticulum (RER)?

Steroid hormone synthesis Signup and view all the answers

Which of the following is a primary function of the smooth endoplasmic reticulum (SER) in hepatocytes (liver cells)?

Glycogenolysis and glycogen synthesis Signup and view all the answers

Which of these statements accurately describes a key function of the SER in the detoxification process?

The SER produces enzymes like P450, which directly break down toxins. Signup and view all the answers

Which of the following is NOT a function of mitochondria?

Protein synthesis Signup and view all the answers

Which of the following is a TRUE statement about the structure of mitochondria?

Mitochondria contain their own unique DNA and ribosomes. Signup and view all the answers

Which of the following accurately describes how the SER contributes to the formation of chylomicrons?

The SER combines monoglycerides and proteins to form lipoproteins, which are precursors to chylomicrons. Signup and view all the answers

Which of these statements about the function of the SER in muscle cells is correct?

The SER stores calcium ions, which are essential for muscle contraction. Signup and view all the answers

Study Notes

Cell Structures

A cell consists of three basic structures: plasma membrane, cytoplasm, and organelles

Membranes

There are two types of membranes: epithelial and connective tissue membranes
Epithelial membranes include:
- Cutaneous membranes
- Serous membranes
- Mucous membranes
Serous membranes:
- Line the inner face of body cavities not connected to the external environment
- Consist of a simple, squamous epithelium (mesothelium) lined up on a thin connective tissue
- Secrete a serous fluid that wets the surface
Mucous membranes:
- Line body cavities directly or indirectly connected to the external environment
- Special cells secrete mucus
Synovial membranes:
- Line the joint space inside movable joints
- Do not contain a continuous epithelium
- Made up of flat connective tissue cells and adipose tissue elements

Cell Membrane

The lipid bilayer forms the main structure of biological membranes
Proteins in the membrane determine its function
Proteins can be classified into two classes: peripheral proteins and integral proteins
Integral proteins:
- Can be completely embedded in the lipid bilayer
- Can have parts that protrude towards the surface
- Can be embedded in the outer or inner half of the lipid bilayer
- Can extend across the lipid bilayer and meet the aqueous microenvironment on both sides of the membrane (transmembrane proteins)
Peripheral proteins:
- Completely outside the lipid layer
- Do not constitute a continuous layer
Functions of proteins in the membrane:
- Transport: form hydrophilic channels and transport substances across the membrane
- Enzyme activity: act as enzymes in metabolic pathways
- Signal transduction: allow signal molecules to bind and transmit messages to the cell
- Binding between cells: bind neighboring cells together
- Cell-cell recognition: enable cell recognition by other cells
- Attachment to the extracellular matrix: attach the cytoskeleton to the extracellular matrix

Carbohydrates of Membrane

Proteoglycans are carbohydrates attached to the outer surface of the cell with small proteins
Functions:
- Form recognition regions of the cell
- Create a negatively charged cell surface
- Make cells stick together
- Act as receptors

Functions of Cell Membrane

Separate the cell from the external environment and control the entry and exit of matter
Selective permeability: allow certain substances to enter the cell while keeping others out
Ensure cell and organelle integrity
Transport molecules across the membrane
Initiate metabolic reactions
Regulate metabolic reactions
Bind cells together

Endoplasmic Reticulum (ER)

Functions:
- Participate in protein synthesis
- Perform protein glycosylation
- Make quality control of proteins
- Selectively send synthesized proteins to other organelles to form their structure
RER (Rough Endoplasmic Reticulum):
- Involved in protein synthesis, glycosylation, and quality control
- Sends proteins to other organelles to form their structure
SER (Smooth Endoplasmic Reticulum):
- Involved in steroid hormone synthesis, glycogen production, cholesterol and bile production, detoxification, and storing calcium ions

Mitochondria

A double-membrane organelle with variable numbers depending on the cell's function
Contains unique DNA and ribosomes
Functions:
- Acts as the energy (ATP) production center of the cell
- Stores excess calcium in the cytosol and returns it to the cell when necessary
- Plays a role in hormone synthesis
- Initiates apoptosis (programmed cell death)

Ribosomes

Found individually or in groups on the surface of the cytosol-facing membrane of the RER, on the surface of the outer nucleus, and in the cytoplasm
Made up of protein and ribonucleic acid (RNA) molecules
Functions:
- Carry out protein synthesis

Golgi Apparatus

Not found in prokaryotes and red blood cells
Exchanges products synthesized in the cell and ensures they are transported to their destination by packaging
Consists of three parts: flat sacs, secretory granules, and vacuoles
Functions:
- Makes secretion
- Synthesizes glycoproteins
- Packages and concentrates secretions
- Forms lysosomes in the RER region
- Preserves membrane integrity by adding vesicles to the cell membrane by exocytosis

Lysosomes

Defense and digestive organelle
Contains degrading enzymes called hydrolase produced in the ER and Golgi complex
Functions:
- Digests large molecule nutrients
- Digests bacteria, viruses, and toxins
- Releases calcium in bone

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Description

This quiz covers the basic structures of cells, including plasma membrane, cytoplasm, and organelles, as well as types of membranes in the human body.