Biology Chapter on Cell Structure and Function

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Questions and Answers

What is the primary function of the plasma membrane?

To provide energy for cellular processes

To store genetic information

To synthesize proteins

To maintain the integrity of the cell (correct)

Which of the following statements best describes cell theory?

Cell function is unrelated to the cell's structure

Cells can spontaneously generate from non-living matter

All living organisms are composed of cells and all cells arise from pre-existing cells (correct)

All cells are identical in function and structure

Which movement process does not require energy?

Active transport

Endocytosis

Simple diffusion (correct)

Vesicular transport

What term describes the diffusion of water through a selectively permeable membrane?

Osmosis Signup and view all the answers

Which component is NOT part of the plasma membrane structure?

Mitochondria Signup and view all the answers

What is the role of facilitated diffusion in cellular transport?

It helps larger molecules pass through the membrane using protein channels Signup and view all the answers

Which classification identifies glands based on their cellular structure?

Unicellular and multicellular glands Signup and view all the answers

What is a characteristic of connective tissue compared to epithelial tissue?

Connective tissue has a larger amount of intercellular substance. Signup and view all the answers

What is a characteristic feature of unicellular organisms?

They are composed of only one cell Signup and view all the answers

Which type of connective tissue is primarily found in a fetus and is located in the umbilical cord?

Mucous connective tissue Signup and view all the answers

What is a direct function of skeletal muscle tissue?

Movement of bones within the skeleton Signup and view all the answers

Which type of tissue displays striations and is under voluntary control?

Skeletal muscle Signup and view all the answers

What separates the nucleus from other cell structures?

Nuclear membrane Signup and view all the answers

What is the jelly-like fluid in the nucleus called?

Karylymph Signup and view all the answers

What is the primary function of ribosomes?

Protein synthesis Signup and view all the answers

Which of the following is true about the smooth endoplasmic reticulum?

Site of lipid synthesis Signup and view all the answers

Which part of the Golgi complex processes and sorts proteins?

Both A and C Signup and view all the answers

What is the main function of mitochondria in a cell?

Energy generation Signup and view all the answers

Which type of endoplasmic reticulum is associated with ribosomes?

Rough endoplasmic reticulum Signup and view all the answers

What structures do Golgi bodies consist of?

4-8 membranous sacs Signup and view all the answers

Which of the following describes the nucleolus?

A non-membrane bound mass Signup and view all the answers

What is the primary function of glandular epithelium?

Secretion Signup and view all the answers

Which type of epithelium is specialized for areas with a high degree of wear and tear?

Stratified epithelium Signup and view all the answers

What type of gland secretes hormones directly into the bloodstream?

Endocrine gland Signup and view all the answers

Which of the following is a characteristic of simple epithelium?

Single-layered structure Signup and view all the answers

What is not a type of epithelial cell shape?

Trapezoidal Signup and view all the answers

Which type of gland releases its secretions through ducts to the surface of the epithelial tissue?

Exocrine gland Signup and view all the answers

Which type of epithelial tissue would primarily line the respiratory tract?

Pseudo-stratified epithelium Signup and view all the answers

What is the main difference between exocrine and endocrine glands?

Location of secretion release Signup and view all the answers

Which type of epithelial arrangement is characterized by a single layer of cells that appears stratified?

Pseudo-stratified epithelium Signup and view all the answers

Which of the following substances is typically secreted by exocrine glands?

Sweat Signup and view all the answers

What is the function of the mitochondrion's matrix?

Energy transduction through respiration Signup and view all the answers

Which description accurately characterizes lysosomes?

Contain enzymes that can digest all types of macromolecules Signup and view all the answers

What are the primary components of the cytoskeleton?

Microfilaments, microtubules, and intermediate filaments Signup and view all the answers

What is a primary role of centrosomes in the cell?

Movement of chromosomes during cell division Signup and view all the answers

Which tissue type serves as a covering for body surfaces and cavities?

Epithelial tissue Signup and view all the answers

Which of the following statements is true regarding the structure of lysosomes?

They are formed from the Golgi apparatus Signup and view all the answers

Which type of cells commonly contain cilia?

Upper respiratory tract cells Signup and view all the answers

What is the main characteristic of epithelial tissue?

Covers body surfaces and lines cavities Signup and view all the answers

What type of information does histology provide?

Structural organization of tissues Signup and view all the answers

How do lysosomes contribute to autolysis?

Through the release of digestive enzymes upon cell death Signup and view all the answers

Study Notes

Unit 2: Structure of Cell & Tissue – Its Components and Their Functions

Cells are the fundamental structural and functional units of the body.
Cytology is the branch of science dealing with the study of cells.
Robert Hooke observed and named cells in 1665 from cork slices under a microscope.
Some organisms are unicellular (composed of a single cell), while others are multicellular.
The average diameter of a cell ranges from 2-120 micrometers (µm).

Cell Theory

Proposed by Matthias Schleiden and Theodor Schwann in 1839.
All living organisms are composed of cells and cell products.
Cells are the basic units of structure and function of all living organisms.
All cells come from the division of pre-existing cells.
An organism's activities and interactions are a result of the combined actions of all its cells.

Organelles (Detailed Diagram Included)

Nucleus: The control center of the cell. Contains DNA, responsible for inherited traits.
DNA: Contains coded information for inherited characteristics.
Mitochondria: Generate energy for cellular processes through oxidative metabolism.
Golgi Complex: Collects, packages, and distributes molecules within the cell.
Endoplasmic Reticulum: Smooth and rough networks moving and storing materials.
Lysosomes: Digest cellular nutrients and waste materials.
Cytoplasm: Jelly-like fluid between the nucleus and cell membrane. Contains organelles.
Ribosomes: Tiny protein-producing factories.
Vacuoles: Storage areas for fats and other substances.
Peroxisomes: Contain enzymes for particular reactions, such as detoxifying harmful molecules.
Cell Membrane: Double-layered fatty material that controls the passage of materials into and out of the cell. Its thickness is about 4.5 nanometers (nm)
Centrioles: Aid in cell division.

Plasma Membrane

A thin outer layer that maintains the integrity of the cell.
Primarily composed of phospholipids, cholesterol, glycolipids, and carbohydrates.
Functions:
- Separates the cytoplasm from the extracellular fluid.
- Separates one cell from another.
- Provides a surface for chemical reactions to occur.
- Regulates the movement of materials into and out of the cell.

Movement Across Cell Membranes

Passive Transport: Movement of substances across the membrane without energy expenditure.
- Diffusion: Random movement of molecules from high to low concentration. (Examples: gases/air in alveoli, and other substances)
- Facilitated Diffusion: Larger molecules use protein channels to pass through the membrane. (e.g. amino acids)
- Osmosis: Special type of diffusion referring to the passage of water across a selectively permeable membrane.
- Filtration: Small molecules pass through a membrane due to pressure. (Kidney function example)
Active Transport: Movement of substances across the membrane that requires energy expenditure.
- Utilizes transport proteins that bind to the transported substances.
- Most importantly, ions move against the concentration gradient.
  - Primary Active Transport: Energy comes directly from ATP hydrolysis(e.g., Na+-K+ pump).
  - Secondary Active Transport: Driven by energy stored in the concentration gradient of ions.

Vesicular Transport

Fluids containing large particles and macromolecules are transported across cellular membranes inside bubble-like, membranous sacs called vesicles.
Types include endocytosis (moving into the cell) and exocytosis (moving out of the cell). Details about specific types (phagocytosis, pinocytosis, receptor-mediated endocytosis, etc.) are given in the document.

Cytoplasm

A semi-transparent, elastic fluid containing suspended particles, tubules, and filaments (cytoskeleton).
Primarily water (75-90%).
Contains proteins, carbohydrates, lipids, and inorganic substances.
The inorganic component is in solution form.

Organelles (Continued)

Specialized compartments with specific shapes, playing roles in cell growth, maintenance, repair, and control. (Various types are covered within the provided text, along with illustrations)

Nucleus (Continued)

Oval-shaped, largest structure in a cell.
Contains the cell's hereditary material (DNA).
Controls cell activity and structure.
Separated from other cell structures by a double membrane called the nuclear membrane.
Has pores to facilitate communication with the cytoplasm.
Contains cytoplasm-like fluid (nucleoplasm), the genetic material (chromosomes), and a non-membrane-bound mass of material called the nucleolus.
DNA, RNA, and protein assists ribosome construction.

Endoplasmic Reticulum (Continued)

A double-membrane channel that is continuous with the nuclear membrane.
Involved in intracellular material exchange with the cytoplasm.
Transports materials between different parts of the cell.
Acts as a storage area for synthesized molecules.
Together with the Golgi complex, involved in synthesis and packaging.

Ribosomes

Tiny granules made of rRNA.
Site of protein synthesis.

Two types of Endoplasmic Reticulum (ER)

Smooth ER: No ribosomes. Site of lipid and steroid hormone synthesis. Present mainly in lipid-forming cells (adipocytes, interstitial cells, etc.)
Rough ER: Contains ribosomes. Site of protein synthesis, processing, and packaging. Mainly present in protein-forming cells (pancreatic acinar cells, plasma cells, etc.)

Golgi Complex (Continued)

Network of membranous sacs. Processes, sorts, packages, and delivers proteins to various parts of the cell.

Mitochondria (Continued)

Small, spherical, rod-shaped or filamentous organelles generating energy.
Possess two membranes, the inner membrane being folded into cristae
The central cavity of a mitochondrion is the matrix.
Vital for maintaining proper calcium ion concentrations within the cell.
Facilitates energy transduction through respiration (cellular respiration), and thermogenesis (heat production).

Lysosomes (Continued)

Membrane-enclosed spheres formed from Golgi complexes.
Single membrane.
Diameter (250-750nm).
Contain digestive enzymes.
Important for digesting worn-out cell components, external bacteria, and other material.
Also involved in programmed cell death (autolysis).

Some Other Organelles

Cytoskeleton: A complex network of filaments (microfilaments, microtubules, and intermediate filaments) that provides structural support and facilitates movement within the cell.
Centrosome: Contains centrioles. Involved in cell division.
Cilia/Flagella: Thread-like appendages that enable movement. Found mainly in reproductive organs and the respiratory tract.

Tissues

Groups of similar cells working together to perform specific functions.
Histology: The study of tissues.
Four major tissue types: Epithelial, connective, muscle, and nervous tissue. (Details about each tissue type are provided in separate sections)

Epithelial Tissue

Covers body surfaces, lines body cavities and ducts, forms glands.
- Covering and lining epithelium: Forms outer coverings, lines internal organs, and is part of sensory organs (smell, hearing, touch, etc.) and reproductive organs.
- Glandular epithelium: Makes and releases substances such as mucus, digestive juices, etc. (Located in organs like breast, lungs, stomach, etc.)
Classification of Epithelial Tissue based on layers and cell shape:
- Simple Epithelium: Single layer (absorption, filtration).
- Stratified Epithelium: Multiple layers (protection).
- Pseudostratified Epithelium: Appears layered but is really single (secretion, absorption)
  - Shape Classification:
    - Squamous: Flattened cells (e.g. lining of lungs)
    - Cuboidal: Cube-shaped cells (e.g. kidney tubules)
    - Columnar: Tall, column-shaped cells (e.g. intestines)

Connective Tissue

Characterized by cells that are more widely spaced and have abundant intercellular matrix (fibers in a ground substance).
Embryonic Connective Tissue: Mesenchyme (tissue all other connective tissues evolve from), mucous connective tissue
Adult Connective Tissue: Broadly categorized into connective tissue proper, cartilage, bone, blood/vascular tissue
Functions: Binding and structural support, protection, transport, and insulation.
Components: Fibers (collagen, elastic, reticular), ground substance, cells (e.g., fibroblasts, adipocytes, chondrocytes, osteocytes)

Muscle Tissue

Specialized contractile cells (fibers) that enable movement.
Three types: Skeletal muscle (voluntary movement), smooth muscle (automatic movements such as peristalsis), and cardiac muscle (heart contractions)

Nervous Tissue

Composed of neurons and supporting cells.
Function: Transmit electrical signals throughout the body.
Found in the brain, spinal cord, and nerves.

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Test your knowledge on cell structure, the plasma membrane, tissue types, and cellular processes with this quiz. Explore key concepts related to biological membranes, tissue classification, and the characteristics of different cell types. Perfect for students studying biology at any level.