Cell Biology Overview Quiz

Bacterial Cell Envelope

• The outermost layer of the bacterial cell envelope is the glycocalyx.
• The bacterial cell wall is composed of peptidoglycan.
• Plasmid DNA functions to provide unique phenotypic characteristics to bacteria.

Ribosomes and Peroxisomes

• Ribosomes are involved in translating mRNA into proteins.
• A polysome refers to multiple ribosomes working on a single mRNA molecule.
• Peroxisomes are characterized by oxidative crystals.

Cells: Shape and Structure

• White blood cells have an irregular shape.
• Amoeboid movement refers to the ability of cells to change shape and move.
• The nucleus of a cell was discovered by Robert Brown.

Cell Cycle

• The cell cycle is a series of events that take place in a cell leading to its division and duplication.
• The cell cycle includes the following phases:
  • G1 Phase: Cell growth and preparation for DNA replication.
  • S Phase: DNA synthesis.
  • G2 Phase: Cell growth and preparation for mitosis.
  • M Phase: Mitosis (cell division).

Centrosome

• The centrosome is the major microtubule-organizing center (MTOC) in eukaryotic cells.
• It plays a role in various cellular processes, including sensory reception, locomotion, and embryogenesis.

Fluid Mosaic Model

• The Fluid Mosaic Model explains the structure of the cell membrane.
• The model emphasizes the quasi-fluid nature of lipids, enabling lateral movement of proteins within the bilayer.

Epithelial Cells

• Keratin is a protein that protects epithelial cells from damage.

Tissues

• A tissue is a group of similar cells that work together to perform a specific function.
• Tissues are essential for the division of labor in multicellular organisms.
• Tissues contribute to increased organization and efficiency within the organism.

Plant Tissues

• Plant tissues can be divided into two main categories:
  • Meristematic Tissue: Cells retain the ability to divide and are responsible for growth.
  • Permanent Tissue: Cells have lost the ability to divide and have taken on a specific function.

Meristematic Tissue

• Meristematic tissue is present in the growing regions of plants, such as roots, shoots, and stems.
• The cells are typically spherical, oval, or rectangular, with no intercellular spaces and absent vacuoles.
• They are actively dividing and have dense cytoplasm and prominent nuclei.

Permanent Tissue

• Permanent tissue forms when meristematic cells lose their ability to divide and differentiate into specialized cells.
• These cells have a defined shape, size, and function.
• Permanent tissues are characterized by large central vacuoles and thick/thin cell walls.

Functions of Permanent Tissue

• Permanent tissue serves various functions including:
  • Protection
  • Support
  • Storage
  • Photosynthesis

Types of Permanent Tissue

• Permanent tissue is classified as:
  • Simple Tissue: Composed of one type of cells.
  • Complex Tissue: Composed of more than one type of cells.

Simple Tissues

• Simple tissues include:
  • Collenchyma Tissue: Living cells with irregularly thickened walls, providing flexibility to plant parts.
  • Parenchyma Tissue: Living cells with thin walls, often specialized for storage or photosynthesis.
    • Aerenchyma: Loosely packed parenchyma tissue with air spaces, providing buoyancy.
    • Chlorenchyma: Parenchyma tissue containing chlorophyll, facilitating photosynthesis.
  • Sclerenchyma Tissue: Dead cells with thick walls, providing toughness and support.

Protective Tissues

• Protective tissues in plants include:
  • Epidermis: The outermost layer of plant parts, protecting from injury, infection, and water loss.
  • Cork: A protective layer forming on mature roots and shoots, regulating water and gas exchange.

Complex Permanent Tissue

• Complex tissues are composed of more than one type of cell and work together for a specific function.
• Ex: Vascular tissue is a complex tissue that transports water, minerals, and food throughout the plant.

Vascular Tissue

• Vascular tissue comprises two main types:
  • Xylem: Conducts water and minerals from roots to shoots.
    • Xylem Parenchyma: For food storage.
    • Tracheids and Vessels: For water conduction.
    • Xylem Fibers: For rigidity and support.
  • Phloem: Conducts food materials from leaves to other parts of the plant.
    • Sieve Tubes: For food conduction.
    • Companion Cells: For supporting and regulating sieve tubes.
    • Phloem Parenchyma: For food storage.
    • Phloem Fibers: For rigidity and support.

Animal Tissues

• Animal tissues are categorized into four main types:
  • Epithelial Tissue: Covers and protects the body, forming linings for organs.
  • Muscular Tissue: Responsible for movement and contraction.
  • Connective Tissue: Provides support, structure, and connects tissues.
  • Nervous Tissue: Transmits signals and coordinates body functions.

Epithelial Tissue

• Epithelial tissue is tightly packed and forms a continuous sheet.
• It serves as a protective barrier against injury and infection, and plays a role in absorption and excretion.
• Epithelial tissue is classified based on cell shape and arrangement:
  • Squamous Epithelium: Flattened cells
    • Simple Squamous: Single layer, found in lining of mouth.
    • Stratified Squamous: Multiple layers, found in skin.
  • Cuboidal Epithelium: Cube-shaped cells, found in lining of glands.
  • Columnar Epithelium: Column-shaped cells, found in lining of intestines.
  • Ciliated Epithelium: Cuboidal or columnar cells with cilia on their surface, found in the respiratory tract.

Connective Tissue

• Connective tissue is characterized by cells embedded in a matrix.
• The matrix can be jelly-like, fluid, dense, or rigid.
• Connective tissue provides support, structure, and connects tissues.
• It is classified into several types including:
  • Areolar Connective Tissue: Loose tissue found between skin and muscles, supporting internal organs.
  • Adipose Connective Tissue: Stores fat, providing insulation and energy reserves.
  • Cartilage: Strong and flexible tissue found in joints, ears, and nose.
  • Blood: Fluid connective tissue composed of red blood cells, white blood cells, and platelets.
  • Bone: Hard and rigid tissue providing support and protection to the body.
  • Tendons: Dense fibrous tissue connecting muscles to bones.
  • Ligaments: Dense fibrous tissue connecting bones to bones.

Adipose Connective Tissue

• Aggregation of fat cells
• Cells are rounded/oval and contain large fat droplets
• Located below the skin and between internal organs
• Functions:
  • Prevents body from mechanical shocks
  • Fat reservation
  • Acts as insulation
  • Temperature regulation

Skeletal Connective Tissue

• Types:
  • Cartilage
  • Bones
• Bones:
  • 300 bones in a child
  • 206 bones in an adult
  • Longest bone: Femur (thighs)
  • Shortest bone: Stapes (ear)

Cartilage

• Widely spaced out cells
• Matrix is gel-like and slightly elastic
• Flexible
• Occurrence:
  • Ear pinna, nose tip, trachea, larynx
  • Smoothens bone surfaces at joints
• Function:
  • Support and flexibility to body parts

Bones

• Strong, non-flexible, hard and rigid
• Matrix is hard and composed of calcium and phosphorus compounds
• Functions:
  • Forms a framework
  • Supports the body
  • Provides shape to body
  • Protects vital body organs like brain, lungs, etc.
  • Layers:
    • Meninges
    • 22 bones in the brain (8 cranial & 14 facial)

Fluid Connective Tissue

• Connects different parts of the body
• Maintains continuity
• Types:
  • Blood
  • Lymph

Blood

• Function: transports gases, digested food, hormones, waste materials
• Composition:
  • Plasma (55%):
    • 90% water
    • Proteins, glucose, salts, hormones, fats, vitamins
  • Solid (45%):
    • Red Blood Cells (RBCs)
    • White Blood Cells (WBCs)
    • Platelets

Red Blood Cells (RBCs)

• Red in colour due to the presence of heme (Fe)
• Heme has a high affinity towards oxygen, transporting it throughout the body for respiration and energy production

White Blood Cells (WBCs)

• Also known as leukocytes
• Prevent infection and provide a defense mechanism for the body

Platelets

• Also known as thrombocytes
• Help in blood clotting
• Reduced in dengue

Lymph

• Yellow fluid
• Function:
  • Transports digested fat from small intestine to blood
  • Drains excess fluid from intercellular spaces and returns it to blood
  • Filters microbes and destroys them

Test your knowledge of the bacterial cell envelope, ribosomes, cell structure, and the cell cycle. This quiz covers essential concepts including the functions of various cellular components and their roles in biological processes. Perfect for biology students looking to enhance their understanding!