Cell Structure and Transport Quiz

Cell Structure

• The three main parts of a cell are the plasma membrane, the cytoplasm, and the nucleus.

Plasma Membrane Structure

• The plasma membrane is a phospholipid bilayer with embedded proteins.
• The phospholipid bilayer has a hydrophilic head and a hydrophobic tail.
• The phospholipids arrange themselves with their heads facing the watery environment inside and outside the cell, and their tails facing each other in the interior of the membrane.
• Proteins embedded in the membrane act as channels, receptors, and enzymes, allowing molecules to pass through the membrane and perform various functions.

Passive vs. Active Transport

• Passive transport does not require energy, and moves substances down their concentration gradient (from high concentration to low concentration).
• Active transport requires energy, usually in the form of ATP, and moves substances against their concentration gradient (from low concentration to high concentration).

Na+/K+ Pump

• The Na+/K+ pump is an active transport mechanism that pumps sodium ions out of the cell and potassium ions into the cell, using ATP as an energy source.
• This pump maintains the concentration gradient of sodium and potassium ions, which is crucial for nerve impulse transmission, muscle contraction, and other cell functions.

Cell in Hypotonic Solution

• A hypotonic solution has a lower concentration of solutes than the cell's interior.
• In a hypotonic solution, water will move into the cell, causing it to swell and possibly burst (lysis).

Endocytosis & Exocytosis

• Endocytosis is the process of bringing substances into the cell by engulfing them in a vesicle.
• There are three types of endocytosis: phagocytosis (cell eating), pinocytosis (cell drinking), and receptor-mediated endocytosis.
• Exocytosis is the process of releasing substances from the cell by fusing a vesicle containing the substance with the plasma membrane.

Cytosol

• The cytosol is the fluid portion of the cytoplasm, composed mainly of water, dissolved substances, and various organelles.
• It provides a medium for chemical reactions and acts as a transport pathway for molecules within the cell.

Transcription

• Transcription occurs in the nucleus of the cell.
• Its main purpose is to copy the genetic information from DNA into a messenger RNA (mRNA) molecule.

Mitosis

• Mitosis is the process of cell division, resulting in two identical daughter cells.
• The four stages of mitosis are prophase, metaphase, anaphase, and telophase.

Four Main Types of Tissue

• Epithelial tissue covers body surfaces, lines body cavities, and forms glands.
• Connective tissue supports and binds together other tissues.
• Muscle tissue is responsible for movement.
• Nervous tissue transmits impulses throughout the body.

Cell Junctions

• Tight junctions: Seal cells together, preventing leakage between cells.
• Desmosomes: Anchor cells together, providing strength and support.
• Gap junctions: Allow communication between cells through channels that connect their cytoplasm.

Epithelial Tissue Function

• The primary function of epithelial tissue is protection.
• It also serves as a barrier against pathogens and regulates the passage of substances.

Endocrine vs. Exocrine Glands

• Endocrine glands secrete hormones directly into the bloodstream, without any ducts.
• Exocrine glands secrete their products into ducts that lead to the surface of the body or to another organ cavity.

Connective Tissue Types

• Bone tissue: Provides structural support and protection. It is characterized by its hard and rigid matrix.
• Cartilage tissue: Provides support and flexibility. It has a more flexible matrix than bone, containing chondrocytes embedded within.

Muscle Tissue Types

• Skeletal muscle: Attached to bones, responsible for voluntary movement.
• Smooth muscle: Found in the walls of internal organs, responsible for involuntary movement.
• Cardiac muscle: Found only in the heart, responsible for pumping blood.

Nervous Tissue Function

• The main functions of nervous tissue are to receive, transmit, and integrate information.
• It does this through specialized cells called neurons.

Tissue Repair

• Tissue repair begins with inflammation, a process that brings white blood cells to the injured area to fight infection and clean up debris.
• After inflammation, regeneration occurs, where new cells replace damaged ones.
• If regeneration is not possible, fibrosis occurs, where the damaged area is filled with scar tissue.

Skin Layers

• The three main layers of the skin are the epidermis, dermis, and hypodermis.
• The epidermis is the outermost layer, composed of stratified squamous epithelium.
• The dermis is a thicker layer of dense connective tissue.
• The hypodermis is the deepest layer, composed of adipose tissue.

Melanocytes in the Epidermis

• Melanocytes are specialized cells in the epidermis that produce the pigment melanin.
• Melanin provides protection from harmful ultraviolet (UV) radiation.

Epidermis Layers

• The five layers of the epidermis from deepest to most superficial are the stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (in thick skin only), and stratum corneum.

Dermis Functions

• The dermis is responsible for providing structural support to the skin and containing blood vessels, nerves, glands, and hair follicles.
• The dermis also plays a role in temperature regulation and sensation.

Hair and Sebaceous Glands

• Hair functions as protection and insulation.
• Sebaceous glands produce sebum, an oily substance that lubricates and waterproofs the skin and hair.

Skin Functions

• The skin serves as a protective barrier against pathogens and injury.
• It also regulates body temperature, synthesizes vitamin D, and provides sensory reception.

Wound Healing

• The stages of wound healing are inflammation, proliferation, and remodeling.
• Inflammation involves clotting of blood and recruitment of inflammatory cells to the injury site.
• Proliferation involves the growth of new cells and blood vessels.
• Remodeling involves the reorganization of collagen fibers to form scar tissue.

Test your knowledge on cell structure, including the plasma membrane and its components. Explore the differences between passive and active transport, along with the function of the Na+/K+ pump. This quiz will help reinforce your understanding of key concepts in cellular biology.