Proteins Overview Quiz

Protein Types

• Fibrous Proteins: Long strands providing mechanical support and tensile strength; can contract and return to original length. Examples: collagen and muscle proteins.
• Globular Proteins: Compact and spherical; biologically active, involved in transporting molecules, immune responses, and regulating growth and development.
• Enzymes: Biological catalysts that lower activation energy for reactions; can be highly specific or act on multiple substrates; crucial for sustaining biological processes.

ATP & Cellular Energy

• Adenosine Triphosphate (ATP): Primary energy-transfer molecule in cells; oxygen is required for ATP production.
• Triphosphate Tail: Contains high-energy bonds; transferring a phosphate group to another molecule grants it temporary energy, which is lost once work is done.
• Energy Dynamics: ATP storage and release are essential for driving chemical reactions in cells, highlighting the transient nature of ATP.

Plasma Membrane Structure

• Fluid Mosaic Model: Describes the plasma membrane as a phospholipid bilayer with randomly dispersed proteins, which is mainly impermeable to water-soluble molecules.
• Functions: Separates intracellular fluid (ICF) from extracellular fluid (ECF).

Chemical Composition of Cell Membranes

• Lipids:

  • Phospholipids: Form the membrane's foundation; features hydrophilic phosphate heads and hydrophobic fatty acid tails, crucial for membrane resealing.
  • Cholesterol: Stabilizes the membrane structure while maintaining flexibility.

• Proteins:

  • Integral proteins span the membrane; major roles include transport, enzyme functions, and cell recognition.
  • Peripheral proteins are loosely attached and largely serve as enzymes and structural components.

• Carbohydrates: Coat the extracellular surface, forming glycocalyx; involved in cell recognition and tissue identification.

Cell Junctions

• Function: Connect or adhere cells together.
• Types of Junctions:
  • Tight Junctions: Seal adjacent cells, maintaining the environment balance and communication.
  • Receptor-Mediated Endocytosis: Specific intake of substances through receptor binding.
  • Exocytosis: Process of transporting substances out of the cell through vesicles.
  • Transcytosis: Movement into, across, and out of a cell, facilitating transport through tissues.
  • Vesicular Trafficking: Transfers substances within the cell without leaving it.

Membrane Potential

• Resting Membrane Potential: Average of -70 mV; characterized by a charge difference across the membrane, with a more negative inside.
• Ion Balance: High concentration of Na+ outside and K+ inside; K+ channels are leakier, influencing membrane potential.
• Active Transport: Maintains ion gradients, ensuring the cell's resting potential is stable amidst Na+ leakage.

Plasma Membrane Receptors

• Role: Enable cell-environment interactions through ligand binding.
• Contact Signaling: Cells recognize each other through physical contact; significant for growth and immunity.
• Chemical Signaling: Ligands bind to receptors, triggering intracellular responses; one ligand can result in multiple cellular changes.

Tissues Overview

• Definition: Groups of similar cells performing common functions; essential for organ complexity and function.
• Types of Tissue:
  • Nervous: Control functions, encompassing neurons and supportive cells.
  • Muscle: Facilitates movement; consists of skeletal, cardiac, and smooth muscle types.
  • Epithelial: Forms coverings and lines cavities; can be covering or glandular epithelium.
  • Connective: Provides structural support.

Nervous Tissue

• Function: Regulates body functions through electrical impulse transmission.
• Cell Types:
  • Neurons: Generate and transmit impulses.
  • Supporting Cells: Offer protection and support to neurons.

Muscle Tissue

• Movement: Enables voluntary and involuntary actions; contraction arises from actin and myosin filaments.
• Types:
  • Skeletal: Voluntary with striations, attached to bones.
  • Cardiac: Involuntary, striated, located in the heart.
  • Smooth: Involuntary, non-striated, found in hollow organs.

Epithelial Tissue

• General Functions: Forms boundaries and regulates substance passage.
• Types:
  • Covering Epithelium: Lines external and internal surfaces.
  • Glandular Epithelium: Comprises the glands of the body.
• Apical Surface: Faces open spaces, critical for function and interaction.### Jaundice and Genetic Disorders
• Jaundice indicates liver failure, characterized by yellowing of the skin and eyes.
• Albinism results in a lack of pigmentation, leading to red or pink eyes due to visible blood vessels.
• Argyria is a condition caused by excessive silver consumption, resulting in a blue discoloration of the skin.

Skin Appendages

• Skin appendages include structures associated with skin but are not skin itself.

Hair (Pili)

• Hair grows from follicles and is composed of dead, keratinized cells.
• Root: embedded in the skin, protects against loss.
• Shaft: visible part of hair projecting out of the skin.
• Functions include sensory perception and protection from UV light and debris.
• Hair structure consists of three layers:
  • Medulla: central core; absent in thin hair.
  • Cortex: several layers of flattened cells; prevents excessive thickness.
  • Cuticle: outermost layer with heavily keratinized cells arranged like shingles.

Structures Associated with Hair

• Hair Follicle: extends from epidermis into dermis with three layers, providing structure and support.
• Root Hair Plexus: nerve endings at the base of the hair bulb, enabling sensation.
• Dermal Papilla: supplies capillaries necessary for hair growth.
• Arrector Pili: smooth muscle associated with each hair follicle; causes goosebumps.

Hair Characteristics

• Hair shape is determined by the follicle: round for straight, oval for wavy, flattened for curly hair.
• Hair color is due to melanin in the cortex; pheomelanin results in red hair, while gray or white occurs with aging due to decreased melanin.

Hair Growth Phases

• Hair matrix: rapidly dividing cells in the hair bulb.
• Growth phase: active cell division; old cells pushed upward.
• Resting phase: inactive; hair remains in the follicle.
• Shedding phase: hair detaches from the follicle.

Types of Hair

• Vellus hair: fine, thin hair, more common in children and females.
• Terminal hair: thick, coarse hair, prevalent in adults, especially in males.

Hair Loss and Baldness

• Hair thinning is common with age; hair loss can exceed replacement.
• Male-pattern baldness is linked to genetic factors and androgen hormones.

Nails

• Nails are located at the tips of fingers and toes, composed of hard keratinized cells.
• Structure: root, nail plate, free edge; nail growth occurs in the nail matrix.

Skin Glands

Sweat Glands

• Composed of myoepithelial cells that contract to aid in sweat secretion.
• Sweat contains water, salts, and metabolic wastes.

Burns

• 1st Degree: painful, reddened skin; no scarring.
• 2nd Degree: pain, blisters, longer healing time; minimal scarring if not disturbed.
• 3rd Degree: full-thickness burn affecting all skin layers; requires significant medical intervention and can lead to dehydration.

Bone and Skeletal Tissue

• Functions of bones encompass support, protection, attachment for muscles, mineral and fat storage, blood cell formation, and hormone production.

Types of Cartilage

• All cartilage features chondrocytes.
• Hyaline cartilage: most abundant type; found in joints and respiratory structures.
• Elastic cartilage: similar to hyaline, with more elastic fibers; found in the ear and epiglottis.
• Fibrocartilage: provides tensile strength; found in vertebral discs and knee joints.

Types of Cartilage Growth

• Appositional growth: new cartilage is added to the surface.
• Interstitial growth: chondrocytes divide, secreting matrix within existing cartilage.