Cell Biology Quiz - Membrane Transport and Cycle

Cell Theory

• Cells are the fundamental units of all living things
• All living organisms are composed of cells
• All cells arise from pre-existing cells

Cellular Organelles

• Organelles are "little organs" within cells, performing specific tasks
• Non-membranous organelles: Not enclosed by membranes, in direct contact with cytosol -Cytoskeleton -Microfilaments -Intermediate filaments -Microtubules -Cilia -Microvilli -Flagella -Centrioles -Ribosomes
• Membranous organelles: Enclosed by membranes, isolated from cytosol -Mitochondria -Endoplasmic Reticulum (ER) -Rough ER -Smooth ER -Golgi Apparatus -Lysosomes -Peroxisomes -Nucleus

Levels of Organization

• Chemical Level: Atoms combined to form molecules
• Cellular Level: Cells are the fundamental units of life
• Tissue Level: Groups of similar cells working together
• Organ Level: Different tissues combine to form organs
• Organ System Level: Organs working together as a system
• Organism Level: Multiple organ systems interacting to form a complete organism

Introduction to Cells

• Cells are the smallest units considered living
• Typical cell size is approximately 0.1 mm in diameter
• Cell functions depend on underlying chemistry of their parts, including membranes, organelles and protein production processes

Cellular Differentiation

• Cellular differentiation: The process where generalized cells develop into specialized cells with specific functions
• A fertilized ovum (zygote) holds the genetic potential to develop into any cell type in the body
• Through cell division and differentiation, the zygote gives rise to various specialized cell types

Cellular A&P

• Cells provide different compartments, enabling storage, transport, and other functions
• The human body is approximately two-thirds water
• Cells distribute water and dissolved substances within/around the body
• Plasma Membrane: A layer separating the inside and outside of a cell
• Cytoplasm: The internal content of the cell
• Intracellular Fluid: The fluid inside the cell (cytosol)
• Extracellular Fluid: The fluid outside the cell

Cell - Plasma Membrane

• Composed of: -Phospholipid bilayer -Cholesterol -Proteins -Integral -Transmembrane -Peripheral -Glycocalyx (a carbohydrate layer outside cells)
• Phospholipid bilayer:
  • Measures 6-10 nm
  • Two layers of phospholipids
  • Hydrophilic heads face outside
  • Hydrophobic tails face inside
• Phospholipids interspersed with cholesterol molecules
  • Functions as a plasma membrane stiffener
• Proteins
  • Integral proteins: Permanently attached, often span the cell membrane and can transport water or solutes
  • Peripheral proteins: Temporarily attached to inner or outer membrane surfaces
  • Glycocalyx is a carbohydrate layer. Attached to proteins or lipids, functions in cell recognition, binding to extracellular structures, and lubrication

Cell - Cytoskeleton

• No membrane
• Functions include: internal framework, transportation highway
• Components: Proteins -Microfilaments -Intermediate filaments -Microtubules -Kinesin & Dynein movement on microtubules
• Centrioles:
  • No membrane
  • Composed of microtubules
  • 2 centrioles form a centrosome
  • Control DNA movement during cell division
• Ribosomes
  • No membrane
  • Made of ribosomal RNA & protein
  • Responsible for protein synthesis
  • Two classifications -Free Ribosomes (Found throughout the cytoplasm, make proteins that stay in the cytosol) -Fixed/Bound Ribosomes (Attached to the rough endoplasmic reticulum, make proteins to be exported out of the cell)

Cell - ER

• Endoplasmic Reticulum (ER)
  • Network of sacs and tubules in the cytoplasm
  • Cisternae (sacs and tubules) are continuous with the nuclear envelope
  • Fixed ribosomes are attached to rough ER

Cell - Golgi Apparatus

• Involved in modifying, sorting and packaging proteins for secretion or use within the cell
• Incoming transport vesicles deliver materials to the cis face (receiving side)
• Materials pass through the cisternae
• Vesicles eventually bud off from trans face (shipping side) to deliver processed materials

Cell - Lysosomes

• Vesicles containing enzymes that break down waste materials and cellular debris
• Enzymes function inside lysosomes so they don't cause harm elsewhere
• Extracellular material can be brought into the cell via vesicles/endocytosis.
• Digest parts of cells and cellular debris.

Cell - Mitochondria

• Double membrane organelles responsible for cellular respiration, where energy (ATP) is produced
• Cristae are folds of the inner membrane
• Matrix is the area inside the inner membrane
• Contains enzymes for respiration

Cell - Nucleus

• Control center of the cell
• Contains DNA and regulates gene expression
• Nuclear Envelope: Double membrane surrounding nucleus
• Nuclear Pores: Allow exchange of material between nucleus and cytoplasm
• Nucleolus: Structure within nucleus involved in ribosome production
• Nucleoplasm: The fluid inside the nucleus

Cell - DNA

• Stored in the nucleus of eukaryotes
• Instructions for RNA and protein synthesis
• One human cell's DNA is approximately 2 meters in length
• Double Helix
• Nucleosomes
• Chromatin
• Chromosome

Transcription & Translation

• DNA: instructions for building proteins
• Transcription: DNA to RNA process
• Translation: (mRNA) to protein process

DNA - Gene

• Functional unit of heredity, determines a characteristic
• Contains ~300-3000 nucleotides

DNA - Transcription

• Producing an RNA complement from a given gene (mRNA, messenger RNA): the process of making a copy of a DNA sequence into a complementary RNA sequence
• DNA sequence is used as a template to produce a complementary RNA molecule

DNA - Translation

• Using the mRNA sequence to create a protein
• mRNA sequence is used as a code to assemble amino acids in a specific order, creating a protein
• Happens in the ribosome

Membrane Transport

• Plasma membrane is selectively permeable
• Characteristics of material to pass: size, shape, lipid solubility, electrical charge.
• Characteristics of cell membrane: What lipids/proteins are present, how they’re arranged.
• Diffusion: Movement of materials from an area of high concentration to low concentration.
• Osmosis: Movement of water across a selectively permeable membrane from a region of high water concentration to low water concentration.
• Tonicity:
  • Isotonic Solution: Solute concentrations are equal inside and outside the cell, water movement is balanced
  • Hypotonic solution: Solute concentration is lower outside the cell than inside the cell; water moves into the cell; cell swells and can burst if too much water enters [lysis]
  • Hypertonic solution: Solute concentration is higher outside the cell than inside the cell; water moves out of the cell; cell shrinks and shrivels [crenation]
• Passive Transport:
  • Simple Diffusion: Movement of small, nonpolar molecules directly through the phospholipid bilayer
  • Facilitated Diffusion: Transport of larger or charged molecules via membrane proteins (carrier proteins or channels)
• Active Transport: Requires energy (ATP) to move molecules against their concentration gradient.
  • Carrier-mediated transport: Transport of larger molecules via membrane proteins
  • Vesicular transport: Materials move in or out of the cell enclosed in vesicles (Endocytosis/Exocytosis)

Cell Cycle

• Mitosis: Somatic cells divide to create two identical cells.
  • Function: Growth, repair, and asexual reproduction
  • Stages: Interphase, mitosis, cytokinesis
• Meiosis: Sex cells divide to create four genetically unique cells (gametes).
  • Function: Sexual reproduction
  • Stages: Interphase, meiosis 1, meiosis 2

Cancer

• If DNA is damaged or mutates, stop & go signals for cell division can be altered
• Tumor: Uncontrolled cell division
• Cancer: Uncontrolled, harmful cell division
• Cancerous cells compete with normal cells for resources
• Benign tumor: Non-cancerous cells remain within original tissue, seldom a threat
• Malignant tumor: Cancerous, invades surrounding tissue, disrupts function, and stimulates blood vessel growth (angiogenesis)
• Metastasis: Cells migrate to other areas and establish new tumors

Test your knowledge on key concepts in cell biology, focusing on the plasma membrane, transport mechanisms, and the cell cycle. This quiz covers essential topics like cellular structures, transport types, and organelle functions. Perfect for students studying cell biology at any level.