Three Different Cell Shapes: Refer to Figure 3.1 for graphical representation.
Shape 1: Example description.
Shape 2: Example description.
Shape 3: Example description.
LO 3.1b: Name and Describe the Composition of Extracellular Materials
Most Abundant Extracellular Material Options:
(a) Extracellular matrix
(b) Extracellular fluid
(c) Cellular secretions
(d) Interstitial fluid
Blood Plasma:
Blood plasma is an example of: (a) Extracellular matrix (b) Extracellular fluid (c) Cellular secretions (d) Interstitial fluid.
LO 3.1c: List the Major Regions of a Generalized Cell and Their Functions
The Three Main Parts of a Generalized Cell:
(1) Plasma Membrane
(2) Cytoplasm
(3) Nucleus
3.2 The Plasma Membrane
LO 3.2: Chemical Composition of the Plasma Membrane
Chemical Composition Fill in the Blanks:
The plasma membrane is a phospholipid bilayer with embedded proteins, arranged as a fluid mosaic. The polar head of a phospholipid is hydrophilic, and the nonpolar tails are hydrophobic. Membrane proteins are responsible for most of the specialized functions of the plasma membrane.
Function of Cholesterol in Plasma Membrane: Acts to stabilize the fluidity of the membrane under various temperatures.
Function of Glycocalyx: Provides protection, immunity to infection, and is involved in cell recognition and adhesion.
Four Functions of the Plasma Membrane:
Defines cell boundaries
Controls entry and exit of substances
Communicates with other cells
Involved in cell signaling.
3.3 Intercellular Junctions
LO 3.3: Structure and Function of Cell Junctions
Types of Cell Junctions:
Tight Junction: Impermeable junction helps keep cells from separating.
Desmosome: Anchoring junctions that prevent tearing.
Gap Junction: Allows ions to pass from cell to cell, facilitating communication.
3.4 Passive Membrane Transport
LO 3.4a: Passive Transport Processes
Definitions:
Passive Transport: Movement of substances across membranes without the use of energy.
Concentration Gradient: The difference in concentration of a substance between two areas.
Types of Diffusion:
Simple Diffusion: Movement of small, nonpolar molecules across the membrane.
Facilitated Diffusion: Requires a transport protein to move molecules across.
Osmosis: Movement of water across a selectively permeable membrane.
Key Characteristics for Plasma Membrane Crossing:
Size of the molecule
Polarity of the molecule.
Selective Permeability: The plasma membrane allows some substances to pass while restricting others.
Osmosis Explanation:
The movement of water through a membrane that is impermeable to solute; water moves from a region of low solute concentration to high solute concentration.
3.5 Active Membrane Transport
LO 3.5a: Active Transport Mechanisms
Differences Between Passive and Active Transport: Active transport requires energy (ATP) to move substances against their gradient, whereas passive transport does not.
Primary Active Transport Energy Source: Direct use of ATP.
Secondary Active Transport Energy Source: Indirectly uses energy from primary active transport.
Similarities of Active Transport and Carrier-Mediated Facilitated Diffusion:
Both require a transport protein in the membrane.
Both can move substances in opposite directions.
Sodium-Potassium Pump Details:
For each ATP used, 3 Na+ are pumped out and 2 K+ are pumped in; results in a higher concentration of K+ inside and Na+ outside.
LO 3.5b: Types of Vesicular Transport
Type of Transport for Hormone Release: (c) Exocytosis.
Transport Processes Characteristics:
Requires ATP
Involves transport proteins
Moves large substances or bulk transport of substances
LO 3.5c: Endocytosis Types
Pinocytosis: Nonselective sampling of extracellular fluid.
Phagocytosis: Involves the formation of pseudopods to engulf large particles.
Receptor-mediated Endocytosis: Specific movement of molecules such as cholesterol into a cell.
3.6 Selective Diffusion and Membrane Potential
LO 3.6: Membrane Potential
Definition of Membrane Potential: The voltage difference across the plasma membrane.
Resting Membrane Potential: Reference example, skeletal muscle cell is determined to be −70 mV (cytoplasmic side is negative relative to the extracellular side).
Cations in Extracellular and Intracellular Fluid:
Extracellular: Na+
Intracellular: K+.
Leaky Channels: More leakage channels for K+.
Diffusion Explanation: Outward diffusion of K+ is greater than inward diffusion of Na+, making the cytoplasmic side more negative.
Sodium-Potassium Pump Role: Maintains the resting membrane potential by routine transport of Na+ and K+ ions.
3.7 Cell Adhesion Molecules
LO 3.7: Functions of Cell Adhesion Molecules
Roles of Cell Adhesion Molecules (CAMs):
Cell signaling and communication
Help cells adhere to surroundings
Regulate cell growth and movement.
Definition of Ligand: A molecule that binds to a receptor. Examples include hormones and neurotransmitters.
3.8 Cytoplasmic Organelles
LO 3.8a: Structure and Function of Mitochondria
Function of Mitochondria: Produce ATP through aerobic respiration.
Cristae: Infoldings of the inner mitochondrial membrane that increase surface area for ATP production.
Mitochondrial Content in Skeletal Muscle Cells vs Blood Cells: Skeletal muscle cells contain more mitochondria due to higher energy demands.
LO 3.8b: Ribosomes and Endoplasmic Reticulum
Location and Protein Production of Free Ribosomes: Found in cytosol, produce cytosolic proteins.
Location and Protein Production of Membrane-bound Ribosomes: Attached to the endoplasmic reticulum, produce proteins for export or for membrane integration.
Functions of Rough Endoplasmic Reticulum:
Synthesizes proteins for secretion
Helps form cellular membranes
Modifies and packages newly formed proteins.
Functions of Smooth Endoplasmic Reticulum:
Lipid synthesis
Detoxification processes
Calcium ion storage.
LO 3.8c: Lysosomes vs. Peroxisomes
Enzymes in Lysosomes: Digestive enzymes that break down waste materials and cellular debris.
Enzymes in Peroxisomes: Oxidative enzymes that detoxify harmful substances and metabolize fatty acids.
Liver and Phagocyte Examples: Liver cells have numerous peroxisomes for detoxifying; phagocytes have abundant lysosomes for degrading pathogens.
LO 3.8d: Cytoskeletal Elements
Types of Cytoskeletal Elements:
Microfilaments: Smallest diameter, involved in cell shape and motility.
Intermediate Filaments: Provide strength to the cell, most stable.
Microtubules: Largest diameter, form the mitotic spindle and assist in organelle movement.
3.9 Cilia and Microvilli
LO 3.9a: Centrioles
Cilia and Flagella Formation: Extensions formed from centrioles, termed basal bodies.
LO 3.9b: Function and Example of Cilia and Microvilli
Function of Microvilli: Increase surface area for absorption, e.g., intestinal epithelial cells.
Function of Cilia: Move substances across the cell surface, e.g., respiratory tract epithelial cells.
Function of Flagella: Propel cells, e.g., sperm cells with a single flagellum.
3.10 The Nucleus
LO 3.10: Structure and Function of Nucleus Components
Fundamental Units of Chromatin: Nucleosomes or histones.
Short Bar-like Bodies: Formed from coiled chromatin during cell division, termed chromosomes.
Parts of the Nucleus and Their Functions:
Nuclear Envelope: Encloses the nucleus and separates it from cytoplasm; controls entry/exit.
Nucleoli: Synthesize ribosomal RNA (rRNA).
Chromatin: Genetic material, condenses to form chromosomes during cell division.
3.11 The Cell Cycle
LO 3.11a: Phases and Key Events of the Cell Cycle
Subphases of Interphase:
G1 (Gap 1): Cell growth and preparation for DNA replication.
S (Synthesis): DNA replication occurs.
G2 (Gap 2): Prep for mitosis, including further growth and organelle replication.
Phases of Mitosis:
(a) Anaphase
(b) Metaphase
(c) Prophase
(d) Telophase
From start to finish the order of the phases is: Prophase, Metaphase, Anaphase, Telophase.
LO 3.11b: DNA Replication Process
Replicated Chromosome Structure: Consists of two sister chromatids attached at a centromere.
Enzyme for Complementary Nucleotide Positioning: DNA polymerase.
Result of Semiconservative Replication: Each new DNA molecule consists of one parental strand and one newly synthesized strand.
3.12 Messenger RNA and Protein Synthesis
LO 3.12a: Define Gene and Genetic Code
Gene: A segment of DNA that codes for a protein.
Genetic Code: The set of rules defining how the information in DNA is translated into proteins.
Number of Protein-Encoding Genes: Approximately 20,000-25,000 genes in the human genome.