Cell Biology: Eukaryotic Cells Overview

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Questions and Answers

What is the primary function of membrane-bound organelles in eukaryotic cells?

They compartmentalize cellular processes, allowing for specialized functions within the cell.

What are the main components of the cell wall in plant cells?

The cell wall in plant cells is primarily composed of cellulose.

How do organelles interact to maintain cellular functions?

Organelles work together by transferring materials and information, facilitating processes like energy production and protein synthesis.

Describe one key function of the plasma membrane in eukaryotic cells.

The plasma membrane regulates the passage of substances in and out of the cell, maintaining homeostasis. Signup and view all the answers

What role do ribosomes play in the cell, and how do their sizes differ between eukaryotic and prokaryotic cells?

Ribosomes are responsible for protein synthesis; eukaryotic ribosomes are larger (80S) compared to smaller prokaryotic ribosomes (70S). Signup and view all the answers

Explain how the structure of the plasma membrane aids in the absorption of nutrients.

The phospholipid bilayer's structure, along with microvilli, increases surface area, enhancing nutrient absorption. Signup and view all the answers

What is the significance of the nuclear envelope in eukaryotic cells?

The nuclear envelope safeguards the nucleus, controlling molecular access and separating transcription from translation. Signup and view all the answers

What distinguishes primary active transport from facilitated diffusion?

Primary active transport requires energy to move substances against their concentration gradient, while facilitated diffusion relies on passive movement down the gradient. Signup and view all the answers

What is the primary function of the rough endoplasmic reticulum in eukaryotic cells?

The rough ER is primarily responsible for protein synthesis and modification. Signup and view all the answers

How does the structure of the cell wall contribute to its function in plant cells?

The cell wall provides structural support and protection, primarily composed of cellulose. Signup and view all the answers

Describe the interaction between the Golgi apparatus and the rough endoplasmic reticulum.

The Golgi apparatus modifies proteins that are synthesized in the rough ER. Signup and view all the answers

What role do lysosomes play in animal cells?

Lysosomes contain digestive enzymes that break down macromolecules and organelles. Signup and view all the answers

Explain the significance of mitochondria in cellular respiration.

Mitochondria are critical for ATP production through cellular respiration. Signup and view all the answers

What is the function of peroxisomes within eukaryotic cells?

Peroxisomes are involved in the oxidation of fatty acids and detoxification of hydrogen peroxide. Signup and view all the answers

How does the cytoskeleton contribute to cellular functions?

The cytoskeleton provides structural support, aids in intracellular transport, and facilitates cell division. Signup and view all the answers

Why are internal membranes important for cellular efficiency?

Internal membranes compartmentalize reactions, enhancing efficiency by localizing biochemical processes. Signup and view all the answers

What are the two types of cells, and how do they differ?

The two types of cells are prokaryotic and eukaryotic. Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have both. Signup and view all the answers

Describe the primary role of the Golgi apparatus within the endomembrane system.

The Golgi apparatus processes, modifies, and tags proteins and lipids for specific destinations. It also adds sugar molecules to these macromolecules through glycosylation. Signup and view all the answers

How do lysosomes contribute to the cell's immune response?

Lysosomes contain digestive enzymes that break down pathogens and recycle cellular components, aiding in the immune response, especially in processes like phagocytosis. Signup and view all the answers

What distinguishes the rough endoplasmic reticulum from the smooth endoplasmic reticulum?

The rough endoplasmic reticulum (RER) has ribosomes attached and is involved in synthesizing and modifying proteins, whereas the smooth endoplasmic reticulum (SER) lacks ribosomes and synthesizes lipids and detoxifies drugs. Signup and view all the answers

Explain how transport vesicles function in the endomembrane system.

Transport vesicles shuttle proteins and lipids between the endoplasmic reticulum, Golgi apparatus, plasma membrane, and other organelles. Signup and view all the answers

What is the basic function of the plasma membrane?

The plasma membrane regulates the movement of substances in and out of the cell, maintaining homeostasis and protecting cellular integrity. Signup and view all the answers

Identify the primary components of the endomembrane system.

The primary components of the endomembrane system include the plasma membrane, nuclear envelope, lysosomes, vesicles, endoplasmic reticulum, and Golgi apparatus. Signup and view all the answers

What essential principle does cell theory emphasize about the origin of new cells?

Cell theory emphasizes that new cells arise from pre-existing cells. Signup and view all the answers

Study Notes

4.1 Studying Cells

Cells are the fundamental units of all living organisms
Two types of cells: Prokaryotic (bacteria, archaea) and eukaryotic (plants, animals, fungi, protists)
Microscopy used to study cells
- Light microscopes use visible light, up to 400x magnification, suitable for live specimens
- Electron microscopes give high magnification
  - Transmission electron microscope (TEM) for internal structures
  - Scanning electron microscope (SEM) for surface details and 3D imagery
- Magnification enlarges images, resolving power allows distinguishing between adjacent structures
Cell theory proposed by Schleiden, Schwann, and Virchow
- All living things are made of cells
- The cell is the basic unit of life
- New cells arise from pre-existing cells

4.4 The Endomembrane System and Proteins

Endomembrane system includes: plasma membrane, nuclear envelope, lysosomes, vesicles, endoplasmic reticulum (ER), Golgi apparatus
Components of Endomembrane system
- Do not include mitochondria or chloroplast membranes
- Functions: Modifies, packages, and transports proteins/lipids

1. Endoplasmic Reticulum (ER)

Rough ER (RER): Ribosomes attached
- Synthesizes and modifies proteins (e.g., folding, adding side chains)
- Produces phospholipids for membranes
- Abundant in protein-secreting cells (e.g., liver)
Smooth ER (SER): Lacks ribosomes
- Synthesizes lipids, carbohydrates, and steroid hormones
- Detoxifies drugs and poisons
- Stores calcium ions (e.g., in sarcoplasmic reticulum for muscle contractions)

2. Golgi Apparatus

Processes and tags proteins and lipids for specific destinations
Structure: flattened membrane sacs (cisternae)
- Cis face: Receiving side for vesicles
- Trans face: Shipping side
Adds sugar molecules to proteins/lipids (glycosylation)

3. Lysosomes

Digestive enzymes break down macromolecules, recycle organelles, and destroy pathogens
Function in immune responses (e.g., phagocytosis by macrophages)

4. Transport Vesicles

Shuttle proteins/lipids between ER, Golgi, plasma membrane, and other organelles

4.5 Cytoskeleton

Microfilaments (actin filaments)
- Thinest (7nm), made of actin
- Functions: Cellular movement, shape maintenance, division (e.g., cleavage furrow), and intracellular transport
- Powered by ATP and work with myosin for muscle contractions
Intermediate filaments
- Diameter: 8-10nm; purely structural
- Functions: Maintain cell shape, anchor nucleus and organelles
- Examples: Keratin (in hair, nails, skin)
Microtubules
- Largest (25nm), hollow tubes of α-tubulin and β-tubulin dimers
- Functions: Resist compression, vesicle transport, chromosome segregation during cell division
- Structural components of flagella and cilia (9+2 arrangement)

Special Structures

Centrosomes and centrioles: Microtubule organizing centers in animal cells, play a role in spindle formation during cell division
Flagella and cilia: Flagella: Few, long structures for movement (e.g., sperm); Cilia: Numerous, short structures for movement or substance transport (e.g., respiratory tract)

4.6 Connections between Cells and Cellular Activities

Extracellular Matrix (ECM) in Animal Cells
- Composition: Collagen, proteoglycans, and integrins
- Functions: Provides structural support, facilitates cell communication (e.g., blood clotting mechanisms)
Intercellular Junctions
- Plasmodesmata (plant cells): Channels connecting adjacent plant cells, allowing nutrient and water transport
- Tight junctions (animal cells): Watertight seals between epithelial cells (e.g., bladder lining)
- Desmosomes (animal cells): Spot-weld-like connections, resist stretching (e.g., skin, cardiac tissue)
- Gap junctions (animal cells): Protein-lined pores for ion/nutrient transport, important in cardiac muscle contraction

Chapter Summary Table: Components of Prokaryotic vs. Eukaryotic Cells

A table comparing prokaryotic and eukaryotic cells
- Discusses cell Components and their function in prokaryotes, animal cells and plant cells
Plasma Membrane, Cytoplasm and Nucleus
- Comparing the presence or absence

5.1 Overview of Structure and Function

Plasma membrane is the outermost layer of a cell
- Defines cell boundaries and regulates interactions with environment
- Functions: Selective barrier (controls entry/exit of substances), cell communication (contains markers for self-recognition and intercellular signaling), Flexibility (allows shape changes e.g. red blood cells in capillaries), Signal Transmission (integral proteins detect extracellular signals and initiate intracellular responses)
Key components of the plasma membrane
- Phospholipids: Form bilayer; amphipathic
- Proteins: Integral (embedded in the bilayer; transport molecules, act as receptors), Peripheral (loosely attached to surface of bilayer; enzymatic activity, cytoskeletal attachment, cell recognition)
- Cholesterol: Found between phospholipids; Maintains membrane fluidity across temperature variations; prevents membranes from becoming too rigid or too fluid
- Carbohydrates: Found on the exterior surface; attached to proteins (glycoproteins) or lipids (glycolipids); Functions: Cell recognition and signaling

5.2 Passive Transport

Passive transport moves substances across membranes without cellular energy
- Substances move from high to low concentration down a concentration gradient
- Includes diffusion, facilitated diffusion, and osmosis
Selective Permeability of Membranes
- Plasma membranes are selectively permeable
- Allows certain molecules to pass freely (e.g., lipid-soluble)
- Polar molecules, ions, and larger molecules require transport proteins
Diffusion
- Net movement of molecules from high to low concentration
- Factors affecting diffusion rate: concentration gradient, temperature, molecular mass, solvent density
Facilitated diffusion
- Uses channel and carrier proteins for substances that cannot diffuse directly
- Channel proteins: Provide hydrophilic passage
- Carrier proteins: Bind to molecules, change shape, and transport across membrane
Osmosis
- Movement of water across a semipermeable membrane from high water potential (low solute) to low water potential (high solute)
- Key terms: Isotonic, hypertonic, hypotonic solutions

5.3 Active Transport

Active transport moves substances against their concentration or electrochemical gradients, requiring energy (ATP)
- Maintains ion gradients essential for processes like nerve signaling
Types of Active Transport
- Primary active transport: Direct use of ATP to pump substances (e.g., Na+/K+ ATPase)
- Secondary active transport (co-transport): Uses energy stored in an electrochemical gradient created by primary active transport (e.g., Na+-glucose symporter)
Carrier Proteins in Active Transport
- Uniporters, Symporters, Antiporters

5.4 Bulk Transport

Endocytosis: Moves large particles into the cell using vesicles
- Phagocytosis ("cell eating")
- Pinocytosis ("cell drinking")
- Receptor-mediated endocytosis
Exocytosis: Exports materials out of the cell via vesicles

Study Notes: Eukaryotic and Prokaryotic Cells

Comparing eukaryotic and prokaryotic cells
- Features like nucleus, size, chromosomes, organelles, cell walls, ribosomes, and division type (mitosis vs. binary fission)

Eukaryotic Cell Components and Functions

Detailed descriptions of the Structure and Function of Cell components e.g Plasma Membrane, Cytoplasm and its contents, Organelles, Nucleus

Key Concepts for Biological Framework

Big Idea 1: Evolution drives unity and diversity
- Evidence of endosymbiosis: Mitochondria and chloroplasts evolved prokaryotic cells
- Shared conserved processes indicate common ancestry
Big Idea 2: Utilization of free energy
- Compartmentalization enhances efficiency by localizing reactions
- Internal organelles maintain homeostasis and energy use
Big Idea 4: Biological interactions
- Organelle interactions (e.g., Golgi, ER, mitochondria) for essential cellular functions

Specialized Structures in Eukaryotic Cells

Unique features of animal and plant cells
- Lysosomes, centrosomes, chloroplasts, central vacuole, cell wall

Prokaryotic Cell Components and Functions

Features like capsule, cell wall, and nucleoid are described

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Description

Test your knowledge on the primary functions and interactions of organelles in eukaryotic cells. This quiz covers essential components, including cell membranes, organelle roles, and transport mechanisms. Perfect for students studying cell biology and related subjects.