Chapter 2 Study guide

Cell Structure and Function

Overview of Eukaryotic Cell Anatomy

The eukaryotic cell contains various specialized organelles, each with distinct functions essential for cellular life. Understanding the structure and function of these organelles is foundational in Anatomy & Physiology.

• Nucleus: The control center of the cell, containing genetic material (DNA).

• Rough Endoplasmic Reticulum (RER): Studded with ribosomes, involved in protein synthesis and modification.

• Golgi Apparatus: Processes, sorts, and packages proteins and lipids for secretion or use within the cell.

• Mitochondrion: The powerhouse of the cell, responsible for ATP production through cellular respiration.

• Microvilli: Finger-like projections that increase surface area for absorption.

Key Cell Organelles and Their Functions

• Nucleolus: Located within the nucleus; site of ribosome synthesis.

• Lysosome: Contains digestive enzymes; breaks down waste and cellular debris. Often called the "demolition crew" of the cell.

• Peroxisome: Detoxifies harmful substances, such as hydrogen peroxide.

• Mitochondrion: Contains its own DNA, inherited maternally.

Cell Membrane Structure

The cell membrane, also known as the plasma membrane, is a selectively permeable barrier that surrounds the cell, maintaining homeostasis and mediating communication with the environment.

• Structure: Composed of a phospholipid bilayer with embedded proteins.

• Function: Regulates entry and exit of substances, provides protection, and facilitates cell signaling.

Cytoskeleton Components

The cytoskeleton provides structural support, facilitates movement, and organizes cellular components.

• Microtubules: Hollow tubes that maintain cell shape and assist in cell division.

• Microfilaments: Thin filaments involved in cell movement and shape changes.

• Intermediate Filaments: Provide mechanical strength to cells.

Cell Division: Mitosis and Cytokinesis

Cell division is essential for growth, repair, and reproduction. Mitosis refers to nuclear division, while cytokinesis is the division of the cytoplasm.

• Stages of Mitosis:

  1. Prophase: Chromatin condenses into chromosomes; spindle fibers form.

  2. Metaphase: Chromosomes align at the cell's equator.

  3. Anaphase: Sister chromatids separate and move to opposite poles.

  4. Telophase: Nuclear envelopes reform; chromosomes decondense.

• Cytokinesis: Division of the cytoplasm, resulting in two daughter cells.

Key Equations:

• DNA Replication occurs during $\text{Interphase S}$.

Endocytosis and Exocytosis

Cells transport materials across their membranes via endocytosis and exocytosis.

• Phagocytosis: "Cell eating"; engulfment of large particles.

• Pinocytosis: "Cell drinking"; uptake of fluids and small molecules.

• Receptor-mediated endocytosis: Specific uptake of molecules via receptor binding.

Cellular Transport Mechanisms

Cells move substances across membranes by passive and active transport.

• Diffusion: Movement of molecules from high to low concentration.

• Osmosis: Diffusion of water across a semipermeable membrane.

Table: Major Cell Organelles and Their Functions

Organelle	Main Function	Additional Info
Nucleus	Stores genetic material (DNA)	Site of transcription
Nucleolus	Ribosome synthesis	Located inside nucleus
Rough ER	Protein synthesis and modification	Studded with ribosomes
Golgi Apparatus	Protein and lipid processing	Packaging and sorting
Mitochondrion	ATP production	Contains its own DNA
Lysosome	Digestion of cellular waste	Contains hydrolytic enzymes
Peroxisome	Detoxification	Breaks down hydrogen peroxide
Microvilli	Increase surface area	Found in absorptive cells

Sample Multiple Choice Explanations

• Mitosis: Refers only to nuclear division; cytokinesis is the division of the cytoplasm.

• Endocytosis Types: Phagocytosis engulfs large particles; receptor-mediated endocytosis is highly specific.

• Cytoskeleton Elements: Microtubules, microfilaments, and intermediate filaments are the three main components.

• DNA Replication: Occurs during the S phase of interphase.

• Nuclear Pores: Allow passage of RNA and proteins, but not chromatin.

• Double Membrane: Unique to mitochondria and the nucleus.

• Plasma Membrane: The single-layered membrane surrounding the cell.

Key Definitions

• Chromatin: The complex of DNA and proteins in the nucleus.

• Centrioles: Rod-shaped structures involved in cell division.

• Interphase: The phase of the cell cycle when the cell grows and DNA is replicated.

Summary Table: Stages of Mitosis

Stage	Main Events
Prophase	Chromosomes condense, spindle forms
Metaphase	Chromosomes align at equator
Anaphase	Sister chromatids separate
Telophase	Nuclear envelope reforms

Additional info:

• Some content inferred from standard cell biology knowledge to provide complete explanations.

• Tables reconstructed for clarity and completeness.