BIOL 115 - Chapter 7 Slide Notes

Chapter 7: Inside the Cell

Introduction to Cells

  • Cells are the fundamental units of life. Understanding their structure and function is essential for biological sciences.

So What’s a Theory?

  • In science:

    • Broader than a hypothesis, providing a general explanation.

    • Can lead to new, testable hypotheses.

    • Based on substantial evidence, indicating it is not merely speculative.

  • Theories consist of two primary components:

    • Pattern: Observations of consistent occurrences in nature.

    • Process: Mechanisms or explanations causing these patterns.

  • Misconceptions include equating theories with mere guesses or beliefs.

Theories in Biology

The Cell Theory

  • Addresses the composition of organisms:

    • All organisms are made of cells (pattern).

    • All cells arise from preexisting cells (process).

  • Key historical influence from Hooke's microscope, which enhanced understanding of cells.

  • Cells represent one of the five essential attributes of life alongside energy, information, replication, and evolution.

Cells: Common Features

Chemistry (Biomolecules)

  • Lipids: Form selective permeable membranes.

  • Nucleic Acids: Store and transmit genetic information.

  • Proteins: Execute various cellular functions.

  • Carbohydrates: Serve roles in energy provision, structural support, and cellular identity.

Structural Components

  • Plasma Membrane: Encases the cell, providing separation from the environment.

  • Chromosomes: Houses genetic material.

  • Ribosomes: Synthesizes proteins, essential for cellular functions.

Functions of Cells

  • Essential functions include survival, growth, reproduction, genetic information processing, macromolecule production, energy acquisition, and environmental interaction.

  • Emphasizes the role of biomolecules, membranes, and transport mechanisms in cellular function.

Cells: Differences

Structural Components

  • Differences in structure between prokaryotic and eukaryotic cells include:

    • Chromosomes: Vary in number and shape, e.g., linear in eukaryotes vs. circular in prokaryotes.

    • Ribosomes: Vary in size (70S vs. 80S).

    • Plasmids: Present in prokaryotes, absent in most eukaryotes.

    • Cell Wall:

      • Composition varies; prokaryotic cell walls may contain peptidoglycan.

      • Gram-positive bacteria have thick peptidoglycan layers, while gram-negative bacteria have thinner layers and outer membranes.

Cells: Classification

  • Based on morphology:

    • Eukaryotic: Contain membrane-bound nuclei.

    • Prokaryotic: Lack nuclei.

Extracellular Matrix – Eukaryotic Cells

  • Function: Protection and communication between cells.

  • Composition: Primarily glycoproteins.

Function of the Endomembrane System in Eukaryotes

Overview

  • Eukaryotic cells require an endomembrane system to:

    • Compartmentalize cellular functions, enhancing efficiency.

    • Organize various cellular activities, including transport and processing of materials.

Key Components of the Endomembrane System

  • Nuclear Envelope: Controls traffic in/out of the nucleus.

  • Endoplasmic Reticulum (ER): Synthesizes proteins and lipids.

  • Golgi Apparatus: Modifies, sorts, and packages proteins for transport. Works in tandem with rough and smooth ER.

  • Lysosomes: Digestive organelles responsible for breaking down macromolecules.

  • Vesicles/Vacuoles: Storage and transport organelles.

  • Plasma Membrane: Regulates material transport across the cell.