Cell Biology Chapter on Organelles

Prokaryotic Cells

• Prokaryotic cells are significantly smaller than eukaryotic cells.
• They lack a nucleus and other membrane-bound organelles.
• Prokaryotes include bacteria and archaea.

Textbook Information

• Hard copies of the textbook are no longer available from the publisher.
• Options to acquire the textbook include purchasing a used copy, borrowing it from the library, or buying the 4th edition for the same price as indicated on the eClass website.

Lab 1 Information

• Lab 1 begins this week (week of Sept 16th) for all groups (1-8).
• Participants will not attend an in-lab session for Lab 1.
• The lab is completed independently and can be completed before September 22nd.
• Lab 1 materials are provided via the Simbio virtual lab software, details of which are available in the Lab 1 section of eClass.
• The access key is located within the "SimUText Registration Instructions for Students (Fall 2024)" document.
• Students must purchase the lab manual from the bookstore before Lab 1 starts.

Quizzes Information

• An eClass quiz was available today.
• The first Mastering Biology quiz will be available next Monday.
• A practice quiz with no grade weight will be available this week.
• These quizzes are used for familiarization with the Mastering Biology format.

Learning Strategies

• Study Cycle: A recommended approach to learning.
• Using Learning Outcomes: A strategy for active learning.
• Metacognition: A method involving analyzing one's own thought processes.
• Evidence-based study strategies: Strategies supported by research.

Metacognition Definition

• Metacognition is described as having a "big brain outside of your brain" that observes and analyzes the operations of your "regular" brain.

Prokaryotes

• Prokaryotes are bacteria/archaea cells.
• This information can be found by reviewing past slides.

Eukaryotic Cell Structure, Function, and Evolution

• This is a study topic related to eukaryotic cells.

The Eukaryotic Cell

• Eukaryotic cells are larger than prokaryotic cells.
• The genetic material (genome) is enclosed within a nuclear envelope.
• Eukaryotic cells contain membrane-bound organelles with specific functions.
• These cells have a cytoskeleton containing motor proteins.

Major Eukaryotic Organelles

• Nucleus (including its lamina and nucleolus)

• Ribosomes

• Endomembrane System (includes the endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles)

• Nuclear envelope (or membrane)

• Mitochondria

• Chloroplasts

• Cytoskeleton

• Plasma membrane

• Cell wall (some eukaryotes only, not all)

• Note: Peroxisomes are excluded from this list.

Basic Structure of Animal and Plant Cells

• Information about the basic structure of animal and plant cells.
• Understanding of general structure and function of organelles is necessary.

BioFlix Tours

• Check out the BioFlix tours of animal and plant cells on Mastering Biology.

Membrane Bound Organelles

• These organelles increase the surface area relative to volume, increasing the capacity for membrane-requiring reactions.
• They create compartments that lead to specialization of function within the cell.

Molecules in the Cell

• Molecules continuously move throughout the cell, in and out of the cell, and between different structures.

The Nucleus

• The nucleus contains the nuclear genome.
• It separates hereditary material from the rest of the cell.
• The nucleus is surrounded by a double membrane (also called a nuclear envelope), which consists of two lipid bilayers.

The Nuclear Lamina

• The nuclear lamina provides structural support.
• It is found inside the nucleus, positioned under the double membrane.
• It is composed of intermediate filaments.

Nucleolus

• The nucleolus is responsible for ribosomal RNA (rRNA) synthesis and ribosomal subunit assembly.
• It is a non-membrane-bound structure within the nucleus.

Nuclear Transport

• Nuclear pores control the movement of substances into and out of the nucleus.
• Molecular transport is regulated by the pores, the main pathways within the nuclear envelope.

Nuclear Pore Complexes

• Multiprotein complexes are embedded in the nuclear envelope.
• They control the transport of molecules between the cytoplasm and nucleus.

Targeting Molecules to the Nucleus

• Larger molecules can be targeted to the nucleus.
• Signal sequences are involved in regulating traffic between the nucleus and cytoplasm.
• A Nuclear Localization Signal (NLS) is an amino acid sequence directing movement to the nucleus. Other proteins also play roles.

Signal Sequences

• Signal sequences aid in regulating traffic between the nucleus and cytoplasm.
• Specific sequences direct proteins to different locations within the cell or vice-versa (out of the nucleus).
• Nuclear Export Signals (NES) facilitate transport out of the nucleus.

The Nuclear Envelope and the Endomembrane System

• The nuclear envelope is part of the endomembrane system.
• The endomembrane system consists of related membranes (e.g., nuclear envelope, endoplasmic reticulum, Golgi, lysosomes, vesicles, and vacuoles) that are structurally and functionally interconnected.

Endomembrane System Functions

• The endomembrane system carries out numerous functions within the cell:
  • Synthesis, modification, and secretion of proteins
  • Synthesis of lipids and detoxification of toxins
  • Transport and breakdown of large biomolecules

Endomembrane System Evolution

• A hypothesis suggests that the various membranes of the endomembrane system arose as invaginations or infoldings of the plasma membrane.

Endomembrane System Proteins

• Different parts of the endomembrane system require specific proteins.

Protein Movement Between Cell Compartments

• Vesicles are frequently utilized for moving proteins between cell compartments.
• Vesicles are membrane-enclosed sacs that facilitate the transport of materials between different cell organelles or from the cell to the external environment.

Explore the essential functions and roles of membrane-bound organelles in cells through this quiz. Learn about the significance of the nucleus and how these structures help manage the surface area to volume ratio. Test your knowledge on cell transport mechanisms and organelle characteristics.