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Questions and Answers
What is biology?
What is biology?
Biology is the science of life studying all aspects about living organisms, including their structure, functions, and interactions with their environment.
Which of the following are branches of biology? (Select all that apply)
Which of the following are branches of biology? (Select all that apply)
Who concluded that all plants are made of cells?
Who concluded that all plants are made of cells?
Matthias Schleiden
What are the two basic types of cellular organization?
What are the two basic types of cellular organization?
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Match the following cellular characteristics with prokaryotic or eukaryotic cells:
Match the following cellular characteristics with prokaryotic or eukaryotic cells:
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Eukaryotic cells do not contain any membranous organelles.
Eukaryotic cells do not contain any membranous organelles.
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What is the function of the cell membrane?
What is the function of the cell membrane?
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Which of the following is true regarding ribosomes in prokaryotes and eukaryotes?
Which of the following is true regarding ribosomes in prokaryotes and eukaryotes?
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The basic structural and functional units of all living organisms are called __________.
The basic structural and functional units of all living organisms are called __________.
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What is required to study cells effectively due to their small size?
What is required to study cells effectively due to their small size?
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Study Notes
Biology Lecture 1
- Biology is the science of life, studying all aspects of living organisms (plants, animals, and humans), including their structure, functions, and interactions with their environment.
- Branches of biology include, but are not limited to: cell biology, histology, genetics, physiology, and embryology.
Objectives
- Define biology and identify its branches, cell theory, and cell organization.
- Compare prokaryotes and eukaryotes.
- Identify the general structure of eukaryotic animal cells.
- Describe the microscopic and molecular structure of the cell membrane.
- Outline cell membrane function.
Cytology & Cell Biology
- Cytology and cell biology is a branch of biology studying cells, their structure, physiological properties, interactions with their environment, division, function, and death.
- This study is conducted at both the microscopic and molecular levels.
Cell Theory
- Matthias Schleiden (1838): All plants are made of cells.
- Theodore Schwann (1839): All animals are made of cells.
- Rudolf Virchow (1855): All cells come from pre-existing cells.
- All living organisms are made up of cells
- Cells are the fundamental structural and functional units of living organisms
- New cells originate from pre-existing cells
Cellular Organization
- There are two basic types of cellular organization:
- Prokaryotes: Simple cells; lack a nucleus and membrane-bound organelles (e.g., bacteria).
- Eukaryotes: More complex cells; have a nucleus and membrane-bound organelles (e.g., plant and animal cells).
Comparison Prokaryotes and Eukaryotes
| Feature | Prokaryotes | Eukaryotes |
|---|---|---|
| Cell Size | 0.1-5 μm | 10-100 μm |
| Nucleus | Absent | Present |
| Membrane-bound Organelles | Absent | Present |
| DNA | Single, circular | Linear |
| Ribosomes | Smaller | Larger |
Structures of Prokaryotic and Eukaryotic Cells (Diagram)
- The diagram shows the structures of a prokaryotic (bacterial) cell and a eukaryotic (mammalian) cell, labelling various organelles. These diagrams help visualizing the difference in cell structures between prokaryotes and eukaryotes.
The Human Body
- The human body is composed of cells, tissues, organs, and systems.
- Cells: Structural and functional units of all living organisms.
- Tissues: Formed of similar cells performing a specific function.
- Organs: Composed of tissues to perform specific functions.
- Systems: Groups of organs working together to perform interconnected functions; for example, the digestive system.
How to Study Cells
- Microscopes are used to study small cells, achieving magnification and resolution.
- Light Microscope (LM): Used for initial observation.
- Electron Microscope (EM): Provides more magnification and detail; structures can appear as grey, black (electron-dense) or white (electron-lucent) under EM.
Staining for Light Microscopy
- Tissues and their components are mostly colorless. Stains are used to color different components differently.
Hematoxylin and Eosin Stain (H&E)
- Hematoxylin: A basic stain that colors acidic components (e.g., nucleic acids) blue; structures that take up the blue color are called basophilic.
- Eosin: An acidic stain that colors basic components red; structures that take up the red color are called acidophilic. Notably, the nucleus is usually basophilic and the cytoplasm may be basophilic or acidophilic, depending on the specific cells components present there.
Electron Microscope (EM)
- Allows for greater magnification for more detail in cell structure viewing.
- Structures under EM can appear as either:
- Grey to black (electron-dense), or
- White (electron-lucent).
General Structure of Eukaryotic Animal Cells
- Eukaryotic animal cells vary in shape and size.
- Each cell contains two main parts:
- Cytoplasm: Contains cytosol (viscous fluid with enzymes, ions, and metabolites); organelles (living structures essential for life); and inclusions.
- Nucleus: Inclusions (non-living structures not essential for life); metabolically inert.
Organelles
- Membranous organelles: Have a membrane boundary around them; for example, mitochondria, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, peroxisomes.
- Non-membranous organelles: No membrane boundary; for example, ribosomes, microfilaments, microtubules, and intermediate filaments, centrioles, cilia, and flagella.
Pinocytosis, Phagocytosis, and Receptor-Mediated Endocytosis
- Endocytosis is the process of cells taking in materials by engulfing them. This encompasses:
- Phagocytosis: Ingestion of solid materials (e.g., bacteria).
- Pinocytosis: Ingestion of fluid materials.
- Receptor-mediated endocytosis: Uptake of specific molecules (e.g., low-density lipoproteins, hormones) through specific receptors on cell surfaces.
Cell Membrane
- Molecular structure of the cell membrane: Three main components include lipids, proteins, and carbohydrates (including glycoproteins and glycolipids).
- Lipids form a bilayer; phospholipids have polar heads and nonpolar tails; cholesterol regulates membrane fluidity.
- Proteins (integral and peripheral): Integral proteins span the membrane; peripheral proteins are situated on the surface.
Glycocalyx
- The glycocalyx is a carbohydrate-rich layer outside the cell membrane; it's formed by glycoproteins and glycolipids.
- The glycocalyx plays a critical role in: cell recognition, intercellular adhesion, and contains digestive enzymes.
Transport across Cell Membrane
- The cell membrane controls the movement of substances through passive and active processes.
- Passive transport involves no energy expenditure, such as diffusion (simple and facilitated)
- Active transport uses energy to move substances against a concentration gradient.
- Vesicular transport involves the formation of vesicles for the transfer of large molecules (endocytosis/exocytosis).
Functions of Cell Membrane
- Structural integrity: Maintaining the cell's shape.
- Regulation of transport: Entering and exiting materials from the cell
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Description
This quiz explores fundamental concepts in biology, including cell structure and classification. Test your knowledge of cellular organization, characteristics of prokaryotic and eukaryotic cells, and key historical figures in the field of biology. Perfect for beginners looking to understand the basics.
