Cell Biology - 1st Lec. PDF

Summary

This document is a lecture on cell biology. It discusses the fundamental units of living organisms, different types of cells (prokaryotic and eukaryotic) and their characteristics, basic building blocks and historical figures related to the topic. It explains how to differentiate between plant and animal cells and provides insight into cell structure.

Full Transcript

# Cell Biology ## Cytology The study of cells as fundamental units of living organisms. ## Cells - Basic building unit of human body. - **Microorganisms:** Bacteria & amoebae exist as single cells. - **Animal:** Has millions of differentiated cells. - **Size:** Wide ranges (large, medium, small)...

# Cell Biology ## Cytology The study of cells as fundamental units of living organisms. ## Cells - Basic building unit of human body. - **Microorganisms:** Bacteria & amoebae exist as single cells. - **Animal:** Has millions of differentiated cells. - **Size:** Wide ranges (large, medium, small) - **Shape:** Rounded, flattened, spindle, cuboidal, columnar, rod. ## Cytology - **Cyto = Cell** - **Ology = Science** - **Cells:** - **Tissue:** - **Organ:** - **System:** - **Whole Body:** ## How to Observe an Object? - **Naked eye** - **Light Microscope** - **Electron Microscope** ## Relative Sizes on a Logarithmic Scale The scale begins on the far left with atoms at 0.1 nanometers and ends on the far right with adult females at 1 meter. In between are the following: - Protein at 1 nanometer - Lipids at 1 nanometer - Flu virus at 10 nanometers - Mitochondria at 100 nanometers - Bacteria at 1 micrometer - Plant cell at 10 micrometers - Animal cell at 100 micrometers - Human egg at 100 micrometers - Frog egg at 1 millimeter - Chicken egg at 10 millimeters - Ostrich egg at 100 millimeters ## Historical Figures - **Robert Hooke:** The first person to observe cells and described them as open spaces within plant tissue. - **Van Leeuwenhoek:** First acknowledged microscopist and microbiologist in history. - **Matthias Schleiden & Theodor Schwann:** Proposed that all living organisms are composed of cells. This “cell theory” was a milestone in the development of modern biology. ## Cellular Organization - All living organisms except viruses have cellular organization and consist of one or many cells. - **Unicellular:** The organisms with only one cell, such as bacteria and protozoa. - **Multicellular:** Organisms with many cells such as most plants and animals. ## Cell Types - **Prokaryotic:** Unicellular organisms with no membrane-bound nucleus or organelles. - **Eukaryotic:** Any cell containing a defined nucleus with membrane-bound organelles. | Characteristic | Prokaryotic Cell | Eukaryotic Cell | |---|---|---| | Definition | Unicellular organism with no membrane-bound nucleus or organelles | Any cell containing a defined nucleus with membrane-bound organelles | | Examples | Bacteria | Animal, plant, fungi,... | | Nucleus | Absent (nucleoid region) | Present (membrane bound) | | Cell Size | Small (less than 1 micrometer to 5 micrometers) | Large (10-100 micrometers) | | Organism Type | Unicellular | Usually multicellular | | Organelles | Absent | Present | | DNA Replication | Replicates entire genome at once | Highly regulated with selective origins and sequences | | Chromosomes | One long single loop of DNA and plasmids | More than one | | Ribosomes | Small | Large | | Growth/Generation time | Faster | Slower | | Cell Wall | Complex | Simple (Plant+Fungi) | ## Similarities Both Prokaryotic and Eukaryotic cells have the following: - Cytoplasm. - Plasma membrane. - The ability to store hereditary information. ## Plant Cell vs. Animal Cell The following table summarizes the main differences and similarities between plant and animal cells: | Feature | Plant Cell | Animal Cell | | --- | --- | --- | | Definition | Basic structural & functional units of plants | Basic structural & functional units of animals | | Size & Shape | Larger | Smaller | | Cell Wall | Have cell wall made up of (cell membrane and cellulose). Made up of cellulose, just below the cell wall | Absent | | Plasma Membrane | Present | Present | | Vacuoles | Have a large central vacuole that can occupy up to 90% of the cell's volume. | Have many & small vacuoles, smaller than the plant cell. | | Centrioles | Absent | Present (involve in the cell division) | | Microvilli | Absent | Present in the intestinal lining (Increase the surface area for the food absorption) | | Cilia and Filaments | Absent | Present (allow movement of cells or part of the cell, ex. sperm to the ova) | | Plastids | Present (giving pigmentation color to the plants and facilitate trapping of light energy used for photosynthesis process) | Absent| ## Plant Cell vs. Animal Cell Similarities Both plant and animal cells are eukaryotic and share the following: - Have a true nucleus enclosed and separated from other organelles by a nuclear membrane. - Have similar reproduction processes of mitosis and meiosis, controlled by the cell nucleus. - Have membrane-bound, cell organelles performing the same functions. ## Animal Cell Anatomy The following list describes the parts of an animal cell: - **Centrosome** - **Peroxisome** - **Lysosome** - **Ribosomes** - **Centriole** - **Cilium** - **Cell Membrane** - **Smooth Endoplasmic Reticulum** - **Nucleus** - **Nuclear Pore** - **Nucleolus** - **Nucleoplasm** - **Nuclear Envelope** - **Rough Endoplasmic Reticulum** - **Golgi Apparatus** - **Mitochondrion** - **Secretory Vesicles** - **Cytoplasm** ## Cell Structure - **Cell Membrane:** This is the outermost layer that encloses the cell. It’s selectively permeable so only certain molecules can pass through. - **Nucleus:** The brain of the cell. Contains the DNA, which controls the cell’s activities. - **Cytoplasm:** This is the jelly-like substance found inside the cell. It’s where the cell’s organelles are suspended. It includes the organelles, matrix, and nonliving inclusions. - **Organelles:** Substructures within a cell that have specific functions and form a working unit. - **Matrix:** The fluid substance found between the organelles. - **Nonliving Inclusion:** Aggregates of non-living molecules. ## Thank you.

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