Cell Biology - 1st Lec. PDF

# 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.