Transcript cells
Ch 4 (Honors Bio) Ch 3 (Bio) CELL STRUCTURE AND FUNCTION The Cell • The cell is the smallest unit of life • smallest unit that can carry out life processes. Chapter 4 Section 2 Introduction to Cells Cellular Organization Discoveries Leading to The Cell Theory • Robert Hooke – 1665 -observed cork through a light microscope • Anton Van Leewenhoek – 1675 -observed LIVING cells. • Matthias Schleiden – 1883 –all plants are made of cells. • Theodor Schwann – 1839 –all animals are made of cells • Rudolph Virchow-1855- all cells must come from other cells The Cell Theory • all living organisms are made of one or more cells. • cells are the basic units of structure and function • cells come only from pre-existing cells. Two Basic Types of Cells Prokaryotic Cell • Do not have a nucleus • Do not have organelles (internal membranebound structures) – Most unicellular organisms are prokaryotes. – Bacteria Eukaryotic Cell • Cells that do have a nucleus. • They do have organelles. – Most multicellular organisms are eukaryotes. – Yeast and algae (unicellular, eukaryotes) – Plant and animal Features Common to Cells: • Cytoplasm – Gel like material that protects, supports and suspends organelles. Common Features cont…. All cells have DNA. (DeoxyriboNucleic Acid) Chromosomes vs Chromatin Common Features cont…. • Cell (plasma) membrane – Semi-permeableallows some materials in and keeps others out. This helps to maintain cellular homeostasis. • SELECTIVE PERMEABILITY Structure of the Plasma Membrane • Phospholipid Bilayer -2 layers of phospholipids. • Phospholipid- phosphate head attached to two lipids (fatty acid tails). • Polar phosphate group allows membrane to interact with its environment. • Fatty acid tails create a water-insoluble layer in the middle which is non-polar. Cell membrane Structure • Fluid mosaic model-membrane is flexible • Cholesterol-keeps fatty acid tails from sticking together • Transport proteins -allow needed substances to move through the membrane Chapter 4 Parts of the Cell Bellringer: Cell Differences • What is the difference between a prokaryotic cell and a eukaryotic cell? Give an example of each cell type. Nucleus • “Command center” • Surrounded by a nuclear envelope • Contains genetic material: – chromatin – chromosomes Chromatin vs Chromosomes • CHROMATIN – When the cell is not actively dividing • CHROMOSOMES – When the cell is dividing Nucleolus and Ribosomes • Nucleolus-makes ribosomes Ribosomes- build proteins • Can be found floating in the cytoplasm or attached to endoplasmic reticulum Endoplasmic Reticulum (ER) • Series of folded membranes allow a large amount of work to be done in a small amount of space • Transportation unit for the cell Rough Endoplasmic Reticulum (RER) – Has Ribosomes attached – Protein synthesis Smooth ER – Produce and store lipids Golgi Apparatus Vesicles • Flattened tubular membranes • Packaging plant • Modify, sort, package, and transport proteins throughout the cell VACUOLES • Storage sacs – Store food, enzymes, waste • Animal cells have many small vesicles. LYSOSOMES • Full of digestive enzymes • Digest excess or worn organelles, food particles, viruses, and bacteria • Surrounded by membrane that prevents it from destroying the cell • Can burst causing cell death Chapter 4 Mitochondria • Cellular respiration -converts food into energy • Cell “Powerhouse” • Number of mitochondria depends upon the function of the cell – Ex: muscles cells have more mitochondria than fat cells Cytoskeleton • Cytoskeleton – tiny fibers that give structure and support to the cell. – Microfilament- thin and tubular…support the cell membrane. – Microtubule- thick and tubular also branched. Act as “rails” on which materials move through the cell. Cilia and Flagella • Aid in movement and feeding • Composed of microtubules • Flagella-long, whiplike projections • Cilia-short, numerous hair-like projections that move in a wavelike motion Centriole • Help with cell reproduction • Only found in animal cells Cell wall • Rigid outer covering PLANT CELLS • Located outside the cell membrane • Provides support and protection • Helps produce turgor pressure • Plastids – Color pigments of cells • Examples: – Chloroplast – Located in plant cells, some bacteria, and protists. • Capture light energy to produce (and store) food • Contain chlorophyll-green pigment that traps light energy Large Central Vacuole • Plant cells • Storage-stores food, enzymes, wastes, etc Animal Cell Plant Cell Plant cell vs. Animal Cell Plant vs Animal cells • – – Animal Cell vs. Plant cell • • • • Animal Cell DO contain centrioles. DO NOT contain a cell wall or plastids. Plant Cell DO contain a cell wall, plastids, and a large central vacuole. DO NOT contain centrioles The pictures and examples were taken from a variety of websites.