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Cell Theory and Types of Cells. Objective: Identify functions of organelles found in eukaryotic cells, including the nucleus, cell membrane, cell wall, mitochondria, chloroplasts, and vacuoles. ( ACOS #2). Living Things have Cells. Cells. 2 Types of Organisms.
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Cell Theory and Types of Cells Objective: Identify functions of organelles found in eukaryotic cells, including the nucleus, cell membrane, cell wall, mitochondria, chloroplasts, and vacuoles. (ACOS #2)
Living Things have Cells Cells 2 Types of Organisms • All living things are composed of 1 or more cells. • A cell is a membrane-covered structure that contains all of the materials necessary for life. • Membrane separates the contents of the cell from it’s environment. • Most cells are too small to be seen with the naked eye. • Unicellular- single celled organisms • Multicellular- many celled organisms
Unicellular Organisms Characteristics • Single celled • Various modes of locomotion • Flagella • Cilia • Pseudopods • Asexual reproduction- a single parent produces offspring that are identical to the parent; most unicellular org. reproduce this way • Examples: bacteria, some kinds of fungi, and most protists • Some live in colonies or singularly • Cells are identical • Must carry out all life processes
Multicellular Organisms Characteristics • Made of many cells • Grow by making more small cells, not by making cells larger • Larger size: Many are small, but usually larger than single-celled organisms • Longer life: Life span is not limited to the life span of any single cell • Specialization: Each type of cell has a particular job; For example- cardiac muscle cell is specialized muscle cell (Heart muscle cells contract and make the heart pump blood.) • Sexual reproduction: two parents produce offspring that will share characteristics of both parents. Most animals and plants reproduce this way.
Cells and the Cell Theory • Robert Hooke- first person to describe cells • Hooke built a microscope to look at tiny objects. • Looked at a thin slice of cork (from the bark of trees) • Cork looked like little boxes • Cell means “little rooms” in Latin
Anton van Leeuwenhoek • Dutch merchant • Made his own microscope • Looked at pond scum • Saw small organisms in the water; He named them animalcules (little animals) • 1st person to see bacteria and yeasts (both are unicellular organisms)
The Cell Theory States Contributors • All organisms are made of one or more cells. • The cell is the basic unit of structure and function of all living things. • All cells come from existing cells. • Matthias Schleiden- studied plants • Theodor Schwann- studied animals • Rudolf Virchow- all cells come only from other cells
Parts of a Cell Cell Membrane Cytoplasm • Surrounds all cells • Serves a boundary between cell and external environment • Protective layer that covers the cell’s surface • Acts as a barrier • Controls materials going into and out of the cell • Gelatin-like substance • Inside the cell • Holds all the cell’s organelles
Parts of a Cell (cont.) Organelles Pictures of bacterial, plant, and animal cells with organelles • Tiny, membrane-bound cell structures • Perform specific functions within the cell • Different types of cells have different organelles
Parts of a Cell (cont.) Nucleus Cell Wall • Organelle inside cells considered to be the “brain” • Controls all cell activities • Contains the deoxyribonucleic acid (DNA) • DNA- genetic material that carries information needed to make new cells and new organisms • Rigid outside layer of plant and bacterial cells • Provides structure and protection • Separate inside of cell from outside environment
Parts of the Nucleus • Nuclear membrane/envelope- membrane that surrounds the nucleus; protects the nucleus; materials pass in and out through pores • Chromatin- thin strands floating in nucleoplasm; contain genetic material- instructions for directing the cell’s functions • Nucleolus- small, round structure; produces ribosomes
Parts of a Cell (cont.) Mitochondria Endoplasmic Reticulum • Rod-shaped structures • Known as the “powerhouses” of the cell • Convert energy in food molecules to energy the cell can use to carry out its functions • A maze of passageways • Carry proteins and other materials from one part of the cell to another
Parts of a Cell (cont.) Ribosomes Golgi bodies • Small, grain like bodies • Float in the cytoplasm and attached to endoplasmic reticulum • Factories to produce proteins • Look like flatten sacs and tubes • Thought of as cell’s mail room • Receive proteins and newly formed materials form the ER, package them, and distribute them to other parts of the cell
Parts of Cell (cont.) Chloroplasts Vacuoles • Green structures floating in the cytoplasm • Found in the cells of plants and some other organisms • Capture energy from sunlight and use it to produce food for the cell • Water-filled sac floating in the cytoplasm • The storage area of cells- food, waste products, and other materials. • Most plant cells have one large vacuole. • Some animal cells do not have vacuoles; others do.
Parts of Cell (cont.) Lysosomes • Small, round structures • Contain chemicals that break down certain materials in the cell • Cell’s cleanup crew
Specialized Cells • Plants and animals contain many cells. • In multicellular organisms, the cells are often quite different from each other and are specialized to perform specific functions. • In many celled organisms, cells are often organized into tissues, organs, and organ systems.
Cell Size A Few Large Cells Many Small Cells • Most cells are small. • A few cells are big. • A chicken egg is one big cell. • Physical reason why most cells are so small • Cells take in food and get rid of wastes through their outer surface • As cells get larger, they need more food and produces more waste. • Therefore, more materials pass through its outer surface
Two Kinds of Cells • All cells have cell membranes, organelles, cytoplasm, and DNA. • Two basic types of cells- cells without a nucleus and cells with a nucleus. • Cells that have no nucleus are prokaryotic cells. • Cells that have a nucleus are eukaryotic cells. • Prokaryotic cells are further classified into two groups: eubacteria and archaebacteria.
Two Kinds of Cells Prokaryotic Cells Eukaryotic Cells • Cells without nucleus • Single-celled organisms • No membrane bound organelles • Two groups: Eubacteria and Archaebacteria • Cells with nucleus • Most are multicellular • Membrane bound organelles • Include animals, plants, and fungi, but not archaebacteria or eubacteria
Prokaryotic Cells and Prokaryotes (p. 27) Eubacteria Archaebacteria • Most common prokaryotes • Commonly called bacteria • No nucleus • DNA is long, circular molecule that’s shaped sort of like a rubber band • No membrane covered organelles • Have ribosomes- tiny, round organelles made of protein and other materials • Cell wall with cell membrane just inside • Some live in soil and water and others live in other organisms • Called archaea (ar KEE uh) • Not as common as bacteria but similar in some ways • Single-celled • Have ribosomes, cell membrane, and circular DNA • Lack nucleus and membrane-bound organelles • Also called extremophiles due to living in places where conditions are extreme
Eukaryotic Cells and Eukaryotes • Euk. cells are the largest cells. Plant cells and animals cells are euk. cells. • Microscopic but 100X larger than bacterial cells • Have a nucleus • Nucleus holds the cell’s DNA • Have organelles that have different functions (specific jobs) • Organisms made of euk. cells are called eukaryotes. • Eukaryotes are multicellular, meaning “many cells.” • Examples: Multicellular eukaryotes- Animals, plants, some protists such as green algae, and fungi such as mushrooms; Unicellular eukaryotes- protists such as amoebas and fungi such as yeasts
plant cell animal cell Plants and animals are made up of many eukaryotic cells. Plant and Animal Cells
Video Quiz: The Cell is the Basic Unit of Structure and Function
References • Cells: The Basic Units of Life. Ancient Lights.(1994). Retrieved August 29, 2009, fromDiscovery Education: http://streaming.discoveryeducation.com/