Transcript The Cell
The Cell History, Structures, and Functions Early Microscopes In 1665, Robert Hooke used an early compound microscope to look at a thin slice of cork, a plant material. Cork looked like thousands of tiny, empty chambers. Hooke called these chambers “cells.” Cells are the basic units of life. Copyright Pearson Prentice Hall The Discovery of the Cell The Discovery of the Cell Copyright Pearson Prentice Hall Hooke’s Drawing of Cork Cells The Cell Theory In 1838, Matthias Schleiden concluded that all plants were made of cells. In 1839, Theodor Schwann stated that all animals were made of cells. In 1855, Rudolph Virchow concluded that new cells were created only from division of existing cells. These discoveries led to the cell theory. Copyright Pearson Prentice Hall The Discovery of the Cell Cell Theory • All organisms are made of cells • The basic unit of living things is the CELL • All cells come from preexisting cells Compound Light Microscopes • Uses light and multiple objectives to magnify objects • Can view a living organism • Magnifies to micrometers Electron Microscopes Electron microscopes reveal details 1000 times smaller than those visible in light microscopes. Electron microscopy can be used to visualize only nonliving, preserved cells and tissues. Copyright Pearson Prentice Hall Exploring the Cell Exploring the Cell Copyright Pearson Prentice Hall Scanning electron microscopes (SEMs) • Produce three-dimensional images of cells • Specimens do not have to be cut into thin slices Exploring the Cell Copyright Pearson Prentice Hall Transmission electron microscopes (TEMs) • Used to study cell structures and large protein molecules • Specimens must be cut into ultra-thin slices Cells are classified into two categories, depending on whether they contain a nucleus. Eukaryotes are cells that contain nuclei. Prokaryotes are cells that do not contain nuclei. Copyright Pearson Prentice Hall Prokaryotes and Eukaryotes Prokaryotes •Prokaryotes do not have membrane-bound organelles. •Prokaryotic cells are generally smaller and simpler than eukaryotic cells. •Bacteria are prokaryotes. Copyright Pearson Prentice Hall Prokaryotic cells have genetic material that is not contained in a nucleus. Copyright Pearson Prentice Hall Eukaryotes Eukaryotic cells contain a nucleus in which their genetic material is separated from the rest of the cell. Plants, animals, fungi, and protists are eukaryotes. Cell Organelles Copyright Pearson Prentice Hall All cells are surrounded by a thin, flexible barrier known as the cell membrane. Many cells also produce a strong supporting layer around the membrane known as a cell wall. Cell Membrane Copyright Pearson Prentice Hall The cell membrane regulates what enters and leaves the cell and also provides protection and support. Cell Walls Cell walls are found in plants, algae, fungi, and many prokaryotes. Strong and stiff nonliving layer outside the cell protection Copyright Pearson Prentice Hall Contains cellulose to provide support and Cytoplasm • Watery substance found between the nucleus and cell membrane and contains the organelles (parts of the cell) Nucleus Nucleus The nucleus is the control center of the cell. Copyright Pearson Prentice Hall The nucleus contains nearly all the cell's DNA and with it the coded instructions for making proteins and other important molecules. Nucleus The Nucleus Nucleolus Nuclear envelope Nuclear pores Copyright Pearson Prentice Hall Chromatin Ribosomes Ribosomes Copyright Pearson Prentice Hall Description - Ribosomes are small particles of RNA and protein that can be attached or found throughout the cytoplasm. Function - One of the most important jobs carried out in the cell is making proteins. BOTH Endoplasmic Reticulum There are two types of ER—rough and smooth. Copyright Pearson Prentice Hall Endoplasmic Reticulum Ribosomes Endoplasmic Reticulum Rough ER Smooth ER • Description – series of highly folded membranes that contains ribosomes • Function - produces proteins and transports them to the Golgi. Releases proteins to be transported in the vesicle • BOTH • Description- series of highly folded membranes that does not contain ribosomes • Function produces lipids and transports them to the Golgi. Releases lipids to be transported in the vesicle • BOTH Golgi apparatus Copyright Pearson Prentice Hall Description appears as a stack of closely apposed membranes. Function - Sorts, modifies, packages, stores, and transports materials. Both Mitochondria Copyright Pearson Prentice Hall Description – Rod-shaped that has greatly folded inner membrane (cristae) Function - Convert the chemical energy stored in food into compounds that are more convenient for the cell to use. Both Mitochondrion Vacuoles Vacuole Vacuole Copyright Pearson Prentice Hall Description - Sacs in the cytoplasm Function - Stores food, water, wastes and other material. BOTH Lysosome • Description small round sacs • Function break down excess or worn out organelles, food particles, old cells, viruses, or bacteria • “Garbage disposal of the cell” • Animal cells only Chloroplasts Chloroplast Copyright Pearson Prentice Hall Description – large green structures that contain chlorophyll (green pigment) Function - Chloroplasts capture energy from sunlight and convert it into chemical energy in a process called photosynthesis. Plant only Centriole Copyright Pearson Prentice Hall Description - cylinder shaped structure Function located near the nucleus and help to organize cell division. Animal Only Cytoskeleton Cilia – short hair-like projections that move in a wavelike motion to assist in movement Flagella – long whip-like projection that assist in movement in unicellular organisms Copyright Pearson Prentice Hall Description- network of protein rods (microfilaments) and tubes (microtubules) Function – forms a framework that helps the cell to maintain its shape. The cytoskeleton is also involved in movement. BOTH Cytoskeleton Copyright Pearson Prentice Hall Cell membrane Endoplasmic reticulum Microtubule Microfilament Ribosomes Mitochondrion