7-1 Life Is Cellular Copyright Pearson Prentice Hall

The Discovery of the Cell 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 Hooke’s Drawing of Cork Cells Copyright Pearson Prentice Hall

The Discovery of the Cell 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 The cell theory states: All living things are composed of cells. Cells are the basic units of structure and function in living things. New cells are produced from existing cells. Copyright Pearson Prentice Hall

Prokaryotes and Eukaryotes Cells come in a variety of shapes and sizes. All cells: – are surrounded by a barrier called a cell membrane. – at some point contain DNA. Copyright Pearson Prentice Hall

Prokaryotes and Eukaryotes Cells are classified into two categories, depending on whether they contain a nucleus. The nucleus is a large membrane-enclosed structure that contains the cell's genetic material in the form of DNA. The nucleus controls many of the cell's activities. Copyright Pearson Prentice Hall

Prokaryotes and Eukaryotes Prokaryotes Prokaryotic cells have genetic material that is not contained in a nucleus. Prokaryotes do not have membrane-bound organelles. Prokaryotic cells are generally smaller and simpler than eukaryotic cells. Bacteria are prokaryotes. Copyright Pearson Prentice Hall

Prokaryotes and Eukaryotes – Eukaryotic cells contain a nucleus in which their genetic material is separated from the rest of the cell. – Eukaryotic cells are generally larger and more complex than prokaryotic cells. – Eukaryotic cells generally contain dozens of structures and internal membranes. – Many eukaryotic cells are highly specialized. – Plants, animals, fungi, and protists are eukaryotes. Copyright Pearson Prentice Hall

7-1 The cell theory states that new cells are produced from nonliving material. existing cells. cytoplasm. animals. Copyright Pearson Prentice Hall

7-1 The person who first used the term cell was Matthias Schleiden. Lynn Margulis. Anton van Leeuwenhoek. Robert Hooke. Copyright Pearson Prentice Hall

7-1 Which organism listed is a prokaryote? protist bacterium fungus plant Copyright Pearson Prentice Hall

7-1 One way prokaryotes differ from eukaryotes is that they contain DNA, which carries biological information. have a surrounding barrier called a cell membrane. do not have a membrane separating DNA from the rest of the cell. are usually larger and more complex. Copyright Pearson Prentice Hall

Eukaryotic Cell Structures Structures within a eukaryotic cell that perform important cellular functions are known as organelles. Cell biologists divide the eukaryotic cell into two major parts: the nucleus and the cytoplasm. The Cytoplasm is the portion of the cell outside the nucleus. Copyright Pearson Prentice Hall

Eukaryotic Cell Structures Plant Cell Copyright Pearson Prentice Hall Nuclear envelope Ribosome (free) Ribosome (attached) Mitochondrion Golgi apparatus Vacuole Nucleolus Nucleus Smooth endoplasmic reticulum Rough endoplasmic reticulum Cell wall Cell membrane Chloroplast

Eukaryotic Cell Structures Copyright Pearson Prentice Hall Smooth endoplasmic reticulum Ribosome (free) Ribosome (attached) Golgi apparatus Mitochondrion Rough endoplasmic reticulum Cell membrane Nucleus Nuclear envelope Nucleolus Centrioles Animal Cell

Nucleus The nucleus is the control center of the cell. The nucleus contains nearly all the cell's DNA and with it the coded instructions for making proteins and other important molecules. Copyright Pearson Prentice Hall

Nucleus The Nucleus Copyright Pearson Prentice Hall Nucleolus Nuclear envelope Nuclear pores Chromatin

Ribosomes One of the most important jobs carried out in the cell is making proteins. Proteins are assembled on ribosomes. Ribosomes are small particles of RNA and protein found throughout the cytoplasm. Copyright Pearson Prentice Hall

Endoplasmic Reticulum Copyright Pearson Prentice Hall Ribosomes Endoplasmic Reticulum There are two types of ER—rough and smooth.

Golgi Apparatus The Golgi apparatus appears as a stack of closely opposed membranes. Copyright Pearson Prentice Hall

Vacuoles In many plant cells there is a single, large central vacuole filled with liquid. Copyright Pearson Prentice Hall Vacuole

Vacuoles Vacuoles are also found in some unicellular organisms and in some animals. The paramecium contains a contractile vacuole that pumps excess water out of the cell. Copyright Pearson Prentice Hall Contractile vacuole

Mitochondria and Chloroplasts Mitochondria Nearly all eukaryotic cells contain mitochondria. Mitochondria convert the chemical energy stored in food into compounds that are more convenient for the cell to use. Copyright Pearson Prentice Hall Mitochondrion

Mitochondria and Chloroplasts Chloroplasts Plants and some other organisms contain chloroplasts. Chloroplasts capture energy from sunlight and convert it into chemical energy in a process called photosynthesis. Copyright Pearson Prentice Hall Chloroplast

Mitochondria and Chloroplasts Copyright Pearson Prentice Hall

Cytoskeleton The cytoskeleton is a network of protein filaments that helps the cell to maintain its shape. The cytoskeleton is also involved in movement. The cytoskeleton is made up of: microfilaments microtubules Copyright Pearson Prentice Hall

Cytoskeleton Copyright Pearson Prentice Hall Ribosomes Mitochondrion Endoplasmic reticulum Cell membrane Microtubule Microfilament

Centrioles are located near the nucleus and help to organize cell division. Copyright Pearson Prentice Hall Cell Organelle Interactive Plant and Animal Model Interactive

7-2 In the nucleus of a cell, the DNA is usually visible as a dense region called the nucleolus. the nuclear envelope. granular material called chromatin. condensed bodies called chloroplasts. Copyright Pearson Prentice Hall

7-2 Two functions of vacuoles are storing materials and helping to break down organelles. assemble proteins. maintain homeostasis. make new organelles. Copyright Pearson Prentice Hall

7-2 Chloroplasts are found in the cells of plants only. plants and some other organisms. all eukaryotes. most prokaryotes. Copyright Pearson Prentice Hall

7-2 Which of the following is NOT a function of the Golgi apparatus? synthesize proteins. modify proteins. sort proteins. package proteins. Copyright Pearson Prentice Hall

7-2 Which of the following is a function of the cytoskeleton? manufactures new cell organelles assists in movement of some cells from one place to another releases energy in cells modifies, sorts, and packages proteins Copyright Pearson Prentice Hall

Unicellular Organisms: One cell carries out all life functions. Copyright Pearson Prentice Hall

Colonial Organisms: Groups of single celled organisms live together. Larger size makes it harder for organisms to eat. All/most cells do most functions. Copyright Pearson Prentice Hall

Multicellular Organisms: Groups of specialized cells working together. The simplest multicellular organism: Copyright Pearson Prentice Hall

But what is a slime mold? Copyright Pearson Prentice Hall

Organization Within An Organism Nature has levels of organization Unique properties emerge at successively higher levels Atoms are organized into molecules In multicelled species, cells are organized into tissues, organs, and organ systems All organisms consist of one or more cells Emergent properties: Life emerges at the cellular level

Levels of Organization

Microscopes Microscopes are devices that produce magnified images of structures that are too small to see with the unaided eye. Copyright Pearson Prentice Hall

Microscopes Light Microscopes The most commonly used microscope is the light microscope. Light microscopes produce clear images of objects at a magnification of about 1000 times. Copyright Pearson Prentice Hall

Microscopes Compound light microscopes allow light to pass through the specimen and use two lenses to form an image. Copyright Pearson Prentice Hall

Microscopes Electron Microscopes To study even smaller objects, scientists use electron microscopes. Copyright Pearson Prentice Hall

Exploring the Cell 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 Transmission electron microscopes (TEMs) Used to study cell structures and large protein molecules Specimens must be cut into ultra-thin slices Copyright Pearson Prentice Hall

Exploring the Cell Scanning electron microscopes (SEMs) Produce three-dimensional images of cells Specimens do not have to be cut into thin slices Copyright Pearson Prentice Hall

Exploring the Cell Copyright Pearson Prentice Hall Scanning Electron Micrograph of Neurons

7-1 Electron microscopes are capable of revealing more details than light microscopes because electron microscopes can be used with live organisms. light microscopes cannot be used to examine thin tissues. the wavelengths of electrons are longer than those of light. the wavelengths of electrons are shorter than those of light. Copyright Pearson Prentice Hall

Estimating Field Diameter of a Microscope (2) Line up major division on opposite edge (1) Set up so that the finely divided part overlaps one edge of the field Field diameter= 0.52 mm

Estimating Field Diameter of a Microscope (2) Line up major division on opposite edge (1) Set up so that the finely divided part overlaps one edge of the field Field diameter= 0.52 mm