THE CELL History Structures and Functions THE DISCOVERY

THE CELL History, Structures, and Functions

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

CELL THEORY All organisms are made of cells The basic unit of living things is the CELL All cells come from preexisting cells

PROKARYOTES AND EUKARYOTES 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 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

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. COPYRIGHT PEARSON PRENTICE HALL

CELL ORGANELLES

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. COPYRIGHT PEARSON PRENTICE HALL

CELL MEMBRANE The cell membrane regulates what enters and leaves the cell and also provides protection and support. COPYRIGHT PEARSON PRENTICE HALL

CELL WALLS Cell walls are found in plants, algae, fungi, and many prokaryotes. Strong and stiff nonliving layer outside the cell Contains cellulose to provide support and protection COPYRIGHT PEARSON PRENTICE HALL

CYTOPLASM Watery substance found between the nucleus and cell membrane and contains the organelles (parts of the 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 Chromatin Nucleolus Nuclear envelope Nuclear pores COPYRIGHT PEARSON PRENTICE HALL

RIBOSOMES 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 COPYRIGHT PEARSON PRENTICE HALL

ENDOPLASMIC RETICULUM There are two types of ER—rough and smooth. Endoplasmic Reticulum Ribosomes COPYRIGHT PEARSON PRENTICE HALL

ENDOPLASMIC RETICULUM Rough ER Smooth ER Description – series of highly folded membranes that contains ribosomes Description- series of highly folded membranes that does not contain ribosomes Function - produces proteins and transports them to the Golgi. Releases proteins to be transported in the vesicle Function produces lipids and transports them to the Golgi. Releases lipids to be transported in the vesicle BOTH

GOLGI APPARATUS Description appears as a stack of closely apposed membranes. Function - Sorts, modifies, packages, stores, and transports materials. Both COPYRIGHT PEARSON PRENTICE HALL

MITOCHONDRIA 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 COPYRIGHT PEARSON PRENTICE HALL

VACUOLES Description - Sacs in the cytoplasm Function - Stores food, water, wastes and other material. BOTH Vacuole COPYRIGHT PEARSON PRENTICE HALL

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 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 COPYRIGHT PEARSON PRENTICE HALL

CENTRIOLE Description - cylinder shaped structure Function located near the nucleus and help to organize cell division. Animal Only COPYRIGHT PEARSON PRENTICE HALL

CYTOSKELETON 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 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

CYTOSKELETON Cell membrane Endoplasmic reticulum Microtubule Microfilament Ribosomes Mitochondrion COPYRIGHT PEARSON PRENTICE HALL