Download Section 2 Introduction to Cells

Chapter 4
Cell Structure and Function
Table of Contents
Section 1 The History of Cell Biology
Section 2 Introduction to Cells
Section 3 Cell Organelles and Features
Section 4 Unique Features of Plant Cells
Chapter 4
Section 1 The History of Cell Biology
Objectives
• Name the scientists who first observed living and
nonliving cells.
• Summarize the research that led to the development
of the cell theory.
• State the three principles of the cell theory.
• Explain why the cell is considered to be the basic
unit of life.
Chapter 4
Section 1 The History of Cell Biology
The Discovery of Cells
• All living things are made up of one or more cells.
• A cell is the smallest unit that can carry on all of the
processes of life.
Chapter 4
Section 1 The History of Cell Biology
The Discovery of Cells, continued
• Hooke
– In 1665, Robert Hooke discovered cells in slices of
cork.
• Leeuwenhoek
– In 1673, Anton van Leeuwenhoek was the first to
observe living cells in microorganisms;
Leeuwenhoek called these organism animalcules
~ we now call them protists.
Chapter 4
Section 1 The History of Cell Biology
The Cell Theory
• The cell theory states that all living organisms are
made of one or more cells, cells are the basic units of
structure and function, and cells come only from preexisting cells.
• In 1838, the German botanist Matthias Schleiden
concluded that all plants were composed of cells
• In 1839, Theodor Schwann concluded the same thing
for animals
• In 1855, Rudolf Virchow noted that all cells come
from other cells
Chapter 4
THE CELL THEORY
1.
Every living organism is made of one or more cells.
2. The cell is the basic unit of structure and function. It is
the smallest unit that can perform life functions.
3. All cells come from preexisting cells.
Chapter 4
Section 1 The History of Cell Biology
The Cell Theory, continued
• Cellular Basis of Life
– All living things are made of organized parts,
obtain energy from their surroundings, perform
chemical reactions, change with time, respond to
their environment, and reproduce.
Chapter 4
Section 2 Introduction to Cells
Objectives
• Explain the relationship between cell shape and cell
function.
• Identify the factor that limits cell size.
• Describe the three basic parts of a cell.
• Compare prokaryotic cells and eukaryotic cells.
• Analyze the relationship among cells, tissues,
organs, organ systems, and organisms.
Chapter 4
Section 2 Introduction to Cells
Cell Diversity
• Cell Shape
– A cell’s shape reflects its function.
Chapter 4
Section 2 Introduction to Cells
Cell Diversity, Continued
• Cell Size
– Cell size is limited by a cell’s surface area–tovolume ratio.
Chapter 4
Section 2 Introduction to Cells
Cell size differs amongst species
Chapter 4
Section 2 Introduction to Cells
Cell Size
• Unicellular organisms are made up of one cell
• Multicellular organisms are made up of many cells
that often specialize according to function differentiation
Chapter 4
Section 2 Introduction to Cells
Specialized Animal Cells
Red Blood Cells
Cheek Cells
Bone Cells
Chapter 4
Section 2 Introduction to Cells
Prokaryotic Cells
-Cells lack a nucleus
and membranebound organelles
-Includes bacteria
-Single, circular
chromosome in
nucleoid region
-Surrounded by cell
membrane and a cell
wall made up of
peptidoglycan
-Divided into two domains,
I.e., Archaea and Bacteria
Chapter 4
Section 2 Introduction to Cells
Eukaryotic Cells
-Cells have a nucleus and membrane-bound organelles
-Incudes protists, fungi, plants, and animals
Chapter 4
Section 2 Introduction to Cells
Comparing Prokaryotes and Eukaryotes
Click below to watch the Visual Concept.
Visual Concept
Chapter 4
Section 2 Introduction to Cells
Basic Parts of a Eukaryotic Cell
• The three basic parts of a cell are the plasma
membrane, the cytoplasm, and the nucleus.
Chapter 4
Section 2 Introduction to Cells
Basic Parts of a Cell, continued
• Plasma Membrane
– The cell’s outer boundary, called the plasma
membrane (or the cell membrane), covers a cell’s
surface and acts as a barrier between the inside
and the outside of a cell.
Chapter 4
Section 2 Introduction to Cells
Basic Parts of a Cell, continued
• Cytoplasm
– The region of the cell that is within the plasma
membrane and that includes the fluid, the
cytoskeleton, and all of the organelles except the
nucleus is called the cytoplasm.
– The part of the cytoplasm that includes molecules
and small particles, such as ribosomes, but not
membrane bound organelles is the cytosol
– About 20% of the cytosol is made up of protein
Chapter 4
Section 2 Introduction to Cells
Basic Parts of a Cell, continued
• Nucleus
– The nucleus is a membrane-bound organelle that
contains a cell’s DNA.
Chapter 4
Section 2 Introduction to Cells
Cellular Organization
• In multicellular eukaryotes, cells organize into tissues,
organs, organ systems, and finally organisms.
Chapter 4
Section 3 Cell Organelles
and Features
Objectives
• Describe the structure and function of a cell’s plasma
membrane.
• Summarize the role of the nucleus.
• List the major organelles found in the cytosol, and describe their
roles.
• Identify the characteristics of mitochondria.
• Describe the structure and function of the cytoskeleton.
Chapter 4
Section 3 Cell Organelles
and Features
Plasma Membrane
• Selectively permeable, separates internal
metabolic reactions from the external
environment, and allows cell to excrete waste
• Membrane Lipids
– Cell membranes consist of a phospholipid
bilayer.
– Phospholipids have a polar, hydrophilic (“waterloving”) phosphate head and two nonpolar,
hydrophobic (“water-fearing”) fatty acid tails
– Cholesterol gives membrane firmness and
prevents freezing in low temperatures
Chapter 4
Structure of
Lipid Bilayer
Section 3 Cell Organelles
and Features
Chapter 4
Section 3 Cell Organelles
and Features
Plasma Membrane, continued
• Membrane Proteins
– Cell membranes often contain proteins embedded
within the phospholipid bilayer.
– Proteins help move large molecules or aid in cell
recognition (peripheral and integral)
Chapter 4
Section 3 Cell Organelles
and Features
Plasma Membrane, continued
• Fluid Mosaic Model
– The fluid mosaic model states that the
phospholipid bilayer behaves like a fluid more than
it behaves like a solid.
– As a result of such lateral movement, the pattern,
or “mosaic,” of lipids and proteins in the
cellmembrane constantly changes
Chapter 4
Section 3 Cell Organelles
and Features
Nucleus
• The nucleus directs the cell’s activities and stores DNA.
• When a cell is not dividing, the DNA is in the form of a
threadlike material called chromatin
• When a cell is about to divide, the chromatin condenses to
form chromosomes
• Nuclear Envelope
– The nucleus is surrounded by a double membrane
called the nuclear envelope.
• Nucleolus
– The nucleolus is the place where DNA is concentrated
when it is in the process of making ribosomal RNA.
Chapter 4
Section 3 Cell Organelles
and Features
Nucleus of a Cell
Chapter 4
Section 3 Cell Organelles
and Features
Mitochondria
• Mitochondria harvest energy from organic
compounds and transfer it to ATP.
• Mitochondrial DNA – endosymbiotic origin
Chapter 4
Section 3 Cell Organelles
and Features
Ribosomes
• Ribosomes are either free or attached to the rough
ER and play a role in protein synthesis.
• Made of protein and RNA molecules
• Ribosome assembly begins in the nucleolus and is
completed in the cytoplasm
Chapter 4
Section 3 Cell Organelles
and Features
Ribosomes
Click below to watch the Visual Concept.
Visual Concept
Chapter 4
Section 3 Cell Organelles
and Features
Endoplasmic Reticulum – intracellular highway
• The rough ER prepares proteins for export or
insertion into the cell membrane.
– Most abundant in cells that produce large amounts of
protein for export, such as digestive glands and
antibody-producing cells
• The smooth ER builds lipids, like cholesterol, and
participates in detoxification of toxins.
– In ovaries and testes, smooth ER produces estrogen
and testosterone, respectively
– In skeletal and heart muscle cells, smooth ER releases
calcium, which stimulates contraction
– Abundant in liver and kidneys for detoxification
Chapter 4
Section 3 Cell Organelles
and Features
Endoplasmic Reticulum (ER) and Ribosomes
Visal Concept
Chapter 4
Section 3 Cell Organelles
and Features
Golgi Apparatus
• The Golgi apparatus processes and packages
proteins; proteins get address labels that direct them
to other parts of the cell
Chapter 4
Section 3 Cell Organelles
and Features
Vesicles
• Vesicles, including lysosomes (digestive enzymes)
and peroxisomes (detoxification enzymes – liver and
kidneys), are classified by their contents.
• Lysosomes digest worn-out organelles in a process
called autophagy; digestion of damaged or extra cells
by the enzymes of their own lysosomes is called
autolysis
•Protein Synthesis
–The rough ER, Golgi apparatus, and vesicles
work together to transport proteins to their
destinations inside and outside the cell.
Chapter 4
Section 3 Cell Organelles
and Features
Processing of Proteins
Chapter 4
Section 3 Cell Organelles
and Features
Cytoskeleton
• The cytoskeleton is made of protein fibers that help
cells move and maintain their shape.
• The cytoskeleton includes microtubules,
microfilaments, and intermediate filaments.
Chapter 4
Section 3 Cell Organelles
and Features
Cytoskeleton
Click below to watch the Visual Concept.
Visual Concept
Chapter 4
Section 3 Cell Organelles
and Features
Cytoskeleton, continued
• Cilia and Flagella
– Cilia and flagella are hairlike structures that
extend from the surface of the cell, where they
assist in movement.
Chapter 4
Section 3 Cell Organelles
and Features
Structure of Cilia and Flagella
Click below to watch the Visual Concept.
Visual Concept
Chapter 4
Section 3 Cell Organelles
and Features
Cytoskeleton, continued
• Centrioles
– Centrioles consist of two short cylinders of
microtubules at right angles to each other and are
involved in cell division.
Chapter 4
Section 4 Unique Features
of Plant Cells
Objectives
• List three structures that are present in plant cells but not in
animal cells.
• Compare the plasma membrane,the primary cell wall, and the
secondary cell wall.
• Explain the role of the central vacuole.
• Describe the roles of plastids in the life of a plant.
• Identify features that distinguish prokaryotes, eukaryotes,
plant cells, and animal cells.
Chapter 4
Section 4 Unique Features
of Plant Cells
Plant Cells
• Plant cells have cell walls, central vacuoles, and
plastids.
Chapter 4
Section 4 Unique Features
of Plant Cells
Cell Wall
• In plant cells, a rigid cell wall covers the cell
membrane and provides support and protection.
Chapter 4
Section 4 Unique Features
of Plant Cells
Parts of a Cell Wall
Click below to watch the Visual Concept.
Visual Concept
Chapter 4
Section 4 Unique Features
of Plant Cells
Central Vacuole
• Large central vacuoles store water, enzymes, and
waste products and provide support for plant tissue.
Chapter 4
Section 4 Unique Features
of Plant Cells
Plastids
• Plastids store starch and pigments.
– Chloroplasts – use light energy to make
carbohydrates from carbon dioxide and water;
thylakoids contain green pigment chlorophyll that
absorbs light energy
– Chromoplasts – contain colorful pigments
– Amyloplasts – store starch
Chapter 4
Section 4 Unique Features
of Plant Cells
Comparing Cells
• Prokaryotes, animal cells, and plant cells can be
distinguished from each other by their unique
features.
Chapter 4
Section 4 Unique Features
of Plant Cells
Comparing Plant and Animal Cells