Table of Contents Chapter 4

Full text

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Cell Structure and Function

Chapter

4

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

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Section 1 The History of Cell Biology

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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.

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Section 1 The History of Cell Biology

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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.

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Section 1 The History of Cell Biology

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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.

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Section 1 The History of Cell Biology

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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 pre- existing 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

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Chapter

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Visual Concept

Cell Theory

Section 1 The History of Cell Biology

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Section 1 The History of Cell Biology

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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.

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Section 2 Introduction to Cells

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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.

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Section 2 Introduction to Cells

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Cell Diversity

• Cell Shape

– A cell’s shape reflects its function.

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Section 2 Introduction to Cells

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Cell Diversity, Continued

• Cell Size

– Cell size is limited by a cell’s surface area–to- volume ratio.

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Cell size differs amongst species

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Section 2 Introduction to Cells

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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

Section 2 Introduction to Cells

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Specialized Animal Cells

Section 2 Introduction to Cells

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Bone Cells Cheek Cells

Red Blood Cells

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Prokaryotic Cells Chapter

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-Cells lack a nucleus and membrane-

bound organelles -Includes bacteria -Single, circular chromosome in nucleoid region

-Surrounded by cell membrane and a cell wall made up of

peptidoglycan

Section 2 Introduction to Cells

-Divided into two domains, I.e., Archaea and Bacteria

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Eukaryotic Cells

Section 2 Introduction to Cells

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Cells have a nucleus and membrane-bound organelles -Incudes protists, fungi, plants, and animals

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Chapter

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Comparing Prokaryotes and Eukaryotes

Section 2 Introduction to Cells

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Section 2 Introduction to Cells

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Basic Parts of a Eukaryotic Cell

• The three basic parts of a cell are the plasma membrane, the cytoplasm, and the nucleus.

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Chapter

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Internal Organization of a Cell

Section 2 Introduction to Cells

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Section 2 Introduction to Cells

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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.

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Section 2 Introduction to Cells

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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

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Section 2 Introduction to Cells

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Basic Parts of a Cell, continued

• Nucleus

– The nucleus is a membrane-bound organelle that contains a cell’s DNA.

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Section 2 Introduction to Cells

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Cellular Organization

• In multicellular eukaryotes, cells organize into tissues, organs, organ systems, and finally organisms.

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Chapter

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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.

Section 3 Cell Organelles and Features

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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 (“water- loving”) phosphate head and two nonpolar,

hydrophobic (“water-fearing”) fatty acid tails

– Cholesterol gives membrane firmness and prevents freezing in low temperatures

Section 3 Cell Organelles and Features

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Structure of Lipid Bilayer

Section 3 Cell Organelles and Features

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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)

Section 3 Cell Organelles and Features

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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

Section 3 Cell Organelles and Features

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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.

Section 3 Cell Organelles and Features

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Nucleus of a Cell

Section 3 Cell Organelles and Features

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Mitochondria

• Mitochondria harvest energy from organic compounds and transfer it to ATP.

• Mitochondrial DNA – endosymbiotic origin

Section 3 Cell Organelles and Features

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Ribosomes

• Ribosomes are either free or attached to the rough ER and play a role in protein synthesis.

• Made of protein an RNA molecules

• Ribosome assembly begins in the nucleolus and is completed in the cytoplasm

Section 3 Cell Organelles and Features

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Chapter

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Ribosomes

Section 3 Cell Organelles and Features

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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 Section 3 Cell Organelles and Features

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Chapter

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Endoplasmic Reticulum (ER) and Ribosomes

Section 3 Cell Organelles and Features

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Golgi Apparatus

• The Golgi apparatus processes and packages

proteins; proteins get address labels that direct them to other parts of the cell

Section 3 Cell Organelles and Features

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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

Section 3 Cell Organelles and Features

•Protein Synthesis

–The rough ER, Golgi apparatus, and vesicles work together to transport proteins to their

destinations inside and outside the cell.

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Processing of Proteins

Section 3 Cell Organelles and Features

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Cytoskeleton

• The cytoskeleton is made of protein fibers that help cells move and maintain their shape.

• The cytoskeleton includes microtubules, microfilaments, and intermediate filaments.

Section 3 Cell Organelles and Features

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Chapter

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Cytoskeleton

Section 3 Cell Organelles and Features

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Chapter

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Cytoskeleton, continued

• Cilia and Flagella

– Cilia and flagella are hairlike structures that extend from the surface of the cell, where they assist in movement.

Section 3 Cell Organelles and Features

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Chapter

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Structure of Cilia and Flagella

Section 3 Cell Organelles and Features

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Cytoskeleton, continued

• Centrioles

– Centrioles consist of two short cylinders of

microtubules at right angles to each other and are involved in cell division.

Section 3 Cell Organelles and Features

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Chapter

4

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.

Section 4 Unique Features of Plant Cells

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Plant Cells

• Plant cells have cell walls, central vacuoles, and plastids.

Section 4 Unique Features of Plant Cells

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Cell Wall

• In plant cells, a rigid cell wall covers the cell membrane and provides support and protection.

Section 4 Unique Features of Plant Cells

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Chapter

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Parts of a Cell Wall

Section 4 Unique Features of Plant Cells

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Central Vacuole

• Large central vacuoles store water, enzymes, and waste products and provide support for plant tissue.

Section 4 Unique Features of Plant Cells

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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

Section 4 Unique Features of Plant Cells

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Comparing Cells

• Prokaryotes, animal cells, and plant cells can be distinguished from each other by their unique

features.

Section 4 Unique Features of Plant Cells

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Chapter

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Comparing Plant and Animal Cells

Section 4 Unique Features of Plant Cells

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