Chapter 3 Cells 2017 Pearson Education Inc Chapter

• Chapter 3 Cells © 2017 Pearson Education, Inc.

Chapter 3 The Cell: Module Hyperlinks • • 3. 1 Cells are the fundamental units of life 3. 2 Plant vs. animal cells 3. 3 Membranes: structure 3. 4 Membranes: function 3. 5 The nucleus 3. 6 Organelles in protein production 3. 7 Chloroplasts and mitochondria 3. 8 Other organelles © 2017 Pearson Education, Inc.

3. 1 Opening Questions: Are all living things made of cells? • What are at least five things you know about cells? © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 1 All living organisms consist of cells. • Some living organisms have just one cell. • Some living organisms have trillions of cells. Cells are the fundamental units of life © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 1 Cells can be grouped into two categories. • Prokaryotic cells – – Small, simple cells No organelles First appeared 3. 5 BYA Unicellular • Eukaryotic cells – – Larger, complex cells Membrane-enclosed organelles First appeared 2. 1 BYA Unicellular or multicellular Are you a prokaryote or a eukaryote? © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 1 Cells can be grouped into two categories All cells on Earth can be classified into two general kinds: Are Homo sapiens – Bacteria (humans) a – Small, simple cells prokaryote – Single celled or a 2. Eukaryotic cells – Plants, animals, fungi and protists eukaryote? 1. Prokaryotic cells – Larger, more complex cells – Single celled or multicellular .

3. 1 Cells can be grouped into two categories. • Prokaryotic cells – Bacteria and Archaea © 2017 Pearson Education, Inc. • Eukaryotic cells – Plants, Animals, Fungi, and Protists Chapter Table of Contents

3. 1 All prokaryotes are relatively simple single-celled organisms. • There are two domains of prokaryotes: Bacteria and Archaea. • Prokaryotic fossils date back at least 3. 5 billion years. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 1 Bacteria have some unique features and some features common to all cells. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 1 Bacteria have common and some unique features • • • Common features Cell wall Plasma membrane Cytoplasm Ribosomes Nucleoid region with DNA • • • Unique features Capsule Flagellum Plasmids Pili

3. 2 Opening Questions: What are you really made of? • Did you know that scientists estimate that only maybe one in 10 of the cells in your body are actually human! The rest are largely prokaryote cells. These good bacteria help us digest food, synthesize vitamins, and protect against disease. • How is it possible to have more bacteria cells than human cells? • Does knowing the above change your view of bacteria? © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 2 Animals and Plants are made of eukaryotic cells that contain organelles. • Compared to prokaryotic cells, eukaryotic cells are relatively large (10 -fold bigger) and more complex. • Eukaryotic cells contain organelles, which are membrane-enclosed structures that perform specific functions. Prokaryotes do not contain organelles! © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 1 Eukaryotic cells are bigger and more complex • Animals, fungi, plants, and protists are all eukaryotes. • Eukaryotes evolved from prokaryotes around 2 billion years ago.

3. 2 Plant and animal cells have many organelles in common. • All eukaryotic cells are fundamentally alike. • All eukaryotic cells have: – Plasma membrane – Nucleus – Mitochondria – Ribosomes – Cytoplasm – Endoplasmic reticulum – Golgi © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 2 Structure of an idealized animal cell © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 2 Structure of an idealized plant cell © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 2 Animal and plant cells have some unique organelles. • Animal cells have lysosomes. • Plant cells have chloroplasts, cell walls, and central vacuoles. Looking at cells under a microscope, you see cell walls and chloroplasts. What type of cells are these? © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 2 Some cells have unique organelles • Only animal cells have lysosomes. • Only plant cells have chloroplasts, cellulose cell walls, and central vacuoles. • Some animal cells, protists and prokaryotic cells have flagella and/or cilia – Plant cells do not • Bacteria have – Peptidoglycan cell wall, plasma membrane, cytoplasm, ribosomes, DNA – Some bacteria have capsule, flagellum, cilia, thylakoid membranes .

3. 3 Every cell is surrounded by a plasma membrane. • All cells are surrounded by a plasma membrane. • Membranes regulate the passage of materials. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 3 Membranes are made of lipids • Plasma membranes are made from two layers of phospholipids and integrated proteins. © 2017 Pearson Education, Inc.

3. 3 Structure of a plasma membrane © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 4 Membranes regulate the passage of materials. • Cells are surrounded by a plasma membrane. • Organelles may have their own outer and internal membranes. The most important function of any membrane is to regulate the flow of materials. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 4 Membranes regulate what substances can enter and leave the cell. • Every membrane is selectively permeable. • Some substances flow freely. • Others pass under certain circumstances. • Some cannot pass. © 2017 Pearson Education, Inc. GO YIELD STOP Chapter Table of Contents

3. 4 Transport across membranes can be passive or active. • Passive transport requires no energy. – Substances move along a concentration gradient from high to low. • Active transport requires energy. – Substances move against a concentration gradient from low to high. Active transport is like trying to get into a crowded club! © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 4 Passive transport: Diffusion Higher concentration • Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration. Lower concentration © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 4 Passive transport: Osmosis aquaporins • The diffusion of water is called osmosis. • Water will always flow from an area of higher water concentration to an area of lower water concentration. • Aquaporins are proteins in the plasma membrane for osmosis © 2017 Pearson Education, Inc. Lower concentration Higher concentration Chapter Table of Contents

3. 4 Passive transport: Facilitated diffusion Higher concentration • Large molecules can move through embedded transport proteins via facilitated diffusion. • Substances still move from an area of higher concentration to an area of lower concentration. © 2017 Pearson Education, Inc. Lower concentration Chapter Table of Contents

3. 4 Active transport requires energy to move substances. • Active transport involves moving a substance from an area of lower concentration to an area of higher concentration. • Moving a substance against its concentration gradient always requires an expenditure of energy. © 2017 Pearson Education, Inc. Lower concentration Higher concentration Chapter Table of Contents

3. 4 Active transport is usually driven by a protein that sits within the membrane. Here, you can see a protein called the sodium-potassium (Na+/K+) pump moving three sodium ions into the cell. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 4 Active transport is usually driven by a protein that sits within the membrane • the sodium-potassium (Na+/K+) pump moves three sodium ions out of the cell and two potassium ions into the cell. This membrane protein uses the energy from ATP hydrolysis

3. 4 Cells can also transport substances by fusing a portion of the cell membrane. • Exocytosis is the export from the cell. • Endocytosis is the import into the cell. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 5 Opening Questions: Where did you get your chromosomes from? • Human cells contain 46 chromosomes. • What are at least three things that you know about chromosomes? • Can you draw a chromosome? • What is it made of? © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 5 Only eukaryotic cells contain organelles surrounded by membranes. • The most prominent membrane-enclosed organelle is the nucleus. • Every eukaryotic cell (including plant and animal cells) contains a nucleus. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 5 The nucleus contains most of the cell’s DNA stored in chromosomes. • The nucleus, surrounded by an envelope and containing DNA, directs the activities of the cell. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 5 The nucleus is surrounded by a double membrane called the nuclear envelope. • Protein-lined nuclear pores in the nuclear envelope allow certain molecules, such as RNA, to pass through. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 5 The nucleus houses the chromosomes. • DNA molecules are wrapped around proteins to form fibers called chromatin. • Each very long chromatin fiber twists and folds to form a chromosome. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 5 The nucleus contains a darker area called a nucleolus. • The nucleolus is a particular location within the nucleus. • This area produces ribosomal RNA (r. RNA), an important component of a ribosome. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 6 Opening Questions: Who’s in charge? • Think of the cell as analogous to a factory. However, instead of producing widgets, the cellular factory produces proteins. • What roles might the following organelles play in the cell factory? – Plasma membrane – Nucleus – Ribosomes – Mitochondria © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 6 DNA directs a cell’s activities through the production of proteins. • DNA in the nucleus contains the instructions for making proteins. • Proteins are very important molecules in our cells. They are involved in virtually all cell functions. © 2017 Pearson Education, Inc. DNA RNA Protein Chapter Table of Contents

3. 6 Several organelles are involved in protein manufacture. Endoplasmic Reticulum (ER) Ribosomes floating or attached to ER Golgi Apparatus © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 6 Protein production involves two steps: 1. Transcription in the nucleus results in the production of RNA from DNA. 2. Translation at the ribosomes results in the production of proteins. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 6 After transcription, RNA travels from the nucleus to a ribosome. • Ribosomes are where proteins are made. • Some ribosomes are bound to the membrane of the rough ER. • Other ribosomes float freely in the cytoplasm. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 6 The endoplasmic reticulum (ER) is filled with membranes. • The smooth ER contains enzymes that produce lipids (such as steroid hormones). • The rough ER contains ribosomes that produce many kinds of proteins. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 6 Proteins are finalized and packaged in the Golgi apparatus. • The Golgi apparatus finishes, sorts, and ships cell products. • The Golgi apparatus finishes cell products in vesicles, small bubbles made of membrane. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 6 Lysosomes are a type of vesicle that contains digestive enzymes. • Lysosomes can dissolve large food molecules, old cellular components, or invasive organisms such as bacteria. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 7 Opening Questions: What if your organelles went missing? • What would happen if all the ribosomes in your cells disappeared? • What would happen if half of the mitochondria in your cells disappeared? © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 7 Two organelles help provide energy for the cell. • Chloroplasts are found in all plant cells and the cells of some algae. • Mitochondria are found in both plant and animal cells (mitochondrion is singular). © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 7 Chloroplasts are the organelle of photosynthesis. • In photosynthesis, the energy of sunlight is used to create molecules of sugar. • Chloroplasts require a supply of water and carbon dioxide (CO 2). • The sugars produced by photosynthesis provide the energy to power the cell. Within a cell, chloroplasts are visible as green blobs. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 7 The chloroplast © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 7 Mitochondria are the organelle of cellular respiration. • Cellular respiration uses oxygen (O 2) to harvest energy from molecules of sugar. • The harvested energy is stored as chemical energy in molecules of ATP, which can then be used to power many other cellular processes. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 7 The mitochondrion © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 8 Opening Questions: Plant cells vs. animal cells • List three structures in the plant cell that are not found in animal cells. • For each of these structures, explain why it is useful for plant cells, but not for animal cells. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 8 Vacuoles function in the general maintenance of the cell. • Vacuoles are intracellular sacs. • Some are for storage, such as for food, nutrients, or pigments. • Some pump water out of a cell. • Many plant cells have a very large central vacuole. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 8 Some cells have moving appendages. • Flagella propel the cell through their whip-like motion. • Cilia move in a coordinated backand-forth motion. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 8 Some cells are supported by a rigid cell wall surrounding the membrane. • Plant, fungus, and some prokaryotic cells have a rigid cell wall. • Plants can stand upright in part because their rigid cell walls are made of cellulose. Note: Animal cells do not have a cell wall! © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 8 Animal cells maintain their shape with an internal cytoskeleton. • The cytoskeleton is a network of protein fibers that provides mechanical support, anchorage, and reinforcement. The cytoskeleton network can be quickly dismantled and reassembled, providing flexibility. © 2017 Pearson Education, Inc. Chapter Table of Contents

3. 8 Animal cells stick together. • Animal cells produce a sticky extracellular matrix that helps hold cells together. Cells are held together into a tissue by the extracellular matrix. © 2017 Pearson Education, Inc. Chapter Table of Contents