CAMPBELL BIOLOGY IN FOCUS Urry Cain Wasserman Minorsky
CAMPBELL BIOLOGY IN FOCUS Urry • Cain • Wasserman • Minorsky • Jackson • Reece 4 A Tour of the Cell Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge © 2014 Pearson Education, Inc.
Do now: §A cell (cube shape) is 5 cm in length. Calculate surface area to volume ratio. Show all work. §How are prokaryotic cells different from eukaryotic cells? Categorize the kingdoms into each §How are plant cells different from animal cells?
Do now: §Categorize the following statements as belonging to eukaryotic cells, prokaryotic cells, both or neither § Has a nucleus § Has ribosomes § Evolved first § Bacteria contain these types of cells § Your desk
Check yourself: §Why is it beneficial for oxygen to reach mitochondria faster? §Why is it beneficial for carbon dioxide to exit the cell faster? §How is this related to surface area? §How is this related to volume?
Check yourself: §Which type of cell is most desirable? Pick the statement that takes into all factors of an advantageous cell size §A cell with a small volume §A cell with a large surface area to volume ratio §A cell with a small surface area to volume ratio
§Which cell would be most likely to survive under intense competition? Explain. §Cube 3 cm §Sphere with radius 3 cm §Cylinder with diameter 1 cm and height 3 cm
If a large surface area to volume ratio is desirable… §Then how did eukaryotic cells survive and flourish over time?
Overview: The Fundamental Units of Life § All organisms are made of one or more cells. § Smallest unit of life § All cells are related by their descent from earlier cells § Though cells can differ substantially from one another, they share common features © 2014 Pearson Education, Inc.
Why are cells small? § Metabolic requirements set upper limits on the size of cells § The ratio of surface area to volume of a cell is critical § As the surface area increases by a factor of n 2, the volume increases by a factor of n 3 § Small cells have a greater surface area relative to volume © 2014 Pearson Education, Inc.
Figure 4. 6 Surface area increases while total volume remains constant 5 1 1 Total surface area [sum of the surface areas (height width) of all box sides number of boxes] 6 150 750 Total volume [height width length number of boxes] 1 125 6 1. 2 6 Surface-to-volume ratio [surface area volume] © 2014 Pearson Education, Inc.
Concept 4. 1: Biologists use microscopes and the tools of biochemistry to study cells § Most cells are between 1 and 100 m in diameter, too small to be seen by the unaided eye © 2014 Pearson Education, Inc.
10 m 0. 1 m Human height Length of some nerve and muscle cells Chicken egg 1 cm 100 m 1 m 100 nm 1 nm 0. 1 nm © 2014 Pearson Education, Inc. Frog egg Human egg Most plant and animal cells Nucleus Most bacteria Mitochondrion EM 1 mm LM 1 m Unaided eye Figure 4. 2 Smallest bacteria Viruses Ribosomes Proteins Lipids Small molecules Atoms Superresolution microscopy
§ Most subcellular structures, including organelles (membrane-enclosed compartments), are too small to be resolved by light microscopy © 2014 Pearson Education, Inc.
§ Two basic types of electron microscopes (EMs) are used to study subcellular structures § Scanning electron microscopes (SEMs) focus a beam of electrons onto the surface of a specimen, providing images that look three-dimensional § Transmission electron microscopes (TEMs) focus a beam of electrons through a specimen § TEM is used mainly to study the internal structure of cells © 2014 Pearson Education, Inc.
Figure 4. 3 50 m Light Microscopy (LM) Brightfield (stained specimen) Phase-contrast Differential-interference contrast (Nomarski) 10 m 50 m Brightfield (unstained specimen) Fluorescence Confocal Electron Microscopy (EM) Longitudinal section Cross section of cilium Cilia Scanning electron microscopy (SEM) © 2014 Pearson Education, Inc. 2 m Transmission electron microscopy (TEM)
Do Now Q#1 categorize kingdoms § Prokaryotic § Bacteria § Archaea § Eukaryotic § Protists § Fungi § animals § plants © 2014 Pearson Education, Inc.
Do Now Q #1: differences between eukaryotic and prokaryotic Eukaryotic Prokaryotic § DNA in a nucleus that is bounded by a membranous nuclear envelope § No nucleus § Membrane-bound organelles (ex: mitochondria, ER) § No membrane-bound organelles § larger § DNA in an unbound region called the nucleoid
Comparing Prokaryotic and Eukaryotic Cells § Basic features of all cells § Plasma membrane § Semifluid substance called cytosol/cytoplasm § Chromosomes (carry genes- segments of DNA) § Ribosomes (make proteins) © 2014 Pearson Education, Inc.
Is this a prokayotic or eukaryotic cell? Fimbriae Nucleoid Ribosomes Plasma membrane chromosome Cell wall Capsule (a) A typical rod-shaped bacterium © 2014 Pearson Education, Inc. Flagella 0. 5 m (b) A thin section through the bacterium Bacillus coagulans (TEM)
Do now: • • • A cube is 5 cm. X 5 cm The diffusion penetration is. 3 centimeters. What is the surface area to volume ration? What is the extent of diffusion? Show ALL work! © 2014 Pearson Education, Inc.
Review Of Organelles • Organelle : cell : : organ system : : organism • Structure enables function! © 2014 Pearson Education, Inc.
Cell/Plasma Membrane § Structure: § The general structure of a biological membrane is a double layer of phospholipids § Function § selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell © 2014 Pearson Education, Inc.
A Panoramic View of the Eukaryotic Cell § A eukaryotic cell has internal membranes that divide the cell into compartments—organelles § The plasma membrane and organelle membranes participate directly in the cell’s metabolism Animation: Tour of an Animal Cell Animation: Tour of a Plant Cell © 2014 Pearson Education, Inc.
Figure 4. 7 a M 1 A C M M 2 B M 3 D L E E 1 E 2 K E 3 F J G H © 2014 Pearson Education, Inc. I
Figure 4. 7 a ENDOPLASMIC RETICULUM (ER) Flagellum Smooth ER Rough ER Nuclear envelope Nucleolus NUCLEUS Chromatin Centrosome Plasma membrane CYTOSKELETON: Microfilaments Intermediate filaments Ribosomes Microtubules Microvilli Golgi apparatus Peroxisome Mitochondrion © 2014 Pearson Education, Inc. Lysosome
Figure 4. 7 b A 1 A 2 A 3 M L A K J B i 1 i. 2 i. 3 C D E H F © 2014 Pearson Education, Inc. G I
Figure 4. 7 b Nuclear envelope Nucleolus Chromatin Rough endoplasmic reticulum Smooth endoplasmic reticulum NUCLEUS Ribosomes Central vacuole Golgi apparatus Microfilaments CYTOIntermediate SKELETON filaments Microtubules Mitochondrion Peroxisome Plasma membrane Cell wall Wall of adjacent cell © 2014 Pearson Education, Inc. Chloroplast Plasmodesmata
Figure 4. 8 a Nucleus Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Rough ER Pore complex Ribosome Close-up of nuclear envelope © 2014 Pearson Education, Inc. Chromatin
Nucleus Structure: § The nuclear envelope encloses the nucleus, separating it from the cytoplasm § The nuclear membrane is a double membrane; each membrane consists of a lipid bilayer Function: § The nucleus contains most of the DNA in a eukaryotic cell § DNA contains information on how to make proteins © 2014 Pearson Education, Inc.
Ribosomes: Protein Factories § Structure: § Made up of two parts, small § Function: § Ribosomes carry out protein synthesis § In the cytosol (free ribosomes) § On the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes) © 2014 Pearson Education, Inc.
Endomembrane System- **important topic on the AP exam** § Components of the endomembrane system § Nuclear envelope § Endoplasmic reticulum § Golgi apparatus § Lysosomes § Vacuoles § Plasma membrane § These components are either continuous or connected through transfer by vesicles © 2014 Pearson Education, Inc.
The Endoplasmic Reticulum: Biosynthetic Factory § Structure: § The ER membrane is continuous with the nuclear envelope § There are two distinct regions of ER § Smooth ER: lacks ribosomes § Rough ER: surface is studded with ribosomes Video: Endoplasmic Reticulum Video: ER and Mitochondria © 2014 Pearson Education, Inc.
Functions of Smooth ER § The smooth ER § Synthesizes lipids § Metabolizes carbohydrates § Detoxifies drugs and poisons § Stores calcium ions © 2014 Pearson Education, Inc.
Functions of Rough ER § The rough ER § Has bound ribosomes, which secrete glycoproteins (proteins covalently bonded to carbohydrates) § Distributes transport vesicles, proteins surrounded by membranes § Is a membrane factory for the cell © 2014 Pearson Education, Inc.
The Golgi Apparatus: Shipping and Receiving Center § Structure: § The Golgi apparatus consists of flattened membranous sacs called cisternae § Functions § Modifies products of the ER § Manufactures certain macromolecules § Sorts and packages materials into transport vesicles Video: ER to Golgi Traffic Video: Golgi 3 -D Video: Golgi Secretion © 2014 Pearson Education, Inc.
Lysosomes: Digestive Compartments § Structure: § membranous sac of hydrolytic enzymes § Function § Lysosomal enzymes can hydrolyze proteins, fats, polysaccharides, and nucleic acids § Lysosomal enzymes work best in the acidic environment inside the lysosome § Also take part in phagocytosis © 2014 Pearson Education, Inc.
Vacuoles: Diverse Maintenance Compartments § Vacuoles are large vesicles derived from the endoplasmic reticulum and Golgi apparatus § Food vacuoles are formed by phagocytosis § Contractile vacuoles, found in many freshwater protists, pump excess water out of cells § Central vacuoles, found in many mature plant cells, hold organic compounds and water © 2014 Pearson Education, Inc.
Figure 4. 14 Central vacuole Cytosol Nucleus Central vacuole Cell wall Chloroplast Plant cell vacuole © 2014 Pearson Education, Inc. 5 m
The Endomembrane System: A Review § The endomembrane system is a complex and dynamic player in the cell’s compartmental organization © 2014 Pearson Education, Inc.
Figure 4. 15 -1 Nucleus Rough ER Smooth ER Plasma membrane © 2014 Pearson Education, Inc.
Figure 4. 15 -2 Nucleus Rough ER Smooth ER cis Golgi trans Golgi © 2014 Pearson Education, Inc. Plasma membrane
Figure 4. 15 -3 Nucleus Rough ER Smooth ER cis Golgi trans Golgi © 2014 Pearson Education, Inc. Plasma membrane
Mitochondria and chloroplasts change energy from one form to another § Mitochondria are the sites of cellular respiration, a metabolic process that uses oxygen to generate ATP § Chloroplasts, found in plants and algae, are the sites of photosynthesis § Peroxisomes are oxidative organelles © 2014 Pearson Education, Inc.
Figure 4. 16 ______ What is happening here? ______ What kind of cell Is this? ______ What is happening here? What kind of cell is This? At least one cell _____________ What kind of cell is this? © 2014 Pearson Education, Inc.
Figure 4. 16 Endoplasmic reticulum Engulfing of oxygenusing nonphotosynthetic prokaryote, which becomes a mitochondrion Nucleus Nuclear envelope Ancestor of eukaryotic cells (host cell) Mitochondrion Nonphotosynthetic eukaryote At least one cell Engulfing of photosynthetic prokaryote Chloroplast Mitochondrion Photosynthetic eukaryote © 2014 Pearson Education, Inc.
§ The endosymbiont theory § An early ancestor of eukaryotic cells engulfed a nonphotosynthetic prokaryotic cell, which formed an endosymbiont relationship with its host § The host cell and endosymbiont merged into a single organism, a eukaryotic cell with a mitochondrion § At least one of these cells may have taken up a photosynthetic prokaryote, becoming the ancestor of cells that contain chloroplasts Video: ER and Mitochondria Video: Mitochondria 3 -D © 2014 Pearson Education, Inc.
The Evolutionary Origins of Mitochondria and Chloroplasts § Mitochondria and chloroplasts have similarities with bacteria § Enveloped by a double membrane § Contain free ribosomes and circular DNA molecules § Grow and reproduce somewhat independently in cells © 2014 Pearson Education, Inc.
Figure 4. 17 Mitochondrion Intermembrane space Outer membrane DNA Free ribosomes in the mitochondrial matrix © 2014 Pearson Education, Inc. Inner membrane Cristae Matrix 0. 1 m
Mitochondria: Chemical Energy Conversion § Structure: § They have a smooth outer membrane and an inner membrane folded into cristae § The inner membrane creates two compartments: intermembrane space and mitochondrial matrix § Function: § Some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix § Cristae present a large surface area for enzymes that synthesize ATP © 2014 Pearson Education, Inc.
Figure 4. 18 a Ribosomes Stroma Inner and outer membranes Granum Thylakoid DNA Intermembrane space (a) Diagram and TEM of chloroplast © 2014 Pearson Education, Inc. 1 m
Chloroplasts: Capture of Light Energy § Structure: Chloroplast includes § Thylakoids, membranous sacs, stacked to form a granum § Stroma, the internal fluid § Chloroplasts contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis § Chloroplasts are found in leaves and other green organs of plants and in algae © 2014 Pearson Education, Inc.
Peroxisomes: Oxidation § Structure: § Peroxisomes are specialized metabolic compartments bounded by a single membrane § Function: § Peroxisomes produce hydrogen peroxide and convert it to water Video: Cytoskeleton in Neuron © 2014 Pearson Education, Inc.
Cytoskeleton § Structure: § The cytoskeleton is a network of fibers extending throughout the cytoplasm § Function: § It organizes the cell’s structures and activities, anchoring many organelles Video: Microtubule Transport Video: Organelle Movement Video: Organelle Transport © 2014 Pearson Education, Inc.
Components of the Cytoskeleton § Three main types of fibers make up the cytoskeleton § Microtubules are thickest of the three components of the cytoskeleton § Microfilaments, also called actin filaments, are thinnest components § Intermediate filaments are fibers with diameters in a middle range © 2014 Pearson Education, Inc.
Table 4. 1 © 2014 Pearson Education, Inc.
Figure 4. 22 Centrosome Microtubule Centrioles © 2014 Pearson Education, Inc.
Cilia and Flagella § Microtubules control the beating of cilia and flagella, microtubule-containing extensions projecting from some cells § How are flagella and cilia different? § Flagella are limited to one or a few per cell, while cilia occur in large numbers on cell surfaces © 2014 Pearson Education, Inc.
Microfilaments (Actin Filaments) § Microfilaments are thin solid rods, built from molecules of globular actin subunits § Function: § Muscle: The structural role of microfilaments is to bear tension, resisting pulling forces within the cell § Bundles of microfilaments make up the core of microvilli of intestinal cells © 2014 Pearson Education, Inc.
Intermediate Filaments § Intermediate filaments are larger than microfilaments but smaller than microtubules § They support cell shape and fix organelles in place § Intermediate filaments are more permanent cytoskeleton elements than the other two classes © 2014 Pearson Education, Inc.
Concept 4. 7: Extracellular components and connections between cells help coordinate cellular activities § Most cells synthesize and secrete materials that are external to the plasma membrane § These extracellular materials are involved in many cellular functions © 2014 Pearson Education, Inc.
Cell Walls of Plants § The cell wall is an extracellular structure that distinguishes plant cells from animal cells § Prokaryotes, fungi, and some protists also have cell walls § Structure: § Plant cell walls are made of cellulose fibers embedded in other polysaccharides and protein § Function: § The cell wall protects the plant cell, maintains its shape, and prevents excessive uptake of water © 2014 Pearson Education, Inc.
§ Plasmodesmata are channels between adjacent plant cells § Through plasmodesmata, water and small solutes (and sometimes proteins and RNA) can pass from cell to cell Video: Collagen Model Video: Extracellular Matrix Video: Fibronectin © 2014 Pearson Education, Inc.
Figure 4. 26 a © 2014 Pearson Education, Inc.
The Extracellular Matrix (ECM) of Animal Cells § Animal cells lack cell walls but are covered by an elaborate extracellular matrix (ECM) § The ECM is made up of glycoproteins such as collagen, proteoglycans, and fibronectin § ECM proteins bind to receptor proteins in the plasma membrane called integrins © 2014 Pearson Education, Inc.
Cell Junctions § Neighboring cells in an animal or plant often adhere, interact, and communicate through direct physical contact § There are several types of intercellular junctions that facilitate this § Plasmodesmata § Tight junctions § Desmosomes § Gap junctions © 2014 Pearson Education, Inc.
Figure 4. 27 Tight junctions prevent fluid from moving across a layer of cells Tight junction TEM 0. 5 m Tight junction Intermediate filaments Desmosome TEM 1 m Gap junction Space between cells Plasma membranes of adjacent cells © 2014 Pearson Education, Inc. Extracellular matrix TEM Ions or small molecules 0. 1 m
Tight Junctions, Desmosomes, and Gap Junctions in Animal Cells § Animal cells have three main types of cell junctions § Tight junctions § Desmosomes § Gap junctions § All are especially common in epithelial tissue Animation: Desmosomes Animation: Gap Junctions Animation: Tight Junctions © 2014 Pearson Education, Inc.
Do now: §Compare the following organelles to an organ system and justify your comparison: § Mitochondria § Lysosome § Nucleus § ER/Golgi
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