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Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Chapter 4  Cell Structure and Function.

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Presentation on theme: "Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Chapter 4  Cell Structure and Function."— Presentation transcript:

1 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Chapter 4  Cell Structure and Function

2 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e What Are the Basic Attributes of Cells?  All cells share common features –DNA and RNA –plasma membrane –cytoplasm consists of all the fluid and structures that lie inside the plasma membrane but outside of the nucleus –The fluid portion of the cytoplasm (cytosol) contains water, salts, and organic molecules –Most of the cell’s metabolic activities occur in the cell cytoplasm

3 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e glycoprotein carbo- hydrate extracellular fluid (outside) cytoplasm (inside) cholesterol membrane protein channel protein cytoskeleton A phospholipid bilayer helps to isolate the cell's contents Proteins help the cell communicate with its environment The Plasma Membrane Fig. 4-2  Functions: –isolates the cell’s contents from the external environment –regulates the exchange of essential substances –allows communication between cells –creates attachments within and between cells –regulates biochemical reactions

4 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e EUKARYOTIC CELLS

5 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e mitochondrion cytosol flagellum vesicle ribosomes on rough ER centriole intermediate filaments (cytoskeleton) Golgi apparatus cytoplasm lysosome exocytosis of material from the cell nuclear pore basal body nuclear envelope chromatin (DNA) nucleolus nucleus plasma membrane rough endoplasmic reticulum free ribosome smooth endoplasmic reticulum micro- (cytoskeleton) tubules microfilaments Fig. 4-3 A Generalized Animal Cell

6 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Fig. 4-4 central vacuole cytosol plastid vesicle lysosome cytoplasm plasmodesmata cell wall plasma membrane intermediate filaments (cytoskeleton) free ribosome ribosomes nucleus nucleolus nuclear pore chromatin nuclear envelope smooth endoplasmic reticulum rough endoplasmic reticulum Golgi apparatus chloroplast mitochondrion microtubules (cytoskeleton) cell walls of adjoining plant cells A Generalized Plant Cell

7 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e What Are the Major Features of Eukaryotic Cells?  Cell walls –outer surfaces of plants, fungi, and some protists –Plant cell walls are composed of cellulose –Fungal cell walls are made of chitin –Cell walls are porous, allowing oxygen, carbon dioxide, and water carrying dissolved molecules to flow easily through them –Plasmodesmata - openings that connect adjacent cells in plants –The plasma membrane is located just beneath the cell wall

8 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e What Are the Major Features of Eukaryotic Cells? microfilaments intermediate filaments microtubules microtubules (red) nucleus microfilaments (blue) (a) Cytoskeleton (b) Light micrograph showing the cytoskeleton  Cytoskeleton –provides shape, support, movement, cell division –The cytoskeleton is composed of three types of protein fibers: –microfilaments –intermediate filaments –microtubules

9 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Table 4-2 Cytoskeleton

10 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Cilia and Flagella 0.1 micrometer cilium plasma membrane basal body section of cilium central pair of microtubules protein “arms” Paramecium  Functions: –move the cell through fluid –move fluid past the cell  Both cilia and flagella are slender extensions of the plasma membrane supported by microtubules.

11 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e How Cilia and Flagella Move Fig. 4-7 return stroke cilia lining trachea flagellum of human sperm surface of human egg cell (a) Cilium continuous propulsion plasma membrane direction of locomotion power stroke (b) Flagellum propulsion of fluid

12 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e (b) Nucleus of a yeast cell(a) The nucleus nuclear envelope nuclear pores nucleolus ribosomes chromatin nucleus nuclear pores with nuclear pore complex  Control center –Nuclear envelope - consists of a double membrane perforated by nuclear pores –Chromatin –Nucleolus The Nucleus

13 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Ribosomes Fig ribosome mRNA amino acid polyribosome growing protein  small particle composed of ribosomal RNA and proteins  site of protein synthesis in the cytoplasm

14 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e  Vesicles are membranous sacs that transport substances  The endoplasmic reticulum (ER) is a series of interconnected membranes that form a labyrinth of interconnected flattened sacs and channels within the cytoplasm –All the proteins and phospholipids of cell membranes are synthesized in the ER Endoplasmic Reticulum

15 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e ribosomes smooth ER rough ER vesicles  There are two forms of ER: –Smooth endoplasmic reticulum has no ribosomes, detoxifies drugs, and synthesizes lipids like steroid hormones made from cholesterol –Rough endoplasmic reticulum is studded with ribosomes and synthesizes proteins destined for other membranes or for secretion Endoplasmic Reticulum

16 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Vesicles from the ER merge with the Golgi apparatus Vesicles carrying modified protein leave the Golgi apparatus Golgi apparatus –Functions: sorts, chemically alters, and packages important molecules –It synthesizes some polysaccharides used in plant cell walls, such as cellulose and pectin –It packages the finished molecules into vesicles that are then transported to other parts of the cell (lysosomes) or to the plasma membrane for export The Golgi Apparatus

17 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Lysosomes  Serve as the cell’s digestive system –A lysosome fuses with a food vacuole and digests food into basic nutrients –Digest worn-out organelles Golgi apparatus digestive enzymes lysosome food vacuoles The Golgi apparatus modifies the enzymes as they pass through its compartments The enzymes are packaged into lysosomes, which bud from the Golgi apparatus food (extracellular fluid) Digestive enzymes are synthesized on ribosomes and travel through the rough ER (cytoplasm) The enzymes are packaged into vesicles and travel to the Golgi apparatus A lysosome fuses with a food vacuole, and the enzymes digest the food

18 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Vacuoles  Serve many functions, including water regulation, support, and storage –Most cells contain one or more –sacs of cell membrane filled with fluid containing various molecules –Many freshwater organisms possess contractile vacuoles composed of collecting ducts, a central reservoir, and a tube leading to a pore in the plasma membrane that carries excess water out of the organism

19 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e (a) Paramecium (b) Contractile vacuole contractile vacuole central reservoir pore collecting ducts Water enters the collecting ducts and fills the central reservoir The reservoir contracts, expelling water through the pore Contractile Vacuoles Fig. 4-15

20 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e  Central vacuoles –Found in plants –Functions: –To maintain water balance –To store hazardous wastes, nutrients, or pigments –To provide turgor pressure on the cytoplasm to keep cells rigid Vacuoles cytoplasm (a) Turgor pressure provides support central vacuole cell wallplasma membrane When water is plentiful, it fills the central vacuole, pushes the cytoplasm against the cell wall, and helps maintain the cell's shape When water is scarce, the central vacuole shrinks and the cell wall is unsupported Deprived of the support from water, the plant wilts Water pressure supports the leaves of this impatiens plant (b) Loss of turgor pressure causes the plant to wilt

21 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Mitochondria outer membrane inner membrane matrix cristae 0.2 micrometer  Extract energy from food molecules to make ATP –“Powerhouse” of the cell –Double membrane with cristae

22 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e outer membrane inner membrane stroma thylakoid channel interconnecting thylakoids granum (stack of thylakoids) 1 micrometer Chloroplast  Site of photosynthesis –Double membrane –The thylakoid membranes contain the green pigment chlorophyll, which capture sunlight and make sugar from CO 2 and water (photosynthesis)

23 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Plastids starch globules plastid 0.5 micrometer  Storage –Only in plants and photosynthetic protists –Double membrane –Storage containers for various molecules, such as pigments or starch

24 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Review Questions 1.Describe the structures and features shared by all cells. 2.Define organelle. 3.Which organelles are found in plants not animals? 4.Describe each major structure and know its function.

25 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e PROKARYOTIC CELLS

26 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Prokaryotic Cells Are Simpler Than Eukaryotic Cells Fig chromosome (nucleoid region) chromosome (nucleoid region) pili ribosomes food granule prokaryotic flagellum capsule capsule or slime layer cell wall plasma membrane photosynthetic membranes plasma membrane cytoplasm plasmid (DNA) (b) Spirilla (c) Cocci (a) Generalized prokaryotic cell (bacillus) (d) Internal structure (e) Photosynthetic prokaryote

27 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e What Are the Major Features of Prokaryotic Cells?  Most prokaryotic cells (bacteria) are less than 5 µm long, with a simple internal structure compared to eukaryotic cells –They usually have a stiff cell wall –Prokaryotic cells can take several shapes: –Rod-shaped (bacilli) –Spiral-shaped (spirilla) –Spherical (cocci)

28 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e What Are the Major Features of Prokaryotic Cells?  Prokaryotic cells –Some bacteria and archaea are propelled by flagella –Infectious bacteria may have polysaccharide adhesive capsules and slime layers on their surfaces –Pili are protein projections in some bacteria that further enhance adhesion –In the central region of the cell is an area called the nucleoid, which is separate from the cytoplasm –Within the nucleoid is a single, circular chromosome of DNA –Small rings of DNA (plasmids) are located in the cytoplasm

29 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e What Are the Major Features of Prokaryotic Cells?  Prokaryotic cells –No nuclear membrane or membrane-bound organelles –Some have internal membranes used to capture light –Extensive cytoskeleton –The cytoplasm may contain –food granules –ribosomes

30 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e Review Questions 1.Explain the major differences between prokaryotic and eukaryotic cells. 2.Describe the structure and function of the major surface features of bacteria. 3.Describe the internal features of bacteria.

31 Copyright © 2011 Pearson Education Inc.Biology: Life on Earth, 9e A Protein Is Manufactured and Exported Fig Vesicles merge with the plasma membrane and release antibodies into the extracellular fluid Vesicles fuse with the Golgi apparatus, and carbohydrates are added as the protein passes through the compartments The protein is packaged into vesicles and travels to the Golgi apparatus Antibody protein is synthesized on ribosomes and is transported into channels of the rough ER Completed glycoprotein antibodies are packaged into vesicles on the opposite side of the Golgi apparatus (extracellular fluid) (cytoplasm) vesicles Golgi apparatus forming vesicle


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