1. Chapter 4 Cell Structure (Sections 4.8 - 4.13)

2. 4.8 The Endomembrane System
The endomembrane system includes rough and smooth endoplasmic reticulum (ER), vesicles, and Golgi bodies
This system makes and modifies lipids and proteins; it also recycles and disposes of molecules and particles
endomembrane system
Series of interacting organelles (endoplasmic reticulum, Golgi bodies, vesicles) between nucleus and plasma membrane; produces lipids, proteins

3. The Endomembrane System

4. Endoplasmic Reticulum
endoplasmic reticulum (ER)
Organelle that is a continuous system of sacs and tubes
An extension of the nuclear envelope
Site where many new polypeptide chains are modified
Rough ER is studded with ribosomes that make polypeptides that enter the ER as they are assembled
Smooth ER has no ribosomes: Enzymes assemble lipids that form cell membranes, and break down substances

5. A Variety of Vesicles
Small, membrane-enclosed, saclike vesicles form in a variety of types, either on their own or by budding
Many vesicles transport substances from one organelle to another, including endocytic vesicles and exocytic vesicles
Other vesicles include peroxisomes, lysosomes, and vacuoles (including central vacuoles)

6. Key Terms
vesicle
Small, membrane-enclosed, saclike organelle; different kinds store, transport, or degrade their contents
lysosome
Enzyme-filled vesicle that functions in intracellular digestion
peroxisome
Enzyme-filled vesicle that breaks down amino acids, fatty acids, and toxic substances

7. Key Terms
vacuole
A fluid-filled organelle that isolates or disposes of waste, debris, or toxic materials
central vacuole
Fluid-filled vesicle in many plant cells

8. Golgi Bodies
Enzymes in a Golgi body finish proteins and lipids that are delivered by vesicles from the ER
Golgi body
Modifies polypeptides and lipids; attaches phosphate groups or oligosaccharides, and cuts certain polypeptides
Sorts and packages the finished products into vesicles that carry them to lysosomes or to the plasma membrane

9. Functions of the Endomembrane System
polypeptide
RNA
Rough ER Some of the RNA
in the cytoplasm
is translated into polypeptide chains by ribosomes attached to the rough ER. The chains enter the rough ER, where they are modified into final form. 1
Vesicles Vesicles that bud from the rough ER carry some of the new proteins to Golgi bodies. Other proteins
migrate through the interior of the rough ER, and end up in the smooth ER. 3
Figure 4.16 Endomembrane system, where many proteins are modified and lipids are built. These molecules are sorted and shipped to cellular destinations or to the plasma membrane for export.
nucleus
ribosome attached to ER
vesicle budding from ER
Fig ,3, p. 62

10. Functions of the Endomembrane System (cont.)
Smooth ER
Some proteins from the rough ER are packaged into new vesicles and shipped to Golgi bodies. Others become enzymes of the smooth ER. These enzymes assemble lipids and inactivate toxins. 2
Golgi body
Proteins arriving in vesicles from the ER are modified into final form and sorted. New vesicles carry them to the plasma membrane or to lysosomes. 4
Plasma membrane
A vesicle’s membrane fuses with the plasma membrane, so the contents of the vesicle are released to the exterior of the cell. 5
Figure 4.16 Endomembrane system, where many proteins are modified and lipids are built. These molecules are sorted and shipped to cellular destinations or to the plasma membrane for export.
protein in smooth ER
Fig ,4,5, p. 62

11. 4.9 Mitochondria and Plastids
Mitochondria make ATP by breaking down organic compounds in the oxygen-requiring pathway of aerobic respiration
Chloroplasts are plastids that produce sugars by photosynthesis

12. Function of Mitochondria
mitochondrion
Double-membraned organelle that produces ATP by aerobic respiration in eukaryotes

13. Mitochondrion outer membrane outer compartment inner compartment
Figure 4.17 The mitochondrion. This organelle specializes in producing large quantities of ATP.
inner membrane
Fig. 4.17a, p. 64

14. Mitochondrion
Figure 4.17 The mitochondrion. This organelle specializes in producing large quantities of ATP.
Fig. 4.17b, p. 64

15. Energy powerhouse; produces many ATP by aerobic respiration
Mitochondrion
Energy powerhouse; produces many ATP by aerobic respiration
Figure 4.17 The mitochondrion. This organelle specializes in producing large quantities of ATP.
Fig. 4.17c, p. 64

16. Origins of Mitochondria
Theory of endosymbiosis: Mitochondria evolved from aerobic bacteria that took up permanent residence inside a host cell
Resemble bacteria in size, form, and biochemistry
Have their own DNA, which is similar to bacterial DNA
Divide independently of the cell, and have their own ribosomes

17. Chloroplasts and Other Plastids
An organelle that functions in photosynthesis or storage, e.g. chloroplast, amyloplast
chloroplast
Organelle of photosynthesis in the cells of plants and many protists

18. Chloroplast Structure
Two outer membranes enclose a semifluid interior (stroma) that contains enzymes and chloroplast DNA
In the stroma, a highly folded stack of membrane (grana/granum ) forms a single, continuous compartment
Photosynthesis takes place at the thylakoid membrane, which incorporates pigments such as chlorophylls, which are green

19. Photosynthesis
Chlorophylls and other molecules in the thylakoid membrane use the energy in sunlight to synthesize ATP
ATP is used to build carbohydrates (sugars) from carbon dioxide and water

20. Specializes in photosynthesis
Chloroplasts
Figure 4.18 The chloroplast, a defining character of photosynthetic eukaryotic cells. Bottom, transmission electron micrograph of a chloroplast from a tobacco leaf (Nicotiana tabacum). The lighter patches are nucleoids where the chloroplast’s own DNA is stored.
Chloroplast
Specializes in photosynthesis
Fig. 4.18a, p. 65

21. Specializes in photosynthesis
Chloroplast
Specializes in photosynthesis
Plant Cell
Mitochondrion
Figure 4.18 The chloroplast, a defining character of photosynthetic eukaryotic cells. Bottom, transmission electron micrograph of a chloroplast from a tobacco leaf (Nicotiana tabacum). The lighter patches are nucleoids where the chloroplast’s own DNA is stored.
Fig. 4.18b, p. 65

22. Chloroplast Structure

23. (inner membrane system folded into flattened disks)
two outer membranes
stroma
thylakoids
(inner membrane system folded into flattened disks)
Figure 4.18 The chloroplast, a defining character of photosynthetic eukaryotic cells. Bottom, transmission electron micrograph of a chloroplast from a tobacco leaf (Nicotiana tabacum). The lighter patches are nucleoids where the chloroplast’s own DNA is stored.
Fig. 4.18c, p. 65

24. Other Plastids
Chromoplasts are plastids that make and store pigments other than chlorophylls
Red, orange, and yellow pigments color many flowers, leaves, fruits, and roots

25. 4.12 Summary: Plant Cells

26. Summary: Animal Cells

27. Modifies proteins made by ribosomes attached to it
Nucleus
Keeps DNA separated from cytoplasm; makes ribosome subunits; controls access to DNA
nuclear envelope
nucleolus
DNA in nucleoplasm
Cytoskeleton
Structurally supports, imparts shape to cell; moves cell and its components
microtubules
Ribosomes
(attached to rough ER and free in cytoplasm) Sites of protein synthesis
microfilaments
Intermediate
filaments
Rough ER
Modifies proteins made by ribosomes attached to it
Mitochondrion
Energy powerhouse; produces many ATP by aerobic respiration
Smooth ER
Makes lipids, breaks down carbohydrates and fats, inactivates toxins
Centrioles
Special centers that produce and organize microtubules
Golgi Body
Finishes, sorts, ships lipids, enzymes, and proteins
Figure 4.26 Organelles and structures typical of A plant cells and B animal cells.
Plasma Membrane
Selectively controls the kinds and amounts of substances moving into and out of cell; helps maintain cytoplasmic volume, composition
Lysosome
Digests, recycles materials
B Typical animal cell components.
Fig. 4.26b, p. 70

28. Summary: Cell Components

29. Key Concepts Eukaryotic Cells
Cells of protists, plants, fungi, and animals are eukaryotic
They have a nucleus and other membrane-enclosed compartments
Cells differ in internal parts and surface specializations

30. 4.13 The Nature of Life
Life is a property that emerges from cellular components, but a collection of those components in the right amounts and proportions is not necessarily alive
Characteristics of life:
A set of properties unique to living things
Collectively, these properties characterize living things as different from nonliving things

31. Characteristics of Living Things
They make and use organic molecules of life
They consist of one or more cells
They engage in self-sustaining biological processes such as metabolism and homeostasis
They change over their lifetime by growing, maturing, and aging
They use DNA as hereditary material
They have the collective capacity to change over successive generations by adapting to environmental pressures