1. Eukaryotic Cells

2. Eukaryotic organisms
Algae
Protozoa
Fungi
Plants
Animals

3. Eukaryotic Cells FLAGELLA AND CILIA CELL WALL and GLYCOCALYX
PLASMA MEMBRANE
CYTOPLASM
MEMBRANE-BOUND ORGANELLES
NON-MEMBRANE-BOUND ORGANELLES
RIBOSOMES:
CENTROSOME

4. FLAGELLA AND CILIA
These are used for cellular locomotion or for moving substances along the surface of the cell.
Flagella are few and long. Algae of the genus Euglena use a flagella for locomotion
Cilia are more numerous and shorter. Protozoa use cilia for locomotion.
Ciliated cells of the human respiratory system move mucous and debris along the surface of the cells in the bronchial tubes and trachea to clear the lungs.
Prokaryotic flagella rotate, but the eukaryotic flagellum moves in a wavelike manner.

5. Flagella and Cilia
Figure 4.23a, b

6. MICROTUBULES
Both flagella and cilia are anchored to the plasma membrane by a basal body, which consists of nine pairs of microtubules arranged in a ring, plus another two microtubules in the center of the ring, an arrangement called a array.
Microtubules are made up of a protein called tubulin.

7. Microtubules are made from tubulin 9 pairs + 2 arrangements
Figure 4.23c

8. CELL WALL and GLYCOCALYX
Most eukaryotic cells have cell walls, although they are much simple or than those of prokaryotic cells.
Algae, fungi, and plants have cellulose in their cell walls
Eukaryotic cells that lack a cell wall and have direct contact with the environment may have a glycocalyx, which is a sticky carbohydrate.

9. CELL WALL and GLYCOCALYX
The glycolcalyx strengthens the cell surface, helps attach cells together, and contributes to cell-cell recognition.
Eukaryotic cells do not contain peptidoglycan.
Antibiotics such as penicillins and cephalosporins only act against peptidoglycan and therefore do not affect human eukaryotic cells.

10. Flagella with microtubules
Cell wall
Plasma membrane
Figure 4.22a

11. PLASMA MEMBRANE
The plasma membrane of eukaryotic and prokaryotic cells is very similar in function and structure.
Eukaryotic membranes have different proteins, and also contain carbohydrates, which serve in cell to cell recognition.
Bacteria take advantage of these sites and attach there.
Eukaryotic plasma membranes also contain sterols, which are complex lipids not found in prokayriotic plasma membranes (with the exception of Mycoplasma).
Sterols help the membranes resist lysis from increased osmotic pressure.

12. PLASMA MEMBRANE
Substances can cross the plasma membrane by diffusion or active transport, or a mechanism called endocytosis.
This occurs when a segment of the plasma membrane surrounds a particle, encloses it, and brings it into the cell.
This process is called phagocytosis when the plasma membrane projects a pseudopod (false foot), engulfs the particle and brings it the cell.

13. White Blood Cell Pseudopod

14. CYTOPLASM Located inside the plasma membrane and outside the nucleus.
Cytosol is the fluid portion of the cytoplasm.
Only eukaryotic cytoplasm has a cytoskeleton:
Microfiaments
Microtubules
Cytoskeleton provides support and shape, and assists in transporting substances through the cell.
They can also move the entire cell, as in phagocytosis.
The movement of cytoplasm from one part of the cell to another to distribute nutrients is called cytoplasmic streaming.

15. CYTOPLASM
Many of the important enzymes found in the cytoplasmic fluid of prokaryotes is contained within organelles of eukaryotes.
Some organelles are bound by a membrane and other organelles are non-membrane bound.

16. MEMBRANE-BOUND ORGANELLES
NUCLEUS ER
GOLGI COMPLEX
LYSOSOMES
VACUOLES
MITOCHONDRIA
CHLOROPLASTS
PEROXISOMES

17. NUCLEUS Usually the largest structure in the cell.
Contains almost all of the cell’s hereditary information (DNA).
Some DNA is also found in mitochondria and in the chloroplasts of photosynthetic organisms.
The nucleus is surrounded by a double membrane called the nuclear envelope which has tiny channels (nuclear pores) which allow the nucleus to communicate with the cytoplasm.
Within the nucleus are one or more nucleoli which are condensed regions of chromosomes where ribosomal RNA is being synthesized.
The nucleus also contains some proteins called histones, which wrap around the DNA and organize it.

18. Nucleus
Nucleolus
Figure 4.22a

19. Nucleus
Figure 4.24

20. NUCLEUS Chromatin: a thread-like mass of dormant DNA.
Chromatin shortens and thickens into chromosomes during replication.
Prokaryotic chromosomes do not undergo this process, do not have histones, and are not enclosed in a nuclear envelope.
Eukaryotic cells divide by mitosis and meiosis; these processes do not occur in prokaryotic cells.

21. Endoplasmic Reticulum
An extensive network of channels which are continuous with the nuclear envelope.
Rough ER is studded with ribosomes, the sites of protein synthesis.
Proteins synthesized by ribosomes that are attached to rough ER enter the channels within the ER to be processed and sorted.
Thus, rough ER are protein factories.

22. Endoplasmic Reticulum
Figure 4.25

23. Endoplasmic Reticulum
Smooth ER extends from the rough ER to form a separate network.
Smooth ER does not have any ribosomes.
It contains unique enzymes; it synthesizes phospholipids, fats, and steroids such as estrogen and testosterone.
In liver cells, the enzymes of smooth ER detoxify drugs.

24. GOLGI COMPLEX
Most of the proteins synthesized by ribosomes from rough ER are transported to other regions of the cell.
The first step in the transport pathway is through the Golgi complex.
Proteins synthesized by ribosomes on the rough ER are surrounded by a portion of the ER membrane, which eventually buds to form a transport vesicle.
This transport vesicle fuses with the Golgi complex, releasing the proteins into the channels of the Golgi complex.

25. Golgi Complex
Figure 2.8

26. GOLGI COMPLEX
Within the Golgi complex, the proteins are modified into glycoproteins, glycolipids, and lipoproteins.
Some of the processed proteins leave the Golgi complex in secretory vesicles, which detach from the Golgi membrane and deliver the proteins to the plasma membrane, where they are discharged from the cell.
Some of the processed proteins leave the Golgi complex in vesicles that are called storage vesicles.
The major storage vesicle is a lysosome.

27. LYSOSOMES
Lysosomes are formed from the Golgi complexes and look like membrane-enclosed spheres.
Unlike mitochondria, lysosomes have only one membrane and lack internal structure.
They contain as many as 40 different kinds of powerful digestive enzymes capable of breaking down various molecules.
They can also digest bacteria that enter the cell. Human white blood cells, which use phagocytosis to ingest bacteria, contain large numbers of lysosomes.

28. VACUOLES
A space or cavity in the cytoplasm that is enclosed by a membrane.
Made by the Golgi complex
Functions:
Temporary storage organelles for proteins, sugars, etc.
Store wastes and poisons to prevent toxicity to the cytoplasm.
Take up water, enabling plant cells to increase in size and also provide rigidity to leaves and stems.

29. Vacuoles
Figure 4.22b

30. MITOCHONDRIA
Rod-shaped organelles which appear throughout the cytoplasm of most eukaryotic cells.
There can be as many as 2000 mitochondria and one cell.
Mitochondria have a double membrane; the outer membrane is smooth but the inner membrane is arranged in a series of folds called cristae.
The center of the mitochondrion is a semi-fluid substance called the matrix.

31. Mitochondrion
Figure 4.27

32. MITOCHONDRIA
The convolutions of the cristae provide an enormous surface area on which chemical reactions can occur.
Some proteins that function in cellular respiration, including the enzyme that makes ATP, are located on the cristae, and many of the metabolic steps involved in cellular respiration occur in the matrix.
Mitochondria are called the powerhouses of the cell because of their central role in ATP production.

33. MITOCHONDRIA
Mitochondria contain their own ribosomes and DNA and are able to replicate themselves and make their own proteins.
It is theorized that they have evolved from bacteria millions of years ago, which have a symbiotic relationship within the organism.

34. Endosymbiotic Theory
Figure 10.2

35. CHLOROPLASTS Only found in algae and green plants.
Contains the pigment chlorophyll plus enzymes required for photosynthesis.
Contain ribosomes, DNA, and enzymes involved in protein synthesis.
Capable of multiplying on their own within the cell.
Chloroplasts and mitochondria replicate by binary fission like bacteria.

36. Chloroplast
Figure 4.28

37. PEROXISOMES Similar to lysosomes but they are smaller
Contain one or more enzymes that can oxidize various substances including alcohol.
The end product of the oxidation reaction is hydrogen peroxide, which is a very toxic compound.
However peroxisomes also contain the enzyme catalase, which decomposes hydrogen peroxide, so it is safe within the cell.
Peroxisomes can also be used to digest bacteria that have invaded the cell.

38. NON-MEMBRANE-BOUND ORGANELLES
RIBOSOMES
CENTROSOME

39. RIBOSOMES
Attached to the outer surface of rough ER are ribosomes or floating free in the cytoplasm.
They are the sites of protein synthesis in the cell.
They are larger (80S instead of 70S) and denser than the ribosomes of prokaryotic cells.
The free ribosomes synthesize proteins which are used inside the cell, and they do not have a membrane.
The membrane-bound ribosomes are the ones attached to the rough ER.
These ribosomes synthesize proteins destined for insertion in the plasma membrane or for export from the cell.
Ribosomes within the mitochondria synthesize special mitochondrial proteins.

40. Ribosomes
Complete 80S Ribosome
Figure 4.19

41. CENTROSOME Located near the nucleus.
It consists of proteins fibers and two centrioles, which are cylinders of small fibers.
They organize the spindles that appear during mitosis to help the duplicated chromosomes move towards opposite ends of the cell.
Each of the two centrioles in the centrosome is arranged so that the long axis of one centriole is at a right angle to the long axis of the other.

42. Centrioles
Centrioles

43. CENTROSOME

44. Figure 2.1

45. EUKARYOTIC
PROKARYOTIC
One circular chromosome, not membrane-bound
Paired chromosomes, membrane-bound
No histones
Histones present
No organelles
Organelles present: Golgi complex, ER, mitochondria, chloroplasts
Peptidoglycan cell walls
Polysaccharide cell walls
Reproduce by binary fission
Reproduce by mitosis
No true nucleus; no nuclear membrane
True nucleus; nuclear membrane; also has nucleoli
Glycocalyx present as capsule or slime layer
Present in some cells that lack a cell wall
Plasma membrane has no carbohydrates and lack sterols
Plasma membrane has carbohydrates and sterols
No cytoskeleton
Has a cytoskeleton
Ribosomes are small (70S)
Ribosomes are large (80S)