1. Cell Structure
And Function

2. Cell Theory All organisms are composed of one or more cells.
Cells are the basic unit of structure and function in organisms.
All cells come only from other cells.

3. The Cell
Cells are small so they can exchange materials with their surroundings.

4. Sizes of Living Things

5. Essential Tasks of Living Things
Obtain food and energy
Convert energy from an external source into a form that works within the cell
Construct and maintain the molecules that make up cell structures
Carry out chemical reactions
Eliminate wastes
Reproduce
Keep records of how to build structures

6. Types of Cells
Eukaryotic
Prokaryotic

7. Eukaryotic Cells
All cells are surrounded by a plasma membrane made of phospholipids and proteins.
have membrane bound intracellular organelles.
The most prominent organelle is the nucleus that controls the workings of the cell.

8. Eukaryotic Cells: Membrane

9. Eukaryotic: Structural Components
Plasma membrane  regulates what enters and exits the cell.
Inside the plasma membrane, the nucleus is surrounded by cytoplasm.
Plant cells have a cell wall in addition to the plasma membrane.

10. Eukaryotic: Organelles
Animal and plant cells have organelles.
Organelles compartmentalize functions within the cell.
Animal vs. Plant Cells
organelles are similar to each other except that centrioles and lysosomes are present only in animal cells, and chloroplasts are present only in plant cells.

11. Eukaryotic: Animal Cell

12. Eukaryotic: Plant Cell

13. Cell Organelles

14. Nucleus Structure Chromatin: DNA and proteins
Nucleolus: Chromatin and ribosomal subunits
Nuclear envelope: Double membrane with pores
Nucleoplasm: semifluid medium inside the nucleus.

15. Nucleus and the Nuclear Envelope

16. Ribosomes
Protein synthesis occurs at tiny organelles called ribosomes.
Ribosomes are composed of a large subunit and a small subunit.
Ribosomes can be found alone in the cytoplasm, in groups called polyribosomes, or attached to the endoplasmic reticulum.

17. Ribosomes

18. Endomembrane System Consists of: Nuclear envelope (see nucleus slide)
Endoplasmic reticulum
Golgi apparatus
Vesicles

19. Endomembrane: Endoplasmic Reticulum
Endoplasmic reticulum (ER)  a system of membranous channels and sacules.
Rough ER is studded with ribosomes and is the site of protein synthesis and processing.
Smooth ER lacks ribosomes and is the site of synthesis of phospholipids and the packaging of proteins into vesicles, among other functions.

20. Endomembrane: Endoplasmic Reticulum

21. Endomembrane: Endoplasmic Reticulum

22. Endomembrane: Golgi Apparatus
The Golgi apparatus consists of a stack of curved saccules.
The Golgi apparatus receives protein and also lipid-filled vesicles from the ER, packages, processes, and distributes them within the cell.
This organelle may also be involved in secretion.

23. Endomembrane: Golgi Apparatus

24. Endomembrane: Vesicles
Lysosomes
In animal cells only
vesicles produced by the Golgi apparatus.
Lysosomes contain hydrolytic enzymes and are involved in intracellular digestion.

25. Endomembrane: Vesicles

26. Endomembrane: Vesicles
Vacuoles
Larger in plant than animal cells
Large membranous sacs in the cell that store substances (including water)
Note: vesicles are smaller forms of vacuoles

27. Endomembrane: Vesicles

28. Endomembrane: Vesicles
Peroxisomes
Peroxisomes are vesicles than contain enzymes.
The enzymes in these organelles use up oxygen and produce hydrogen peroxide.
Peroxisomes are abundant in the liver where they produce bile salts and cholesterol and break down fats.

29. Endomembrane: Vesicles

30. Energy-Related Organelles
The two energy-related organelles of eukaryotes are chloroplasts and mitochondria.
Both organelles house energy in the form of ATP.

31. Chloroplasts In plant cells only
A chloroplast is bounded by two membranes enclosing a fluid-filled stroma that contains enzymes.
Membranes inside the stroma are organized into thylakoids that house chlorophyll.
Chlorophyll absorbs solar energy and carbohydrates are made in the stroma.

32. Chloroplasts

33. Mitochondria Mitochondria are found in plant AND animal cells.
Mitochondria are bounded by a double membrane surrounding fluid-filled matrix.
The inner membranes of mitochondria are cristae.
The matrix contains enzymes that break down carbohydrates and the cristae house protein complexes that produce ATP (usable form of energy in cells).

34. Mitochondria

35. The Cytoskeleton
a network of filaments and tubules that extends from the nucleus to the plasma membrane.
The cytoskeleton contains three types of elements responsible for cell shape, movement within the cell, and movement of the cell:
Actin filaments
Microtubules
Intermediate filaments

36. Cytoskeleton: Actin Filaments
occur in bundles or mesh-like networks.
Actin filaments play a structural role in intestinal microvilli and also interact with motor molecules, such as myosin.

37. Cytoskeleton: Microtubules
small hollow cylinders made of the globular protein tubulin.
Microtubules help maintain the shape of the cell and act as tracks along which organelles can move.

38. Centrosome
Assembles and co-ordinates the activity of the spindle fibres when the cell divides
Made up of:
Centrioles
Cilia
flagella

39. Centrosome: Centrioles
Centrioles are short cylinders with a pattern of microtubule triplets.
9 sets of microtubule triplets, with no microtubules in the middle
Centrioles may be involved in microtubule formation and disassembly during cell division and in the organization of cilia and flagella.

40. Centrosome: Centrioles

41. Centrosome: Cilia and Flagella
Cilia (small and numerous) and flagella (large and single) have a pattern of microtubules and are involved in cell movement.
Cilia and flagella move when the microtubule doublets slide past one another.
Cilia moves in wave-like motion (e.g. in trachea)
Flagella produce an undulating, whip-like motion
Each cilium and flagellum has a basal body at its base.

42. Centrosome: Cilia and Flagella

43. Size Prokaryotic Cells Eukaryotic Cells
Small (about the size of mitochondria)
Between 1 – 10 micrometres
Eukaryotic Cells
Between 10 – 100 micrometres

44. Kingdoms Prokaryotic Kingdoms Eukaryotic Kingdoms **Bacteria Archaea
Protista
Fungi
Animalia
Plantae

45. Complexity Prokaryotes Lack membrane bound organelles
Most bacteria have these constant features:
Outer Boundary: Cell wall
Plasma membrane
Cytoplasm: Ribosomes (thousands)
Thylakoids (Cyanobacteria)
Innumerable enzymes

46. Complexity Eukaryotic Very complex
Many membrane bound organelles, vesicle and transport systems
See yesterdays note

47. Nucleus Prokaryotic Cells Eukaryotic Cells
Nucleoid: Chromosome (single loop of DNA)
Bacterial cells may have plasmids
Self-replicating DNA molecules that contain genes such as antibiotic resistance
Often used in genetic engineering
Eukaryotic Cells
DNA is contained in the membrane bound nucleus

48. Reproduction Prokaryotes binary fission (cells budding off)
Creates clones of existing cells
Some have pili that help cells attach to surfaces and exchange plasmids with other prokaryotic cells
Eukaryotes
Mitosis (cell division)
Meiosis (formation of sex cells)

49. Other Important Points
Prokaryotic Cells
Bacteria that can carry out photosynthesis have thylakoids that develop from invaginations of cell membrane
Thylakoids work same way as those in chloroplasts do
Many bacteria also have cilia and flagella to help with locomotion

50. Prokaryotic Cells

51. Prokaryotic Cells

52. Evolution of Eukaryotic Cell
Endosymbiotic hypothesis.
Eukaryotes arose from a symbiotic relationship between various prokaryotes.
Heterotrophic bacteria became mitochondria.
Cyanobacteria became chloroplasts.
Host cell was a large eukaryotic cell.

53. Evolution of the eukaryotic cell