1. Cells Wassily Kandinsky (1866-1944)
Cells. “little rooms” L. discovered w microscopes c Fascination ever since.
More powerful scopes reveal more details. Cell, stained for mitochondria, actin, and nucleus
photos, videos of cell functions
Wassily Kandinsky ( )

2. - all organisms are composed of cells
Cell Theory:
- all organisms are composed of cells
- all cells come from other cells
Cell Theory: all orgs composed of cells, all cells come from other cells. No spontaneous life. Expts with broth in flask showed this. Recall Ch 1 on scientific method. Only when flask was open to air did anything grow.
Despite progress in biotech, humans cannot make a cell.
Figure 4.1x

3. Scanning electron microscope (SEM)
Electron microscopes invented in 1950s
beam of electrons instead of light. greater resolving power of electron microscopes
allows greater magnification, reveals cellular details
TEM
Figure 4.1B

4. Cell size and shape relate to function
Minimum
Maximum
At minimum, a cell must be large enough to house the parts it needs to survive and reproduce: DNA, enzymes, organelles. Review metric units text p73.Krogh, 3rd ed.
Sizes of cells: range fr .1 m - 1 m (nerve cells) mag.
Most cells btw 1 – 100 m. not visible w/eye alone. Size related to function. Long nerve cells transmit msg btw brain and body parts quickly. Bird eggs contain nutrients for embryo. Blood cells need to fit into small vessels.
maximum size limited by amount of surface needed to obtain nutrients from environment and dispose of wastes
Figure 4.2

5. A small cell has a greater ratio of surface area to volume than a large cell of the same shape
. Lgr cells = lgr surface area, but smaller surface/volume ratio. (for same shape).
Ex. 30 m cell vs 27 X 10 m cells. Same vol, 3X surface area. Basic math principle. Recall diffusion, osmosis expts. How much cpd can diffuse and how fast from each cell? Surface area must be adequate for cell’s survival. Some cells alter shape to avoid size problem, ex long skinny nerve cells, muscle cells. Shape keeps surface/vol ratio viable.
Surface area of one large cube = 5,400 µm2
Total surface area of 27 small cubes = 16,200 µm2
Figure 4.3

6. 2 kinds of cells: prokaryotic and eukaryotic
Prokaryotic cells - “before nucleus”
- small, relatively simple cells
Single-celled organisms
May not require oxygen
No organelles (with membranes)
microns. Eukys are microns. Prokaryotic (bact, archaea) vs eukaryotic (all other life); nuclear membrane. Proky cells smaller 2-8 m long. Contain DNA coiled in nucleoid region (no memb). Proky may not need O2. Some can metabolize w/out O2, some are poisoned by O2.

7. A prokaryotic cell has: - plasma membrane - rigid cell wall
sticky capsule
Prokaryotic flagella
Ribosomes
Nucleoid region with DNA
Some w/ flagella
Capsule
Cell wall
Plasma
membrane
Cell wall has unique components, diagnostic for bacteria. Antibiotics can block construction of bact cell walls. Result is that bact burst
Ribosomes to translate nucleic acids into proteins. Plasma memb, then rigid cell wall (proky style) gives protectn, shape. Chemically complex, allows I.D. of prokys. Some prokys have another outer layer, capsule, sticky coating to fasten proky to its envt. Ex. bact in streams, moving water; tissues inside animal body. Pili (pilus) short projections for attachment. Flagella- longer for motility.
E. coli movement: flagella move clockwise, forward motion. counterclockwise causes spinning. response to chemosignals (sense food).
Nucleoid region (DNA)
Pili
Figure 4.4

8. Prokaryotic cells, Bacillus polymyxa
Figure 4.4x1

9. Eukaryotic cells - functional compartments
- true nucleus
- larger: microns
- often multicellular
- organelles surrounded by membranes
- usually need O2
are partitioned into functional compartments. Euky cells-= plant and animal cells. Similarities and differences. Animal- nucleus surrounded by memb. Lots of specialized organelles in cytoplasm (fluid-filled space btw nuke and plasma membrane). @ orgnll is compartment, separated by memb. Rxns of life, metabolism, occur w/in orgnll. Allows conditions favorable for dift rxn to exist w/in same cell, w/out interfering w/each other. Membs of orgnll provide extra surface area for enz. to anchor, speeding rxn series. Not depdt on diffusion or random movement of molcs to get reagents to next enzyme.

10. a group of organelles that manufactures and distributes cell products
Endomembrane System
a group of organelles that manufactures and distributes cell products
nucleus
endoplasmic reticulum (ER), ribosomes
Golgi complex, vesicles
Separates cvell into compartments. Transport vesicles move proteins btw compartments. Cell products: proteins and membranes
Nuclear DNA makes mRNA, which moves thru pores into cytoplasm. Joins up w ribosomes, made w/ rRNA from nucleolus. Millions of ribos present in cell; constantly made.

11. nucleus is the control center
ENDOMEMBRANE SYSTEM
nucleus is the control center
largest organelle
nuclear envelope
contains DNA that directs cell’s activities
DNA copy goes into every progeny cell

12. Two membranes of nuclear envelope
NUCLEUS
Chromatin
Two membranes of nuclear envelope
Nucleolus
Pore
Nucleus control center. DNA attached to proteins, appears as threads=chromatin. Occasionally attached to nuclear memb. Control mech? Nuclear envelope = double memb w/pores that selectively allow molcs to pass. Control of protein synthesis by control of RNA. Nucleolus=mass of chromatin (DNA+proteins) and RNA, other proteins. Site of syn. of ribosome components.
NOTE continuity of membs, nuke envelope to RER. Endomembrane system.=collection of organelles
Make and distribute cell products, include membs., other impt molcs. Creates large comprt separate fr. cytoplasm.
ROUGH ENDOPLASMIC RETICULUM
Ribosomes
Figure 4.6

13. nucleus nuclear pores Figure: 04-04b Title: The nucleus. Caption:
(b) An electron micrograph of a yeast cell that was frozen and broken open to reveal its internal structures. The large nucleus, with nuclear pores penetrating its nuclear envelope, is clearly visible.

14. Rough endoplasmic reticulum
Makes proteins, membranes 1 2 3 4
Transport vesicle buds off
Ribosome
Sugar chain
Glycoprotein
Secretory (glyco-) protein inside transport vesicle
ROUGH ER
Polypeptide
Rough ER: makes membs and ribos on surface make proteins. Is a series of flattened sacks, covered w/ ribos. Tog, create vesicles filled w protein, ready to send off. Ex. secretory protein (glyco-prt), antibody. Carbo side chains often added here.
For proteins that aren’t secreted or imbedded in membs, translated on free ribos in cytoplasm. Released into cytosol. Signal molc is 1st portion of protein made by ribo.
Figure 4.8

15. SMOOTH ER ROUGH ER Nuclear envelope Ribosomes SMOOTH ER ROUGH ER
Note bumps on membs = ribos
Figure 4.9

16. The Golgi complex finishes, sorts, and ships cell products
Golgi apparatus
Golgi apparatus
“Receiving” side of Golgi apparatus
Transport vesicle from ER
Finish = add or trim carbohydrate side chains. Phosphate grps added. Serve as shipping tags to direct protein for export or elsewhere. Membranous sacs w/ internal space. Delivery sacs pinched off. Exocytosis - fuse w plasma memb, dumped outside
Golgi apparatus- stcks of sacs, not interconnected. Amt dept on how actively that cell is secreting. Receiving, modify, sort and ship. Diag. Transport vesicles may become part of other organelles (lysosome) or plasma memb.
New vesicle forming
“Shipping” side of Golgi apparatus
Transport vesicle from the Golgi
Figure 4.10

17. Lysosomes sacs of digestive enzymes budded off the Golgi
Fuse with membrane around debris
LYSOSOME
Nucleus
Recycling of worn out cell machinery. Also, holding tank for undigestable stuff. Is this reason for aging of cells? Too much garbage accumulated?
Figure 4.11A

18. Lysosomal enzymes digest food destroy bacteria
recycle damaged organelles
function in embryonic development in animals
Storage of undigestable waste
Storage of waste may be reason for cell aging: garbage accumulates.
Supported by symptoms of certain diseases
Pombe’s = missing hydrolytic enz , glycogen accumulates in liver cells.
Tays- Sachs = lack lipid-digesting enz, lipids accum in brain neurons. Fatal early. ID of genetic carriers, typically 1/100 in general pop, higher in certain ethnic groups.
Pombe’s disease - glycogen
Tay-Sachs disease - lipids

19. Transport vesicle (containing inactive hydrolytic enzymes)
Rough ER
Transport vesicle (containing inactive hydrolytic enzymes)
Plasma membrane
Golgi apparatus
Engulfment of particle
Lysosome engulfing damaged organelle
“Food”
LYSOSOMES
Digestion
Food vacuole
Figure 4.11B

20. Smooth endoplasmic reticulum
synthesizes lipids
regulates carbohydrate metabolism (liver)
breaks down toxins and drugs (liver)
Stores Ca++ in muscle cells
Smooth ER continuous w RER. Interconnected tubules w/o ribos. enz are imbedded in memb. Synthesis of lipids (fatty acids, phoslpd, steroids) each cell’s SER makes particular products, ex steroid hormones. In liver cells, SER breaks down toxins, drugs. W repeated doses, SER builds up and can cause tolerance to drugs and to related drugs, if chemically similar enough. SER regulates amt of glucose released into blood fr liver (recall stored as glycogen, a polymer of glucose). Also stores Ca++ in muscle cells, releases when needed for contraction.

21. Nucleus, ribosomes, RER ,SER, Golgi, vesicles
Endomembrane system
Nucleus, ribosomes, RER ,SER, Golgi, vesicles
Transport vesicle from Golgi
Transport vesicle from ER
Rough ER
Plasma membrane
Vacuole
Nucleus
Lysosome
Golgi apparatus
Smooth ER
Nuclear envelope
Figure 4.14

22. Vacuole in plants Lysosomal storage of pigments, poisons
Water relations
Central vacuole
Nucleus
Figure 4.13A

23. plant cells
large central vacuole
rigid cell wall
chloroplasts

24. in plants and some protists
Chloroplasts
in plants and some protists
convert solar energy to chemical energy in sugars
Chloroplast
Stroma
Inner and outer membranes
Granum
Intermembrane space
Figure 4.15

25. cellular respiration Mitochondrion Outer membrane Intermembrane space
Inner membrane
Cristae
Matrix
Figure 4.16

26. The CYTOSKELETON helps organize a cell’s structure and activities
network of protein fibers
Figure 4.17A

27. Intermediate filament
microtubule
Intermediate filament
microfilament
25 nm
10 nm
7 nm
Tubulin subunit
Actin subunit
Fibrous subunits
cell rigidity, anchor & tracks for organelles, mitosis
reinforce cell, anchor organelles
Cell shape, movement

28. Nuclei (yellow) and actin (red)
Figure 4.6x

29. Cilia and flagella locomotor appendages
composed of a core of microtubules wrapped in the plasma membrane
Basal body

30. Cell surfaces protect, support, and join cells
Surfaces allow exchange of signals and molecules.
Plant cells connect by plasmodesmata
No advantage to multicellularity unless cells can communicate.
Note: bacterial colonies now known to communicate, via electrical signals. Also, biofilms: colonies with specific structure to allow for best growth of the entire colony.

31. PLASMODESMATA Walls of two adjacent plant cells Vacuole
Layers of one plant cell wall
Pectin, polygalacturonides as cement between cell walls. Breaks down during ripening process.
Cytoplasm
Plasma membrane
Figure 4.19A

32. sticky layer of glycoproteins binds cells together in tissues
Animal cells - surrounded by an extracellular matrix
sticky layer of glycoproteins
binds cells together in tissues
can also protect and support cells

33. Tight junctions can bind cells together into leakproof sheets
Anchoring junctions link animal cells
Gap junctions allow substances to flow from cell to cell
TIGHT JUNCTION
ANCHORING JUNCTION
COMMUNICATING
JUNCTION
Plasma membranes of adjacent cells
Extracellular matrix
Figure 4.19B

34. Eukaryotic organelles fall into 4 functional groups
1. Manufacture and transport – dependent on network of membranes
Nucleus
Ribosomes
Rough, smooth ER
Golgi apparatus

35. 2. Breakdown – all single-membrane sacs
Lysosomes (in animals, some protists)
Peroxisomes
Vacuoles (plants)

36. 3. Energy Processing – involves extensive membranes embedded with enzymes
Chloroplasts
Mitochondria

37. 4. Support, Movement, Communication
Cytoskeleton – includes cilia, flagella, filaments, microtubules
Cell walls
Extracellular matrix
Cell junctions