1. CELL ORGANELLES MS. GAYNOR AP BIOLOGY / CHAPTER 6 (PART 2)

2. ORGANELLES Very small Perform various functions for cell
Found in the cytoplasm
May or may not be membrane- bound

3. BASIC ANIMAL CELL ORGANELLES
Ribosome (attached)
Nucleolus
Ribosome (free)
Nucleus
Cell Membrane
Nuclear envelope
Mitochondrion
Smooth
endoplasmic
reticulum
Rough
endoplasmic
reticulum
Centrioles
Golgi apparatus

4. BASIC PLANT CELL ORGANELLES

5. CELL OR PLASMA MEMBRANE
STRUCTURE
Made of double layer (bilayer) of:
phospholipids and proteins
Surrounds outside of ALL cells
FUNCTION (JOB)
Controls what enters or leaves the cell
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains

6. PHOSPHOLIPIDS
Heads contain glycerol & phosphate and are hydrophilic (attract water)
Tails are made of fatty acids and are hydrophobic (repel water)
Make up a bilayer where tails point inward toward each other
Can move laterally to allow small molecules (O2, CO2, & H2O to enter)

7. CELL MEMBRANE IN PLANTS
ADDITIONAL FUNCTION IN PLANTS:
Pushes out against the cell wall to maintain cell shape and protect

8. CELL WALL STRUCTURE Found in: plants Made of cellulose Fungi
Made of chitin
Bacteria
Made of peptidoglycan
FUNCTION (JOB)
Protect
Maintain shape
CELL WALL
Cell wall

9. PLANT CELL WALL
Two layers of cell wall
Primary Cell Wall (Outer )
Cellulose only
Secondary Cell Wall (Inner)
Cellulose & Lignin
Cell membrane is innermost layer

10. CYTOPLASM OF A CELL STRUCTURE Jelly-like substance Mostly water
aqueous solution
FUNCTION (JOB)
Provides a solution for chemical reactions to take place in
Holds organelles in place
cytoplasm

11. NUCLEUS STRUCTURE Contains the DNA in chromosomes
Bounded by a nuclear envelope (membrane) with pores
Usually the largest organelle
FUNCTION (JOB)
Controls the normal activities of the cell

12. NUCLEAR ENVELOPE Double membrane surrounding nucleus
Also called nuclear membrane
Contains nuclear pores for materials to enter & leave nucleus
Connected to the rough ER
Nuclear pores

13. INSIDE THE NUCLEUS The genetic material (DNA) is found
DNA is condensed & wrapped around proteins forming
as CHROMOSOMES in dividing cells
(TIGHTLY COILED)
DNA is spread out
And appears as CHROMATIN in non-dividing cells
(NOT TIGHTLY COILED)

14. Genes that make up the DNA molecule code for different proteins
WHAT DOES DNA DO?
DNA is the hereditary material of the cell
Genes that make up the DNA molecule code for different proteins

15. NUCLEOLUS STRUCTURE Inside nucleus Cell may have 1 to 3 nucleoli
Disappears when cell divides
FUNCTION (JOB)
Makes ribosomes (ribosomal subunits)

16. CYTOSKELETON STRUCTURE FUNCTION (JOB) Made of proteins
Microfilaments are threadlike & made of ACTIN
Microtubules are tubelike & made of TUBULIN
FUNCTION (JOB)
Network of fibers that help cell maintain cell shape
Also help move organelles around

17. Table 6.1

18. MITOCHONDRION (PLURAL = MITOCHONDRIA)
STRUCTURE
Bean shape
DOUBLE membrane
Has its own DNA
Folded inner membrane called CRISTAE (increases surface area for more chemical reactions)
Interior called MATRIX

19. MITOCHONDRION (CON’T)
FUNCTION (JOB)
“Powerhouse” of cell
Makes cellular energy (ATP)
More active cells like muscle cells have MORE mitochondria
Site of CELLULAR RESPIRATION (burning glucose)

20. INTERESTING FACT ---
Mitochondria Come from cytoplasm in the EGG cell during fertilization
Therefore …
You inherit your mitochondria from your mother!

21. CHLOROPLASTS STRUCTURE Bean shape DOUBLE membrane
Sacs (“coins”) called Thylakoids
Thylakoids stack called Granum (pl. =grana)
Stroma – gel in middle
Has its own DNA
FUNCTION (JOB)
Found only in autotrophs
Carries out photosynthesis

22.  RIBOSOMES STRUCTURE Made of PROTEINS and rRNA FUNCTION (JOB)
Make proteins
amino acids to make proteins
Process called TRANSLATION 

23. RIBOSOMES (CON’T)
Can be attached to Rough ER (proteins made exit cell) OR
Be free (unattached) in the cytoplasm
(proteins made stay INSIDE cell)

24. ROUGH ENDOPLASMIC RETICULUM (RER)
STRUCTURE
Has ribosomes on its surface
FUNCTION (JOB)
Helps to make proteins for export out of cell

25. SMOOTH ENDOPLASMIC RETICULUM (SER)
STRUCTURE
Has NO ribosomes on its surface
Usually attached to RER
FUNCTION (JOB)
Makes lipids (membranes)
Regulates calcium (muscles)
Destroys toxins (Liver)

26. ENDOMEMBRANE SYSTEM
Includes nuclear membrane connected to ER connected to cell membrane (transport)

27. GOLGI APPARATUS (BODIES)
STRUCTURE
Stacks of flat sacs
Looks like pancakes with syrup drips
“Pankcakes” NOT connected
FUNCTION (JOB)
Modify
Sort
Package
molecules from ER for storage OR transport in transport vesicles
Transport vesicle
“syrup bubble”

28. GOLGI BODIES flattened sacs
Have a receiving side (cis face) & a shipping or transporting side (trans face)
Receive proteins made by ER
Transport vesicles with modified proteins pinch off
CIS
TRANS
Transport vesicle

29. Membrane proteins and lipids
Are synthesized in the ER and Golgi apparatus
Figure 7.10
Transmembrane
glycoproteins
Secretory
protein
Glycolipid
Golgi
apparatus
Vesicle
glycoprotein
Membrane glycolipid
Plasma membrane:
Cytoplasmic face
Extracellular face
Secreted 4 1 2 3 ER

30. Moves fluids or small particles across cell surface
CILIA & FLAGELLA
FUNCTION (JOB) of Flagella
Moves WHOLE cells
FUNCTION (JOB) of Cilia
Moves fluids or small particles across cell surface

31. CILIA & FLAGELLA STRUCTURE Made of protein tubes called microtubules
Shorter
more numerous
Flagella
Longer
fewer (usually 1-3)

32. CENTRIOLES STRUCTURE FUNCTION (JOB)
Found only in animal cells inside CENTROSOMES
Paired structures near nucleus (“t” shape”
Made of microtubules
FUNCTION (JOB)
Appear during cell division
Help to pull chromosome pairs apart to opposite ends of the cell

33. CENTRIOLES & THE MITOTIC SPINDLE
**Made of MICROTUBULES (Tubulin)

34. LYSOSOMES STRUCTURE FUNCTION (JOB) They have a low pH
Contain hydrolytic digestive enzymes
FUNCTION (JOB)
Break down food, bacteria & old cell parts
Lyse & release enzymes to break down/recycle cell parts
Programmed for cell death (APOPTOSIS)
Think= “Lysol” cleaner
(a) Phagocytosis: lysosome digesting food
1 µm
Lysosome contains
active hydrolytic
enzymes
Food vacuole fuses with lysosome
Hydrolytic
enzymes digest
food particles
Digestion
Food vacuole
Plasma membrane
Lysosome
Digestive
Nucleus

35. VACUOLES STRUCTURE Fluid filled sacks for storage
Small or absent in animal cells
Plant cells have a large Central Vacuole
Surrounded by a membrane called a TONOPLAST
No vacuoles in bacterial cells

36. VACUOLES (CON’T) In plants, vacuoles store Cell Sap
FUNCTION (JOB)
In plants, vacuoles store Cell Sap
Includes storage of sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes

37. CONTRACTILE VACUOLE STRUCTURE Found in FRESHWATER
unicellular protists like paramecia
FUNCTION (JOB)
Regulate water intake by pumping out excess (homeostasis)
Keeps the cell from lysing (bursting)

38. PEROXISOMES FUNCTION (JOB)
Produce hydrogen peroxide (H2O2) and convert it to water
H2O2 is also toxic to a cell, and an enzyme made by the peroxisome can break down H2O2
Chloroplast
Peroxisome
Mitochondrion
1 µm
Figure 6.19

39. INTRACELLULAR JUNCTIONS
ANIMALS:
Tight junctions: btw neighboring cells; prevents leakage between cells
Desmosomes: riveted, anchoring junction; strong sheets of cells
Gap junctions: cytoplasmic channels; allows passage of materials or current between cells
INTRACELLULAR JUNCTIONS

40. INTRACELLULAR JUNCTIONS
PLANTS:
Plasmodesmata: cell wall “holes”; water and solute passage in plants
Similar to GAP JUNCTIONS in animals

41. NOW…LET’S PRACTICE 

42. LIMITS Diffusion limits cell size
Movement from higher [ ] to lower [ ]
Larger the distance, slower the diffusion rate
A cell 20 cm would require months for nutrients to get to the center
DNA limits cell size
larger cells need more DNA…Needs more of everything!
Most cells have just one nucleolus

43. Surface area to volume ratio limits size
Volume increase more rapidly than surface area.
Cell size doubles, 8x as much volume, but only 4x as much surface area