STPM Form 6 Biology - ER, Golgi Apparatus, Lysosome

1. Endoplasmic
Recticulum & Golgi
Apparatus

2. Nucleus & ER

3. Rough ER
 Ribosomes synthesize
excreted proteins
 Stored in cisternae or
vesicle
 Modify proteins
 Glycosylation of
proteins
 Delivery of membrane
associated proteins
 Often interacts with the
Golgi
 Salivary glands &
Pancreas

4. Rough Endoplasmic Reticulum
Functions:
starting point of
BIOSYNTHETIC
PATHWAY
Synthesis of:
• proteins
• carbohydrate chains
• phospholipids
PROTEIN
MODIFICATION

5. Membrane Factory

6. Rough ER vs Smooth ER

7. Smooth ER
 Storage and metabolism
of carbohydrates
 Detoxification reactions
in liver
 Synthesis and Transport
of Lipids

8. Synthesis of steroid hormones
 Endocrine cells
 gonad
 adrenal cortex

9. Glucose release from liver
 Gluconeogenesis
 Glycogen become
glucose

10. Sarcoplasmic recticulum
 Muscle cell
 Storage and release
Calcium ions

11. Golgi
Apparatus
MOLECULAR WAREHOUSE
AND FINISHING FACTORY

13. Most commonly found in

15. ER and Golgi
 Often adjacent in cytoplasm of
cell
 Both are membrane producers
 Membrane has sides
 Vesicles are produced inside
out
 Vesicle fuses with surface and
excreted proteins are released
and integral proteins are added
along with membrane
 ER often performs first steps of
modification that is later finished
in Golgi

16. Golgi apparatus
 Complex collection of membrane
 Has polarity
 Cis and trans surfaces
 Responsible for secretion
 Very prominent in cells that serve secretory
functions-such as epithelial cells
 Modifies structures previously synthesized in
the ER

18. Cytoplasmic membranes-1
movement of molecules (proteins, lipids,
neurotransmitters) from donor to acceptor compartment
–

20. Golgi Function
 Cis face is nearer the center of cell
 Cis face is often adjacent to ER
 Trans face is nearer the cell membrane
 Activity is directional
 Starts at cis face and moves to trans

21. Fig. 6-13
cis face
(“receiving” side of 0.1 µm
Golgi apparatus) Cisternae
trans face
(“shipping” side of TEM of Golgi apparatus
Golgi apparatus)

22. ER and Golgi
 Synthesis in ER but
modification in Golgi
 Modification of sugar
groups in enzymes
 Each cisternae contains
different enzymes

23. Examples of Golgi Function
 Replace sugars placed on glycoproteins
 Modification of phospholipid acylgroups and
head groups
 Molecule targeting and assembly
 Production of vesicles to delivery membrane
associated molecules and excreted molecules to
cell surface

24. Importance of Golgi
 The Golgi Body interacts mostly with the
Endoplasmic Reticulum, plasma membrane, and
lysosomes of the cell.
 Glycosylation in the Golgi Apparatus is the
mechanism that directs certain proteins to
their proper cellular locations.
 Without the Golgi body the cell would die, because
it wouldn’t be able to create lysosomes which
break down food for the cell.
 Also, proteins wouldn’t go where they need to
(lacking the transport modification).

26. Cell Wall Formation

28. Cell Renewal
 Cells and their molecules age and become less
effective
 An important cellular function is renewal
 Old molecules and organelles are recycled
 New phospholipids are produced for the
membrane
 Toxic molecules need to be collected and
detoxified
 Sometimes a cell needs to commit suicide
 Called autolysis or apoptosis

29. Vesicle Organelles
Perform many of the renewal functions
 Lysosome
 Peroxisome
 Glyoxisome

30. Lysosome
 Contains digestive enzymes used to
degrade macromolecules or
organelles
 Originates in ER but enzymes are
activated in Golgi
 ER produce enzymes and membranes
 Golgi modifies and activates enzymes
 Important in macrophages for
degradation of particles acquired
via phagocytosis
 Used to degrade organelles-
autophagy

31. Nucleus 1 µm
Intracellular digestion
pH 4-5
RNAase
DNAase
Protease
Carbohydrase Lysosome
Digestive
Lipase enzymes
Phosphatase Lysosome
Plasma
membrane Digestion
Food vacuole
(a) Phagocytosis

32. Vesicle containing 1 µm
two damaged organelles
Autophagy
Old and worn
out organelles
can be
recycled Mitochondrion
fragment
Peroxisome
fragment
Lysosome
Peroxisome
Mitochondrion Digestion
Vesicle
(b) Autophagy

33. Cell Death
 Sometimes used in development of
organism
 Hand development
 Certain cells are programmed to die at
appropriate times
 Defense against viral or intracellular
bacterial infections
 Self-destruct
 Program is started by T cells
 Apoptosis is often accomplished by
leaky or popping lysosomes

34. Peroxisomes
 Acts as detoxifying agent
 Convert toxic hydrogen
peroxide to water
 Peroxisomes are formed by
aggregation of lipids and
proteins (not formed in ER)
 Self-replicate using cytosol
protein
 Many are found in liver cells
 Degrade alcohols into peroxide
then into water and oxygen

35. Peroxisome
 Also responsible for degradation of fatty acids
in cytosol
 Modify fatty acids and phospholipids and
incorporate into peroxisome membrane

36. Glyoxysomes
 Specialized peroxisomes found
in plant seeds
 Recognize appropriate signals
and begin to degrade stored
fat in seed
 Fat is converted to sugars
which allows seedling to
sprout
 Once photosynthesis starts,
glyoxysomes degrade