8/12/2019 Pengantar Biologi Sel
1/81
Cell Structure and Function
8/12/2019 Pengantar Biologi Sel
2/81
Cell Size
8/12/2019 Pengantar Biologi Sel
3/81
8/12/2019 Pengantar Biologi Sel
4/81
4
Cell Structure Eukaryotic Cells
8/12/2019 Pengantar Biologi Sel
5/81
5
Eukaryotic Cells
8/12/2019 Pengantar Biologi Sel
6/81
6
Eukaryotic Cells
8/12/2019 Pengantar Biologi Sel
7/81
8/12/2019 Pengantar Biologi Sel
8/81
8/12/2019 Pengantar Biologi Sel
9/81
8/12/2019 Pengantar Biologi Sel
10/81
Lipids
Areas of the molecule enriched for "C" and "H" are hydrophobic.Fatty acids tails are composed of carbon and hydrogen and are
hydrophobic.
Phospholipids are amphipathic, and have hydrophilic andhydrophobic character in the same molecule. Interactions with watercause the phospholipids to form a bilayer, with hydrophobic fattyacid tails inside the bilayer and hydrophilic groups exposed to water.
This basic structure makes the membrane a barrier to hydrophilicmolecules. The interior of the membrane is fluid, with a viscosityabout equal to olive oil. Cholesterol in membranes alters fluidity.
8/12/2019 Pengantar Biologi Sel
11/81
Proteins
Proteins of membranes aredivided into two generalclasses: Integral membrane proteins Peripheral membrane
proteins
8/12/2019 Pengantar Biologi Sel
12/81
Integral membrane proteins
Membrane ion channels, enzyme linked membrane receptors,
and G-protein linked receptorsare integral membrane proteins that bindtheir ligand (signal) and then cause
second messengers to be produced insidethe cell.
8/12/2019 Pengantar Biologi Sel
13/81
Movement Across the Plasma Membrane
A few molecules move freely Water, Carbon dioxide, Ammonia, Oxygen
Carrier proteins transport some molecules Proteins embedded in lipid bilayer Fluid mosaic model describes fluid nature of
a lipid bilayer with proteins
8/12/2019 Pengantar Biologi Sel
14/81
8/12/2019 Pengantar Biologi Sel
15/81
Membrane Proteins
1. Channels or transporters Move molecules in one direction
2. Receptors Recognize certain chemicals
8/12/2019 Pengantar Biologi Sel
16/81
Membrane Proteins
3. Glycoproteins Identify cell type
4. Enzymes Catalyze production of substances
8/12/2019 Pengantar Biologi Sel
17/81
Membrane receptors generally function by binding the signal, or ligand andcausing the production of a second signal (second messenger) that causes acellular response. The diagram shows how the receptor for insulin functions.
8/12/2019 Pengantar Biologi Sel
18/81
Activation of protein kinases
8/12/2019 Pengantar Biologi Sel
19/81
Cytoplasm Viscous fluid containing organelles components of cytoplasm
Interconnected filaments & fibers Fluid = cytosol Organelles (not nucleus)
storage substances
8/12/2019 Pengantar Biologi Sel
20/81
8/12/2019 Pengantar Biologi Sel
21/81
21
Endomembrane System
Endomembrane system -a series of membranes throughout thecytoplasm-divides cell into compartments wheredifferent cellular functions occur
1. endoplasmic reticulum2. Golgi apparatus3. lysosomes
8/12/2019 Pengantar Biologi Sel
22/81
Endoplasmic Reticulum
Helps move substances within cells
Network of interconnected membranes
Two types
Rough endoplasmic reticulum Smooth endoplasmic reticulum
8/12/2019 Pengantar Biologi Sel
23/81
Rough Endoplasmic Reticulum
Ribosomes attached to surface Manufacture protiens Not all ribosomes attached to rough ER
May modify proteins from ribosomes
8/12/2019 Pengantar Biologi Sel
24/81
Smooth Endoplasmic Reticulum
No attached ribosomes Has enzymes that help build molecules
Carbohydrates Lipids
8/12/2019 Pengantar Biologi Sel
25/81
25
Endomembrane System
Rough endoplasmic reticulum (RER) -membranes that create a network ofchannels throughout the cytoplasm-attachment of ribosomes to themembrane gives a rough appearance-synthesis of proteins to be secreted, sentto lysosomes or plasma membrane
8/12/2019 Pengantar Biologi Sel
26/81
26
Endomembrane System
Smooth endoplasmic reticulum (SER) -relatively few ribosomes attached
-functions:-synthesis of membrane lipids-calcium storage
-detoxification of foreign substances
8/12/2019 Pengantar Biologi Sel
27/81
8/12/2019 Pengantar Biologi Sel
28/81
28
Endomembrane System
Golgi apparatus -flattened stacks of interconnectedmembranes-packaging and distribution of materials todifferent parts of the cell-synthesis of cell wall components
8/12/2019 Pengantar Biologi Sel
29/81
Golgi Apparatus
Involved in synthesis of plant cell wall Packaging & shipping station of cell
8/12/2019 Pengantar Biologi Sel
30/81
Golgi Apparatus Function
1. Molecules come in vesicles
2. Vesicles fuse with Golgi membrane
3. Molecules may be modified by Golgi
8/12/2019 Pengantar Biologi Sel
31/81
Golgi Apparatus Function(Continued)
4. Molecules pinched-off in separate vesicle
5. Vesicle leaves Golgi apparatus
6. Vesicles may combine with plasmamembrane to secrete contents
8/12/2019 Pengantar Biologi Sel
32/81
8/12/2019 Pengantar Biologi Sel
33/81
33
8/12/2019 Pengantar Biologi Sel
34/81
34
Endomembrane System
Lysosomes -membrane bound vesicles containingdigestive enzymes to break downmacromolecules-destroy cells or foreign matter that the cellhas engulfed by phagocytosis
8/12/2019 Pengantar Biologi Sel
35/81
Lysosomes
Contain digestive enzymes Functions
Aid in cell renewal Break down old cell parts Digests invaders
8/12/2019 Pengantar Biologi Sel
36/81
36
8/12/2019 Pengantar Biologi Sel
37/81
37
Endomembrane System
Microbodies -membrane bound vesicles
-contain enzymes-not part of the endomembrane system-glyoxysomes in plants contain enzymes
for converting fats to carbohydrates-peroxisomes contain oxidative enzymesand catalase
8/12/2019 Pengantar Biologi Sel
38/81
38
Endomembrane System
Vacuoles -membrane-bound structures with variousfunctions depending on the cell type
There are different types of vacuoles:-central vacuole in plant cells-contractile vacuole of some protists-vacuoles for storage
8/12/2019 Pengantar Biologi Sel
39/81
8/12/2019 Pengantar Biologi Sel
40/81
Mitochondria
Break down fuel molecules ( cellular respiration) Glucose Fatty acids
Release energy ATP
8/12/2019 Pengantar Biologi Sel
41/81
41
Mitochondria
Mitochondria -organelles present in all types ofeukaryotic cells-contain oxidative metabolism enzymes fortransferring the energy withinmacromolecules to ATP-found in all types of eukaryotic cells
8/12/2019 Pengantar Biologi Sel
42/81
42
Mitochondria
-surrounded by 2 membranes-smooth outer membrane
-folded inner membrane with layerscalled cristae -matrix is within the inner membrane
-intermembrane space is locatedbetween the two membranes-contain their own DNA
8/12/2019 Pengantar Biologi Sel
43/81
43
Mitochondria
8/12/2019 Pengantar Biologi Sel
44/81
8/12/2019 Pengantar Biologi Sel
45/81
45
Cytoskeleton
Cytoskeleton -network of protein fibers found in alleukaryotic cells-supports the shape of the cell-keeps organelles in fixed locations
-helps move materials within the cell
8/12/2019 Pengantar Biologi Sel
46/81
8/12/2019 Pengantar Biologi Sel
47/81
47
Cytoskeleton
8/12/2019 Pengantar Biologi Sel
48/81
Examples of the cytoskeleton inepithelial cells
In the epithelial (skin)cells of the intestine, allthree types of fibers arepresent. Microfilaments
project into the villi, givingshape to the cell surface.Microtubules grow out ofthe centrosome to the cell
periphery. Intermediatefilaments connectadjacent cells throughdesmosomes.
8/12/2019 Pengantar Biologi Sel
49/81
49
Extracellular Structures
Extracellular structures include:-cell walls of plants, fungi, some protists-extracellular matrix surrounding animalcells
8/12/2019 Pengantar Biologi Sel
50/81
50
Extracellular Structures
Cell walls-present surrounding the cells of plants,fungi, and some protists-the carbohydrates present in the cell wallvary depending on the cell type:
-plant and protist cell walls - cellulose-fungal cell walls - chitin
8/12/2019 Pengantar Biologi Sel
51/81
51
Extracellular Structures
Extracellular matrix (ECM) -surrounds animal cells-composed of glycoproteins and fibrousproteins such as collagen-may be connected to the cytoplasm viaintegrin proteins present in the plasmamembrane
8/12/2019 Pengantar Biologi Sel
52/81
52
Extracellular Structures
8/12/2019 Pengantar Biologi Sel
53/81
Centrioles
Pairs of microtubular structures Play a role in cell division
8/12/2019 Pengantar Biologi Sel
54/81
Molecule Movement & Cells
Passive Transport
Active Transport
Endocytosis
(phagocytosis & pinocytosis) Exocytosis
8/12/2019 Pengantar Biologi Sel
55/81
Passive Transport
No energy required
Move due to gradient differences in concentration, pressure, charge
Move to equalize gradient High moves toward low
8/12/2019 Pengantar Biologi Sel
56/81
Types of Passive Transport
1. Diffusion
2. Osmosis
3. Facilitated diffusion
8/12/2019 Pengantar Biologi Sel
57/81
Diffusion
Molecules move to equalize concentration
8/12/2019 Pengantar Biologi Sel
58/81
Osmosis
Special form of diffusion
Fluid flows from lower solute concentration
Often involves movement of water
Into cell Out of cell
8/12/2019 Pengantar Biologi Sel
59/81
Solution Differences & Cells solvent + solute = solution Hypotonic
Solutes in cell more than outside Outside solvent will flow into cell
Isotonic Solutes equal inside & out of cell
Hypertonic Solutes greater outside cell Fluid will flow out of cell
8/12/2019 Pengantar Biologi Sel
60/81
8/12/2019 Pengantar Biologi Sel
61/81
Facilitated Diffusion
Differentially permeable membrane
Channels (are specific) help moleculeor ions enter or leave the cell Channels usually are transport proteins
(aquaporins facilitate the movement ofwater) No energy is used
8/12/2019 Pengantar Biologi Sel
62/81
Process of Facilitated Transport
Protein binds with molecule Shape of protein changes Molecule moves across membrane
8/12/2019 Pengantar Biologi Sel
63/81
Active Transport
Molecular movement Requires energy (against gradient) Example is sodium-potassium pump
8/12/2019 Pengantar Biologi Sel
64/81
8/12/2019 Pengantar Biologi Sel
65/81
Endocytosis
Movement of large material Particles
Organisms Large molecules
Movement is into cells
Types of endocytosis bulk-phase (nonspecific) receptor-mediated (specific)
8/12/2019 Pengantar Biologi Sel
66/81
Process of Endocytosis
Plasma membrane surrounds material Edges of membrane meet Membranes fuse to form vesicle
8/12/2019 Pengantar Biologi Sel
67/81
Forms of Endocytosis
Phagocytosis cell eating Pinocytosis cell drinking
8/12/2019 Pengantar Biologi Sel
68/81
Exocytosis
Reverse of endocytosis Cell discharges material
8/12/2019 Pengantar Biologi Sel
69/81
Exocytosis
Vesicle moves to cell surface Membrane of vesicle fuses Materials expelled
8/12/2019 Pengantar Biologi Sel
70/81
8/12/2019 Pengantar Biologi Sel
71/81
8/12/2019 Pengantar Biologi Sel
72/81
Chemical Signals
What is the difference between hormones andparcrine factors?
8/12/2019 Pengantar Biologi Sel
73/81
Signal Transduction
What elements are involved in cell signaling?
Importance of signal
8/12/2019 Pengantar Biologi Sel
74/81
Importance of signaltransduction
Facilitates cell-cell signaling Coordination of growth and differentiation Inducing metabolic responses to
environmental factors Involves extracellular signaling molecules,
their interaction with target cells, and
subsequent intracellular events
Signal transduction - general
8/12/2019 Pengantar Biologi Sel
75/81
g gsteps
1) Synthesis and release of signalingmolecules
2) Transport of signal to target cell 3) Detection of signal by a specific
receptor protein 4) Intracellular events, often mediated
by second messengers, that changemetabolism or gene expression
5)Termination of the signal andresponse
8/12/2019 Pengantar Biologi Sel
76/81
Will focus on steps 3 to 5
Step 3 - involves cell-surface receptors Four main types:
Ion-channel receptors (e.g., acetylcholinereceptor)
G protein-linked receptors Receptors associated with tyrosine kinases
Receptors with intrinsic enzymatic activity
8/12/2019 Pengantar Biologi Sel
77/81
8/12/2019 Pengantar Biologi Sel
78/81
G protein-linked receptors
Overview: Signal molecule binds to recepter Receptor activates a G protein
Activated G protein activates an effectorenzyme that produces a second messenger
Second messenger molecule induces
metabolic changes
General structure of G protein-
8/12/2019 Pengantar Biologi Sel
79/81
plinked receptors
Seven transmembrane alpha helices Loop between helices 5&6 involved in
interactions with G protein
Similar in structure to rhodopsin
8/12/2019 Pengantar Biologi Sel
80/81
G Protein-Linked Receptors
What is a G protein? What does this type of receptor look like?
8/12/2019 Pengantar Biologi Sel
81/81