Chapter 3 Cells

1
Chapter 3 Cells
2
Chapter 3 Cells

• Overview of the Cellular Basis of Life
• Historical Perspectives
• 1665, described
  and named cells
• 1839, Schleiden Schwann all living things
  consist of cells
• 1858, all cells come from cells
• Cell Theory
• A cell is the basic structural functional unit
  of living organism
• Health depends on both individual and the
  collective activities of its cells

Robert Hooke
Rudolf Vichow
Vichow was right!
3

• Cell Overview
• outer boundary
• Cytoplasm
• semifluid medium
• membrane bound structures with
  specific functions suspended in the cytosol
• membrane bound repository of genetic
  material
• Not all cells have at maturity
• Yes, some cells have more than one in humans.

Plasma membrane
Cytosol
Organelles
Nucleus
4
The Generalized Cell

• The Plasma Membrane Structure
• The Model (Singer Nicolson)
• Phospholipid Bilayer
• head
• tails
• (transmembrane) with hydophilic portions
  protruding into aqueous environments these can
  float freely in the membrane then can have
  whole through them (carriers)!
• attached to the surface membrane
  may anchor the cytoskeleton (cytoplasmic) or be
  enzymatic

Fluid Mosaic
Hydrophilic
Hydrophobic
Integral Proteins
Peripheral Proteins
5

• Glycocalyx sugar covering Cell-cell
  recognition markers and delivery ports for
  endocytosis

6
Fig. 3.4
7

• Specialization of the Plasma Membrane
• Microvilli
• Membrane Junctions
• Tight Junctions
• Desmosomes

Gap junctions
8

• Why do we have to know this little stuff?

Pemphigus vulgaris
9
Organelles

• Small specialized structures for particular
  functions
• Most have that separates
  interior of organelles from cytoplasm
• Related to specific structure and function of the
  cell

membranes
10
Centrioles

• In specialized zone near nucleus Centrosome
• Each unit consists of microtubules
• Before cell division, centrioles ,
  move to ends of cell and become spindle fibers

divide
11
Cilia

• Appendages projecting from cell surfaces
• Capable of
• Moves materials over the cell surface

movement
12
Flagella

• Similar to cilia but longer
• Usually only exists per cell
• Move the cell itself in wavelike fashion
• Example Sperm cell

one
13
Microvilli

• Extension of plasma membrane
• the cell surface area
• Normally many on each cell
• One tenth to one twentieth size of cilia
• Do not move

Increase
14
Ribosomes
protein

• Sites of synthesis
• Composed of a large and small subunit
• Types
• Free
• Attached to

endoplasmic reticulum
15
Endoplasmic Reticulum

• Types
• Attached ribosomes
• Proteins produced and modified within
• Not attached ribosomes
• Manufacture lipids
• Cisternae Interior spaces isolated from rest of
  cytoplasm

Rough (RER)
Smooth (SER)
16
Golgi Apparatus

• Modification, packaging, distribution of proteins
  and lipids for secretion or internal use
• Flattened membrane sacs stacked on each other

17
Function of Golgi Apparatus
18
Action of Lysosomes
19
Peroxisomes and Proteasomes

• Peroxisomes
• Smaller than lysosomes
• Contain enzymes to break down fatty and amino
  acids
• is a
  by-product of breakdown
• Proteasomes
• Consist of large protein complexes
• Include several enzymes that break down and
  recycle proteins in cell

Hydrogen peroxide
20
Mitochondria
Cellular energy

• Provide for cell
• Major site of ATP synthesis
• Membranes
• Cristae Infoldings of inner membrane
• Substance located in space
  formed by inner membrane

Matrix
21
Nucleus

• DNA dispersed throughout
• Consists of
• Nuclear envelope Separates nucleus from
  cytoplasm and regulates movement of materials in
  and out
• Condenses to form
  chromosomes during cell division
• Nucleolus Assembly site of large and small
  ribosomal units

Chromatin
22
The Cell in Detail

• You should be able to identify from a picture,
  drawing or slide the following cell structures
  and describe their functions. (Table 3.1)
• Cell membrane
• Cytoplasm
• cytosol
• Nucleus
• Nucleolus
• Chromosomes

23

• Ribosome
• Endoplasmic Reticulum

24

• Golgi Apparatus
• Cytoskeletal Elements
• Microtubules
• Microfilaments
• Intermediate Filaments
• Centrioles

25

• Mitochondria
• Cilia and Flagella
• vs. microvilli

26

• Lysosomes
• Peroxisomes

27
Extracellular Materials

• Extracellular Materials substances outside of
  cells
• extracellular fluid (ECF)
  includes interstitial fluid blood plasma,
  cerebral spinal fluid
• are secreted by
  cells into the body fluid(s)
• Cell glue of protein and
  polysaccharides that bind body cells together
• Summary cells are in an extracellular fluid
  called interstitial fluid that is derived from
  the blood and also contains cellular products

Body Fluids
Cellular Secretions
Extracellular matrix
28
Diffusion

• Movement of solutes from an area of higher
  concentration to lower concentration in solution
• Concentration or density gradient
• Difference between two points
• How easily a liquid flows
• Movie

Viscosity
29
Diffusion
30
The Plasma Membrane Functions

• Membrane Transport 1
• processes move through the cell membrane
  without any energy input
• Diffusion

Passive
Simple
31

• Diffusion
• Na and K channels
• Osmosis
• What factors influence the rate of diffusion?

Facilitated
32
Osmosis

• The diffusion of water down its concentration
  gradient through a selectively permeable
  membrane.
• Aquaporins
• Total of solutes
  (particles)
• Tonicity tension of a solution imparted by
  solutes
• So, the water on each side of a membrane can be
  described in relative terms as
• Isotonic
• Hypotonic
• Hypertonic

Osmolarity
33
(No Transcript)
34
(No Transcript)
35

• Movie

36
Some Questions

• During osmosis, does water flow from
• the isotonic to the isotonic environment?
• What is dynamic equilibrium?
• the hypertonic to the hypotonic environment?
• the hypotonic to the hypertonic environment?
• the isotonic to the hypertonic environment?
• If body fluids have a 0.9 NaCl
• What happens when a body cell is exposed to a
  1.0 NaCl?
• What happens when a body cell is exposed to a
  0.8 NaCl?

37
(No Transcript)
38

• Membrane Transport 2
• Active processes
• Move substances uphill or against their
  concentration gradient most often is
  the energizer for this process
• Active Transport is the mechanism
• an
  mechanism

ATP
Na - K ATPase
antiport
39
(No Transcript)
40

• Na - K ATPase 1
• Na - K ATPase 2

41

• Secondary Active transport
• Na higher in ECF Na - K ATPase
• Na back down its
  gradient, through facilitated transport channel
  with a Glucose molecule a

diffuses
symport
42

• Vesicular Transport
• Endocytosis
• Phagocytosis
• Pinocytosis
• Bulk-phase
• Receptor-mediated
• Exocytosis Movie

43

• Membrane Transport 3
• liquid and substances pass
  through holes in a partition.
• Glomerular capillaries in the kidneys allow
  passage of everything from the blood except most
  proteins and blood cells.

Filtration
44

• Is this an example of passive or active
  transport, or filtration? (fig. 3.8)

45
Resting Membrane Potential

• The cell membrane is more permeable to some
  molecules than to others.
• Membrane Potentials
• A , or electrical potential due to the
  separation of charges by the cell membrane.
• Resting Membrane Potential occur in all cells due
  to
• RMP ranges from -20 to -200 millivolts (mV)
• state of the cell

Voltage
Concentration Gradients
Active Transport Pumps
Electrical Gradients
Polarized
46

• Inside of the cell is electrically neutral
• Outside of the cell is electrically neutral
• But,
• higher outside of cell
• Membrane impermeable to Na
• higher inside of cell
• Membrane permeable to K
• K diffuses down its concentration gradient
• This concentration difference make a loss of
  positive charges inside the cell
• maintains this imbalance How?

Na
K
Na - K ATPase
47
(No Transcript)
48

• But there is more,
• reinforce the
  ion concentration on the inside and outside of
  the cell
• Electrical forces resist K diffusion out of the
  cell
• An produces the RMP

Electric charges
electrochemical gradient
Fig. 9.7
49

• Na - K ATPase 1
• Na - K ATPase 2

50
Assignments

• Describe the structural characteristic of cells
  that are highly specialized to do the following
  (a) synthesize and secrete proteins (b) actively
  transport substances into the cell (c)
  synthesize lipids and (d) phagocytize foreign
  substance.
• The transport of glucose into and out of most
  cells, such as muscle and fat cells, occurs by
  facilitated diffusion. Once glucose enters a
  cell, it is rapidly converted to other molecules,
  such as glucose-6-phosphate or glycogen. What
  effect does this conversion have on the ability
  of the cell to acquire glucose? What affect does
  this have on osmosis? Explain.
• What is cystic fibrosis? What are the specific
  defects that result in this disorder?
• Describe the structure and function of each
  cellular organelle.
• Case Study 3.x

51
(No Transcript)