1 Chapter 7 Cellular Structure and Function 7.1 Cell Discovery and Theory.
-
Upload
jonah-parrish -
Category
Documents
-
view
217 -
download
2
Transcript of 1 Chapter 7 Cellular Structure and Function 7.1 Cell Discovery and Theory.
1
Chapter 7 Cellular Structure and Function
7.1 Cell Discovery and Theory
2
The History of the Cell Theory
Cells are the basic units of living things
Before microscopes people believed diseases were caused by curses and supernatural spirits (wrath of God)
The idea that a living thing like a bacteria could cause disease or infection never occurred. Why?
3
Development of the Light Microscope
Today's microscope is a compound microscope with two lenses Eyepiece lens Objective lens
Can magnify 1500 times
4
Simple Light Microscope
Developed by Anton van Leeuwenhoek in the mid 1600
One lens Much like a
magnifying glass
5
The Cell Theory
Robert Hook First to use the
term “cell” Looked a cork
under a microscope, saw the cell walls
6
Robert Hook
Contemporary of Anton van Leeuwenhoek
English Published and
encouraged others to use microscopes
7
Matthias Schleiden
1838 German botanists Examined plants of
all types All plants are
made of cells
8
Theodore Schwann
1839 German zoologist Contemporary of
Schleidens Examined animal
tissues of many types
All animals are made of cells
9
Rudolph Virchow
1855 German physician All cells come from
preexisting cells
10
The Cell Theory
1. All organisms are composed of one or more cells
Unicellular or multicellular
2. The cell is the basic unit of organization of all organisms
Structure Function
3. All cells come from preexisting cells
11
Technology Since the 1800’s
Compound light microscopes continued to improve so that bacteria were able to be classified
Most magnification possible with light microscopes cannot see inner cell parts
12
Electron Microscopes
Developed in the 1940’s Uses magnets to focus a beam of
electrons (in place of light) Can magnify 500,000X Several types
Scanning: looks at surface; get 3-D Transmission: looks at interior Scanning-Tunneling: atoms on surface
13
Microscope Aids
Both light and electron microscopes use dyes and stains which helps to contrast cell and parts
Most dyes and stains kill the cells Most specimens of electron
microscopes need to be in a vacuum and/or coated with gold
14
Two Basic Cell Types
Prokaryote Have plasma
membrane No internal membrane
bound structures Unicellular Smaller in size No specialization Example: bacteria
Eukaryote Have plasma
membrane Internal membrane
bound structures Unicellular and
multicellular Larger size Much specialization Example: animal
15
Two Basic Cell Types
Prokaryote Eukaryote
16
Two Basic Cell Types
17
Chapter 7 Cellular Structure and Function
7.2 The Plasma Membrane
18
Plasma Membrane Diagram
19
Plasma Membrane Micrograph
20
Plasma Membrane Structure
Made of phospholipid bilayer
Polar ends are hydrophilic
Nonpolar ends are hydrophobic
21
Plasma Membrane Function
Job of plasma membrane is homeostasis- maintain balance
For cells to survive they must keep the inside in and the outside out, yet allow some materials to move into and out of the cell
22
Structure Fits Function
The structure of the plasma membrane (how it is put together) allows the plasma membrane its function or job, selective permeability
Selective permeability: the ability to allow some materials into or out of the cell but not other materials
23
Selective Permeability
Out side of cell is different from inside of cell
24
Structure Fits Function
Both the inside of the cell and the outside are water environment so the hydrophilic ends face in and out
The hydrophobic fatty tails are in the middle so that materials can’t pass through easily
25
Structure Fits Function
Role of proteins in plasma membrane Channels or tunnels for substances
to pass through with specific fit Identification of organism and tissue
type Signal sending proteins Provide support for the
phospholipids
26
Plasma Membrane Proteins
27
Plasma Membrane
Cholesterol stabilizes the plasma membrane in animal cells
Animal cells have no cell wall as do plant cell
High blood cholesterol is a risk factor for heart disease and stroke
Animals (including us) produce cholesterol for the stabilization of the cell membrane
28
Fluid Mosaic Model
29
Fluid Mosaic Model
FLUID: Plasma membrane in constant motion with the phospholipids of one layer moving one direction and the phospholipids of the other layer moving in the opposite direction
MOSAIC: something consisting of a number of different things of different types
30
Chapter 7 Cellular Structure and Function
7.3 Structures and Organelles
31
Cellular Boundaries
Plant Cell outer most part is the cell wall; plasma membrane is inside of the cell wall
Also fungi, algae and other Kingdom Protista organisms
Animal Cell outer most part is the plasma membrane
Also protozoans (Kingdom Protista)
32
Cell Wall
Functions to protect and support NOT selectively permeable Porous: let anything in Plant cell wall made of cellulose
(wood)
33
Plant Cell Wall
34
Nucleus
Controls all cell activities
Contains information to make proteins; all parts of the cell depend on proteins to do its job
35
Nucleus
Contains DNA in strands known as chromatin (chromosomes are chromatin that is condensed and visible during cell reproduction)
36
Nucleolus
Found in the nucleus
Organelle that makes ribosomes
Ribosomes are sites where proteins are manufactured
37
Ribosomes
Ribosomes are unique because they do not have a membrane around them
Found in prokaryotes and eukaryotes
Look like pepper on the ER (spaghetti)
38
Nuclear Membrane
Also called Nuclear Envelope
Surrounds the nucleus
Same composition as the plasma membrane
Contains pores to allow large materials to pass out (ribosomes and RNA)
39
Cytoplasm
All the gelatinous material with the organelles inside the cell between the nucleus and the cell membrane
Cytosol is that part of the cytoplasm that is liquid
40
Organelles for Assembly, Transport and Storage
Endoplasmic Reticulum (ER) Golgi Apparatus Vacuoles Lysosomes
All have phospholipid bilayer membrane structure
41
Endoplasmic Reticulum (ER)
Folded membrane like an accordion for workspace
Rough ER contains ribosomes for protein production
Smooth ER (No ribosomes) for lipid production
Tube-like for transport of materials
42
Golgi Apparatus
Takes protein from the ER and makes it ready to be transported
Like UPS, packages it and gives it a destination address
43
Vacuoles
Large central vacuole in plant cells to store water
Smaller vacuoles for storage of food, waste, water, enzymes and other substances in both plant and animal cells
44
Lysosomes
Double membrane bound sac containing digestive enzymes
Digests food particles, engulfed viruses and bacteria, and worn out cell parts
Can fuse with vacuole to digest contents of vacuole
45
Energy Transformers
Chloroplasts Mitochondria
Both have phospholipid bilayer membrane structure
46
Chloroplasts
Capture light energy and produce food to be used later
Pigment chlorophyll give plants their green color
Other plastids store starch, lipids and other pigments
47
Chloroplasts
Double membrane Clear outer Folded inner:
thylakoid Stacks of
membranes sacs grana and liquid stroma
Site of photosynthesis
48
Mitochondria
Break down food to release energy
Found in eukaryotes
49
Mitochondria
Double membrane Outer Folded Inner to
increase membrane space
Some cells need much energy and have hundreds of mitochondria; other cell have few mitochondria because these cells use little energy
Site of cellular respiration
50
Structures for Support and Locomotion
Cytoskeleton Cilia Flagella
51
Cytoskeleton
Internal framework in the cell to keep the organelles in place
Maintains the cell’s shape
Made of microtubules (hollow) and microfilaments (solid) protein fibers
Shown in green
52
Centrioles
Made of groups of microtubules
Function in cell division (Ch. 9)
53
Cilia and Flagella
Enclosed by plasma membrane
Used for locomotion and feeding
Made of pair of microtubules surrounded by 9 additional pairs
54
Cilia
Short numerous hair like projections
Beat like oars on a boat
Line our respiratory system
55
Flagella
Tail like structure that is whip like
May have one flagella or several
Mostly used for locomotion
56
Chapter 7 Cellular Structure and Function
7.4 Cellular Transport
57
Passive Transport
NO energy expended by cell
Diffusion Facilitated
diffusion Osmosis
58
Diffusion
All molecules are in constant motion; called Brownian Motion
The high the temperature the faster the motion because they have more energy
Diffusion is the net movement of particles from higher concentration to lower concentration because of this movement of particles
Diffusion is slow because it is a random process
59
60
Rates of Diffusion
1. Concentration of substances involved More concentrated substances speed up rate of
diffusion
2. Energy by temperature or agitation Increased temperature speeds up rate of
diffusion Agitation or stirring speeds up rate of diffusion
3. Pressure Increased pressure speeds up diffusion because
pressure increases molecular movement
61
Dynamic Equilibrium
Equilibrium is reached when there is no net concentration change
Dynamic because Brownian motion continues
62
Diffusion in Living Systems
In living things materials must diffuse into and out of cells all the time
Concentration gradient exists so that substances will move into the cell until there is the same number on each side
Liquids, solids and gasses can diffuse into and out of a cell
63
Facilitated Diffusion
Diffusion of materials through proteins in cell membranes
NO energy required
Common for sugars and amino acids
64
Osmosis
Diffusion of water through a cell membrane
Cell membranes are selectively permeable
NO energy expended by the cell Moves water from high
concentration to low concentration Must occur for homeostasis to occur
65
Control of Osmosis
Unequal distribution of particles on either side of a selectively permeable membrane
Water moves through the membrane until equilibrium is reached (no net change)
66
Cells in Solutions
Isotonic Solution = same solutes Hypotonic Solution = lower solutes Hypertonic Solution = higher solutes
67
Cells in Isotonic Solutions
Isotonic solutions have the same solute concentration as the cell, so water moves in and out at the same rate; no osmosis; no net change
Dissolved substances outside the cell equals dissolved substances inside the cell
Examples: Normal saline IV solution (0.9% salt) and tap water in most areas
68
Cells in Hypotonic Solutions
Dissolve substances lower outside the cell than inside the cell
Water moves into the cell; cell swells Animal cell bursts Plant cell becomes more firm (higher
turgor pressure); reason why plants are sprayed at grocery store
Example: Distilled water
69
Cells in Hypotonic Solutions
70
Cells in Hypertonic Solutions
Dissolved substances higher outside the cell than inside the cell
Water leaves the cell; cell shrinks Animal cell wrinkled (reason why meat
is salted after cooking) Plant cell plasmolyzed; cell membrane
moves away from cell wall Example: salt water, syrup
71
Cells in Hypertonic Solutions
72
Cells in Solutions
73
Comparing Plant and Animal Cells
74
Active Transport
ENERGY used by the cell Carrier proteins with a SPECIFIC FIT
with a specific molecule Bringing substances into the cell
against the concentration gradient
75
Active Transport
When molecule fits with carrier protein the carrier protein molecule changes shape to allow the molecule to move into or out of the cell
When movement complete, the carrier protein changes back to original shape for another molecule
76
Active Transport
Also used to rid the cell of materials against the concentration gradient
Takes energy to use a pump
Much of your cell’s energy is expended in the sodium-potassium pump (2 K+ in 3 Na+ out)
77
Large Materials Into Cells
Endocytosis, getting large materials INTO the cell
Cell expends energy
Engulfs and forms a vacuole
Example: white blood cells engulfing a bacteria
78
Large Materials Out of Cells
Exocytosis: large materials out of a cell
Cell expends energy
Example: secretions or hormones
Example: waste products
79