what are cells? how many types are there? how cells are put together? chapter 4 we shall cover the...
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What are cells?How many types are there?How Cells Are Put Together?
What are cells?How many types are there?How Cells Are Put Together?
Chapter 4
We shall cover the first part today and the rest next time
Chapter 4
We shall cover the first part today and the rest next time
It is the….
Smallest unit of life
Can survive on its own (or can do so if it
has to)
Is highly organized for metabolism
Senses and responds to environment
Has potential to reproduce
It is the….
Smallest unit of life
Can survive on its own (or can do so if it
has to)
Is highly organized for metabolism
Senses and responds to environment
Has potential to reproduce
What is a CellWhat is a Cell
Structure of CellsStructure of Cells
All start out life with: Plasma membrane Region where DNA
is kept Cytoplasm
All start out life with: Plasma membrane Region where DNA
is kept Cytoplasm
Two types of cells exist:
ProkaryoticEukaryotic
Why Are Cells So Small?Why Are Cells So Small?
Cells absorb stuff across their membranes…
Surface-to-volume ratio
The bigger a cell is, the less surface area there
is per unit volume
Above a certain size, material cannot be moved
in or out of cell fast enough
Cells absorb stuff across their membranes…
Surface-to-volume ratio
The bigger a cell is, the less surface area there
is per unit volume
Above a certain size, material cannot be moved
in or out of cell fast enough
Remember ElephantsRemember Elephants
Why don’t we see 90 foot high elephants. It would be better for them.
They would need ears as big as sail ship sails to cool themselves based on their lack of surface area…
Why don’t we see 90 foot high elephants. It would be better for them.
They would need ears as big as sail ship sails to cool themselves based on their lack of surface area…
Mid 1600s - Robert Hooke observed and
described cells in cork
Late 1600s - Antony van Leeuwenhoek
observed sperm, microorganisms
Mid 1600s - Robert Hooke observed and
described cells in cork
Late 1600s - Antony van Leeuwenhoek
observed sperm, microorganisms
Early DiscoveriesEarly Discoveries
Cell TheoryCell Theory
1) Every organism is composed of one or more
cells
2) Cell is smallest unit having properties of life -
therefore viruses are not considered living
3) Continuity of life arises from growth and division
of single cells - we are all related to the very first
life forms on this Planet
1) Every organism is composed of one or more
cells
2) Cell is smallest unit having properties of life -
therefore viruses are not considered living
3) Continuity of life arises from growth and division
of single cells - we are all related to the very first
life forms on this Planet
Create detailed images of
something that is otherwise too
small to see
Light microscopes Simple or compound
Electron microscopes Transmission EM or Scanning EM
Create detailed images of
something that is otherwise too
small to see
Light microscopes Simple or compound
Electron microscopes Transmission EM or Scanning EM
Tools of Biology - MicroscopesTools of Biology - Microscopes
Limitations of Light MicroscopyLimitations of Light Microscopy
Wavelengths of light are 400-750 nm
If a structure is less than one-half of a wavelength long, it will not be visible
Light microscopes can resolve objects down to about 200 nm in size
Wavelengths of light are 400-750 nm
If a structure is less than one-half of a wavelength long, it will not be visible
Light microscopes can resolve objects down to about 200 nm in size
Tools - Electron MicroscopyTools - Electron Microscopy
Uses streams of accelerated electrons rather than light
Electrons are focused by magnets rather than glass lenses
Can resolve structures down to 0.5 nm
Uses streams of accelerated electrons rather than light
Electrons are focused by magnets rather than glass lenses
Can resolve structures down to 0.5 nm
Electron Microscope
Electron Microscope
incoming electron beam
condenser lens (focuses a beam of electrons onto specimen)
specimen
objective lens
intermediate lens
projector lens
viewing screen (orphotographic film)
Main component of cell membranes
Gives the membrane its fluid properties
Two layers of phospholipids
Main component of cell membranes
Gives the membrane its fluid properties
Two layers of phospholipids
The cells skin - The Lipid Bilayer
The cells skin - The Lipid Bilayer
Fluid Mosaic ModelFluid Mosaic Model
Membrane is a mosaic of Phospholipids Glycolipids Sterols Proteins
Most phospholipids and some proteins can drift
through membrane MOVIE link above
Membrane is a mosaic of Phospholipids Glycolipids Sterols Proteins
Most phospholipids and some proteins can drift
through membrane MOVIE link above
Membrane ProteinsMembrane Proteins
Adhesion proteins - GLUES
Communication proteins - INFO
Receptor proteins - INBOUND
Recognition proteins
Adhesion proteins - GLUES
Communication proteins - INFO
Receptor proteins - INBOUND
Recognition proteins
Continue…How are cells put together?
Continue…How are cells put together?
Watch me please!Watch me please!
Include just Archaea and eubacteria
DNA is not enclosed in nucleus
DNA is not enclosed in nucleus
DNA is not enclosed in nucleus
DNA is not enclosed in nucleus
Generally the smallest, simplest cells
No organelles
Include just Archaea and eubacteria
DNA is not enclosed in nucleus
DNA is not enclosed in nucleus
DNA is not enclosed in nucleus
DNA is not enclosed in nucleus
Generally the smallest, simplest cells
No organelles
Prokaryotic CellsProkaryotic Cells
Prokaryotic StructureProkaryotic Structure
bacterial flagellum pilusplasma membrane
DNA in nucleoid region
cytoplasm, with ribosomes
Most prokaryotic cells have a cell wall outside the plasma membrane, and many have a thick, jellylike capsule around the wall.
bacterial flagellum
Eukaryotic CellsEukaryotic Cells
Have a nucleus and other organelles
Eukaryotic organisms Plants Animals Protistans Fungi
Have a nucleus and other organelles
Eukaryotic organisms Plants Animals Protistans Fungi
Keeps the DNA molecules of eukaryotic cells separated from metabolic machinery of cytoplasm
Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells
Keeps the DNA molecules of eukaryotic cells separated from metabolic machinery of cytoplasm
Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells
WHY HAVE AN NUCLEUS?Functions of Nucleus
WHY HAVE AN NUCLEUS?Functions of Nucleus
Nuclear EnvelopeNuclear Envelope
Two outer membranes (lipid bilayers) Innermost surface has DNA attachment sites Pores span bilayer
Two outer membranes (lipid bilayers) Innermost surface has DNA attachment sites Pores span bilayer
one of two lipid bilayers (facing nucleoplasm)
NUCLEAR ENVELOPE
one of two lipid bilayers (facing nucleoplasm)
nuclear pore (protein complex that spans both lipid bilayers)
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
http://video.search.yahoo.com/video/play?vid=1079578458&vw=g&b=0&pos=1&p=endomembrane+system&fr=yfp-t-501
SEE IT!
Group of related organelles in which lipids are assembled and new polypeptide chains are modified
Products are sorted and shipped to various destinations
POST OFFICE OF THE CELL
Group of related organelles in which lipids are assembled and new polypeptide chains are modified
Products are sorted and shipped to various destinations
POST OFFICE OF THE CELL
Canals inside cellsEndoplasmic Reticulum (ER)
Canals inside cellsEndoplasmic Reticulum (ER)
Components of Endomembrane System
Components of Endomembrane System
Endoplasmic reticulum
Golgi bodies
Vesicles
Endoplasmic reticulum
Golgi bodies
Vesicles
Endoplasmic ReticulumEndoplasmic Reticulum
In animal cells, continuous with nuclear
membrane
Extends throughout cytoplasm
Two regions: rough and smooth
In animal cells, continuous with nuclear
membrane
Extends throughout cytoplasm
Two regions: rough and smooth
Rough ERRough ER
Arranged into flattened sacs Ribosomes on surface give it a
rough appearance Some polypeptide chains enter
rough ER and are modified Cells that specialize in secreting
proteins have lots of rough ER
Arranged into flattened sacs Ribosomes on surface give it a
rough appearance Some polypeptide chains enter
rough ER and are modified Cells that specialize in secreting
proteins have lots of rough ER
Smooth ERSmooth ER
A series of interconnected tubules No ribosomes on surface Lipids assembled inside tubules Smooth ER of liver inactivates
wastes, drugs Sarcoplasmic reticulum of muscle
is a specialized form
A series of interconnected tubules No ribosomes on surface Lipids assembled inside tubules Smooth ER of liver inactivates
wastes, drugs Sarcoplasmic reticulum of muscle
is a specialized form
Golgi BodiesGolgi Bodies
Put finishing touches on proteins and lipids that arrive from ER
Package finished material for shipment to final destinations
Material arrives and leaves in vesicles
Put finishing touches on proteins and lipids that arrive from ER
Package finished material for shipment to final destinations
Material arrives and leaves in vesicles
VesiclesVesicles
Membranous sacs that move
through the cytoplasm
Lysosomes
Peroxisomes
Membranous sacs that move
through the cytoplasm
Lysosomes
Peroxisomes
Central VacuoleCentral Vacuole
Fluid-filled organelle Stores amino acids, sugars, wastes As cell grows, expansion of vacuole as
a result of fluid pressure forces cell wall to expand
In mature cell, central vacuole takes up 50-90 percent of cell interior
Fluid-filled organelle Stores amino acids, sugars, wastes As cell grows, expansion of vacuole as
a result of fluid pressure forces cell wall to expand
In mature cell, central vacuole takes up 50-90 percent of cell interior
ATP-producing powerhouses
Double-membrane system
Carry out the most efficient energy-
releasing reactions
These reactions require oxygen
Similar to Ancient bacteria in chemistry
ATP-producing powerhouses
Double-membrane system
Carry out the most efficient energy-
releasing reactions
These reactions require oxygen
Similar to Ancient bacteria in chemistry
MitochondriaMitochondria
Mitochondrial StructureMitochondrial Structure
Outer membrane faces cytoplasm Inner membrane folds back on itself Membranes form two distinct
compartments ATP-making machinery is embedded in
the inner mitochondrial membrane
Outer membrane faces cytoplasm Inner membrane folds back on itself Membranes form two distinct
compartments ATP-making machinery is embedded in
the inner mitochondrial membrane
ChloroplastsChloroplasts
Convert sunlight energy to ATP through photosynthesisConvert sunlight energy to ATP through photosynthesis
Like Bacteria?Like Bacteria?
Both mitochondria and chloroplasts
resemble bacteria
Have own DNA, RNA, and ribosomes
Both mitochondria and chloroplasts
resemble bacteria
Have own DNA, RNA, and ribosomes
Plant Cell FeaturesPlant Cell FeaturesCENTRAL VACUOLE
LYSOSOME-LIKE VESICLE
GOLGI BODY
SMOOTH ER
ROUGH ER
RIBOSOMES
NUCLEUS
CHLOROPLAST
CYTOSKELETON
MITOCHONDRION
PLASMODESMA
PLASMA MEMBRANE
CELL WALL
Animal Cell FeaturesAnimal Cell Features
CYTOSKELETON
MITOCHONDRION
CENTRIOLES
LYSOSOME
GOLGI BODY
SMOOTH ER
ROUGH ER
RIBOSOMES
NUCLEUS
PLASMA MEMBRANE
Present in all eukaryotic cells
Basis for cell shape and internal organization
Allows organelle movement within cells and, in some cases, cell motility
Present in all eukaryotic cells
Basis for cell shape and internal organization
Allows organelle movement within cells and, in some cases, cell motility
CytoskeletonCytoskeleton
Length of microtubules or microfilaments can change
Parallel rows of microtubules or microfilaments actively slide in a specific direction
Microtubules or microfilaments can shunt organelles to different parts of cell
Length of microtubules or microfilaments can change
Parallel rows of microtubules or microfilaments actively slide in a specific direction
Microtubules or microfilaments can shunt organelles to different parts of cell
Mechanisms of Movement Mechanisms of Movement
Structural component that wraps around the plasma membrane
Occurs in plants, some fungi, some protistans
Structural component that wraps around the plasma membrane
Occurs in plants, some fungi, some protistans
Cell WallCell Wall
Primary cell wall of a young plant
Plasma membrane
Plant CuticlePlant Cuticle
Cell secretions and waxes accumulate at plant cell surface
Semi-transparent
Restricts water loss
Cell secretions and waxes accumulate at plant cell surface
Semi-transparent
Restricts water loss
Matrixes between Animal CellsMatrixes between Animal Cells
Animal cells have no cell walls
Some are surrounded by a matrix of cell
secretions and other material
Animal cells have no cell walls
Some are surrounded by a matrix of cell
secretions and other material
Cell Junctions - [molecular staples]
Cell Junctions - [molecular staples]
Plants Plasmodesmata
Animals Tight junctions Adhering junctions Gap junctions
Plants Plasmodesmata
Animals Tight junctions Adhering junctions Gap junctions
plasmodesma