Download Chapter 4- Cells Organisms are composed of one to many

Chapter 4- Cells
Organisms are composed of one to many microscopic cells
Unicellular
Multicellular
Multicellular organisms are composed of one or more types of tissues
Different types of tissues are grouped to form organs
The Two Major Types of Cells
The Three Domains of Life
Domain Bacteria
•Prokaryotic cells
Domain Archaea
Domain Eukarya includes all of the eukaryotic organisms.
Domain Eukarya
Protists (multiple kingdoms) Kingdom Plantae
Kingdom Fungi
Kingdom Animalia
•Eukaryotic cells
Diagram of a plant cell
All eukaryotic cells and prokaryotic cells have at least three components in common:
Prokaryotic
flagella
Nucleoid region (DNA)
Plasma Ribosomes
membrane
Cell wall
The plasma membrane
Capsule
Pili
The plasma membrane is composed of phospholipids, proteins, and
other materials.
The cytoplasm consists of the entire region of the cell between the nucleus and plasma membrane
The cytosol is the cellular fluid.
Ribosomes, are composed of protein and RNA.
Cell Membrane Structure and Function
The membranes of cells are composed of:
Outside cell
Hydrophilic
head
Hydrophobic
tail
Cytoplasm
(inside cell)
•The lipids belong to a special category called phospholipids
(a) Phospholipid bilayer of membrane
Hydrophilic
region of
protein
Phospholipid
bilayer
Hydrophobic
region of protein
(b) Fluid mosaic model of membrane
The cell membrane is described as selectively permeable
because it allows free passage of some materials and not
others.
-Very small, uncharged molecules can easily pass through the membrane
-Larger molecules and ions (molecules with an
electrical charge) do not pass through the cell
membrane without specific membrane transport
proteins.
Selective membrane permeability is the basis for osmosis.
Osmosis and Water Balance in Cells
Osmosis is the diffusion of water across the cell
membrane in response to differences in concentrations of
solutes (dissolved substances) such as sugars or ions.
Diffusion
Water, like many substances, will move from where it is
more concentrated to where it is less concentrated.
If the concentration of solutes inside and outside the cell is the same, then the cell is
osmotically balanced.
Osmosis and Water Balance in Cells
If the solute concentration is lower outside a cell than inside,
Prokaryotes, protists, fungi, and plants have cell walls that limit
the increase of cell volume through the uptake of water.
If the concentration of solutes outside the cells is higher than inside, water leaves the cell and the cytoplasm shrinks.
Eukaryotic cells share some features that prokaryotes lack
All eukaryotic cells have a:
The nucleus is the major site of genetic information (DNA) storage in eukaryotic cells.
The nuclear envelope
Ribosomes Chromatin
Nuclear
envelope
Nucleolus
Pore
Nuclei also contain nucleoli (nucleolus, sing.),
Eukaryotic nuclear DNA is combined with proteins to
form chromosomes.
•Many of the membranous organelles in the cell belong to the endomembrane system
The endoplasmic reticulum (ER)
Nuclear
envelope
Rough ER
•The “roughness” of the rough ER is due to ribosomes that
stud the outside of the ER membrane
Ribosomes
Rough ER
Ribosomes
Smooth ER
Small globular structures composed of protein and RNA
that generate proteins from amino acids.
4
Transport vesicle
buds off
Ribosome
3
After the rough ER synthesizes a molecule it packages
the molecule into transport vesicles
Secretory
protein inside
transport
vesicle
Protein
1
Polypeptide
2
Rough ER
Smooth ER
lacks the surface ribosomes of rough ER
Nuclear
envelope
Ribosomes
Rough ER
The Golgi apparatus
Works in partnership with ER
The Golgi apparatus of a cell consists of 1 or more Golgi bodies.
The cytoskeleton consists of three major types of long, thin, protein fibers:
Flagella and Cilia
Eukaryotic flagella typically contain a pair of single microtubules, surrounded by a
cylinder of nine paired microtubules (9 + 2 arrangement).
Smooth ER
Mitochondria
Each mitochondrion is enclosed by an envelope
composed of an outer membrane and a highly folded
inner membrane.
Peroxisomes
-surrounded by single membrane
Plant cells
Plant cells are distinguished from most other eukaryotic cells by:
Components of cell walls: Cellulose
- the most abundant organic compound on Earth
Cellulose is a polymer of glucose units, but the glucose monomers are linked together in different orientation.
Non-cellulose components of plant cell walls
Plant cell walls also contain other polysaccharides such as:
Hemicellulose is a polymer of glucose and other sugars.
Pectin
Primary and Secondary Plant Cell Walls
Plant cells that are still growing have only a single cell walllayer, or primary cell wall.
Secondary cell walls
Lignin may be added to the walls of water-conducting
cells, so mature cell walls can no longer stretch.
Plasmodesmata
Large ions and molecules can be transported between the cells.
Chloroplasts
Leaves and other green parts of plants contain organelles called
chloroplasts.
The more general term plastid is used to describe
Plant and algal cells contain from one to
many plastids per cell.
Plant cells are enclosed by an envelope composed of 2 membranes.
The watery stroma contains other enzymes for photosynthesis.
Other types of plastids
Amyloplasts
Chromoplasts
Central vacuole
Study outline for Chapter 4-Cells
--Understand cell membrane structure and function- What are membranes of cells composed of?
-Know the structure of phospholipid bilayer of a membrane
-Understand the concept of selectively permeable
-Know examples of what can pass easily through membranes and substances that will not pass without specific
membrane transport proteins
-Understand osmosis and water balance in cells
-Know terms-osmosis, diffusion, isotonic, hypotonic, hypertonic, contractile vacuole, plasmolysis
-Know the features that eukaryotic cells share but prokaryotes lack
-Know structure and function-nucleus, nuclear envelope, nucleolus, chromosomes
-Know the membranous organelles that belong to the endomembrane system-ER (rough and smooth), ribosomes,
Golgi apparatus, Golgi body, cisternae
-Know the three major types of fibers in the cytoskeleton-microtubules, microfilaments, intermediate filaments
-Understand flagella and cilia- 9 + 2 arrangement
-Know structure and function of mitochondria and peroxisomes
Plant cells are distinguished from most other eukaryotic cells by which 4 cellular features?
-Know functions of cellulose cell walls
-Understand the structure of cellulose
-Know the structure and function of non-cellulose components of plant cell walls: hemicellulose, pectin
-Know the difference between primary and secondary plant cell walls
-Understand the structure and function of plasmodesmata
-Understand structure and function of different types of plastids-chloroplast, chromoplast, leucoplast (amyloplast)
-Know terms-thylakoid, stroma
-Understand structure and function of central vacuole