Transcript Cell Division and Mitosis

Cell Structure and Function
Starr/Taggart’s
Biology:
The Unity and Diversity of Life,
Chapter 4
9e
Key Concepts:
All organisms are composed of cells
The cell is the basic unit of life
All cells have a double-layered plasma
membrane
Membranes consist largely of phospholipid
and protein molecules
Key Concepts:
Organelles are membrane-bound
compartments inside eukaryotic cells
Prokaryotic cells do not have organelles
When cells grow, they increase faster in
volume than in surface area
Different microscopes modify light rays or
accelerated beams of electrons that allow
small images to be observed
Basic Aspects of Cell
Structure and Function
Plasma membrane
Lipid bilayer
Proteins
• Channels, transport, pumps, receptors
DNA-containing region
Cytoplasm
Cell Size and Shape
Surface to Volume Ratio
Volume increases more rapidly than
surface area
Restrictions on
size and shape
Microscopes
A - Light microscope
B - Transmission Electron Microscope
C - Scanning Electron Microscope
Defining Structures of
Eukaryotic Cells
A Plant Cell
An Animal Cell
Major Cellular Components
Nucleus
Ribosomes
Endoplasmic reticulum
Smooth and Rough
Golgi body
Various vesicles
Mitochondria
Cytoskeleton
Components of the Nucleus
Nuclear envelope - Surrounds nucleus
Nucleoplasm - Fluid interior portion
Chromosome - One DNA molecule and
associated proteins
Chromatin - Total collection of all DNA
molecules and associated proteins
Nucleolus - RNA and proteins that will be
assembled into ribosomal subunits
The Nuclear Envelope
Double - membrane system
Two lipid bilayers
Surrounds nucleoplasm
Pores allow exchange
The Cytomembrane System
Organelles in which lipids are assembled
and proteins are produced and modified
Endoplasmic reticulum
Golgi bodies
Vesicles
The Endoplasmic Reticulum
Rough and Smooth
Presence or absence of ribosomes
Rough: Proteins
Smooth: Lipids
Rough ER
Smooth ER
Golgi Bodies
Enzymatic finishes
on proteins and
lipids, and
packaging in
vesicles
Vesicles
Lysosomes
Peroxisomes
Transport
Mitochondria
Production of ATP
Double-membrane
system
Two distinct
compartments
Have their own DNA
Divide on their own
Have ribosomes
Chloroplast
 Found in
photosynthetic
eukaryotes
 Two outer membranes
 Semifluid stroma
 Inner thylakoid
membrane system
 Photosynthetic
pigments
Components of the
Cytoskeleton
 Microtubules
Tubulin subunits
Cell division and
movement
 Microfilaments
Actin subunits
Movement and
shape
Components of the Cytoskeleton
Intermediate
Filaments
Only in animal cells
of specific tissues
Mechanically
strengthen cells or
cell parts and help
maintain shape
Six known groups
Structural Basis of Cell Motility
Three Mechanisms
Length of
microtubule can
change
Parallel
microtubules slide
in opposite
directions
Shunting of
organelles
Sliding mechanism for
beating of flagella
Cell Surface Specializations
Eukaryotic Cell Walls
A single-celled
protist
Plant Cell Wall
Cell secretions form lamella
Plasmodesmata (channels)
Primary and Secondary walls
Plant Cell Walls
Deposition of
layers inside
primary wall
Stiffen wall
Maintain shape
Cell-to Cell Junctions
Plants
Plasmodesmata
Animals
Tight Junctions
Adhering
Junctions
Gap Junctions
Prokaryotic Cells
The Bacteria
No nucleus - DNA in free cytoplasm
Smallest of all cells
Most have a cell wall
Polysaccharides cover cell wall of many
species
No membrane-bound organelles
Flagella lack 9+2 array of microtubules
Bacterial Cell
In Conclusion
 The cell theory states
All living cells are composed of cells
The cell is the smallest unit of life
New cells arise only from pre-existing cells

Cells have a plasma membrane, cytoplasm,
and a region of DNA
 The plasma membrane maintains the cell
as a separate entity
In Conclusion
 The cytoplasm is all the fluids, ribosomes
and organelles in eukaryotic cells between
the nucleus and plasma membrane
 Membranes consist of a bilayer of lipids
and proteins embedded in the bilayer or
attached to the surface.
 Proteins carry out most of cell membrane
functions
In Conclusion
 Membranes divide functional
compartments into organelles
 Prokaryotes do not have organelles
 Organelle membranes separate metabolic
reactions

developed by M. Roig