Cell Structure and Function
Chapter 4
Cell Theory
1) Every organism is composed of one or
more cells
2) Cell is smallest unit having properties of
life
3) Continuity of life arises from growth and
division of single cells
Structure of Cells
All start out life with:
Two types:
– Plasma membrane
– Prokaryotic
– Region where DNA
is stored
– Eukaryotic
– Cytoplasm
– Know figure 4:7
– Know table 4.3
Animal Cell Features
•
•
•
•
•
•
•
•
Plasma membrane
Nucleus
Ribosomes
Endoplasmic
reticulum
Golgi body
Vesicles
Mitochondria
Cytoskeleton
nuclear enevelope
nucleolus
NUCLEUS
DNA + nucleoplasm
microfilaments
vesicle
microtubules
lysosome
components of
cytoskeleton
rough ER
ribosomes
(attached to
rough ER
and free in
cytoplasm)
smooth ER
plasma
membrane
vesicle
Golgi body
mitochondrion
pair of
centrioles
Fig. 4.8b, p. 57
Lipid Bilayer
• Main component of
cell membranes
• Gives the
membrane its fluid
properties
• Two layers of
phospholipids
Membrane Proteins
• Transport proteins
• Receptor proteins
• Recognition proteins
• Adhesion proteins
oligosaccharide
cholesterol
groups
phospholipid
EXTRACELLULAR ENVIRONMENT
(cytoskeletal proteins beneatch
ADHESION
the plasma
PROTEIN
membrane)
open
gated
channel channel
protein proten
(open)
gated
channel
proten
(closed)
(area of
enlargment)
TRANSPORT PROTEINS
active
transport
protein
RECEPTOR
PROTEIN
LIPID BILAYER
RECOGNITION
PROTEIN
CYTOPLASM
PLASMA MEMBRANE
Fig. 4.4, p. 53
Functions of Nucleus
• 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
Components of Nucleus
nuclear envelope
nucleoplasm
chromatin
(DNA + proteins)
Nucleolus
cytoplasm
nucleus
plasma membrane
nuclear envelope
nucleoplasm
chromatin
(DNA + proteins)
nucleus
Fig. 4.11, p. 62
Nuclear Envelope
• Two outer membranes (lipid bilayers)
• Innermost surface has DNA attachment sites
• Pores span bilayer
Chromatin
• Cell’s collection of DNA and associated
proteins
• Chromosome is one DNA molecule and
its associated proteins
• Appearance changes as cell divides
Nucleolus
• Dense mass of material in nucleus
• Area of intense transcription of rRNA
• Materials from which ribosomal subunits are
built
• Genes that encode Ribosome's are located in
this area
Components of Cytomembrane
System
Golgi bodies
Vesicles
Endoplasmic reticulum
Endoplasmic Reticulum
• In animal cells, continuous with
nuclear membrane
• Extends throughout cytoplasm
• Two regions - rough and smooth
Rough ER
• Ribosomes on surface
give it a rough
appearance.
• ER is the site of protein
synthesis.
• Some polypeptide chains
enter rough ER and are
folded and modified
Smooth ER
• No ribosomes on
surface
• Lipids assembled
inside tubules
• Synthesizes steroids,
such as estrogen and
testosterone.
• inactivates wastes,
toxic chemicals and
drugs
Golgi Bodies
• Put finishing touches on proteins
and lipids that arrive from ER
• Package finished material for
shipment to final destinations
outside the cell.
• Material arrives and leaves in
vesicles
Vesicles
• Membranous sacs
that move through the
cytoplasm
• Lysosomes
– Digests, recycles materials
Mitochondria
• ATP-producing powerhouses
• Double-membrane system
• These reactions require
oxygen
Cytoskeleton
• Present in all
eukaryotic cells
• Basis for cell shape
and internal
organization
• Allows organelle
movement within cells
and, in some cases,
cell motility
Cytoskeletal Elements
intermediate
filament
microtubule
microfilament
Cilia and Flagella
• Cilia and Flagella are made up of
microtubules
– Cilia functions to move microorganism or the
movement of substances in the body
• Example: Protozoa move through water by
beating their cilia as small ores
• Example: Cilia found in the body moves mucus
out of the lungs and oocytes down the oviduct
– Flagella functions in the transport of cells
Cilia and Flagella
• Length of microtubules or
microfilaments can change
• Parallel rows of microtubules
or microfilaments actively
slide in a specific direction
• As one side lengthens and
the other side contracts it
causes the flagella or cilia to
bend.