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Chapter 4
Cell Structure and Function
Early Discoveries
• The cell is the lowest level of structure that is
capable of performing all the activities of life.
• The first cells- cork, Robert ___________ in 1665.
• Anton van ________________ - first saw singlecelled organisms in pond water and observed cells
in blood and sperm.
• In 1839, Matthais Schleiden and Theodor
Schwann
– The ________________- all living things
consist of cells.
• A cell theory extension - all ______ come from other
_____.
Cell
• Smallest unit of ____
• Can survive _____________ or has
potential to do so
• Is highly organized for __________
• Senses and responds to ____________
• Has potential to ________________
Structure of Cells
• Prokaryotic vs eukaryotic
cells
•Similarities-
•Differences
•A ___________________. •Euks have chromosomes in
a ____________(compared
•A ______ (semifluid
to a nucleosome in proks.)
substance) within the cell
•Euks have many _______
•_______________
__________________
•__________- organelles
•Eukaryotic cells are
that make proteins
__________times larger
• Larger organisms do not generally have _______cells
than smaller organisms - simply _______cells.
Lipid Bilayer
• Main component of cell
____________
• Gives the membrane its _____
properties
• Two layers of ______________
Fluid Mosaic Model
• Membrane is a mosaic of
– _______________
– ______________
– Sterols
– _______________
Membrane Proteins
•
•
•
•
__________proteins
_________ proteins
Recognition proteins
___________ proteins
Why Are Cells So Small?
• Surface-to-volume ratio
• A bigger cell = less
_________________ per unit volume
• Above a certain size, material cannot be
moved in or out of cell _____________
Diameter (cm):
0.5
1.0
1.5
Surface area (cm2):
0.79
3.14
7.07
Volume (cm3):
0.06
0.52
1.77
6.04:1
3.99:1
Surface- to-volume ratio: 13.17:1
Fig. 4.5, p. 54
Microscopy
• ___________ microscope
-minimum resolution is - _
_______ ( the size of a
small bacterium)
For higher resolution-__________ microscope
-Transmission Electron Microscope
-Scanning Electron Microscope
Animal cell
Animal cells lack:
•_____________
•_____________
•______________
•______________
Fig. 7.7
Plant cells lack:
•__________
•___________
•__________
Plant cell
Fig. 7.8
Most other components are __________by plant and animal cells
1. The nucleus
• contains most of the _____ in a
eukaryotic cell.
– Some genes are in ___________
and _____________
• separated from the cytoplasm by a
____________ membrane.
• Protein pores allow large
macromolecules and particles to
pass through.
• ______________ (located internal
to the membrane)- maintains
nuclear __________
• ___________ (DNA and
associated proteins)
– Each eukaryotic species has a
characteristic number of
_________________.
– A typical human cell has 46
chromosomes, but sex cells
(eggs and sperm) have only 23
chromosomes.
• ___________- densely stained fibers and
granules adjoining chromatin
•Factory for ribosomal RNA (rRNA)
•rRNA is a component of
______________
2. Ribosomes build a cell’s proteins
_____________• contain _______ (from nucleolus) and
__________.
• composed of two subunits
• carry out __________ synthesis.
Fig. 7.10
Ribosomes- (cont.)
• Found in _______locations– 1. “_____” ribosomes -suspended in the
cytosol
– Function: synthesize ______________ proteins
– 2.”_____” ribosomes- attached to the outside of
the __________________________
• Function: synthesize __________ proteins
and ____________ proteins
– Note: Ribosomes can shift locations.
• The _____________________- includes
• the nuclear envelope
• endoplasmic reticulum
• Golgi apparatus
• lysosomes
• vacuoles
• plasma membrane.
• Where are the membranes produced?? The _____
3.The endoplasmic reticulum
• Two regions of ER that differ in
structure and function.
– _______ ER
• ribosomes attached to the
outside
• Packages proteins into
____________________
– __________ ER
• lacks _____________
• Function: synthesize lipids,
including oils, phospholipids,
and steroids
– Also _________________
drugs and poisons
Fig. 7.11
4. The Golgi apparatus
• Function: _________,
____, and ______ cell
products
• Many transport
vesicles from the ER
travel to the ________
__________________
for modification of
their contents.
Cis face
“receiving”
Trans face
“shipping”
____ face _______ vesicles from ER; ______ face ships vesicles out
5. Lysosomes
• a membrane-bounded sac of ________
enzymes
• functions -digest ________________ (proteins,
fats, polysaccharides, and nucleic acids).
• Low pH (5.0)
Nucleus
•massive leakage from
lysosomes can destroy
an cell by __________
Lysosome
Fig. 7.13a
5. Lysosomes (Cont.)
• The lysosomal enzymes and membrane are
synthesized by ________ and then transferred to
the ___________.
• At least some
lysosomes
bud from
the trans
face of
the ______.
Fig. 7.14
5. Lysosomes (Cont.)
• Lysosomes can fuse with __________________ or
another organelle
Inherited diseases affect _______________
metabolism:
– These individuals lack a functioning version of
a normal hydrolytic enzyme.
– Result- Lysosomes are engorged with
______________ substrates.
• ____________ disease in the liver
• Tay-Sachs disease in the brain.
6. Vacuoles
• Vesicles and vacuoles
(larger versions) are
membrane-bound_____ with
varied functions.
– ___ vacuoles, from
phagocytosis, fuse with
lysosomes.
– _________vacuoles, found in
freshwater protists, pump
excess water out of the cell.
– __________ vacuoles are
found in many mature
______cells.
• Functions - stockpiling
proteins or inorganic ions….,
7. Mitochondria and chloroplasts
• Convert energy to forms that
cells can use for work.
• __________ -site of _______
_____________, generating
ATP from the catabolism of
sugars, fats, and other fuels
in the presence of oxygen.
• ___________, found in plants
and eukaryotic algae, are the
site of ________________.
– They convert solar energy
to chemical energy and
synthesize new organic
compounds from CO2 and
H2O.
Mitochondria
Chloroplast
• Mitochondria and chloroplasts– Are _____ part of the endomembrane system.
• Proteins from ____ ribosomes in the cytosol (and a
few from their own ribosomes).
– Contain DNA
– Grow and reproduce as ______________
organelles.
• Almost all ____________ cells have mitochondria.
• Cells may contain one to __________________.
• The number of mitochondria is correlated with
aerobic metabolic activity.
Review
FUNCTION
• Nucleus
DNA
Produce mRNA
• Nucleolus
Produce rRNA
(for ribosomes)
• Ribosomes
Protein synthesis
• Endoplasmic reticulum
Produce membranes
Function
Finishes, sorts, and
ships
_____________
Golgi
Lysosome
Vacuole
•Food vacuole
•Central vacuole (plants)
Mitochondria
Chloroplast
Nucleus
digest -__________
•Transport food to lysosome
•Give plants rigidity
•Produce ATP for energy
•Capture light for energy
(only chloroplasts)
8. -_______________
• generate and degrade -_______________ (H2O2)
in performing various metabolic functions
– H2O2 is _______, but the peroxisome has
another enzyme that converts H2O2 to water.
•Functions:
• break ___________
down for fuel.
•__________ alcohol (and
other harmful
compounds).
•Convert the fatty acids in
seeds to sugars
•Not part of __________- system
9. Cytoskeleton
• The ____________ is a
network of _______
extending throughout
the cytoplasm.
• ________:
– Organizes the
structures and
activities of the cell.
– provides __________
support and maintains
shape of the cell.
– provides ____________
for many organelles and
cytosolic enzymes
– dynamic
Fig. 7.20
•
•
•
•
9. Cytoskeleton (Cont.)
There are three main types of fibers in the
cytoskeleton:
______________
________________
__________________.
microfilaments
(Actin)
Intermediate filaments
(Keratin)
Fig. 7.21b
10. Cell wall – Plant and proks, but not
animal cells
Function in plants: _____________, maintains
its shape, and prevents excessive uptake of
water.
– It also supports the plant against the force of
Plasma membrane
____________.
• Composed of
microfibrils of _______
embedded in a matrix
of proteins and other
polysaccharides.
•steel-reinforced
concrete analogy
11. The extracellular matrix (ECM)
• Functionsupport,
adhesion,
movement, and
regulation
• Animals cells have an
elaborate ____.
• -_________ fibers
embedded in a
network of
________________
• The _______ connect
the ECM to the
_______________.
• Can influence the activity of genes
in the nucleus via a combination
of chemical and mechanical
signaling pathways.
• This may coordinate all the
cells within a tissue.
12. ____________________
• Function- Cell to cell communication and
cell-cell contact
• Plant cells are perforated with
______________, channels allowing cysotol to
pass between cells.
Animal have 3 main types
of intercellular
Animal
Cell Junctions
links:
Fig. 7.28 inset
tight
junctions
adhering
junction
gap
junction
Prokaryotic Cells
• __________________ and Eubacteria
• DNA is NOT enclosed in ____________
• Generally the smallest, ___________
cells
• No _______________
Prokaryotic Structure
pilus
cytoplasm
with ribosomes
DNA
flagellum
capsule
cell plasma
wall membrane