Transcript Chapter 4: Cell Structure

BIOL 3340
Chapter 3
Chapter 4
Microbial Cell Structure
Eucaryotes
Eucaryotic Cell Structure
•membrane-delimited nuclei
•membrane-bound organelles
that perform specific functions
•more structurally complex
than procaryotic cell
•generally larger than
procaryotic cell
Size, Shape, and Arrangement of
Eucaryotes
Yeast cell and Protozoan cell
Functions of the cell organelles
Eucaryotic Membranes
Includes: animal & plant cells, fungi &
protists (protozoa & algae).
 Have a true nucleus with DNA
 DNA is enclosed in a membrane-bound
nucleus
 membrane-enclosed cell organelles

…Eucaryotic Membranes
the fluid mosaic model is based on
eucaryotic membranes
 They are enriched with lipids and
proteins
 They participate in a variety of cell
processes such as cell movement and
transduction

Cell Structure
of Eucaryotes- animal cell
Cell Structure
of Eucaryotes- Plant Cell
…Eucaryotic membrane
Cytoplasm

Many organelles of eucaryotic cells lie in
the cytoplasmic matrix

The cytoplasmic matrix -vast network of
interconnected filaments.
Filaments that form the cytoskeleton:
microfilaments, microtubules, and
intermediate filaments.
 plays role in both cell shape and cell
movement

..Cytoplasmic Matrix
 Viscous
aqueous suspension of
proteins, nucleic acid, dissolved
organic compounds, mineral salts
 Network
of protein fibers similar to
the eukaryotic cytoskeleton.
Cytoplasmic Inclusion Bodies:

granules of organic or inorganic
material that are stockpiled by the
cell for future use.
 some
are enclosed by a singlelayered membrane
Microfilaments
minute protein filaments, 4 to 7 nm
in diameter
 scattered within cytoplasmic matrix
or organized into networks and
parallel arrays
 composed of actin protein
 involved in cell motion and shape
changes

Microtubules
shaped like thin cylinders ~ 25 nm in
diameter
 composed of a- and b-tubulin
 help maintain cell shape
 involved with microfilaments in cell
movements
 participate in intracellular transport
processes

…The Endoplasmic Reticulum
irregular network of branching and fusing
membranous tubules and flattened sacs
(cisternae – s., cisterna).
 rough ER




ribosomes attached
synthesis of secreted proteins by ER-associated
ribosomes
smooth ER


devoid of ribosomes
synthesis of lipids by ER-associated enzymes
The Endoplasmic Reticulum
…The Endoplasmic Reticulum

The ribosomes -sites of synthesis of
some proteins that it transports

transports proteins, lipids, and other
materials within cell.

Ribosomes in the eukaryotic cytoplasm
are larger than prokaryotic ribosomes

Ribosomes are also found within
mitochondria and chloroplasts; the
ribosomes of these organelles are very
similar in structure & size to prokaryotic
Mitochondria

site where ATP is generated by
electron transport and oxidative
phosphorylation
..Mitochondria
Chloroplasts

site of photosynthetic reactions
Nucleus
Nucleus:
 membrane-bound
structure that houses
genetic material of eucaryotic cell
Chromatin
 dense
fibrous material within nucleus
 contains DNA
 condenses to form chromosomes during
cell division
…Nucleus
Nuclear envelope:
 double
membrane structure that
delimits nucleus
 penetrated by nuclear pores
 pores
allow materials to be transported into
or out of nucleus
Nucleolus:
 important in ribosome synthesis
Other cell inclusions
Golgi bodies- involved in
modification, packaging, and
secretion of materials
 Lysosomes- membrane-bound
vesicles found in most eucaryotes
 involved in intracellular digestion
 Vacuoles-transport system

Reproduction
Eucaryotes:
 asexual reproduction
 transverse
fission
 budding
 spore

production
sexual reproduction
 involves
union of compatible nuclei followed
by formation of sexual spores
Bibliography
http://en.wikipedia.org/wiki/Scientific_metho
d
 https://files.kennesaw.edu/faculty/jhendrix/bi
o3340/home.html
 Lecture PowerPoints Prescott’s Principles of
Microbiology-Mc Graw Hill Co.

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