Lecture 4
Cells
1
Yesterday’s Exit Ticket
Describe the key differences between:
Saturated fats
● All C’s are bonded to the max # of H’s possible
● Straight tails
● Solid
● e.g. butter, eggs, steak (any animal-based fat)
●Monounsaturated fats
● TWO Hs missing, and there is one C-C double bond
● One bend in tail
● In avocados, nuts, most oils, and many more!
●Polyunsaturated fats (Omega-3 and -6)
● More than 2 Hs missing, multiple C-C double bonds
● Very bendy tails
● In fish, walnuts, sunflower, soybean, and safflower oil
●
Key Themes
(2) “Think Like a Biologist”: Understand What Life Is.
“Unity” of life: What are the common features of all life?
• Structure and function of cells (and molecules)
Maintenance of a suitable cell environment
• Role of cell structures in life’s energy conversion
3
DNA
1 Synthesis of
mRNA in the
nucleus
Let’s take a closer look at
Fig. 5.26
the
mRNA
NUCLEUS
CYTOPLASM
mRNA
2 Movement of
mRNA into cytoplasm
via nuclear pore
Ribosome
3 Synthesis
of protein
Polypeptide
Amino
acids
information flow
from the nucleus
(gene)
to
protein synthesis
and
beyond
4
The Nucleus
Pores allow information
transfer into and
out of nucleus:
nuclear pores
Fig. 6.10
5
The Nucleus
Pores allow information
transfer into and
out of nucleus:
• RNA moves out (for
protein synthesis)
• Some (gene) regulatory
factors move in
nuclear pores
Fig. 6.10
• Unfortunately, some
viruses can get in too
6
Side Note: Web Resources
• Some Cell Parts:
http://learn.genetics.utah.edu/content/begin/cells/insideacell/
• Crash Courses:
– Macromolecules:
http://www.youtube.com/watch?v=H8WJ2KENlK0&list=PL3EED
4C1D684D3ADF
– Animal Cells:
http://www.youtube.com/watch?v=cj8dDTHGJBY&list=EC3EED
4C1D684D3ADF
– Plant Cells:
http://www.youtube.com/watch?v=9UvlqAVCoqY&list=EC3EED
4C1D684D3ADF
7
Ribosome
Fig. 5.26
Polypeptide
Amino
acids
Ribosome: site of protein synthesis in cell
Free ribosomes, floating in cytoplasm,
make proteins for use in same cell.
8
Some ribosomes are bound to a membrane system
(Endoplasmic Reticulum
or ER)
Bound ribosomes
make proteins like
insulin for export from
the cell
Rough ER
with ribosomes
Fig. 6.12
Proteins for
secretion need to be
wrapped in
membrane vesicles.
9
Let’s follow path of a protein hormone from
synthesis (in pancreas cells) to export:
The endomembrane system for synthesis & export of proteins
Example:
Tracking
an insulin
molecule
Fig. 6.16
10
1. DNA for insulin copied into mRNA and exported from nucleus
2. Insulin is synthesized by ribosomes on rough ER
3. Insulin
protein enters
inside of ER
and moves to
outermost
membrane
Fig. 6.16
11
4. Insulin protein packaged into transport vesicles and
transferred to near side of Golgi apparatus
5. Transport
vesicles fuse
to form first
flat sacks of
Golgi
apparatus
Fig. 6.16
12
6. Processed in Golgi apparatus into mature protein
7. Packaged
into transport
vesicles at
opposite side
of Golgi
apparatus and
transported to
plasma
membrane
Fig. 6.16
13
What happens in the Golgi apparatus?
Protein Processing in the Golgi Apparatus
For insulin: The initially synthesized, larger
“pro-insulin” is cut to the size of the final protein.
Some proteins undergo other modifications
(for example, “mailing labels” are attached).
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The entire process from nucleus to plasma membrane!
Fig. 6.16
15
How to make sure that vesicles don’t go astray?
Cells
Fig. 6.3
16
A cell with part of its cytoskeleton illuminated by fluorescence microscopy
ATP
(a)
Vesicle
Receptor for
motor protein
Motor protein Microtubule
(ATP powered) track of
cytoskeleton
Microtubule
Vesicles
0.25 µm
Fig. 6.21
(b)
17
ATP
Movement of
vesicles along
“tracks” formed
by cytoskeleton
(a)
Vesicle
Receptor for
motor protein
Motor protein Microtubule
(ATP powered) track of
cytoskeleton
Microtubule
Vesicles
0.25 µm
Fig. 6.21
(b)
18
http://www.studiodaily.com/main/technique/tproj
ects/6850.html
1:10-1:30
19
Additional organelle produced by Golgi apparatus
Lysosome: filled with digestive enzymes made on rough ER
ribosomes & modified in Golgi
Fig. 6.16
20
Lysosomes – organelles for intracellular digestion
Digest food particles
brought into cells
Fig. 6.14
Digest old mitochondria
and other organelles
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Lysosomes: Digestive Compartments
• Lysosome is membranous sac with digestive
enzymes
• Lysosomal enzymes break down proteins,
lipids, polysaccharides & nucleic acids
• Lysosomes also recycle organelles
http://www.colorado.edu/ebio/genbio/06_14LysosomeFormation_A.html
22
There are TWO TYPES of ER:
Rough and Smooth Endoplasmic Reticulum
Smooth ER
without
ribosomes
Rough ER
with ribosomes
Fig. 6.12
23
We already discussed rough ER (with ribosomes)
• Synthesizes proteins for secretion from cell
In what type of cells do you expect to find a
particularly high level of rough ER?
A) pancreas cells (make insulin)
B) skin cells (make Vitamin D)
C) testes (make testosterone)
D) fat cells (make protein hormone leptin)
E) A and D
Think-Pair-Share
24
Functions of rough ER
Rough ER (with ribosomes)
• Synthesizes proteins for secretion from cell (cells that
produce protein hormones have a lot of rough ER)
• Synthesizes proteins needed for digestion within lysosomes
Smooth ER (without ribosomes)
• Produces lipids for secretion (e.g. steroid hormones)
25
In what type of cells do you expect to find a
particularly high level of smooth ER?
A) cells of the ovaries (make estrogen)
B) cells of the testes
C) cells of the pancreas
D) A and B
E) A, B and C
Think-Pair-Share
26
Functions of rough ER and smooth ER
Rough ER (with ribosomes)
• Synthesizes proteins for secretion from cell (cells that
produce protein hormones have a lot of rough ER)
• Synthesizes proteins needed for digestion in lysosomes
Smooth ER (without ribosomes)
• Produces lipids for secretion (e.g. steroid hormones; testes
and ovaries have a lot of smooth ER)
• Detoxifies (has enzymes in its membranes that do this)
27
What organ, serving in detoxification,
would be expected to have cells with a
high level of smooth ER?
28
Functions of rough ER and smooth ER
Rough ER (with ribosomes)
• Synthesizes proteins for secretion from cell (cells that
produce protein hormones have a lot of rough ER)
• Synthesizes proteins needed for digestion in lysosomes
Smooth ER (without ribosomes)
• Produces lipids for secretion (e.g. steroid hormones; testes
and ovaries have a lot of smooth ER)
• Detoxifies (enzymes in smooth ER membranes do this;
liver cells have a lot of smooth ER)
29
5 minute break…
30
Cepolina.com
Key Themes
“Think Like a Biologist”: Understand What Life Is.
- “Unity” of life
- “Diversity” of Life
31
Fig. 26-21
EUKARYA
Dinoflagellates
Forams
Ciliates Diatoms
Red algae
Land plants
Green algae
Cellular slime molds
Amoebas
Euglena
Trypanosomes
Leishmania
Animals
Fungi
Sulfolobus
Green nonsulfur bacteria
Thermophiles
Halophiles
(Mitochondrion)
COMMON
ANCESTOR
OF ALL
LIFE
Methanobacterium
ARCHAEA
Spirochetes
Chlamydia
Green
sulfur bacteria
BACTERIA
Cyanobacteria
(Plastids, including
chloroplasts)
32
(a) DOMAIN BACTERIA
(b) DOMAIN ARCHAEA
Prokaryotes
Fig. 1-15
(c) DOMAIN EUKARYA
(Eukaryotes)
Kingdom
Plantae
Protists
(single-celled eukaryotes
and some closely related
multi-cellular
organisms)
Kingdom Fungi
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Kingdom Animalia
Size difference between eukaryotic and prokaryotic cells
Bacteria on cell from mouth of a human
34
Photo by Dr. Gary Kaiser
Review of Eukaryotic Cell
Fig. 5.26
nucleus
endomembrane
system
plasma
membrane
mitochondrion
Animal cell
Fig. 6.9
•Nucleus: Stores genetic information (as DNA)
•Endomembrane system: Utilizes information to make proteins (DNA to
RNA to protein) and exports some of these from cell
•Membrane-bounded organelles (example here: Mitochondrion)
35
Eukaryotic versus Prokaryotic Cells (Bacteria & Archaea)
All have cytoplasm or cytosol
All have plasma membrane surrounding the cell
Eukaryotic cells:
Prokaryotic cells:
Have membrane-bounded
nucleus (with DNA) and
membrane-bounded organelles
No membrane-bounded nucleus
(DNA is concentrated in “nucleoid”)
No membrane-bounded organelles
Fig. 6.6
Fig. 6.9
Rod-shaped
bacterium
Animal cell
TEM picture
36 of
thin section
Two types of bacteria:
Gram positive:
-Lots of peptidoglycan
in cell wall
Gram negative:
- Little to no peptidoglycan
in cell wall and
PATHOGENIC
37
micro.digitalproteus.com
Key Themes
(2) “Think Like a Biologist”: Understand What Life Is.
“Unity” of life: What are the common features of all life?
• Structure and function of cells
• Energy acquisition & conversions in metabolism
38
Major organelles involved in energy metabolism
1) Mitochondria - the cell’s powerhouses
Fig. 1.6(d)
Infoldings of
membrane
Mitochondrion
0.5 µm
Occur in all eukaryotes
– plants, animals, fungi, protists
Role: “Burn” energy-rich molecules to gain ATP
energy for cellular work
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Major organelles involved in energy metabolism
2) Chloroplasts - solar energy collectors/converters
10 µm
Fig. 1-4(j)
Only in plants & algae (= photosynthetic eukaryotes)
Role: Photosynthesis – conversion of solar energy into
energy-rich sugars
40
Animal cell
Plant cell
Most basic components & functions are the same
Animal cell
Fig. 6.9
Plant cell
Unique plant cell features:
Chloroplasts (for photosynthesis)
Cell wall and central vacuole
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(for structural support)
Two types of bacteria:
Gram positive:
-Lots of peptidoglycan
cell wall
Gram negative:
- Little to no peptidoglycan in
in cell wall
42
micro.digitalproteus.com
Today’s Exit Ticket
• Describe prokaryotic, animal, and plant
cells.
• List the key differences between the 3 types.
• What features are common to all 3 cell
types?
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