Download Class6 1-10 Win16 Transport and Organelles Notes

•  Spermaceti whale oil
•  Used by sperm whales in a special organ in
The most valuable the huge head cavity
•  Largely comprised of cetyl palmitate
lipid ever?
www.thisrecording.com
www.greenpeace.org
Peer Instruction
Are membranes with straight lipid tails more or less
permeable than membranes with kinked tails?
Are membranes with long tails more or less permeable
than membranes with short tails?
Are warmer membranes more or less permeable than
colder membranes?
Clicker Question #6
(An over-simplified question)
Imagine a pure membrane from only one of
these four phospholipids:
3
1
4
2
Which membrane will be the most permeable to ethanol?
Tuesday January 10th, 2017
Class 6 Learning Goals
Transmembrane Transport and Organelles
•  After this class, you should be able to:
–  Predict the polarity of any part of an integral membrane protein
–  For each of three types of membrane transport,
–  Describe the logic for the cell of that transport type
–  Describe the mechanism
–  Be able to identify the type of transport from a scenario
–  Name and predict the enzymatic components inside any of the
organelles in the given table
–  Identify membrane movements necessary for
–  organelle function
–  the sorting/production/delivery of non-cytoplasmic proteins
–  Trace the path of transport and development for a protein or lipid
moving through the endomembrane system.
Clicker Question #1
Is the membrane of this cell semi-permeable?
1. Yes, because molecules can cross the membrane easily
2. Yes, because molecules can’t cross the membrane easily.
3. Yes, because some molecules cross the membrane
easily, but other molecules do not cross easily.
4. No, it is not semi-permeable.
Clicker Question #2
What is the difference between Cell A and Cell B?
1.  Cell A actively transports molecules across the
membrane.
2.  Cell B creates a ‘door’ to allow molecules to go down
their concentration gradient and come into the cell .
3.  Cell B uses passive diffusion to push molecules out of
the cell.
4.  Cell B actively transports molecules up a
concentration gradient and out of the cell.
Clicker Question #3
Why is Cell C using so much ATP?
1.  Cell C must spend energy to create transport
proteins.
2.  Cell C must spend energy to actively drive each star
molecule out of the cell.
3.  Cell C must spend energy to actively pull star
molecules in through the green transport proteins.
4.  Cell C must both create transport proteins and ‘fuel’
them with ATP to drive star molecules into the cell.
Clicker Question #4
A permeable poison is added to the water around
bacterial cells. Which adaptation is most likely to
help a cell survive?
1.  Facilitated diffusion: The cell creates a transport protein
that will passively allow poison to flow out of the cell.
2.  Active transport: The cell uses ATP to pump the poison
out of the cell through a costly transport protein.
3.  Passive diffusion: The cell waits for the poison to diffuse
out of the cell into the water.
4.  Active transport: The cell uses ATP to pump a wide
variety of molecules out of a large but inexpensive
transport protein.
Clicker Question #5
Orientation for Page 2:
What does this image show?
1.  A cross section of a transport protein taken within
the hydrophobic area of a membrane.
2.  A cross section of a lipid membrane.
3.  A hollow tube of multiple cells.
4.  A protein floating outside of the hydrophilic layer
of phospholipids.
Clicker Question #6
Q7: Which of these R-groups is most likely to be
in direct contact with the substrate molecule as
it travels through the transport protein?
1. 
2. 
3. 
4. 
5. 
Clicker Question #7
The transport protein is hit with a chemical
cross-linking agent. This makes the protein
extremely rigid. What is the most likely result of
this cross-linking?
1.  The transport protein allows the same
specific molecules to pass through the
membrane more quickly.
2.  The transport protein allows many different
large molecules to pass through very quickly.
3.  The transport protein loses the ability to
transport molecules through the membrane.
1) Draw in the missing steps:
Vesicles can form from membranes:
Peer Instruction
Vesicles can be absorbed into membranes:
This can be spontaneous, but is usually guided by proteins.
2) How can a motor protein help to move a vesicle?
Vesicle video
Peer Instruction
1) Explain these three mechanisms for cellular digestion.
(One sentence each, maximum)
Lysosome
Endosome
Lysosome
Vesicle
from Golgi
apparatus
2) How could vesicles be used to send signals?
Damaged
organelle
Organelles: A General Definition
•  What is an organelle?
–  An organelle is a specific location within a cell characterized
by compartmentalized structures
•  Eukaryotes have some membrane-bound organelles
•  Why separate regions in the cell?
–  Molecules don’t diffuse easily throughout the entire cell.
Concentration can drastically increase reaction rates.
–  Some organelles create unique microenvironments for
special reactions.
Eukaryotes: Animal and Plant Cells
FICTION
Generalized animal cell
Centrioles
Generalized plant cell
Cell wall
Chloroplast
Nucleolus
Nuclear envelope
Chromosomes
Nucleus
Rough ER
Ribosomes
Peroxisome
Smooth ER
Golgi apparatus
Lysosome
Mitochondrion
Cytoskeletal element
Plasma membrane
Nuclear envelope Nucleus
Nucleolus
Chromosomes
Rough ER
Ribosomes
Smooth ER
Golgi apparatus
Vacuole (lysosome)
Peroxisome
Mitochondrion
Plasma membrane
Cytoskeletal
element
Organelles: The Lysosome
Lysosomes are singlemembrane-bound centers
for storage and/or waste
processing. Materials are delivered to the lysosomes by three processes:
-phagocytosis, -autophagy, and -receptor-mediated endocytosis.
(Peroxisomes are very similar, with a
Peroxide-based microenvironment)
Microenvironment: Acidic
Material being
digested within
lysosomes
Clicker Question #8
Why is the lysosome useful?
In other words, why not simply do lysosome-like digestion in
the cytoplasm using the same digestive enzyme?
1. 
2. 
3. 
4. 
5. 
The lysosome provides needed structure for the cell
The lysosome helps to concentrate enzymes and cofactors to help reactions happen more quickly
They lysosome needs to have a membrane in order to
contain enough lipids for the cell
The lysosome is where enzymes are polymerized from
amino-acid monomers
The lysosome restricts dangerous digestion reactions to
a safe and secure location in the cell.
Organelle
Cellular Role
Nucleus
(Covered in great depth in 355)
Lysosome
Peroxisome
Vacuole
Mitochondria
(Covered in depth in Week 5)
Chloroplast
(Covered in great depth in 220)
Rough ER
Smooth ER
Golgi Apparatus
Ribosomes
(Covered in depth next week)
Cytoskeleton
Plasma membrane
(Covered in depth yesterday)
Specialized
components
Microenvironment
Clicker Question #9
The nucleus is the organelle in which DNA is stored
and used.
Which is most likely about the chemical
microenvironment of the nucleus in most cells?
The nuclear microenvironment:
1.  Contains all of the proteins in a cell because the
protein-building instructions are located therein
2.  Has a diversity of mutation-causing chemicals
3.  Allows import of DNA
4.  Is relatively protective against mutation-causing
rays and chemicals
Problem:
Some proteins need to be in the plasma membrane
Some proteins need to be sent outside the cell
…but proteins are far too big to go through even one
side of the plasma membrane…
The EndoMembrane System:
The protein & lipid factory
•  Comprised of
– the rough ER,
– the smooth ER, and
– the Golgi apparatus,
•  The EMS is the primary system
for protein and lipid synthesis.
This system allows
production, processing and
transport of specific and
diverse molecules.
Nucleus
EMS Organelles: The Rough ER
A Protein Synthesis and Processing Complex
• 
• 
• 
• 
The rough ER is contiguous
with the nuclear membrane
New proteins are directly
inserted into the ER
Microenvironment: noncytoplasmic molecular
Lumen of
conditions for protein folding
rough ER
After processing, proteins are
transported to other destinations Ribosomes
on outside
by controlled vesicle budding
Free ribosomes
in cytoplasm
Clicker Question #4
Many functional proteins are translated in the
cytoplasm with no need for the Endomembrane
System.
What is a good reason to use the EMS?
1. 
2. 
3. 
4. 
5. 
To make proteins that are delivered to a specific
organelle
To make proteins that are delivered to the plasma
membrane
To make proteins that fold differently than they would if
they were translated in the cytoplasm
To make proteins with lipid modifications
All of these are good reasons to use the EMS for
translation
EMS Organelles: Smooth ER
A Lipid-Handling Center and Storage Site
•  The smooth ER is the major
processing zone for lipids
•  Smooth ER lacks ribosomes,
naturally
•  ER hosts non-cytoplasmic
molecular conditions and
specialized enzymes
•  After processing, lipids are
transported to other
destinations by controlled
vesicle budding
Smooth endoplasmic reticulum
Lumen of
smooth ER
EMS Organelles: The Golgi Apparatus
A Site of Protein Processing
The cis face is oriented
towards the rough ER
• 
• 
• 
• 
A site for carbohydrate
modification of proteins
Packaging and transport to
cellular locations with
vesicles
Formed by a series of
stacked flat membranous
sacs called cisternae.
Receives products from
the rough ER and sends
finished products to the
cell surface in vesicles.
The trans face is oriented
away from the rough ER
Golgi apparatus
cis face
Vesicle
Lumen
Cisternae
Vesicles
trans face
Golgi Video
Clicker Question #5
What is a reasonably hypothesis about the microenvironment
of the Smooth Endoplasmic Reticulum?
1.  It is more hydrophobic than the rest of the cell
2.  It would be worse for protection of nucleic acids
than the microenvironment in the nucleus
3.  It is good for breaking down protein
4.  It is the same as the cytoplasm.
Key Concepts
• 
• 
• 
• 
• 
• 
Why do you expect amino acid side chains on the outside of an integral
membrane protein (but within the bilayer) to be hydrophobic?
Explain the matches between three possible transport situations…
–  facilitated diffusion, active transport, and passive diffusion
…and three cellular situations
–  a need for extreme rapid transport, intake of a common large molecule,
letting a rare waste molecule out of the cell
What specialized enzymes would you expect in a mitochondrion? In the Rough
ER? What microenvironment is unique to the nucleus? To the peroxisome?
Imagine:
–  1) a lipid destined to become part of the plasma membrane, and
–  2) a protein that will be released outside of the cell.
•  Describe the differences in the pathways taken by each molecule.
Where or when does each pathway utilize the joining of lipid membranes?
Bonus question: Where does the energy come from to move Golgi vacuoles to
different parts of the cell? There are two very different answers…