BIOLOGY 2010: CELL BIOLOGY — FALL 2022
Instructors:
Dr. Wei Guo (guowei@sas.upenn.edu)
Office hour: Wednesdays 11:00 – 12:00 pm, 304E Lynch Labs
Dr. Tatyana (Tanya) Svitkina (svitkina@sas.upenn.edu)
Office hour: Friday 4:00 – 5:00 pm, 304K Lynch Labs
Lectures:
Time: Tuesday and Thursday, 10:15-11:45 am
Place: Leidy 10
TAs:
Brittany MacTaggart (britmact@pennmedicine.upenn.edu)
Trevor Griesman (griesman@pennmedicine.upenn.edu)
Recitation section I (Brittany)
Recitation section II (Trevor)
Tuesdays 5:15 – 6:15 pm (101 Goddard Labs)
Wednesdays 7:00 – 8:00 pm (101 Goddard Labs)
Textbooks:
Molecular Biology of the Cell, 6th or 7th edition by Alberts et al.
The Cell: A Problem Approach, 6th Edition by Wilson and Hunt.
Exams:
- Three midterms
- Each midterm is worth 100 points.
- After normalizing to a common mean/median the lowest score will be dropped.
- There will be no make-up midterm exams.
- The final exam is worth 200 points (50% of final grade)
PLASMA MEMBRANE
Functions:
Preserve contents
Provide communication with the environment
CELLULAR ORGANELLES
Bacteria
(Prokaryotes)
Lysosome:
Degradation of
macromolecules
Eukaryotic cells
Centriole:
Assembly of
mitotic spindle,
cilia and
flagella
Nucleus:
DNA storage
Transcription
Ribosome
assembly
ER:
Synthesis of
proteins and
lipids; calcium
storage
Vesicles:
Endocytosis,
exocytosis,
intracellular
traffic
Golgi
complex:
Posttranslational
modifications;
sorting
Mitochondria:
ATP production;
regulation of
apoptosis
Cytoskeleton:
Cell motility, mechanical tasks
WATER-OIL PHASE SEPARATION
Oil
Vinegar
Hydrophilic molecules
Hydrophobic molecules
AMPHIPATHIC (AMPHIPHILIC) MOLECULES
Water
Micelle formation by soaps
Soap molecules
Soap solution
Dirty cloth
Dirt
Fatty (palmitic) acid
MICELLES AND BILAYERS
LIPOSOMES
IS PLASMA MEMBRANE A BILAYER?
Experiment by Gorter and Grendel, 1925
Lipid area = 2 X Cell area
Langmuir’s trough to measure
area of the lipid monolayer
PHOSPHOLIPIDS
(Example: Phosphatidylcholine = PC)
MAJOR MEMBRANE PHOSPHOLIPIDS
Backbone for
sphingomyelin
MEMBRANE STRUCTURE
MEMBRANE FLUIDITY
PHASE TRANSITION
Nonphysiological
(unsaturated
fatty acid chains
help prevent
freezing)
Normal
physiological
state
(cholesterol
helps prevent
unwanted
permeability)
CHOLESTEROL
PHOSPHOLIPID – CHOLESTEROL INTERACTION
MEMBRANE PERMEABILITY
PC
PHOSPHATIDYLINOSITOLS – SIGNALING LIPIDS
Phosphatidylinositol
Phosphatidylinositol phosphates
monophosphates
biphosphates
PI(3)P
PI(4)P
PI(5)P
PI(3,4)P2
PI(3,5)P2
PI(4,5)P2
triphosphate
PI(3,4,5)P3
Function:
Recruit and/or activate proteins
GLYCOLIPIDS
MEMBRANE BILAYER ASYMMETRY
Sphingomyelin
(SM)
Phosphatidylcholine
(PC)
Phosphatidylethanolamine
(PE)
Phosphatidylserine
(PS)
CELL MEMBRANES
1. Membranes are designed to enclose and compartmentalize a cell
2. Membranes are made of amphipathic molecules:
- Phospholipids
- Cholesterol
- Glycolipids
- Phosphoinositides (phosphatidyl inositols)
3. Membranes properties:
- asymmetric
- fluid
- have limited permeability
4. Functions of membrane lipids:
- structural
- accommodation of proteins
- signaling
- communication with environment