Cell Membrane Flashcards
T OR F
Antiparallel processes happen in the same compartment
FALSE.
Anabolic and catabolic processes are separated compartments so there is no competition for substrate or interference in the reaction
AN EXAMPLE OF ANTIPARALLEL PROCESSING
F.A. synthesis in the CYTOSOL and F.A. oxidation in mitochondria
T OR F
SIMILAR REACTIONS WITH DIFFERENCES PURPOSES DO NOT NEED TO BE IN SEPARATED COMPARTMENTS
FALSE
Similar reactions with DIFFERENT purposes are separated
Ex. F.A. oxidation in mitochondria for energy production, and in peroxide for heat production
Coordination of reactions are involved in?
The same pathway
Ex. TCA and ETC are central point of energy metabolism in cells and are located in the mitochondria
T OR F
NO BIOLOGICAL MEMBRANE = NO LIFE
TRUE
Functions of the plasma membrane (3)
- Regulated the movement of material into and out of the cell
- Facilitated electrical signaling between cells
- Defines the boundaries of organelles and separates complex chemical reactions
T OR F
PLASMA MEMBRANE LACKS OF PROTEINS
FALSE
IS FILLED WITH PROTEINS
Cell membrane are _____ ______ ________ and most of their fluid structure ____ in the plane of the membrane
Dynamic fluid structure
Move
T OR F
THE LIPID BILAYER IS ABOUT 5 NM THIN
FALSE
IS 5NM THICK
WHAT DOES THE LIPID BILAYER PROVIDE ?
Provides the fluid structure of the membrane and serves as a relatively impermeable barrier to the passage of most water soluble molecules
What do some of the membrane protein do
They span the lipid bilayer and mediate many functions of the membrane such as transport and catalysis reactions
Transmembrane proteins serve as
Structural links that connect the Cytoskeleton through lipid bilayer to either the extracellular matrix or an adjacent cell
Other functions of proteins in membrane
Receptors to detect and transducer signals
What is the freeze-fracture technique?
Method to study cell membrane by physically breaking apart (fracturing) a frozen sample of layer
What are the components of a membrane (6)
Lipids - phospholipids, glycolipids Proteins- integral and peripheral Carbohydrates Water Dialing bonds Cholesterin
What are the 3 main lipids in the plasma membrane?
Phospholipids
Sphingolipids
Cholesterol
T OR F
The plasma is 5-10 nm thick
TRUE
Characteristics of the plasma membrane (4)
Thin, pliable, elastic structure 5-10 nm thick
Impedes penetration by water soluble substances
Properties of cell membrane (6)
- Separates the cellular interior from exterior
- Exchanges information with the environment in a controlled manner
- Extremely dynamic
- Membrane get information from cell about metabolic status
- Selective barrier
- Contain enzymes and receptors
The phospholipids molecules have a polar and non polar parts. Which one is hydrophobic and which one is hydrophilic?
Polar is hydrophilic
Non polar is hydrophobic
What molecules are in the polar head
Glycerol
Choline
Phosphate
T or F
Hydrocarbon tails are in the hydrophobic end of the phospholipid molecules
True
They’re in the non polar end which is hydrophobic
What are the 4 major phospholipids molecules found in mammals
- Phosphatidyl-ethanolamine
- Phosphatidyl-serine
- Sphingomyelin
- Sphingosine
From the four major phospholipids found in mammals which one is/are Sphingolipids?
Sphingosine
From the four major phospholipids found in mammals which one is/are Phosphoglycerides?
Phosphatidyl-ethanolamine
Phosphatidyl-serine
Sphyngomyelin
T or F
Phospholipids form Michelle or bilayer in aqueous environments
TRUE
What molecules form micelles
Cone shaped ampiphilic molecules
What molecules form bilayers
Cylinder shaped phospholipids
T OR F
THE SPONTANEOUS CLOSURE OF A PHOSPHOLIPID BILAYER TO FORM A SEALED COMPARTMENT IS ENERGICALLY NON FAVORABLE
FALSE IS MOST ENERGICALLY FAVORABLE
How do phospholipids move in the lipid bilayer?
Through transversal or lateral diffusion
T OR F
Lateral diffusion occurs more often than transferal diffusion
TRUE
IT IS EASIER TO MOVE LATERALY THAN ACROSS
Fluidity of the lipid bilayer depends on
Its composition and the temperature on which it was analyzed
What is phase transition
Change of lipid bilayer from liquid state to a two dimensional rigid crystalline state (gel)
What happens to the phase transitions if the phospholipids chains are shorter and have double bonds
The phase transition and the temperature at which it occurs are lower
T OR F
Lipid bilayer is stabilized by hydrophilic interactions between lipid fatty acid chain
FALSE
STABILIZED BY HYDROPHOBIC
fluidity depends on
Lipid composition
Cholesterin content
Temperature
What happens to the lipids if temperature is low
They show less movement, so its in a paracrystaline state. More rigid.
What happens to the lipids if temperatures are high
More fluidity
T or F
Shorter chains increase the tendency of hydrocarbon tails to interact with one another so that the membrane remains fluid at low temperatures
FALSE
REDUCE THE TENDENCY
T OR F
MORE CHOLESTEROL LESS FLUIDITY
FALSE
MORE FLUIDITY
how do we demonstrate membrane fluidity?
Fluorescent microscopy and FRAP
WHAT IS FRAP
FLUORESCENCE RECOVERY AFTER PHOTOBLEACHING
CONTEXT OF CELL(4)
Extracellular tissue
Basal lamina
Connective tissue
Collagen fibers
What can you find in the connective tissue
The Extracellular matrix with the fibroblast and collagen
Fibroblast produce
Collagen
T OR F
MACROMOLECULES IN THE ECM ARE MAINLY PRODUCED LOCALLY BY FIBROBLASTS IN THE MATRIX
FALSE
BY CELLS IN THE MATRIX
WHAT ARE THE MAJOR CLASSES OF MACROMOLECULES
GLYCOSAMINOGLYCANS GAGS
COLLAGEN
NON COLLAGEN FIBROUS PROTEINS
WHAT ARE THE NON COLLAGEN FIBROUS PROTEINS
LAMININ
NIDOGEN
FIBRONECTIN
WHAT IS COLLAGEN
fibrous, ling, stiff, triple stranded helical protein, rich in praline, glycine and is glycosylated
The human genome contains how many genes coding for different collagen chains?
42
Type 1 collagen
Skin, bone, cornea, internal organs, tendons
Type 2 collagen
Cartilage, inverters disc, notochord
Type 3 collagen
Skin, blood vessels, internal organs
T OR F
TYPE 1 AND 2 COLLAGENS ARE IN THE SKIN AND INTERNAL ORGANS
FALSE IS 1 AND 3
Elastin is
Gives elasticity to tissues
Hydrophobic protein rich in praline and glycine but is not glycosylated
What is the difference between Elastin and collagen
Collagen is glycosylated and Elastin is not
What is a rubber band
Molecules are joined together by covalent bonds to generate cross linked network
T OR F
Glycoproteins in the Extracellular matrix have multiple domains each with a specific binding site for other macromolecules and receptors
NOR DEGRADE KTTRUE
WHAT DOES FIBRONECTIN DO
Helps organize the ECM and cells attach to it
What is the basil lamina
Thin, flexible, though part of Extracellular membrane
What is laminin
The 1ry organizer of the sheet structure of basal lamina
What is laminin composed of
3 polypeptide chains held together by disulfide bonds
T OR F
CELL CANT MAKE ECM NOR ORGANIZE, NOR DEGRADE IT
FALSE
THEY CAN
Integrins do?
Link the cytoskeleton with the ecm
Integrins are
Transmembrane cell adhesion that work as matrix receptors
What are the Cytoskeleton filaments that maintain the shape of cell
Tubulin and actin
Cytoskeleton determines
Cellular organization and polarity
A cell has to (4)
Be correctly shaped
Be physically robust
Internally structure
Change its place and move from one place to another
What 3 different filaments compose the cytoskeleton
Actin filament
Microtubules
Intermediate filament
T OR F
ACTIN IS 24 NM
FALSE IS 7 nm
Microtubules are
Polymers of the protein tubulin
T OR F
TUBULIN IS A HETERODIMER FORM CROM TWO CLOSELYBRELATED GLOBULAR PROTEINS CALLED GAMMA TUBULIN AND BETA TUBULIN
FALSE
ALPHA TUBULIN AND BETA TUBULIN
T OR F
IN TUBULIN, GTP BOUND TO ALPHA TUBULIN IS TRAPPED AND NEVER HYDROLIZED NOR EXCHANGED
TRUE
T OR F
IN TUBULIN, GTP IN ALPHA TUBULIN IS EITHER GTP AND GDP FORM AND IS EXCHANGEABLE
FALSE
IS IN BETA TUBULIN
Microtubules are
Hollow cylindrical structures built from protofilaments each composed of alpha and beta Tubulin HETERODIMER stacked head to tail and then folded into a tube
What Cytoskeleton filament is a HETERODIMER stacked head to tail and then folded into a tube
Microtubulin
Dynamic instability is
Process where microtubules shrink or grow
What causes the microtubules to grow
Addition of GTP containing Tubulin to the end of a protofilament
What causes the microtubules to shrink
If GTP hydrolysis proceeds more rapidly that the addition of new subunits
Where does microtubules originate from
From the specific cellular location known as the microtubules organizing center or MTOC
T or F
In animals cells the matrix is the major MTOC
False
The centrosomes is the major MTOC
What are the MAPS
Microtubules associated proteins
Kinesis and dyenin
How does kinesis travel
Normally towards the plus end
Dyenin travels
Toward minus end
MAPs move
Organelles, Vesicles in cell, and Vesicles with pigments or melanosomes
What is the taxol paclitaxel
Principle of anticancer chemotherapy
Blocking microtubules kills cancer
What is Celia made of
Microtubules
Where is cilia
airways, to clean and remove mucous
What is flagella for
To move cells in liquid environment
Actin subunits form
A tight right handed helix called filamentous actin
What is f-actin
Filamentous actin, right handed helix of actin
Actin is (2)
Flexible
Can polymerize to grow or depolymerize
T OR F
ATP BOUND TO ACTIN HAS LOWER AFFINITY FOR THE NEIGHBORING SUBUNIT AND REMAINS UNSTABLE IN FILAMENT
FALSE
HAS HIGHER AFFINITY AND REMAINS STABLE IN FILAMENT
T OR F
ADP BOUND ACTIN CAN EASILY DISSOCIATE FROM THE FILAMENT
True
A bundle forming cross-linked has
Fascin cross linker
Gel forming cross-linker has
Filament cross linker
What does stress fiber crossing have
Contracting actin filaments
Contractile bundle
Cell cortex cross linker have
Gel like network
Filopodium is
Tight-parallel bundle
Type 1 and 2 intermediary filaments
Acid and basic Kerstin produced in epithelial cells
Type 3 intermediary filaments
Vinentin in fibroblast Endothelial cells and leukocytes Destin in muscle Gila febrile in astrocyte Perinephrine in nerve cells
Type 4 intermediary filaments
Neurofilament heavy, medium, and low
Filensin and phakinin in eyes
Type 5 intermediary filaments
Lamina of nuclear membrane
