S1_L2: Plasma Membrane, Basic Lipid Bilayer, Cytoskeleton, Membrane Junctions, and Extracellular Matrix Flashcards
To serve as a structural support in axons is a major function of the
intermediate filaments
What does a microtubule look like?
Straight and hollow tubes
TRUE OR FALSE: Cytoskeleton is a fixed structure
False
What region do the microtubules grow out from?
Centrioles
What are the names of the three types of fiber in the cytoskeleton
- Actin
- Intermediate filaments
- Microtubules
Acts as a track for motor proteins to walk on and shapes and supports the cell
Microtubules
Which is the thickest fiber?
A. Actin
B. Intermediate filaments
C. Microtubules
C. Microtubules
Which is the component of all cells?
A. Actin
B. Intermediate filaments
C. Microtubules
A. Actin
A globular protein that forms contractile motion and makes up the microfilaments
Actin
What do tight junctions form between membrane domains?
A ladder-like fence
What anchors the cell membrane laterally to another cell membrane?
Desmosomes
Gap junctions allow small (1)__ soluble molecules to move from (2)__ to (3)__
- Water
- cytoplasm
- cytoplasm
Connexons are also known as
Gap junctions
What is the function of the extracellular matrix?
A. Fill up the spaces between cells
B. Reservoir for hormones
C. Provide structural framework
D. All of the above
D. All of the above
Connects the extracellular matrix to proteins within the plasma membrane
Fibronectin
Tight junctions are also known as
Occluding
These are gap junction family proteins
Connexins / connexons
How are intercellular spaces occluded?
Extracellular domains adhere
Channel forming junctions
Gap junctions
Enumerate the 4 functions of the plasma membrane
- Maintains composition between contents of cell & its environment
- Acts as a site for signal transduction
- Provides a matrix for protein transport
- Provides molecular interaction
These make the plasma membrane impermeable to water & water
soluble substances
Membrane lipids
Forms the gate or boundary of the cell, has a 7.5 - 10nm thickness, and highly selective permeability.
Plasma membrane
TRUE OR FALSE: The extracellular fluid contains more sodium and calcium, while the intracellular fluid has more potassium, phosphate, and proteins.
True
TRUE OR FALSE: The extracellular environment is more positive than the intracellular environment because the
plasma membrane sets up ionic gradient
and sodium is more abundant on the
outside. The abundance of phosphate and proteins in the ICF also make it more negatively charged.
True
(1)__ gradients are electrical in nature, while (2)__ gradients are chemical in nature.
- Ionic
- Concentration
TRUE OR FALSE: The plasma membrane is a “fluid-mosaic” model, where membrane lipids exhibit fluidity and can be bent.
True
Contains 3/4 of the total extracellular fluid & salt content. It immediately bathes cell with nutrients.
Interstitium
Determine the corresponding description of the extracellular matrix of the following structures
- ECM of bones
- ECM of skeletal muscle
- ECM of nerve cells
- ECM of the blood
A. Soft
B. Fluid
C. Hard
- C
- C
- A
- B
Determine the corresponding descriptions of the components of the extracellular matrix
- Ground substance of glycosaminoglycans &
proteoglycans - Laminin and fibronectin
- Shock-absorbing
- Collagen and elastin
- Bridge cells & fibrous proteins of CT
A. Fiber-forming elements
B. Packing elements
C. Adhesive proteins
- B
- C
- B
- A
- C
It fills up space between cells, serves as a reservoir for hormones & binds growth factor, participates in wound healing, and acts as a lattice for cell movement in differentiation.
Extracellular matrix
Complex mechanisms of cell adhesion that permit individual cells to communicate. These are sites of contact between adjacent cells.
Membrane junctions
Principal component of microtubules
Tubulin
Long, hollow structures for transport of intracellular vesicles secretion, rapid assembly & disassembly. It forms the spindle in mitosis.
Microtubules
Microtubules are associated with motions of hair-like extensions in respiratory tract, known as (1)___, and worm-like extensions (i.e., sperm cells,
uterine cells), known as (2)___.
- cilia
- flagella
Determine the corresponding details of the ends of microtubules
- Increase of energy will attract microtubules
- No metabolic activity causes a drop in temperature
- Facilitated by cold at (-)
- Pre-formed protein is attached
- Facilitated of warmth; area of high
metabolic activity
A. Assembly end
B. Disassembly end
- A
- B
- B
- A
- A
This permits cell motility, provides means by which organelles can move from one locus to another, and provides binding sites for RNA & proteins.
Cytoskeleton
These link together at z-disks of myofibrils and link dense bodies in smooth muscles. These also connect the nuclear membrane to cell membrane and interconnect spot desmosomes in epithelial cells.
Intermediate filaments
TRUE OR FALSE: Gap junctions / nexuses don’t undergo paracrine signaling. Additionally, it won’t go out of the cell, unlike the desmosome and tight
junctions.
True
TRUE OR FALSE: The opening & closing of gap junctions / nexuses can be regulated by the necessity of ions to pass through.
True
Junctions that are smaller, more local, and oval-shaped cell contact. These have reduced intercellular space and do not have access to ECF.
Gap junctions / Nexuses
Ladder-like proteins at site of contact of 2 cells to stabilize the cells toward each other. These are found at the apical regions of epithelial cells and form a band around the entire cell circumference.
Tight junctions / Occluding junctions / Zonula occludens
Gates that allow some particles to pass through, such as water. These are only found in the apical portions, gastrointestinal area, skin cells, and epithelial cells.
Paracellular gates
Determine the corresponding details of the anchoring junctions
- Found between desmosomes and
hemidesmosomes - Connected laterally to each other but should also be connected to the base
- Bind cells to extracellular matrix of basal lamina via transmembrane linker glycoproteins
- Are macula adherens
- ladder-like areas occupying long stretches of the membrane
A. Desmosomes
B. Zonula adherens
C. Spot desmosome
D. Hemidesmosome
E. Desmogleins
- E
- C
- D
- A
- B
Determine the corresponding details of the anchoring junctions
- Found in areas subject to tense stresses and stretch (e.g., skin, GI cells, skeletal muscle)
- Attach with spot desmosome protein in the middle of the
desmosome - Disk-shaped areas of contact between cells
- Intracellular attachment protein links the transmembrane proteins to intermediate filaments of the cytoskeleton
A. Desmosomes
B. Zonula adherens
C. Spot desmosome
D. Hemidesmosome
E. Desmogleins
- A
- E
- A
- D
Determine the corresponding details of the 3 major types of lipids
- Sugar added to fats
- Has a kink or joint (unsaturated fatty acids)
- abundant in mammalian cells
- absent in the inner mitochondrial membrane & other intercellular membranes
- makes hydrocarbon chains near polar heads partly immobilized
A. Phospholipids
B. Cholesterol
C. Glycolipids
- C
- A
- B
- C
- B
Determine the corresponding details of the 3 major types of lipids
- has a hydrophobic planar steroid ring & hydrocarbon tails
- make membrane more hydrophilic because it attracts more water
- makes membrane less fluid at 37°C & keeps membrane more fluid at <35°C
- carbohydrates covalently bound to membrane lipids
- found in between phospholipid heads
A. Phospholipids
B. Cholesterol
C. Glycolipids
- B
- C
- B
- C
- B
Determine the corresponding details of the motions of lipid structures
- Explains cellular expansion & growth and occurs 107 times per second
- It doesn’t produce a gap in the bilayer and movement is like a Swiss knife
- Occurs about the long axis & very rapidly
- Molecule moves from one monolayer to another, occurs once a month
- Occurs particularly near the center of the bilayer
A. Lateral diffusion
B. Rotation
C. Flexion
D. Flip-flop
- A
- D
- B
- D
- C
Determine the corresponding details of the 2 general types of membrane proteins
- interlacing with the polar heads of the lipids
- amphipathic
- found in either side, could be intracellularly or extracellularly
- no flip-flop motion
- anchored to only one of the leaflets of the membrane
A. Integral proteins
B. Peripheral proteins
- B
- A
- B
- A
- A
Determine the corresponding details of the membrane carbohydrates
- Found in nerve cells & intestinal cells
- Attached to phospholipids
- Found in myelin sheaths
- Attached to protein
A. Galactocerebroside
B. Gangliosides
C. Glycoprotein
D. Glycolipid
- B
- D
- A
- C
These are found on the outer half of the bilayer and make both lipids & proteins more hydrophilic.
Membrane carbohydrates
Enumerate the 7 functions of membrane proteins
- Enzymes
- Transport
- Receptors
- Structural
- Pumps
- Channels
- Antigens
TRUE OR FALSE: All phospholipids are amphipathic
True
Amphipathic: polar head and nonpolar tail
Determine the corresponding details of the 2 general types of membrane proteins
- Span the both membranes intracellularly and extracellularly
- bind covalently with phospholipids or fatty acyl chains
- not amphipathic
- Undergo lateral diffusion
- associate with polar regions of the membrane
A. Integral proteins
B. Peripheral proteins
- A
- A
- B
- A
- B
TRUE OR FALSE: Cholesterol tends to slow down lateral mobility.
True
major histocompatibility proteins and cellular identity markers
Antigens
Increased proportion of unsaturated to saturated fatty acids tend to keep the fluidity of the membrane in ___
temperatures
lower
Saturated fatty acids form ___ and make membrane more viscous and easier to pack.
straight hydrocarbons
TRUE OR FALSE: Hydrocarbon chains are more difficult to pack together
True
Oil does not mix with water because of ___. When the oil is forcibly mixed with water, this breaks the oil.
micelle formation
Phospholipids & glycolipids diffuse laterally & rotate d/t fatty acids with ___ hydrocarbons form kinks
unsaturated