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BIOCHEM Mod 2 > Cell Membrane > Flashcards

Cell Membrane Flashcards

1
Q

Primary Function of Cell membrane

A

proteins/complexes is controlled transport of molecules into and out of the cell through channels, gates, and active carriers

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2
Q

Secondary Function of Cell Membrane

A

proteins/complexes is cellular communication (signaling) through receptors and amplification of secondary messengers

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3
Q

What is the Cell membrane made up of?

A

Phospholipid bilayer; hydrophilic region pointing towards water and hydrophobic region pointing inwards away from water

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4
Q

What is the location and function of Cardiolipin (diphosphatidylglycerol)?

A

Location: inner mitochondrial membrane

Function: stabilizes the electron transport system of mitochondria; decrease blood clots, stabilize respiratory chain enzymes in mitochondria, moves proteins and cholesterol, assists in proper folding of mitochondrial proteins, possibly helps regulate DNA synthesis

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5
Q

Changes of cardiolipin composition can lead to what diseases?

A

Heart failure, diabetes, Alzheimer’s disease, and Parkinson’s disease

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6
Q

Barth Syndrome

A

defects in the enzyme that metabolizes cardiolipin

decreased phosphorylation of ADP to ATP

symptoms: cardiomyopathy, muscle weakness and exercise intolerance

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7
Q

Treponema Pallidum

A

Bacterium responsible for syphilis; produces antibodies against cardiolipin

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8
Q

Phosphatidylserine (PS)

A

major acidic phospholipid in brain

intercellular communication; “flipped” (flippase enzyme) to outer membrane of platelets during platelet activation where it promotes thrombin formation (coagulation); cofactor for the anticoagulant protein C pathway

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9
Q

Phosphatidylethanolamine (PE)

A

predominantly cytoplasmic side; located in both the interior and exterior of cell membranes

regulates membrane curvature; secreted in VLDL

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10
Q

Phosphatidylcholine (PC)

A

located on both sides of cell membrane but usually on exterior

compound of pulmonary surfactant and used to calculate fetal lung maturity

promotes anticoagulant protein C pathway but less than PS

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11
Q

Phosphatidylinositol

A

Located in the interior and exterior of cell membrane as well as nuclear membrane

secondary messenger

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12
Q

Flippase

A

Enzyme that catalyzes the process of moving particular phospholipid molecules from one side of the bilayer to the other when needed

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13
Q

What maintains membrane fluidity and why is it important? Diseases associated with it?

A

Cholesterol maintains membrane fluidity; very important to keep membrane fluidity as to not destroy the cell

Bacteria and viral infections, malaria, entamoeba histolytica, migraines and virgin olive oil (beneficial changes in carbohydrates and lipid metabolism)

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14
Q

What is the worst thing that can happen to a cell membrane?

A

Crystallization

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15
Q

How does cholesterol maintain membrane fluidity?

A

Stiffens lipid bilayer but also prevents crystallization of membrane at colder temperatures

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16
Q

What bonds are associated with the lipid bilayer?

A

Hydrogen bonds and van der wall forces

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17
Q

Where are Lipid Rafts found?

A

Portions of cell membrane saturated with cholesterol and other lipids

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18
Q

Role of Polyene Antifungals

A

binds to ergosterol (like cholesterol but only in fungi); decreases membrane fluidity and creates hydrophilic channel through membrane - causes cell leakage and death

Does not effect human cells since we don’t have ergosterol

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19
Q

Peripheral and Integral Proteins

A

Peripheral located on either side of the bilayer; Intergral proteins located within or across the entire width of bilayer

membrane proteins can contain carbohydrates (glycoproteins)

20
Q

Which proteins maintain RBC cell membrane shape?

A

Spectrin and ankyrin; important in the stabilization of the normal biconcave shape of RBC

21
Q

Two diseases that result in the defects in RBC proteins that maintain the RBC cell membrane shape?

A

Elliptocytosis and spherocytosis

22
Q

Hemoglobinopathies

A

disorders of the globin side chains of hemoglobin (sickle cell anemia, hemolytic anemia, thalassemias) - changes in globins lead to cell deformation - lead to cell death

One point mutation

23
Q

Most important cell membrane function

A

maintain separate chemical environments allowing concentration gradients (due to van der wall forces) of ions/molecules to move in and out of the cell for cellular functions (size and charge also effect permeability)

24
Q

What are the three methods of Membrane Channels?

A
  1. simple diffusion (no energy) - concentration gradient driven (through membrane)
  2. Facilitated Diffusion (no energy) - concentration gradient but speed can change depending on shape of
    gated channel protein
  3. Active Transport - (energy required) - involves carrier protein and changes shape via the release of energy or phosphorylation from nucleotide molecules
25
Q

Sodium Potassium Pump

A

Active transport carrier protein - NOT A MEMBRANE CHANNEL or GATED CHANNEL PROTEIN

26
Q

Ionophore Antibiotics/Antifungals

A

Same outcome of polyene; mechanism is different though; DOES NOT BIND TO ERGOSTOL
Distrupts the balance of various ions inside and outside of cells by interfering with the cell’s maintenance of its membrane function of membrane channels

27
Q

Calcium Channel Blockers

A

Decrease the total transport of calcium into muscle cells thereby decreasing heart contraction and increase the diameter of blood vessels leading to decrease blood pressure (treat hypertension and high blood pressure)

28
Q

H2 blockers and proton pump inhibitors

A

block transport of Hydrogen transport; decrease hydrogen in stomach to reduce heart burn, gastritis, ulcers and reflex disease

29
Q

Aquaporins (-1 and -2) Function

A

integral membrane proteins found the kidney and other organs which help to regulate water flow in and out of cells

30
Q

Group I intracellular receptor proteins

A

signal passes through membrane by diffusion and binds to intracellular target

31
Q

Group II cell surface receptors

A

transmit a message from one side of the lipid bilayer to the other

32
Q

Secondary Messengers used by Group II surface signaling

A

cAMP, Ca2+, DAG, Tyr-P, IP3, PIP

33
Q

Intracellular Steroid Receptors

A

lipid soluble and can cross the membrane; binds with cytoplasmic receptors or activate signaling or continue to receptors in the nucleus to activate transcription factors and DNA snythesis

34
Q

Genomic

A

steroid hormones that affect DNA synthesis

35
Q

Nongenomic

A

Steroid hormones that do not affect transcription

36
Q

Purpose of G-proteins

A

conversion of GDP to GTP to convey an external signal to the inside of the cell

37
Q

Gs

A

cAMP production via adenyl cylase and protein kinase A signaling multiple targets

38
Q

Gi

A

inhibits cAMP production; minor role in stimulation of phospholipase C

39
Q

Gq

A

stimulates phospholipase C

40
Q

G12/13

A

activation leads to changes in the actin cytoskeletion and therefore, regulation of cell cycle and motility

41
Q

Gt

A

transducin molecules found in rods and cones couple visual signals between rhodopsin and cGMP phosphodiesterase

42
Q

Second Messengers (signaling enzymes)

A

Adenyl cyclase, protein kinase A, phospholipase C, protein kinase C

43
Q

Phospholipase C - Protein Kinase C (PKC) Signaling

A

Activation of phospholipase C (via the alpha-subunit of Gq) results in the cleavage of the membrane lipid PIP2 into DAG and IP3

44
Q

Soluble Receptor-Associated Tyrosine Kinases

A

Found on cell membrane; receptor tyrosine kinases, Janus kinases, and Integral guanyl cyclase (aka guanylyl or guanylate cyclase)

45
Q

Janus Kinase and Signal Transducer and Activator of Transcription (JAK-STAT)

A

end result: DNA leading to expression of certain genes

BIOCHEM Mod 2 (8 decks)

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