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Physiology > functional structure of the cell membrane > Flashcards

functional structure of the cell membrane Flashcards

1
Q

what does the cell membrane contain?

A

it contain lipid bilayer, protiens, cholesterol, and carbohydrates

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2
Q

which of the following is true about cell membrane?

A. the cell membrane attached to cytokeleton in the inner surface and extracellular matrix in the outer side.
B. the thickness of the lipid bilayer is :10-11 nm, not even
C. the membrane is permeable
D. the phospholipid bilayer consist of hydrophobic heads and hydrophilic tails

A

A

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3
Q

what is the total thickness of the membrane with proteins?

A

up to 20 nm

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4
Q

what are the functions of cell membrane? list 3

A

•Forms and preserves a cell’s integrity.
•Control water and material transport into and out of the
cell
•Facilitated diffusion, Carrier proteins, Channels, Endo / exocytosis
•Gives a cell its identity: receptors, ID molecules etc.
•Cell movements (ameboid / flagellar / cilliar movements). •Signal transduction
•Determines electrical status of a cell : Excitation of the cell, propagation of an excitation.
•Attachment to extracellular environment.
•Intercellular interactions: junctions, receptor-ligand binding

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5
Q

which of the following is false about the permeability of the cell membrane?

A. gases like CO2, N2, O2 can cross the cell membrane easily without a channel
B. the cell membrane is a selectively permeable membrane
C. ions like K+ can pass without channel
D. charged polar molecules cannot pass the membrane without channels

A

C

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6
Q

true or false

the cholesterol makes up 27% of the cell membrane

A

true

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7
Q

which one is false statement about phospholipids?

A. Phospholipids are a class of lipids that are a major component of all cell membranes.
B. The structure of the phospholipid molecule generally consists of two hydrophobic fatty acid “tails” and a hydrophilic “head” consisting of a phosphate group.
C. The two components are joined together by a hydrogen bonding.
D. The phosphate groups can be modified with simple organic molecules such as choline, ethanolamine or serine.

A

C

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8
Q

true or false..

glycolipids are sugar molecules bonded to phosphate backbone..

A

false

they are sugar molecules bonded to sphingosine backbone

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9
Q

what is the difference between cerebroside and ganglioside?

A

the cerebroside is a single sugar such as glucose and galactose, while ganglioside is multiple sugar which means oligosaccharide

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10
Q

Pathological accumulation of gangliosides in genetical disorders called …………………………….

A

gangliosidosis

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11
Q

what is the advantage of having cholesterol in the plasma membrane?

A

it increases membrane flexibility and stability

and it generally decreases membrane fluidity

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12
Q

which of the following is false about sphingolipids:

A. Sphingolipids are commonly believed to protect the cell surface against harmful environmental factors by forming a mechanically stable and chemically resistant outer leaflet of the plasma membrane lipid bilayer.
B. Metabolites of sphingolipids like ceramide and sphingosine-1 phosphate act like inhibitors for important cellular processes like apoptosis, cell proliferation, inflammation, autophagy, aging and differentiation.
C. They are abundant in lipid rafts.

A

B

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13
Q

what are lipid rafts?

A

Lipid rafts are submicroscopic membrane microdomains rich in sphingomyelin and cholesterol.

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14
Q

all of these are lipid raft’s function except:

A. membrane fluidity
B. protein trafficking
C. inhibits receptor trafficking
D. regulate host - pathogen interaction

A

C

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15
Q

which one of the following about asymmetric distribution of membrane lipids is false?

A. Outer and inner leaflet of bilayer are different in type. This asymmetry is help in the function of the cell membrane.
B. Membranes lose asymmetry in dying cells.
C. Many cytosolic proteins bind to specific lipid head groups found in the cytoplasmic monolayer. They take part in converting extracellular signals into intracellular ones.
D. similar shapes and sizes of membrane lipids creates stability in the thickness and causes curvatures on the membrane.

A

D

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16
Q
  1. the glycolipids are ……………….. bonded to ……………………….
  2. while the glycoproteins are ………………………… bonded to ……………………….
A
  1. carbohydrates / phospholipids

2. carbohydrates/ proteins

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17
Q

membrane proteins are divided into 2 types, mention them and explain each type.

A
  • Integral proteins: A protein molecule (or assembly of proteins) that is permanently attached to the biological membrane. Such proteins can be separated from the biological membranes only using detergents, nonpolar solvents, or sometimes denaturing agents.
  • Peripheral proteins: enzymes, intracellular signal mediators, usually attached to other proteins, but not permanently. They can be extracted without disrupting the membrane.
18
Q 
transmembrane proteins are:
A. mostly channels
B. signaling proteins
C. anchoring proteins
D. enzymes
A

A

19
Q

what are the functional classes of membrane proteins?

A
  1. intercellular joining
  2. enzymatic activity
  3. transport (active/ passive)
  4. cell- cell recognition
  5. anchorage/ attachment
  6. signal transduction
20
Q

Glycosylation of Membrane Components
Lipids + oligosaccharides :
Proteins + oligosaccharides :
Proteins + polysaccharides :

A

Glycolipids
Glycoproteins
Proteoglycans

21
Q

which of the following is false about the function of the membrane carbohydrates:

A. Many of them have a negative electrical charge, giving most cells a surface charge that repels other negative things.
B. Endothelial glycocalyx forms a smooth surface for blood flow and attracts the blood cells preventing unnecessary inflammation etc.
C. The glycocalyx of some cells attaches to the glycocalyx of other cells, thus attaching cells to one another.
D. Many of the carbohydrates act as receptor substances for binding hormones, such as insulin; when bound, this combination activates attached internal proteins that, in turn, activate a cascade of intracellular enzymes.

A

B

22
Q

Membrane carbohydrates function as cell …………

A

IDs

23
Q

lectins are mostly abundant in?

A
  • Red kidney beans
  • Soybeans
  • Wheat
  • Peanuts
  • Potatoes
  • Tomatoes
  • Corn
24
Q

list 2 from the function of lectins..

A
  1. They interfere with the absorbtion of food and minerals, help microorganisms attach to the target cells.
  2. They act like antioxidants, support cell growth.
25
Q

foods that contain lectins are usually rich sources of ………….., …………….., ………………….., …………….., and …………………

A

B vitamins, protein, fiber, and minerals, and healthy fats

26
Q

One example of the powerful biological attributes of lectins is the biochemical warfare agent …………………..

A

ricin

27
Q 
Small projections (about 2 μm).
Highly organized in the intestines in the form of brush border, that creates huge surface area for absorbtion of the nutrients.
on the hair cells in the ear and vestibular system they act as mechanical transducers.
WHAT ARE THEY?
A

MICROVILLUS

28
Q

flat sheets of membrane sustained by the cytoskeleton with high surface to volume ratio. A reserve for cell membrane.
WHAT IS THIS?

A

ruffles

29
Q

seen in dying cells, ameboid movement or isolation of a faulty part of the membrane to limit the damage.
WHAT IS THIS?

A

blebs

30
Q

Pits in the membrane providing reserve membrane during size change. Involved in the endocytosis.
WHAT IS THIS?

A

caveolea

31
Q

Pits larger than cavaolea. Related with cell size change upon osmotic challenge.
WHAT IS THIS?

A

Vocuole

32
Q

Membrane fronts and projections for movement and extension.

WHAT ARE THEY?

A

Lamellapodium, filopodium, microvillus, spike

33
Q

what are the 2 types of cilium?

A

motile cilium

primary cilium

34
Q

Sperm has a tail similar to cilium but longer and stronger, which is called a …………………………

A

flagellum

35
Q

what is the disease linked to primary cilium which highlights its importance?

A

ciliopathies

36
Q

what are the extracellular signals that are received by antenna?

A

including light, low molecular weight chemicals, proteins, and mechanical stimuli.

37
Q

why does the PKD kidney cells show no response to flow?

A

they lack primary cilia

38
Q

What is the main difference between the old and new fluid mosaic model?

A

1.old fluid mosaic
•More lipid / protein
•Uniform thickness

  1. New fluid mosaic
    •Less lipid / protein
    •Variable thickness
39
Q

which of the following is not a function of the cell membrane?
A. Gives a cell its identity
B. Signal transduction
C. Determines electrical status of a cell
D. Intercellular interactions
E. None

A

E

40
Q 
which of the following are permeable  via cell membrane
I. ions
II. small uncharged polar molecules
III. Water
IV. large uncharged polar molecules
V. gases
A. I, II, III, IV
B. II, III, V
C. I, II, IV
D. All
A

B

41
Q

The two components of phospholipids are joined

together by

A

a glycerol or

sphingosine molecule.

42
Q

cholesterol generally increases membrane fluidity

and decreases membrane flexibility and stability

A

False
decreases membrane fluidity
Increases membrane flexibility and stability

Physiology (3 decks)

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