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Histology Quiz 1 > Plasma Membrane > Flashcards

Plasma Membrane Flashcards

1
Q

Changes in cells micro environments under normal and pathological conditions can cause….

A

The same cell type to have variable features and activities

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2
Q

Cells that appear similar in structure often have different families of receptors for signaling molecules such as….

A

Hormones and extra cellular matrix (ECM) components, causing them to behave differently

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3
Q

Breast Fibroblasts and uterine muscle cells

A

-Diverse arrays of receptors
-Exceptionally sensitive to female sex hormones
-most other fibroblasts and smooth muscle cells are insensitive

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4
Q

Specialized cells: don’t memorize table but…

A

All cells can do all sorts of different basic functions, but some specialize and look different (morphology)

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5
Q

Basic structural and functional units of multicellular organisms

A

A. Plasma membrane/ Plasma Lemma/ Cell Membrane
B. Cytoplasm
C. Nucleus

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6
Q

Functions of Plasma Membrane (6)

A
  1. Envelope cell— maintain structure and function
  2. Act as semipermeable membrane — only allow certain things to pass
  3. Place for membrane receptors — recognize macromolecules or other cells, or to be recognized by other cells
  4. Signal transduction into intracellular environment— downstream response within cell (from surface to cytoplasm of nucleus)
  5. Cell to cell interaction
  6. Maintain electrical gradient btwn intra & extra cellular — capacitance (difference of charges on inside of cell to outside of cell)
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7
Q

Her notes on functions of Plasma Membrane

A
  • selective barrier regulating passage of materials in and out
  • facilitating transport of specific molecules
  • keep constant the ion content of cytoplasm (different than ion content of extra cellular fluid)
  • membrane proteins perform recognition and signaling functions (key role in interactions of cell with environment)
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8
Q

Plasma membrane components (4)

A
  1. Phospholipids
  2. Cholesterol
  3. Proteins
  4. Oligosaccharide chains linked (covalently) to phospholipids and proteins
  • is a bilayer —> 7.5-10nm thick
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9
Q

Phospholipid-bilayer structure

A

Inner layer and outer layer

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10
Q

P face

A

Facing cytoplasm —> Inner layer

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11
Q

E face

A

Facing extracellular components —> outer layer

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12
Q

Parts of phospholipid

A
  • Polar, hydrophilic globular head
  • nonpolar, hydrophobic long chain fatty acid (LCFA)
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13
Q

Saturated fatty acid

A

Straight, no dbl bond

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14
Q

Unsaturated fatty acid

A

Bent, has double bond

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15
Q

Why polar head on outside?

A

Attracted to water on outside- turns and chains automatically face inside- same with phospholipids on inner layer

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16
Q

Why bilayer?

A

Phospholipids are most stable when organized in double layer.
Hydrophobic chains in middle away from water, hydrophilic heads contacting the water.

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17
Q

Amphipathic

A

2 parts
1. Hydrophilic polar head that bears a phosphate group
2. Hydrophobic (2 nonpolar LCFA)

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18
Q

Phospholipid names

A

Phosphatidylcholine
Sphingomyelin
Phosphatidylserine
Phsohatidylethanolamine

(Found in eukaryotic cells)

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19
Q

Fluidity is crucial for

A

Exocytosis
Endocytosis
Membrane trafficking
Membrane biogenesis

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20
Q

Fluidity increases when

A
  • Increase temp (related to melting points)
  • Increase in # of unsaturated bonds of fatty acyl tails
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21
Q

Fluidity decreases when

A

decrease in temp

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22
Q

Cholesterol location

A

Embedded in LCFA (in between)

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23
Q

Role of cholesterol

A

Buffering fluidity of membrane with changes in temp

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24
Q

Cholesterol in cold temps

A

Prevents membrane from becoming very ridged— keeps fluid

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25
Q

Cholesterol in hot temps

A

Lowers fluidity so phospholipids don’t arrange too loosely and become too fluid

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26
Q

Proteins of plasma membrane

A

Integral and peripheral

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27
Q

Integral proteins

A

Transmembrane proteins and multi pass proteins
- firmly embedded
- nonpolar AA interact w/ hydrophobic fatty acid chains

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28
Q

Transmembrane proteins

A

Pass all the way through PM from E to P face

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29
Q

Multi pass proteins

A

Passes through membrane multiple times

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30
Q

Peripheral proteins

A

Can be on E or P face, do not go inside membrane
Assists integral proteins

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31
Q

Membrane protein movement

A

Either move laterally or held in place by part of cytoskeleton

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32
Q

Oligosaccharide chains

A

Short chain of saccharides
Attached to phosphohead of proteins and/or lipids
Externally exposed (E Face)

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33
Q

Integral protein categories(6)

A
  1. Pumps
  2. Channels
  3. Receptors
  4. Linkers
  5. Enzymes
  6. Structural proteins
34
Q

Pumps

A

To transport certain ions (such as Na+, amino acids, sugars)

Ex: sodium/potassium pump

35
Q

Channels

A

Allowing passive diffusion of small ions, molecules, and water

Ex: aquaporin— channel for water molecules

36
Q

Receptors (receptor proteins)

A

Allow ligands to bind, such as hormones, antibodies, coated vesicle endocytosis

Bind to ligands/external signals (something that the cell needs to respond to)

37
Q

Linkers (linker proteins)

A

Anchor intracellular cytoskeleton to extracellular matrix
Keep things in place
Ex: integrin family that links cytoplasmic actin filaments to an extracellular matrix protein (fibronectin)

38
Q

Structural proteins

A

Form junction w/ neighboring cells
Ex: epithelial cells, role is to create border and hang onto eachother

39
Q

Peripheral proteins info….

A
  • Bound to one of the 2 phospholipid layers (there is more on the P face)
  • bind to phospholipid group or integral proteins (non-covalent bond)

Ex: spectrin

40
Q

Spectrin does what?

A

Stabilizes cell membrane of erythrocytes (RBCs)

41
Q

Spectrin mutations

A

Hereditary elliptocytes
Hereditary spherocytosis

42
Q

Hereditary elliptocytosis

A

RBCs misshaped- not biconcave - elliptical shaped

43
Q

Hereditary spherocytosis

A

RBCs spherically shaped
Lose flexibility

44
Q

Affect of elliptocytosis and spherocytosis

A

Enlarged spleen
- pain or fullness in left upper abdomen, may spread to left shoulder
- Full w/o eating
- Pressing on stomach
- anemia
- fatigue
- frequent infections
- easy bleeding

45
Q

Glycocalyx

A
  • Saccharides (sugar molecules)
  • Branched
  • Bind to polar head of phospholipid
    ** only on E face
    On TEM image—> fuzzy layer
46
Q

Glycolipids

A

Outer layer phospholipids and membrane proteins with Oligosaccharide chains attached

** Oligosaccharide chains constitute the glycocalyx

47
Q

Movement of material across PM, in or out can be done by

A

Passive transport
Active transport
Vesicular transport

48
Q

Passive transport

A

No energy required
Move from high to low concentration= down concentration gradient or electrochemical gradient

49
Q

Types of passive transport(2)

A
  1. Simple diffusion
  2. Facilitated diffusion
50
Q

Simple diffusion

A

Small molecules
Diffuse easily
Water goes slowly
Exchange of oxygen and CO2 through the lung blood air barrier

51
Q

Facilitated diffusion

A

Channel, carrier/pump

Sodium potassium channels —> porins/ multipass proteins, water —> comes in through protein channel called aquaporin

Carrier —> proteins bind to the molecule —> can transport them by undergoing serious of conformational changes, then released on other side

52
Q

Active transport (2)

A

Energy required (ATP) —> transport molecules against electrochemical gradient via carrier proteins

  1. Primary
  2. secondary
53
Q

Primary active transport

A

Using ATP

54
Q

Secondary active transport (2)

A

Harnessing energy while moving substance up conc gradient while pushing sodium down the gradient
1. Symporter
2. Antiporter

55
Q

Symporter

A

Moving in same direction

56
Q

Antiporter

A

Opposite direction

57
Q

Vesicular transport (2)

A
  1. Endocytosis
  2. Exocytosis
58
Q

Endocytosis (3)

A

“ Take something in”
1. Phagocytosis
2. Pinocytosis
3. Receptor mediated Endocytosis

59
Q

Phagocytosis

A

“Cell eating”

Engulfing something solid such as bacteria or dead cell remnants

60
Q

Cells specialized to do phagocytosis

A

Blood derived cells such as…
Macrophages and neutrophils

Bacteria bind to surface of neutrophil—> surrounded by extensions of plasma Lemma and cytoplasm —> enclosed bacterium in intracellular vacuole (phagosome) —> merges with lysosome to degrade its components

61
Q

Pinocytosis

A

“ cell drinking ”
- small invaginations of cell membrane fuse and entrap extracellular fluid and it’s dissolved contents

62
Q

Receptor mediated Endocytosis

A

Receptors (membrane proteins) aggregate in a membrane region —> invaginates and pinches off —> creates vesicle (endosome)

63
Q

Example of receptor mediated Endocytosis

A

Developing RBCs in bone marrow
- to synthesize hemoglobin, RBCs need iron (Fe)
- plasma has Fe bound to transferrin (glycoprotein)
- Fe- transferrin is Endocytosed via receptor mediated endocytosis by the developing RBC
- RBC breaks down and extracts Fe from it to use it

64
Q

Exocytosis

A

“Throw things out!”
Movement of large molecules from inside to outside of cell by vesicular transport

65
Q

Secretory vesicles/ secretory granules

A

Contains the enzymes accumulated in the apical portion of cells that are ready to be released into the lumen

66
Q

Membrane trafficking

A

Membrane movement and recycling
- portions of cell membrane become part of endocytotic vesicles or vacuoles during endocytosis
- in exocytosis membrane is returned to cell surface
- endo is on one side of cell, exo on other
- maintains equilibrium

67
Q

Cells involved in endocytosis/ absorption in GI tract

A

Simple columnar epithelia

  • small intestine: absorb nutrients from gut lumen
68
Q

Cells involved in exocytosis/ secretion

A

Glandular epithelium
- serous
- mucus

69
Q

Optimization of endo and exocytosis

A

Increasing surface area available

70
Q

Microvilli

A
  • Increase surface area
  • “brush border”
  • # can change —> if you fast # goes down, when you eat again # goes back up
71
Q

Common glands

A
  1. Serous
  2. Mucus
  3. Demilune
72
Q

Serous gland

A

Secreting mainly proteins/ enzymes

73
Q

Mucus gland

A

Secreting mucous

74
Q

Demilune

A

Secretes serous and mucus products

75
Q

Why do cells communicate with eachother?

A
  1. Regulate tissue and organ development
  2. Control their growth and division
  3. Coordinate their functions
76
Q

Types of signaling (5)

A
  1. Endocrine
  2. Paracrine
  3. Synaptic
  4. Autocrine
  5. Juxtacrine
77
Q

Endocrine signaling

A

Signal molecule = hormones—> carried into blood from their sources to target cells through the body

** blood acts as medium

78
Q

Paracrine signaling

A
  • localized
    Chemical ligand diffuses into extracellular fluid but is rapidly metabolized so that it’s effect is only local on target cells near it’s source

Cell produce signal—> to other nearby cells

79
Q

Synaptic signaling

A

Neurons

Neurotransmitters act on adjacent cells through special contact areas call synapses

80
Q

Autocrine signaling

A

Self signaling

Signals bind receptors on the same cells that produced the messenger molecule

81
Q

Juxtacrine signaling

A

Two cells signal eachother through direct physical contact

Important in early embryonic tissue interactions

Signaling molecules are cell membrane-bound proteins which bind surface receptors if the target cell when two cells make direct physical contact.

82
Q

Pseudohypothyroidism

A

Caused by no functioning parathyroid hormone (PTH)

Gland produces PTH but the receptors cannot respond

Short stature, round face, short metacarpals, seizures in childhood, muscle spasms, high phosphate levels in blood, low calcium, fast ossification of bones — less time for bones to grow sufficient (dwarfism)

Histology Quiz 1 (2 decks)

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