Chapter 3 Part 1: Cells-The Living Units Flashcards

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1
Q

Cell Theory

A
  • the cell is the basic structural and functional unit of life
  • organismal activity depends on individual and collective activity of cells
  • cellular activity depends on the relative number of specific sub cellular structures
  • continuity of life has a cellular basis. Cells can only arise from other cells
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2
Q

Plasma Membrane (general)

A
  • selectively permeable barrier surrounding the cell
  • plays a dynamic role in cellular activity
  • provides biological markers for cell-cell recognition
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3
Q

Fluid Mosaic Model

A

Plasma membrane is a bilayer of lipids with imbedded, dispersed proteins

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4
Q

Membrane Lipids

A
  • phospholipids have hydrophobic “tails” and hydrophilic “heads”
  • hydrophobic tails make up the interior of the membrane
  • glycolipids: are lipids with bound carbohydrate chains on the outer surface of the cell membrane
  • cholesterol: helps stabilize the membrane fluidity
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5
Q

Integral Proteins

A

Firmly embedded in the cell membrane

Most protrude from both sides of the membrane as transmembrane proteins

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6
Q

Peripheral Proteins

A

More loosely attached at the surface

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7
Q

Glycoproteins

A

Have attached carbohydrate chains

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8
Q

Functions of Membrane Proteins

A
  • Transport
  • Enzyme Activity
  • Receptors for signal transduction
  • Intercellular joining
  • Cell-cell recognition
  • Attachment to the cytoskeleton and extracellular matrix
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9
Q

Glycocalyx

A

Carbohydrate area on the cell surface (glycolipids and glycoproteins)
Provides biological markers for cell recognition and instruction

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10
Q

Specialization of the Cell Membrane

A

Microvili and Membrane junctions

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11
Q

Microvili

A

Fingerlike projections on the cell membrane that increase Membrane surface area

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12
Q

Membrane Junctions

A

Tight Junctions
Anchoring Junctions
Gap Junctions

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13
Q

Tight Junctions

A

Impermeable (watertight) junction of interlocking Proteins encircling the cell

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14
Q

Anchoring Junctions

A

Anchors 2 cells together

-desmosomes: anchoring junctions that consist of an internal protein plaque and external linker proteins

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15
Q

Gap Junctions

A

Collection of hollow protein channels (connexons) that allow substances to pass between cells

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16
Q

Plasma Membrane Functions

A

Membrane Transport
Membrane Potential
Cell-environment Interactions

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17
Q

Membrane Transport: Passive Processes

A

no cellular energy required
Diffusion: the tendency for molecules or ions to disperse evenly
*concentration gradient: a difference in concentration of a substance between 2 areas (drives diffusion)

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18
Q

Passive Processes: simple diffusion

A
  • Non-polar and lipid-soluble substances

- Diffuse directly through the lipid bilayer

19
Q

Passive Processes: Facilitated Diffusion

A
  • Small lipid insoluble solutes
  • Diffuse through channel proteins
  • Large polar molecules such as simple sugars combine with carrier proteins which move them across
20
Q

Passive Processes: Osmosis

A

-osmosis: diffusion of water across a semipermeable membrane
(occurs when the concentration of water on opposite sides of a membrane)
Osmolarity: total concentration of solute particles in a solution

21
Q

Osmotic Pressure

A

Pressure required to resist further water entry into a cell

  • equal to hydrostatic pressure inside the cell
  • in plant cells, creates internal pressure and stops net water movement
  • animal cells tend to shrink or swell in response to osmotic imbalances
22
Q

Tonicity

A

Measure of the ability of a solution to change cell shape or tone by promoting water flow

  • hypertonic
  • hypotonic
  • isotonic
23
Q

Hypertonic

A
  • a solution with high concentration of solutes than inside the cell
  • cell loses water and shrinks
24
Q

Hypotonic

A
  • a solution with lower concentration of solutes than inside the cell
  • cell gains water and swells
25
Q

Isotonic

A

-a solution with the same concentration of solutes than inside the cell

26
Q

Passive Processes: Filtration

A

The passage of water and solute through a membrane by hydrostatic pressure

(ex: filtration if urine through the kidney tubes)
- pressure gradient pushes fluid from a higher pressure area to a lower pressure area

27
Q

Active Processes

A

Use ATP to move solutes across a membrane
2 Major Mechanisms:
Active Transport
Vesicular Transport

28
Q

Symport Systems

A

2 substances are moved across a membrane in the same direction

29
Q

Antiport Systems

A

2 substances are moved across a membrane in opposite directions

30
Q

Active Transport

A

Primary: direct result of hydrolysis of ATP causing conformational change in the Transport protein. (e.g. Na+-K+ pump)

Secondary: use of an exchange pump (e.g. Na+-K+ pump) indirectly to drive the Transport of other solutes

31
Q

Vesicular Transport

A

Transport of large particles and macromolecules across plasma membrane in membrane vesicles.

32
Q

Exocytosis

A

moves substances from the cell interior to the extracellular space

33
Q

Endocytosis

A

enables large and macromolecules to enter cell

34
Q

Phagocytosis

A

Pseudopodia engulf solids and bring them into cell’s interior

35
Q

Pinocytosis

A

Cell drinking

36
Q

Receptor-Mediated endocytosis

A

Uses receptors in pits all the major mechanisms for specific uptake of macromolecules

37
Q

Membrane Potential

A

*Voltage across a membrane
*Resting Membrane Potential
-results mostly from Na+ and K+ concentration gradients across the membrane due to:
~differential permeability of the plasma membrane to Na+ and K+
~sodium potassium pump

38
Q

Cell-Environment Interactions

A

Role of Cell Adhesion Molecules

Role of membrane receptors

39
Q

Cell Adhesion Molecules

A
  • Anchor cells to the extracellular matrix and each other
  • assist in movement of cells last one another
  • direct white blood cells to injured or infected areas
  • respond to tension at the cell surface
40
Q

Roles of Membrane Receptors (Proteins and Glycoproteins)

A
  • contact signaling
  • electrical signaling
  • chemical signaling
  • g protein-linked receptors and second messengers
41
Q

Contact Signaling

A

Important in normal tissue development and immunity

42
Q

Electrical Signaling

A

Voltage regulated “ion” gates in nervous and muscle tissue respond to voltage changes

43
Q

Chemical Signaling

A

Signal chemicals it ligands (e.g. Neurotransmitters and hormones) bind to membrane receptors

44
Q

G protein linked receptors

A

Binding of a ligand activated a g-protein, causing the release of a second messenger (e.g. Cyclic AMP)