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Bio 1090 Final > Lecture 15 > Flashcards

Lecture 15 Flashcards

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Biology 101 flashcards
1
Q

What membrane defines the cell boundary?

A

Plasma membrane

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2
Q

What defines enclosed compartments

A

Organelles (mitochondria, golgi etc.)

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3
Q

What controls movement of material into and out of the cell/organelles

A

Plasma membrane and organelles

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4
Q

What allows response to external stimuli

A

Plasma membrane

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5
Q

What enables interactions between cells

A

Plasma membrane
(Ex. Tissues, muscles need to communicate with each other)

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6
Q

What provides a scaffold for biochemical activities

A

Mitochondria and chloroplasts
(Energy transduction)

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7
Q

Describe the structure of plasma membrane

A

Trilaminar structure is the lipid bilayer

Lipid bilayer is made up of phospholipids

Proteins are embedded in/associated with the phospholipid bilayer

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8
Q

What is the fluid mosaic model of biological membranes

A

Fluid: components are mobile

Mosaic: diverse ‘particles’ (protein, carbs and cholesterol penetrate the lipid layer) the components can interact

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9
Q

Describe the phospholipid structure

A

Glycerol backbone: 2 fatty acid chains and polar head group linked by a phosphate residue

Phospholipids are amphipathic
( hydrophilic and hydrophobic)

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10
Q

How will phospholipids try to organize themselves

A

In it’s most stable form, liposomes

Micelles only have one hydrophobic chain

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11
Q

Where does phospholipid synthesis occur?

A

Multiple step process at the interface of the cytosol and ER membrane

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12
Q

What does the ER membrane contain

A

Molecular machinery (enzymes) for synthesis and distribution

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13
Q

What are the 3 membrane proteins? Where are they located?

A
  1. Integral - many different functions, span the lipid bilayer, extracellular and extends from membrane
  2. Peripheral - associate with surfaces of the lipid bilayer
  3. Lipid-anchored- attach to a lipid in the bilayer (associated but do not span it)
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14
Q

What are the functions of integral proteins

A
  1. Transport of nutrients and ions
  2. Cell to cell communication (gap junction)
  3. Attachment (through receptors)
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15
Q

Describes lipids movement in relation to a leaflet

A

Lipids move easily, laterally within leaflet

Lipid movement between leaflets are slow and difficult

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16
Q

How do membrane proteins move within the biylayer

A

They diffuse
Restricted movement ( rapid is spatially limited and long range diffusion is slow)
Biochemical medication can change mobility (important for signal transduction)

17
Q

Describe the structure of biological membranes

A

Properties that all membrane share: about 6nm thick, stable, flexible, capable of self assembly

Unique features: different types of lipids and proteins for different functions, differences between cells and organelles within them

18
Q

What is contained in the inner membrane of the mitochondria?

A

Very high concentration of proteins that are needed for electron transport chain and ATP synthesis

19
Q

What is the structure and purpose of the myelin sheath

A

Low amounts of protein and made up of multiple layers of the plasma membrane

Serves as insulation and increases the speed of electrical impulses almond the myelinated fiber

20
Q

What are the leaflets of the membrane? What are the functions?

A

Each layer of the bilayer
Allows for movement of proteins and communication between cells

Each leaflet has distinct structure in many plasma membranes

Outer leaflet contains glycolipids and glycoproteins

21
Q

How does temperature affect fluidity of biological membranes

A

Hotter temps increase fluidity (Liquid crystal)

Lower temps decrease fluidity (crystalline gel)

22
Q

How does membrane fluidity change with the nature of the lipid

A

Membrane fluidity is crucial for cell function

Unsaturated lipids increase fluidity

Saturated lipids reduce fluidity

23
Q

How does lipid composition of membrane change in response to changes in temp

A
  1. Desaturation of lipids
  2. Exchange of lipids chains
24
Q

What does a balance between an ordered (rigid) and disordered (fluid) structure allow

A

Mechanical support and flexibility

Membrane assembly and modification

Dynamic interactions between membrane components (ex. proteins can come together reversibly)

25
Q

How does cholesterol control membrane fluidity

A

A bidirectional regulator

At high temps, stabilizes the membrane and raises the melting point

At low temps, it intercalates between phospholipids and prevents them from clustering together and stiffening

26
Q

How will cholesterol change the fluidity of membrane in a liquid crystal state versus a crystalline gel state

A

Overall changes packing and flexibility of lipids

Added to a liquid crystal membrane: fluidity decreases

Added to a crystalline gel membrane: fluidity will increase

Bio 1090 Final (12 decks)

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