lecture 5: lipids Flashcards

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1
Q

General description of lipids + its 3 classes

A
  • Relatively large molecules + structurally and functionally diverse
    1. phospholipids
    2. fats
    3. steroids
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2
Q

What do lipids do? (7)

A
  1. Form biological membranes (phospholipids)
  2. Store chemical energy (fats)
  3. Insulates body + cushion vital organs in mammals
  4. Act as signalling molecules
  5. Aid in diverse processes in cells (means that they have a lot of other functions)
  6. Capture light energy (pigments in photosynthesis)
  7. Water proofing body structures (with hydrophobic part)
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3
Q

What does a lipid look like?

A
  • Largely non-polar and hydrophobic bc major hydrocarbon component —> C-H —> high chemical energy bc of hilltop electrons that are loosely between molecules (low electronegativity)
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4
Q

Types of lipids found in cells (7)

A
  1. Fats
  2. Phospholipids
  3. Steroids
  4. Glycolipids
  5. Waxes
  6. Vitamins
  7. Photosynthetic pigments
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5
Q

Structure of fats

A
  • Form via dehydration reactions
  • 1 glycerol linked by ester linkages to 3 fatty acids —> not polymers bc can’t have infinite chains of it
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6
Q

Function of fat in animals (3)

A
  1. Long-term energy storage (short term = sugars) —> compact and bc animals have to move around
  2. Body insulation
  3. Cushion to protect vital organs
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7
Q

Function of fat in plants? In what form?

A
  • In seeds: Protective + energy source for embryo (only in seeds bc plants don’t need fat as they don’t have to move)
  • Liquid, oils at room temperature (olive oil, avocado oil) —> unsaturated fats
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8
Q

Difference between saturated and unsaturated fats

A
  1. Animal = saturated fats —> saturated fatty acids
    - Saturated/filled completely with H
    - Linear structure
    - Bad for health
    - More chemical energy than unsaturated
  2. Plants = unsaturated fats —> unsaturated fatty acids
    - NOT saturated with H —> DOUBLE BOND within chain
    - Crooked/bends bc of double bond —> stays in liquid state bc more spaced out and more difficult to solidify
    - Good for health
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9
Q

Phospholipid structure

A
  • Polar (hydrophilic) head: glycerol, phosphate, polar/charged group
  • Non polar (hydrophobic) tail: 2 fatty acids (all C-H bonds)
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10
Q

Function of phospholipids (2)

A
  • Create biological membranes (plasma membrane, nuclear membrane) + cell’s internal compartments
  • Involved in cell communication (cell signaling pathways)
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11
Q

Steroids structure

A

Polar/hydrophilic: R-group
Non polar/hydrophobic: Steroid rings + Isoprene chain (Chain of carbon)
- really different from phospholipid and fats
- mainly hydrophobic

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12
Q

3 functions of steroids + associated steroid?

A
  1. Cholesterol: precursor to make other steroids
  2. Cholesterol: structural molecules in animal cell membrane
  3. Testosterone, estradiol (estrogen): sex hormones, in cell to cell communication
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13
Q

What are hormones?

A

Functional class of molecules involved in cell-to-cell communication

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14
Q

Cholesterol (important precursor) can be used to make… (2)

A
  1. Steroid hormones: long-distance signaling molecules
  2. Bile acids (made in liver): help digest and absorb fats
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15
Q

What are glycolipids and sphingolipids?

A

Components of cell membrane and involved in cell communication

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16
Q

What do waxes do?

A

Used to waterproof structures (ex: cuticle in leaf)

17
Q

What do photosynthetic pigments do?

A

Anchor themselves in membranes and capture light energy (chlorophylle A and B)

18
Q

What are some lipid vitamins

A

Vitamins A, D, E, K —> required for proper cell function

19
Q

What is the plasma membrane made of?

A

Bilayer of phospholipids, other lipids, proteins, carbohydrates
- Majority = lipids & proteins

20
Q

What are lipoproteins?

A
  • Lipids = hydrophobic = cannot dissolve in blood = can’t travel by blood
  • So they are transported from the liver to around the body as part of lipoprotein particles (travel in packages)
  • Several kinds of lipoprotein particles = identified and named based on their densities and diameters
21
Q

LDL vs HDL

A
  1. Low-density lipoprotein (LDL) = “bad cholesterol”
    - Linked with cardiovascular disease like atherosclerosis
    - High LDL = diet rich in saturated or trans fats —> so not influenced by the cholesterol, but by the types of fats that you eat
  2. High-density lipoprotein (HDL) = “good cholesterol”
    - Clears blood by transporting lipids form cells BACK to the liver
    - Linked to protection from atherosclerosis, good heart health
    - High HDL = diet rich in UNsaturated fats & other dietary/lifestyle changes
22
Q

What happens in atherosclerosis?

A
  • Plaque forms overtime in the wall of an artery (not just a buildup of LDL)
  • Plaque rupture can initiate a blood clot —> Blood flow is blocked —> can lead to heart attack (heart) or stroke (brain)
23
Q

What is the term “bad cholesterol” misleading?

A
  • LDL is not bad in normal amounts, only in high amounts
  • Still needed in our biology