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Biochemistry 2019 > Lecture 15-16 > Flashcards

Lecture 15-16 Flashcards

1
Q

Are lipids hydrophobic or hydrophilic?

A

BOTH! lipids are amphipathic

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2
Q

Name the specific hydrophobic and hydrophilic (polar) groups that are found on lipids and work to give them their amphipathic nature.

A

The hydrocarbon group is what is hydrophobic

The carboxyl group is what is hydrophilic (polar)

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3
Q

Describe what it means for a lipid to be “saturated” and compare that to an “unsaturated” lipid

A

Saturated lipids have the maximum number of hydrogens that can be bound to their carbon chain

Unsaturated lipids have “at least one double bond” (this occupies at least one of the places that a hydrogen could have been bonded

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4
Q

Compare Saturated and Unsaturated fatty acids in terms of their Melting points, Flexibility, C-C bonds, and C=C bonds.

A

Saturated Fatty acids:
Melting point: Higher
Flexibility: High
C-C Bonds: All of it’s carbon carbon bonds
C=C Bonds: none of it’s carbon carbon bonds

Unsaturated Fatty acids:
Melting point: Lower
Flexibility: Low
C-C Bonds: Many
C=C Bonds: occur in either "cis or trans" formations
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5
Q

Compare Saturated, Cis-unsaturated, and Trans-unsaturated fatty acids in terms of the shape of their hydrocarbon chain and dietary sources of them

A

Saturated Fatty acids:
Linearly shaped hydrocarbon chain
Animal fats

Cis-unsaturated Fatty acids:
“more bent” hydrocarbon chain
Plant oils and omega fatty acids

Trans-unsaturated Fatty acids:
“less bent” hydrocarbon chain
Processed fats

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6
Q

Palmitoleic, Oleic, Linoleic, Linolenic, Arachadonic Acids, EPA and DHA are all considered to be what type of fatty acid?

A

Cis-unsaturated fatty acids

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7
Q

Lauric, Myristic, Palmitic, Stearic, Arachidic, Behenic, an Linoceric Acids are all considered to be what type of fatty acid?

A

Saturated fatty acids

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8
Q

“partially hydrogenated oils” are considered to be what type of fatty acids?

A

Trans-unsaturated fatty acids

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9
Q

Define micelles (include what forms them)

A

Micelle: a fatty acid that forms a “wedge-shape” and tend to take on spherical forms
(like an ice cream cone)

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10
Q

Describe which end you begin on when naming/numbering a fatty acid

A

begin from the carboxyl-end (functional group: O-C-O ; Alpha carbon) and count toward the Methyl-end (functional group: CH3 ; Omega Carbon)

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11
Q

In terms of Omega Fatty acids, explain what the number in the names mean. (ex. omega 3 and omega 6 fatty acids)

A

The number represents the position of the double bond closest to the methyl (w) group end of the structure of the fatty acid

So omega 3 fatty acids have a double bond 3 carbons away from the methyl group carbon and the double bond is 6 carbons away from the methyl group in omega 6 fatty acids

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12
Q

State the 4 “essential” omega fatty acids but be sure to delineate which of these are considered to be essential omega fatty acids bc they are inefficiently converted (as opposed to just not being able to synthesize them at all).

A

Essential omega fatty acids
LA/Linoleic Acid (w-6)
ALA/Linolenic Acid (w-3)

ALA is inefficiently converted to
EPA (w-3)
DHA (w-3

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13
Q

State the role that omega fatty acids play in humans at the cellular level, nutrition level, and which particular body system they are shown to help the most

A

Omega fatty acids are used in cell membranes

they are a common energy source

They improve cardiovascular health

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14
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Laurate

A

of Carbons: 12

of Double Bonds: 0

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15
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Myristate

A

of Carbons: 14

of Double Bonds: 0

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16
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Palmitate

A

of Carbons: 16

of Double Bonds: 0

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17
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Stearate

A

of Carbons: 18

of Double Bonds: 0

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18
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Arachidate

A

of Carbons: 20

of Double Bonds: 0

19
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Behenate

A

of Carbons: 22

of Double Bonds: 0

20
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Lignocerate

A

of Carbons: 24

of Double Bonds: 0

21
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Palmitoleate

A

of Carbons: 16

of Double Bonds: 1

22
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Oleate

A

of Carbons: 18

of Double Bonds: 1

23
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Linoleate

A

of Carbons: 18

of Double Bonds: 2

24
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Linolenate

A

of Carbons: 18

of Double Bonds: 3

25
Q

Fatty Acids to know:
State the number of carbons and the number of double bonds present in the following fatty acid.

Arachidonate

A

of Carbons: 20

of Double Bonds: 4

26
Q

Describe the structure of a TAG (Triacylglycerol)

A

Triacylglycerols have 2 parts:
1. a glycerol which serves as the polar head

  1. 3 fatty acid chains (tails) that are hydrophobic
27
Q

Describe the structure of a Wax (is it hydrophobic or hydrophilic?)

A

Waxes are similar to TAGs, except they have an alcohol group instead of a glycerol

Waxes are almost entirely hydrophobic

28
Q

Archaebacteria lipid membranes contain branched fatty acids. Describe what a branched fatty acid structure is like.

A

Branched fatty acids: have many methyl groups “branching” off of the carbon chains of the fatty acids

29
Q

State the 3 types of cell membrane lipids found in humans

A

Phospholipids

Glycolipids

Cholesterol

30
Q

What type of lipid comprises the majority component of cell membranes? what 4 subunits must be included in the structure of this lipid?

A

Glycerophospholipids

they contain:
An Alcohol group (hydrophilic group)
A glycerol
A phosphate
Fatty acid chains
31
Q

Some of the common alcohols that are added to create a glycerophospholipid can be divided into 3 groups, AA’s, Sugar-alcohols, and organic alcohols. State the 5 specific alcohols and put them in their appropriate group.

AA’s:

Sugar-alcohols:

Organics:

A

AA’s: Serine

Sugar-alcohols: Inositol or Glycerol

Organics: Ethanolamine or Choline

32
Q

Which type of glycolipid is important for ABO blood type antigens and cell signaling? State the 3 subunits that these feature.

A

Glycosphingolipids

They contain:
A sugar unit (glucose or galactose)
A sphingomyelin unit (which attaches a fatty acid to it’s amine group)
A fatty acid unit

33
Q

Which type of glycolipid is mainly found in plants and bacteria (rarely found in animals)? State the 3 subunits that these feature.

A

Glycoglycerolipids

They contain:
A carbohydrate
A glycerol
a fatty acid

34
Q

What lipid is known to add rigidity to cell membranes? What is the category of lipid that this is a part of? what is the term that is used to describe a collection of these in a blood vessel?

A

cholesterol, which is a sterol

a plaque

35
Q

When multiple hydrocarbon tails are present, lipids will form what structure? State the 2 parts that compose the “dual role” of this structure.

A

a bilayer

  1. A 2-D liquid that allows lateral movement of proteins and lipids
  2. A permeability barrier
36
Q

Cell membranes are made up of several different types of structures that allow for their _____ natures. Name these 3 types of molecules that compose the cell membrane.

A

Flexible

  1. Lipids
  2. Proteins
  3. Carbohydrates
37
Q

In terms of the roles they play in the cell membrane, compare lipid bilayers and carbohydrates

A

Lipid bilayers are the “base component” of cell membranes

Carbohydrates decorate lipids and proteins but are ONLY presented on the surface of the cell (NOT in contact with the cytosol)

38
Q

Compare Integral membrane proteins with peripheral membrane proteins in terms of their location in relationship to the lipid bilayer

A

Integral membrane proteins: span the ENTIRE width of the lipid bilayer

Peripheral proteins span only part of the width of the lipid bilayer

39
Q

Define cotranslational insertion and why it is important

A

Cotranslational insertion: The process by which an integral membrane protein is translated by a ribosome into the cell membrane THEN undergoes folding while already inhabiting the cell membrane

This is important bc it solves the issue of transporting integral membrane proteins into the cell membrane. Membrane proteins have a lot of hydrophobic AA’s displayed on their surfaces, which makes them want to clump together in the aqueous cytoplasm. Inserting them into the PM DURING translation avoids this issue.

40
Q

Describe the 2 types of membrane anchors and explain what they are usually attached to

A

Hydrophobic AA side chains can serve as membrane anchors

Fatty acid groups can also serve as membrane anchors

Membrane anchors are hydrophobic proteins that are used to anchor peripheral membrane proteins into the PM

41
Q

Membrane proteins (that includes integral and peripheral membrane proteins) make up what percentage of the proteome of a cell? Besides being heavily involved in signaling and molecule movement across the membrane, what 2 membrane characteristics are membrane proteins responsible for determining?

A

30%

Membrane proteins help to determine the “thickness and rigidity” of the membrane

42
Q

Lipids are ___fluids, which means they allow only Lateral movement of components. Compare the speed of lateral diffusion and transverse diffusion.

A

2-D

Lateral diffusion is the movement of a lipid “Within the same surface of the membrane” and it is very rapid

Transverse diffusion is the movement of a lipid “to the other surface of the membrane” is very slow
(flip-flop movement of a lipid)

43
Q

Compare what determines the rigidity of the membrane in a bacterial cell and a human cell

A

In bacteria, the rigidity of the PM is determined by it’s “fatty acid composition”

In humans, the rigidity of the PM is determined by it’s “cholesterol content”

44
Q

Membranes are _______ in nature

A

asymmetrical

(meaning that the membrane proteins, cholesterols, glycoproteins, carbohydrates, etc. that composes the PM will not all be “equal on both sides”)

Biochemistry 2019 (32 decks)

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