biochem Flashcards
(87 cards)
1
Q
What is more impactful on health, the type of fat or the quantity of fat consumed?
A
The type of fat
2
Q
What are the main classes of lipids?
A
- Fatty acids
- Triacylglycerols
- Wax esters
- Phospholipids
- Sphingolipids
- Isoprenoids
3
Q
How are lipids defined?
A
Substances from living things that dissolve in nonpolar solvents
4
Q
What are the functions of lipids?
A
- Energy storage
- Membrane structure
- Chemical signals
- Vitamins
- Pigments
5
Q
What are fatty acids?
A
Monocarboxylic acids that typically contain hydrocarbon chains of variable lengths (12 to 20 or more carbons)
6
Q
What is the terminal methyl carbon in fatty acids called?
A
The omega (ω) carbon
7
Q
What characterizes saturated fatty acids?
A
Contain only single carbon-carbon bonds
8
Q
What characterizes unsaturated fatty acids?
A
Contain one or more double bonds
9
Q
What are the two isomeric forms of unsaturated fatty acids?
A
- Cis
- Trans
10
Q
What effect do cis double bonds have on fatty acid chains?
A
They cause a kink in the fatty acid chain
11
Q
At room temperature, how do unsaturated and saturated fatty acids typically behave?
A
- Unsaturated fatty acids are liquid
- Saturated fatty acids are usually solid
12
Q
What are monounsaturated and polyunsaturated fatty acids?
A
- Monounsaturated: have one double bond
- Polyunsaturated: have two or more double bonds
13
Q
How do plants and bacteria acquire fatty acids?
A
They synthesize all fatty acids they require from acetyl-CoA
14
Q
How do animals acquire fatty acids?
A
Primarily from dietary sources
15
Q
What are essential fatty acids?
A
Fatty acids that must be acquired from the diet
16
Q
What are the two types of essential fatty acids mentioned?
A
- Omega-6 fatty acids: Linoleic acid and its derivatives
- Omega-3 fatty acids: α-Linolenic acid and its derivatives
17
Q
What are some benefits of diets with adequate amounts of omega-6 and omega-3 fatty acids?
A
- Lower blood levels of triacylglycerols
- Lower blood pressure
- Decreased platelet aggregation
18
Q
What are eicosanoids?
A
A diverse group of powerful, hormone-like molecules produced in most mammalian tissues
19
Q
What are the three major types of eicosanoids?
A
- Prostaglandins
- Thromboxanes
- Leukotrienes
20
Q
What physiological processes do eicosanoids mediate?
A
- Smooth muscle contraction
- Inflammation
- Pain perception
- Blood flow regulation
21
Q
What is the structure of triacylglycerols?
A
Esters of glycerol with three fatty acids
22
Q
Why are triacylglycerols considered neutral fats?
A
Because they have no charge
23
Q
What differentiates fats from oils?
A
- Fats: solid at room temperature, high saturated fatty acid composition
- Oils: liquid at room temperature, high unsaturated fatty acid composition
24
Q
What roles do triacylglycerols play in animals?
A
- Energy storage
- Insulation at low temperatures
- Water repellent for some animals’ feathers and fur
25
Why are triacylglycerols a better storage form of energy than glycogen?
* Hydrophobic
* Coalesce into anhydrous droplets
26
What are the common forms of protein acylation?
* Myristoylation
* Palmitoylation
27
What is the effect of acylation on proteins?
Influences structural and functional properties of proteins
28
What is the relationship between trans fatty acids and food processing?
Trans fatty acids are side products of margarine production through hydrogenation
29
What is the naming convention for eicosanoids based on their structure?
The first two letters indicate the type of eicosanoid, the third letter indicates modifications, and the number indicates double bonds
30
What are the main precursors for eicosanoids?
* Arachidonic acid
* Eicosapentaenoic acid (EPA)
31
Fill in the blank: Fatty acids react with alcohols to form _______.
esters
32
True or False: Most naturally occurring fatty acids have an odd number of carbons.
False
33
What is the primary function of an ipocyte?
Stores triacylglycerols
## Footnote
Found in adipose tissue
34
How much energy do anhydrous triacylglycerols store compared to glycogen?
An equivalent amount of energy in about one-eighth of the volume
## Footnote
Glycogen binds a substantial amount of water
35
What is the most common composition of waxes?
Complex mixtures of nonpolar lipids
## Footnote
Protective coatings on plants and animals
36
What are wax esters composed of?
Long-chain fatty acids and long-chain alcohols
## Footnote
Examples include carnauba and beeswax
37
What is the defining characteristic of phospholipids?
Amphipathic with a polar head group and hydrophobic fatty acids
## Footnote
Act in membrane formation and emulsification
38
What are the two types of phospholipids?
Phosphoglycerides and sphingomyelins
39
What do phosphoglycerides contain?
Glycerol, fatty acids, phosphate, and an alcohol
40
What is the simplest phosphoglyceride?
Phosphatidic acid
## Footnote
Precursor for all other phosphoglyceride molecules
41
What fatty acids are most common in phosphoglycerides?
Fatty acids with between 16 and 20 carbons
42
What is the role of phosphatidylinositol?
Important structural component of glycosyl phosphatidylinositol (GPI) anchors
## Footnote
GPI anchors attach certain proteins to the membrane surface
43
What do phospholipases hydrolyze?
Ester bonds in glycerophospholipid molecules
44
What are the three major functions of phospholipases?
* Membrane remodeling
* Signal transduction
* Digestion
45
What occurs during membrane remodeling?
Cells alter membrane flexibility by adjusting saturated and unsaturated fatty acids
46
What initiates signal transduction?
Phospholipid hydrolysis by phospholipases
47
Where does fat digestion occur in mammals?
In the small intestine
48
What is the core component of sphingolipids?
Ceramide
## Footnote
A fatty acid amide derivative of sphingosine
49
What is sphingomyelin primarily found in?
Most cell membranes, particularly in the myelin sheath of nerve cells
50
What are glycolipids derived from?
Ceramides
## Footnote
Attached to monosaccharides, disaccharides, or oligosaccharides through an O-glycosidic bond
51
What are the most important classes of glycolipids?
* Cerebrosides
* Sulfatides
* Gangliosides
52
What is a sulfatide?
A sulfated cerebroside
53
What is the most common example of a cerebroside?
Galactocerebroside
## Footnote
Found in brain cell membranes
54
What is the role of PLA2 in snake venom?
Digests cell membranes and causes systemic damage
## Footnote
Includes necrosis of tissues and neurotoxicity
55
What is the most common example of broside?
Cerebroside
## Footnote
Found almost entirely in the cell membranes of the brain.
56
What is a sulfated cerebroside referred to as?
Sulfatide
57
At physiological pH, how are sulfatides charged?
Negatively charged
58
What do gangliosides possess that is significant?
Oligosaccharide groups with one or more sialic acid residues
59
From which tissue were gangliosides first isolated?
Nerve tissue
60
What do the letters M, D, and T indicate in ganglioside nomenclature?
One, two, or three sialic acid residues respectively
61
What do the numbers in ganglioside names designate?
The sequence of sugars attached to ceramide
62
What are glycosphingolipids determinants of?
Blood types
63
What is the most common lysosomal storage disease involving sphingolipid metabolism?
Tay-Sachs
64
What enzyme is deficient in Tay-Sachs disease?
β-hexosaminidase A
65
What are the symptoms of Tay-Sachs disease?
* Blindness
* Weakness
* Seizures
* Mental retardation
66
What are isoprenoids composed of?
Terpenes and steroids
67
How are terpenes classified?
By the number of isoprene units
68
What are carotenoids?
Orange pigments found in plants
69
What do mixed terpenoids consist of?
A nonterpene group attached to the isoprenoid group
70
What is Vitamin K1 also known as?
Phylloquinone
71
What is the role of Vitamin K2?
Plays an important role in blood coagulation
72
What is prenylation?
Covalent attachment of proteins to prenyl groups
73
What are the two types of prenyl groups mentioned?
* Farnesyl
* Geranylgeranyl
74
What are steroids derived from?
Triterpenes with four fused rings
75
What is cholesterol classified as?
Sterol
76
What is the role of cholesterol in animal cells?
* Essential in animal membranes
* Precursor of all steroid hormones, vitamin D, and bile salts
77
What do sex hormones regulate?
Development of primary and secondary sex characteristics and various reproductive behaviors
78
What is the function of aldosterone?
Regulates plasma concentrations of several ions, especially sodium
79
What is cholic acid converted into in the liver?
Bile salt
80
What do cardiac glycosides do?
Increase cardiac muscle contraction
81
What are the two examples of cardiac glycosides mentioned?
* Ouabain
* Digitalis
82
What is the primary function of lipoproteins?
Transport lipid molecules through the bloodstream
83
Where are apolipoproteins synthesized?
In the liver or intestine
84
What are the five classes of apolipoproteins?
* A
* B
* C
* D
* E
85
What are chylomicrons?
Large lipoproteins of extremely low density that transport triacylglycerol and cholesteryl esters
86
What do high-density lipoproteins (HDL) do?
Scavenge excess cholesterol from membranes
87
Why is HDL considered 'good cholesterol'?
It transports excess cholesteryl esters to the liver for conversion into bile acids
