March 2, 2015 --> Cards 1-15 Flashcards Preview

BOARD: Biochemistry (Dental Decks) > March 2, 2015 --> Cards 1-15 > Flashcards

Flashcards in March 2, 2015 --> Cards 1-15 Deck (79):
1

What are the six distinct classes of GAGs

1. Chondroitin Sulfate
2. Dermatan Sulfate
3. Keratan sulfate
4. Heparan sulfate
5. Heparin
6. Hyaluronate

2

Which of the six classes of GAGs is not sulfated?

Hyaluronate
- Is also not covalently attached to protein

3

What is the charge of GAGs? What causes this?

-Highly negatively charged molecules
-The uronic acid and sulfate residues cause GAGs to be negatively charged

4

Describe the general make-up and characteristics of a GAG

Long, linear carbohydrate chains that contain REPEATING DISACCHARIDE units
- Usually contain a hexosamine and a uronic acid

5

Are GAGs branched or unbranched? What acid do they not contain?

They are unbranched and do not contain N-acetylneuraminic acid

6

Where are GAGs located primarily?

on the surface of cells or in the ECM

7

Hyaluronic acid is unique among the GAGs why?

It does not contain any sulfate and is not found covalently attached to proteins as are proteoglycans

8

The majority of GAGs in the body are linked to core proteins forming what?

Proteoglycans (also called mucoppolysaccharides)

9

What structure in microbiology contains a hetropolysaccharide made up of alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) units?

Bacterial cell wall.

10

Describe where Hyaluronate can be found in the body

Synovial fluid
Vitreous humor
ECM of loose CT

11

Describe where Chondroitin sulfate can be found in the body

Cartilage
Bone
Tendon
Ligament
Heart valves

12

Where can Heparan sulfate be found

Basement membranes
Components of cell surfaces

13

Heparin can be found in the body where?

Component of intracellular granules of mast cells lining the arteries of the lungs, liver, and skin

14

Where can Dermatan sulfate be found in body?

Skin
Blood vessels
Heart valves

15

Where can Keratan sulfate be found in body

Cornea
Bone
Cartilage aggregated with chondroitin sulfates

16

What is the most abundant GAG in body

Chondroitin sulfate

17

What is the most heterogenous GAG

Keratan sulfate

18

What GAG serves as an anticoagulant, more sulfated than heparan sulfate

Heparin

19

Which GAG can be described as large polymers and shock absorbing

Hyaluronate

20

Which GAG contains higher acetylated glucosamine than heparin

Heparan sulfate

21

Define Glycoprotein

Proteins with covalently linked oligosaccharide (glycan) chains

22

Function of glycoproteins

Structural components
Transport molecules
Enzymes
Receptors
Hormones

23

Define Proteoglycan

Complex carbohydrates that have a central protein molecule to which many GAGs are attached in a radial (brush-like) pattern

24

What is the composition of a proteoglycan?

95% carbohydrate
5% protein

25

What is the linkage of a GAG to the central protein

Involve a trisaccharide: 2 galactose + 1 xylose

26

GAGs are attached to central protein how? This also means that proteoglycans are rich at the central protein in what molecules?

Serine
Threonine

27

Proteoglycans are located mostly where?

ECM

28

Proteoglycans are most often repeating dissacharides of what molecules?

amino sugar (N-acetyl) and Uronic acid (sugar with COO-)

29

Maltose consists of what two sugars?

2 Glucose molecules

30

Lactose consists of what two sugars?

glucose and galactose

31

Sucrose consists of what two sugars?

Glucose and fructose

32

Describe the formation of a glycosidic bond

Bonds form when the hydroxyl group on the anomeric carbon of a monosaccharide reactis with an OH or NH group of another compound

33

If oxygen is involved, the glycosidic bond is classified as what?
If nitrogen is involved, the glycosidic bond is classified as what?

O-glycosidic (found in polysaccharides)
N-glycosidic (found in glycoproteins and nucleotides)

34

What monosaccharide is the most important of the aldohexoses?

D-glucose

35

Two most important storage polysachharides

Starch and glycogen

36

What two main components make up Starch

Amylose (unbranched)
Amylopectin (highly branched chains w/ a-1,6 linkages)

37

Glycogen has what linkages

a-1,4 linkages and a,1-6 linkages

38

Where is glycogen especially abundant

In the liver

39

Cleavage of glycogen beyond a branching point requires what enzymes?

Glycantransferase
Amylo-alpha-1,6-glucosidase

40

What is the most common organic compound on earth

Cellulose

41

Is cellulose digestible by humans?

Not digestible and is often referred to as "dietary fiber" or "roughage" acting as bulking agent for feces

42

Linkage of cellulose

B-1,4 linkages

43

Term glycan refers to what?

A polysaccharide or an oligosaccharide

44

How does the carbohydrate portion of most glycoproteins differ from that of proteoglycans?

It is shorter and branched

45

Glycolipids are derived from what molecule?

the lipid Ceramide

46

Components of Proteoglycan
Characteristic of Proteoglycan
Role

Protein + GAGs
Long & Straight
Lubrication, ECM, molecular "sieve"

47

Components of Glycoprotein
Characteristic
Role

Protein + Carbohydrate
Short & Branched
Enzymes, Hormones, antibodies, structural proteins

48

Components of Glycolipids
Characteristic
Role

Lipid + Carbohydrate
N/A
Cell membrane receptors

49

What is an important property of Chondroitin Sulfate

Holding water and nutrients, and allowing other molecules to move through cartilage, important because there is no blood supply to cartilage

50

What enzyme will promote depolymerization of the ECM

Hyaluronidase
It splits hyaluronic acid and so lowers its viscosity and increases the permeability of CT and the absorption of fluids

51

What GAG contains the largest proportion of sulfate

Heparin

52

What is a Dextran

A homopolymer of glucose formed by the hydrolysis of sucrose via glycosyl transferase (dextran sucrase)

53

What bacteria can produce dextran?

S. mutans

54

What is a side product of dextran productions

Fructose which is formed into levans (fructans) and stored intracellularly as reserve nutrients

55

T or F, Fructans also increase the adhesion of bacteria to surfaces of the teeth and promote the formation of dental plaque

True

56

Rods contain a photopigment called what?

Rhodopsin

57

Rods are numerous in what part of the retina

Periphery

58

Cones are primarily responsible for what?

Color vision

59

The four different photopigments consits of what?

A protein called an opsin to which a chromophore molecule called retinal is attached.

60

The majority of the bending of light rays is accomplished by what?

Cornea

61

T or F, The shape of the cornea changes with age

False, it does not change

62

majority of the focusing is done by what part of the eye

The cornea, not the lens

63

What part of the eye is analogous to the film in a camera?

Retina

64

Cones are especially densely packed in what area?

Fovea

65

Which part of the eye is filled with vitreous humor?

Posterior segment

66

Which part of the eye is filled with aqueous humor?

Anterior segment (anterior and posterior chambers)

67

Parts of the External ear

Auricle (directs sound waves)
External auditory canal (contains hair and cerumen)

68

Parts of Middle ear

Auditory tube (equalizes pressure)
Ossicles (Malleus, incus, stapes)

69

Parts of Inner ear

Vestibule (saccule and utricle) - balance
Semicircular canals (concerned with equilibrium)
Cochlea ( two membranes, vestibular and basilar)

70

What portion of the inner ear is responsible for hearing

Cochlea, it is the basic functional unit of hearing because this portion transforms fluid vibrations from sound waves into a nerve impulse

71

What is Miosis:

Constriction of the pupil of the eye. Can be caused by a normal response to an increase in light, certain drugs or pathological conditions

72

what is Mydriasis:

Prolonged abnormal dilation of pupil of the eye induced by a drug or caused by a disease and causes the eyes to become extra sensitive to light

73

How to treat mypoia

Myopia is nearsightedness, eye is too long for refractive power of the lens
- Concave lenses are used

74

How to treat hyperopia

Hyperopia is farsightedness, occurs when light entering the eye focuses behind the retina instead of directly on it. Cause by a cornea that is flatter, or an eye that is shorter.
- Convex lenses are used

75

Astigmatism is what?

occurs when the curvature of the lens is not uniform and is corrected with cylindric lenses

76

Presbyopia is what?

The inability of the eye to focus sharply on nearby objects, resulting from the loss of elasticity of the lens with advancing age.
- Corrected with bifocals

77

Hgb value depends on what?

Number of RBCs and amount of Hgb in each RBC

78

Blood leaving the lungs is what % saturated with oxygen? Blood returning to the lungs (venous blood) is what % saturated with oxygen?

98%
75%

79

What sugar is not a reducing sugar?

Sucrose
The reducing groups of both glucose and fructose are involved in the glycosidic bond
- Sucrose contains no anomeric carbon