carbohydrates Flashcards Preview

Medicine Term One > carbohydrates > Flashcards

Flashcards in carbohydrates Deck (70):
1

Function of carbohydrates

Major energy source
Storage
Structural
Protective
Cell- cell communication

2

Storage from of carbohydrate is

glycogen

3

what is a monosaccharide

Monomer of 6 C sugars (simplest form)

4

examples of monosaccharides

glucose, glactose and fructose

5

disaccharides

from monomers that are linked by glycosidic bonds

6

how do covalent bonds from in disaccharides

hydroxyl group of one monosaccharide reacts with anomeric carbon of another monosaccharide

7

What’s an anomeric carbon

carbons mirror images of each other

8

What does anomeric carbon do

(stabilises glucose)
allows oxidation

9

anomeric carbon can be either

alpha or beta

10

Name the 3 disaccharides

Maltose
Lactose
Sucrose

11

reducing sugar can

readily oxidised

12

Breakdown form of starch is

maltose

13

How is lactose formed

glycosidic bond between galactose and glucose

14

Lactose and Maltose are both what?

Reducing sugar

15

Whats sugar is only made in plants

sucrose

16

if anomeric carbon is available for oxidation that makes a

reducing sugar

17

What is an example of a nonreducing sugar

sucrose

18

what is a polysaccharides?

polymer of reoccurring monosaccharide monomers

19

A polymer with a single monomeric species is called a

Homopolysaccharides

20

what are heteropolysaccharides

polymers that have two or more monomer species

21

Examples of polysaccharides

Starch and Glycogen

22

What are the two types of glucose polymers in starch

amylose and amylopectin

23

What are glucose residues linkage in amylose

α1→4

24

What is the difference of amylopectin to amylose

Has additional branched linkage α1→6 (every 24-30 residues)

25

Does starch have lots of reducing ends?

No has a lot of nonreducing ends

26

what structure does amylose and amylopectin form

alpha helix

27

What is the linkage in glycogen

glucose (α1→4) linked sub-units
(α1→6) branches every 8 to 12 residues

28

Why can glycogen release glucose so rapidly

Due to many branching of nonreducing ends

29

Polymers in solutions are

osmotically inactive

30

Glucose transformed into glycogen because

can store high concentration of glucose without impacting osmocity of cells

31

Whats are glycoproteins

Proteins that have carbohydrates covalently attached

32

Carbohydrates attached to proteins do what?

Increases the proteins solubility
Influence protein folding and conformation
Protect it from degradation
Act as communication between cells

33

what are glycosaminoglycans composed of

Un-branched polymers made from repeating units of hexuronic acid and an amino-sugar,

34

what is the function of glycosaminoglycans

forms parts of extracellular mucuses and synovial fluid

35

Where are proteoglycans found?

found on the surface of cells or in between cells in the extracellular matrix

36

What do proteoglycans form part of

connective tissue

37

where are glycoproteins found

found on the outer plasma membrane
extra cellular matrix,
blood
and within cells in the secretory system

38

What is Mucopolysaccharidoses

Genetic disorder caused by the absence of enzyme that breaks down glycosaminoglycans

39

examples of mucopolysaccharidoses disorders

Hurler syndromes

40

Symptoms of Hurler syndrome

Clouding degradation of cornea, arterial wall thickens and causes inflammation and dementia

41

How is dementia caused due to mucopolysaccharidoses

increase in glycosaminoglycans causes a build up of Cerebrospinal fluid

42

First digestion of carbohydrates takes place where with what enzyme acting on substrate

Mouth as Salivary amylase hydrolyses
(α1→4) bonds of starch

43

Main products of carbohydrate digestion

glucose, glactose and fructose

44

Glucose passes through intestinal lumen and absorbed in the blood following low NA ion concentration by an

Indirect ATP powered process

45

What happens when blood glucose concentration is high

Glucose is still powered across the lumen into the blood

46

How does fructose cross lumen membrane and into the blood

Binds to the channel protein GLUT5, moving down conc gradient

47

What happens to polymers that can't be digested by the gut

Increase faecal bulk

48

What are polymers broken down by and yield proceeded

Gut bacteria, CH4 and H2

49

Disaccaride deficiencies due to

generic or damage to gut wall or intestine

50

Characteristics of Disaccaride deficiencies

abdominal distension and cramps

51

Example of Disaccaride deficiencies

Lactose intolerance

52

absence of enzyme lactase causes what

Lactose intolerance

53

How is lactose broken down with disaccharide deficiency

By gut bacteria

54

How can lactose intolerance cause diarrhoea

as Lactose osmotically inactive, therefore draw water from the gut into the lumen

55

What happens when glucose enter the portal blood

immediately phosphorylated into glucose 6 phosphate

56

What is the purpose of G6P

traps glucose in the cell

57

Glucose phosphorylation enzymes

Glucokinase
Hexokinase

58

where is Glucokinase found

the liver

59

which Glucose phosphorylation enzymes catalyses high glucose concentration

Glucokinase

60

Hexokinase properties ie Km and Vmax

Low Km, grab glucose efficiently
Low Vmax, tissues only phosphorylate glucose at lower concentrations

61

What is the3 pathways of G6P

glycolysis
pentose phosphate pathway
glycogenesis

62

What is not present in skeletal muscle

G6P

63

Glycogen formed from

covalently binding
extending chains
chains then broken by glycogen-branching enzyme and re-attached via (α1→6) bonds to give branch points

64

Glycogen phosphorylase removes what from glycogen

G1P

65

Enzyme debranching enzymes help release glucose by

removing 3 glucose residues on branch and attaching to nonreducing end by alpha 1-4 bond, forming more of a straight chain

66

How is glucose finally removed from glycogen

Glucosidase removes the final Glc by breaking a (α1→6) linkage

67

what si left at the end of glycogen degradation

unbranched chain

68

what happens to glycogen in the liver compared to muscle

Liver, glucose 6 phosphatase produces glucose
muscle, glycolysis produces lactate giving ATP

69

von Gierke’s disease cause and symptoms

glucose 6-phosphatase deficiency,
low glucose level
high lactic acid level

70

Skeletal muscle phosphorylase deficiency causing an inability to meet glucose demand of exercise is the cause of what disease

McArdles