Unit 2 - Carbohydrates Flashcards Preview

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Flashcards in Unit 2 - Carbohydrates Deck (20)
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1
Q

A single sugar unit is known as a…

A

Monosaccharide (a monomer of sugar)

2
Q

What is the chemical composition of a carbohydrate?

A

Carbon, oxygen, & hydrogen

3
Q

When two or more monosaccharides are linked they form…

A

A polymer called a polysaccharide.

4
Q

Glucose is a monosacharride composed of six carbons and is therefore a…

A

Hexose monosaccaride

5
Q

Name the two structural variation of the glucose molecule

A
  1. Alpha (α) glucose
  2. Beta (β) glucose
6
Q

How does alpha glucose differ from beta glucose?

A

The hydroxyl group (OH) on carbon 1 is in opposite positions

This affects the structure and properties of the polysaccarides when it bonds

7
Q

How is a disaccharide formed?

A
  • A condensation reaction
  • 2 monosaccharides join together in a condensation reaction.
  • The two hydroxyl groups interact - bonds are broken in the OH group and a new glycosidic bond is formed
  • Water is released
8
Q

Name this dissacharide…

A

Glucose + galactose = Lactose

9
Q

Name this dissacharide…

A

Glucose + glucose = Maltose

10
Q

Name this dissacharide…

A

Glucose + fructose = Sucrose

11
Q

What is a pentose sugar?

A

Sugars that contain five carbon atoms

12
Q

Which two pentose sugars are important components of biological molecules?

A

Ribose (sugar found in RNA) and Dexoyribose (sugar found in DNA)

13
Q

What are the properties of starch?

A
  • Compact
  • Chemical energy store
  • Easily digestible
  • Made of amylose (mainly, 1-4 glycosidic bonds) and amylopectin (1-4 and some 1-6 glycosidic bonds)
  • Insoluble does not create a water potential gradient (doesn’t cause water to enter cells by osmosis which would make them swell up)
14
Q

Describe the properties and structure of amylose.

A
  • Long chains of alpha glucose (unbranched)
  • Joined by 1-4 glycosidic bonds
  • Insoluble (does not create water potential gradient)
  • Metabolically inactive
  • Long chain of glucose that twists into a helix (compact for storage)
  • Helix held together by hydrogen bonds
15
Q

Describe the properties and structure of amylopectin.

A
  • Long, branched chains of alpha glucose
  • Joined by 1-4 glycosidic bonds (chains) and 1-6 glycosidic bonds (branches)
  • 1-6 branching points occur approximately one in every 25 glucose subunits.
  • Compact and idealy for storage
  • Insoluable (do not affect water potential)
  • Branches gives ‘free ends’ so glucose can be added or released quickly
16
Q

Describe the properties and structure of glycogen

A
  • Short, branched chains of alpha glucose
  • Joined by 1-4 glycosidic bonds (chains) and 1-6 glycosidic bonds (branches)
  • Compact and insoluble so good for storage
  • Branching means many ‘free ends so glucose can be released (or stored) quickly
17
Q

What is the function of glycogen?

A
  • Main energy store in animals
  • Stores soluble glucose that affects water potential as insoluble polysaccharide until needed
18
Q

Describe the structure and properties of cellulose.

A
  • Long, unbranched chain of beta (β) glucose
  • Contains 1-4 glcyosidic bonds
  • Beta (β) glucose molecules bond forming straight cellulose chains
  • Every other glucose molecule is orientated at 180 degrees - e.g alternate beta (β) glucose are turned upside down.
  • Chains are linked by hydrogen bonds forming strong fibres called microfibrils (compact)
  • Microfibrils join to make macrofibrils, which combine to make fibres
19
Q

Describe the function of cellulose?

A
  • Cellulose is an important part of our diet as it is very hard to breakdown so if the fibre necessary for a healthy digestive system
  • Cellulose provides structural support for cells
20
Q

How is a disaccharide broken down?

A
  • Hydolysis reaction
  • Addition of water to hydrolyse the disaccharide into (useable) monomers
  • Reactions are catalysed by enzymes
  • These are the opposite of condensation reactions that form glycosidic bonds.