Biology 1A Biological Molecules

What elements does a carbohydrate only contains

Carbohydrates contain only carbon, hydrogen, and oxygen, usually in a ratio of 1:2:1.

What term is used to describe a single monomer sugar

monosaccharide

What is a pair of monosaccharide combined called

A disaccharide.

What does a polysaccharide mean

A carbohydrate that is made up of long chains of monosaccharide units linked together by glycosidic bonds.

Draw the structure of an alpha glucose

Draw the structure of a beta glucose

What is the difference in the structure of the two types of glucose

In Alpha, OH group below Carbon 1, in Beta, OH group above Carbon 1

Name 2 monosaccharide sugars

Glucose and Fructose and ribose

What are all monosaccharides

reducing sugars

Describe the test for reducing sugars

Benedict’s + heat, turns brick red if reducing s is present

What bond join 2 monosaccharides together to form a disaccharide

glycosidic bond

What does a glycosidic bond look like

What is the reaction called which 2 monosaccharides join

condensation

What other molecule is produced when condensation reaction takes place

water

What disaccharide does two alpha glucose join to make

maltose

What monosaccharides is sucrose made from

glucose and fructose

What monosaccharides make lactose

glucose and galactose

What type of sugar is sucrose

non-reducing

What is the reaction called when you add water to break the glycosidic bonds

hydrolysis

How to carry out a test for non-reducing sugars

1. Test for reducing sugars and if result is negative there’s no reducing sugars

2. Put food samples into test tube

3. Add dilute HCl and heat for 5 mins which hydrolyses non-reducing sugars into reducing sugars

4. Add Sodium Hydrogen Carbonate which neutralises the acid solution

5. Test for reducing sugars again, if result is positive shows that reducing sugar is in the solution but non-reducing in original food sample

Why are polysaccharides suitable as storage molecules

They are very large molecules so they are insoluble

Where is starch found

Only in plant cells

What 2 substances is starch a mixture of

Amylose and amylopectin

What is the difference between the structure of amylose and amylopectin

Amylose only has 1-4 glycosidic bonds and is linear and helical, amylopectin has 1-4 and 1-6 glycosidic bonds so it is branched

What are amylose and amylopectin made from?

alpha glucose

What features make starch a good storage molecule

1. insoluble - so doesn’t affect osmosis/water potential of cell

2. easily broken down - rapid storage and release of glucose

3. large molecule - so can’t pass through cell membrane and lost form the cell

4. helical - compact so storing large amounts in small branched molecule, many free ends means storage and release of glucose very rapid

Where is glycogen found

Only in human body

What is glycogen made of

alpha glucose

What bonds does glycogen have

1-4 and 1-6 glycosidic bonds

Where in the body is glycogen stored

some in the muscle for store of glucose for respiration. The liver also stores larger reserves of glucose to break down to maintain a stable blood glucose level

What features of glycogen makes it useful as a storage molecule in muscle tissues

1. very compact - stores higher concentration of glucose

2. more branched - more free ends to release glucose quickly

Where is cellulose found

Only in plants, mainly in cell wall

What’s cellulose’s monomer

beta glucose

How are the beta glucose arranged in the cellulose chain

every other beta glucose is rotated 180

What does the bonding make cellulose

Very straight and long

What are the bonds between the cellulose chains

MANY hydrogen bonds

How is cellulose being strong suited to its function

1. allows transport of water, gases and mineral ions

2. supports the cell when turgid

3. sits on top of cell membrane

What is triglyceride made of

1 molecule of glycerol and 3 fatty acids

What does a molecule of glycerol look like

What’s the formula of a fatty acid

R-COOH

How is a triglyceride formed

What is the bond in a triglyceride

ester bond

What does a saturated fatty acid mean

if the fatty acid chain in the triglyceride have no c-c double bond in the hydrocarbon chain

What’s a feature of saturated fatty acid

They have a high melting point and tend to be found in warm-blooded animals, at room temperature they are solid

What’s unsaturated fatty acid

the fatty acid chain in a triglyceride have a c-c double bond in the hydrocarbon chain. Fatty acid with more than one c-c double bond are called poly-unsaturated fatty acids

What’s a feature of an unsaturated fatty acid

They have a low melting point and are tend to be found in cold-blooded animals, at room temp, they’re liquids

Why does unsaturated fatty acid have a low melting point

Because they can’t pack closely together