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Flashcards in Biological Molecules Deck (19)
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1
Q

Explain how hydrogen bonds form.

A

Oxygen and hydrogen atoms share electrons unequally. The oxygen atoms - greater share of electrons - more negative and hydrogen atoms - fewer electrons - more positive.
The more positive hydrogen atoms are attracted to the more negative oxygen atoms of other molecules forming hydrogen bonds.

2
Q

Why is water a polar molecule?

A

Water is made of oxygen and hydrogen atoms and these do not share electrons equally. Oxygen always has more electrons in a hydroxylic bond so it is more negative whilst the hydrogen atoms are more positive.

3
Q

What are the properties of water that make it important in blood?

A

It helps transport dissolved compounds in to and out of cells since it is a polar molecule and a solvent.
It is a transport medium due it being cohesive and molecules sticking together when transporting around the body.
It is a coolant and resistant to temperature change

4
Q

Describe the formation of glycosidic bonds.

A

A glycosidic bond is formed between two glucose molecules.
Hydroxyl group in carbon 1 of a molecule interacts with the carbon 4 of another in a condensation reaction where water is removed. The two glucose molecules are joined in a glycosidic bond and forms a new molecule: maltose.

5
Q

Explain how the structure of cellulose is related to its function.

A

It made of long,unbranched chain of beta-glucose.
These bond to make straight chain molecule with many hydrogen bonds between each chain strengthening the fibres (microfibrils)
These provide structural support to the cells in plants.

6
Q

Explain why beta glucose once polymerised produces cellulose and not starch.

A

Beta glucose cannot bond easily unlike alpha glucose due to the hydroxyl groups at carbon 1 and 4 being too far apart in the ring structure.

This means that alternate glucose molecules must rotate 180 so the carbon 1 and 4 are close enough to react.

This causes a condensation reaction as water is released and this forms a Glycosidic bond.

7
Q

Chemical elements which make up biological molecules carbohydrates, lipids, proteins and nuclear acids.

A

C,H,O
C,H,O
C,H,O,N,S
C,H,O,N,P

8
Q

Structure and properties of glucose.

A

Glucose is the main energy source in animals and plants.
A ring structure with its chemical bonding containing lots of energy.
It is a polar molecule.
Soluble in water because of the hydrogen bonds between the hydroxyl groups and water.
Being soluble is vital as it means glucose can be dissolved in the cell and it is easy to transport.

9
Q

Structure of amylose.

A

Long unbranched chain of a-glucose.
Angles of glycosidic bonds give it a coiled structure (forming a helix stabilising the hydrogen bonds) making it compact and efficient for storage as it fits into small spaces.

10
Q

Structure of amylopectin.

A

Long, branched chain of a-glucose.
The branches allow enzymes to break down the molecule making it easier to access glycosidic bonds so glucose is released quickly.

11
Q

Structure of glycogen.

A

It is the main storage in animals as they store excess glucose as glycogen.
It is a polysaccharide of a-glucose
More branches than in amylopectin so glucose is released quicker which is important as animals are mobile and require a lot of energy.
Makes it more compact and insoluble.

12
Q

Explain the difference between globular proteins and fibrous proteins.

A

Globular proteins are round and compact.
Their hydrophilic r-groups are pushed to the outer part of the molecule because of the interactions of the hydrophobic and hydrophilic in the tertiary section.
They are soluble/easy to transport.
Fibrous proteins are tough and rope shaped.
Insoluble and strong as they are not reactive and structural

13
Q

Structure of triglycerides.

A

Made from combining one glycerol with three fatty acids.

14
Q

Reducing sugars.

A

Reducing sugars react with the copper ions in the Benedict’s solution resulting in more electrons to the blue Cu2+ ions turning them brick into Cu+.

15
Q

Structure of amino acid.

A

Amine group NH2
Carboxylic group COOH
Variable R- group

16
Q

Synthesis of polypeptides.

A

Amino acids join when the OH in the carboxylic reacts with H of the amine group of another amino acid.
This is a condensation reaction as water is released.

17
Q

Beirut test for proteins.

A
Add sodium hydroxide to make the solution alkaline.
Add copper (II) sulphate

If present it will go purple
Of not it will remain blue.

18
Q

Types of protein.

A

Fibrous. Globular.

  • collagen. -haemoglobin
  • keratin. -insulin
  • elastin. -amylose
19
Q

Triglycerides.

A
1 glycerol (alcohol)
3 fatty acids (carboxylic)

OH groups interact leading to 3 water molecules removed and ester bonds being formed.
Esterification is a condensation reaction.