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Biology > Topic 1: Biological molecules > Flashcards

Topic 1: Biological molecules Flashcards

(58 cards)

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1
Q

What is a condensation reaction

(3 marks)

A
  • chemical reaction joining two molecules
  • forming a chemical bond
  • and releasing a water molecule
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2
Q

What is hydrolysis

(3 marks)

A
  • chemical reaction separating two moelcules
  • breaking a chemical bond
  • using a water molecule
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3
Q

Name three monosaccharides

A
  • glucose
  • fructose
  • galactose
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4
Q

Name three disaccharides

A
  • maltose
  • sucrose
  • lactose
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5
Q

Name threee polysaccharides

A
  • starch
  • glycogen
  • cellulose
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6
Q

Whar is the difference between alpha glucose and beta glucose

A

alpha glucose - OH on bottom
beta glucose - OH at top

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7
Q

How do you test for reducing sugars

A

Add benedicts to the solution, heat gently for 5 minutes, positive result changes to brick red

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8
Q

What is a disaccharide

A

Made of two monosaccharides, joined together by a glycosidic bond between the monomers

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9
Q

Name the components and products of the three disaccharides

A

Glucose + Glucose = Maltose + Water
Glucose + Fructose = Sucrose +Water
Glucose + Galactose = Lactose + Water

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10
Q

Explain how glycosidic bonds are formed

A

Formed by condensation reactions,
between the hydroxide groups (OH). One hydroxide group joins with one hydrogen to form water, and the monomers are held together by a single oxyen which becomes the glycosidic bond

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11
Q

Where is starch found, and what is its function

A

Found in plants,
Storage of glucose

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12
Q

Where is glycogen found and what is its function

A

Found in animals
Storage of glucose

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13
Q

Where is cellulose found and what is its function

A

Found in plants
To provide structural strength to the cell wall

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14
Q

What two polymers form starch

A

Amylose and amylopectin

both made from alpha glucose

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15
Q

Explain the structure of starch

A

The amylose is straight because of the 1,4 glycosidic bonds, making the starch helical.
The amylopectin can form 1,4 and 1,6 glycosidic bonds, making it branched.

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16
Q

Explain the strucure of glycogen

A

Highly branched polymer, yet still easily compactible

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17
Q

Where is starch and glycogen found

In animal and plants

A

starch - in grains in plant cells, e.g in chloroplasts
glycogen - in liver and muslce cells within the human body

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18
Q

How is glycogen adapted for its function

A

Glycogen is highly branched
Enzymes can only work on the glycosidic bond linking the outermost monomer.
By having many branches, glycoge increases the surface area for enzymes to act on, so it can easily be hydrolysed when necessary

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19
Q

Why is cellulose needed in the cell wall

A

It provides strength and supoort when the cell becomes turgid with water, preventing it from bursting

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20
Q

What is a fibril

A

When long chains of cellulose are held together by hyrogen bodning they form a fibril of cellulose. This fibril lays perpendicular to other fibrils to provide added strength.

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21
Q

Explain the importance of insolubility in glucose, starch, and cellulose

4 points

A

Insolubility means that they can be stored in cells without being dissolved.
This is important as the polysaccharides will not affect the water potential of the cell, and therefore will not cause osmosis to occur.
This allows for storage and structure.

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22
Q

What is food test for starch

A

Add iodine to the sample
positive result turns blue/black

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23
Q

What holds together (the reaction) the monomers bonds in lipids

A

Condensation reactions

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24
Q

What is the food test for reducing sugars

Study These Flashcards
A

Benedicts
- Add benedicts to the liquid sample
- heat gently
- positive result turns brick red (orange brown)

25
What are two types of lipids
- phospholipids - triglycerides
26
What do triglycerides consist of
- a glycerol - 3 fatty acids - ester bonds (from condensation reactions)
27
Where do you find saturated vs unsaturated fats
saturated - animal fats unsaturated - plant fats
28
Why are unsaturated fats typically liquid at room temp
- contain double bond - bends the shape, unable to pack together - making them liquid
29
Adaptations of triglycerides related to their properties
- **non-polar, insoluble** in water meaningthey do not affect water potential - **large sa:v ratio**, meaning they can store alot of eergy in a given volume - **high ratio of H :O**, meaning they can release water for organisms in dry environments
30
What does a phospholipid consist of
- phosphate head - 2 fatty acids - glycerol
31
In a phospholipid, which bit is hydrophillic and which is hydrophobic
- head (phosphate) is hydrophillic - tail is hydrophobic
32
How do you test for the presence of lipids
- emulsion test - add ethanol and shake - leave to settle - cloudy-white if positive result - do control with water
33
What three things does an amino acid consist of
- R group - Carboxyl group (COOH) - Amine group (NH2)
34
How many diff aminoa acids are there
20
35
What kind of bonds do amino acids form
Peptide bonds
36
What is the primary structure of a protein
- sequence of amino acids held together by peptide bonds
37
What is the secondary structure of a protein
- local motifs of alpha helices / beta pleated sheets - held by hydrogen bonding
38
What is the tertiary structure of a protein
- 3D folding of the protein - held by disulfide bridges, ionic bonds, hydrogen bonds
39
What is the quaternary structure of a protein
- diff polypeptides joined together by hydrogen bodning and van der waals
40
What are the two types of proteins
Globular, fibrous
41
How do you test for proteins
- biuret test - add bieurts to the sample - positive result gives purple colour from blue
42
How do enzymes work
Lower the activation energy and therefore increase rate of reaction
43
What type of structure are enzymes
globular proteins with tertiary structure
44
Describe the induced fit model
- active site is specific and complementary - one type of substrate witll fit into the active site, forming an enzyme-substrate complex - the structure of the enzyme is altered to fit around the substrate
45
State 5 things that affect rate of enzyme controlled reaction
- conc of enzyme - conc of substrate - temp - pH - any inhibitors
46
Explain how temp affects rate in enzyme controlled reactions
- as temp increases rate increases - more energy more movement - above the optimum rate, enzymes begin to denautre - decreases rate
47
Explain how pH affects rate in enzyme controlled reactions
- pH affects the tertiary structure of the enzyme - enzyme will work best at the optimum ph, and as the pH moves away from this - rate will decrease
48
What consists of a nucleotide
- pentose sugar - nitrogenous base - phosphate
49
What bases can DNA have
- Adenine - Thymine - Cytosine - Guanine
50
What bases can RNA have
- Adenine - Uracil - Cytosine - Guanine
51
What bonds hold together nucleotides
phosphodiester bonds joined through the sugar-phosphate backbone
52
Why is DNA stable
- Phosphodiester backbone protects the reactive bases - H bonds form bridges between bases
53
Describe semiconservative replication of DNA
- DNA helicase breaks the hydrogen bonds between bases - One strand is used as a template to undergo base pairing between free nucleotides - DNA polymerase rejoins the backbone by forming phosphodiester bonds.
54
Describe the structure of ATP
- Ribose - Adenine - 3 phosphates
55
What happens during hydrolysis of ATP
- hydrolysed to form ADP and Pi - catalysed by ATP hydrolase - energy released from the bonds
56
Why is hydrlysis of ATP good for the release of energy
- quick - releases alot at once beacuse the bonds are very unstable
57
What can you do with the inorganic phosphate ion
use it to phosphorylate other things and make it reactive
58
Describe the properties of water | (6)
1. Polar molecule, with uneven distribution of charge 2. Metabolite, used in condensation reactions 3. Solvent, readily diffuses gases and enzymez 4. High specific heat capacity, it can absorb alot of energy without changing its state 5. H-Bonds, keeps it together 6. Cohesion, allows water to travel in the xylem

Biology (19 decks)

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