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Biological molecules Flashcards

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1
Q

What is a monomer?

A

The smaller units from which larger molecules are made

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2
Q

What is a polymer?

A

Molecules made from a large number of monomers joined together in a chain

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3
Q

What does organic compound mean?

A

Compounds containing carbon and hydrogen

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4
Q

What are examples of monomers?

A

Monosaccharides, amino acids and nucleotides

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5
Q

What are examples of polymers?

A

Starch, proteins and DNA

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6
Q

What is a condensation reaction?

A

Two molecules bond together
One water molecule is removed

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7
Q

What is a hydrolysis reaction?

A

Two molecules are broken apart
One water molecule is added

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8
Q

Examples of monosaccharides

A

α glucose/β glucose , fructose and galactose

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9
Q

What are disaccharides?

A

Two monosaccharides joined by a glycosidic bond

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10
Q

Examples of disaccharides

A

glucose + glucose = maltose + water
glucose + fructose = sucrose + water
glucose + galactose = lactose + water

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11
Q

Examples of polysaccharides

A

Starch - store for glucose
Cellulose - structural strength
Glycogen - store of glucose

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12
Q

Explain the structure of starch

A

Formed from two polymers of alpha glucose (amylose and amylopectin)

Amylose - condensation reaction forms a 1-4 glycosidic bond
Amylopectin - 1-6 glycosidic bond, branched polymer increases SA for rapid hydrolysis

Insoluble store of glucose

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13
Q

What is the test for starch?

A

Iodine

Positive test = orange to blue/black

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14
Q

Explain the structure of glycogen

A

Formed from alpha glucose and found in muscle and liver cells

More 1-6 glycosidic bonds to create a highly branched polymer - compacted easily and increase SA

Insoluble store of glucose

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15
Q

Explain the structure of cellulose

A

Formed from beta glucose and found in cell wall (plants)

Provides structural strength to cell wall

1-4 glycosidic bonds, long and straight chains held parallel by many hydrogen bonds (fibrils)

Insoluble - won’t affect water potential

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16
Q

What is the test for reducing sugars?

A

Benedict’s regent (blue as it contains copper (II) sulphate) and heat

Positive test = Brick red

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17
Q

What is the test for non-reducing sugars?

A

Negative benedict’s test - add acid and boil, cool then add alkali to neutralise, then add benedict’s regent and heat again

Positive test = Brick red

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18
Q

What are the groups of lipids?

A

Triglycerides and Phospholipids

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19
Q

What is the properties of triglycerides?

A

Non-polar and hydrophobic

Condensation reaction between one glycerol + three fatty acids [ester bonds]

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20
Q

What is the structure of trigycerides?

A

methyl - CH3
hydrocarbon - (CH2)n
carboxyl - COOH

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21
Q

Define saturated and unsaturated bonds

A

saturated - single bonds
unsaturated - double bonds

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22
Q

What is the test for lipids?

A

Ethanol + water

Positive test = milky white emulsion

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23
Q

What is the structure of phospholipids?

A

Phosphate hydrophilic polar head (PO³−₄)
Glycerol (CH2)
Hydrophobic fatty acid tails

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24
Q

What does amphipathic mean?

A

Have both hydrophobic and hydrophilic parts

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25
What is the function for phospholipids?
Cell membrane component
26
What are proteins?
Polymers made of monomers of amino acids
27
What determines the shape and function of a protein?
The sequence, type and number of amino acids
28
What are some examples of proteins? (min. 3)
Enzymes Cell membrane proteins (e.g. carrier) Hormones Transport proteins (e.g. haemoglobin) Structural proteins (e.g. keratin, collagen)
29
How many amino acids make up a protein?
20
30
What is the structure of an amino acid?
amino - NH2 carboxyl - COOH hydrogen + R group
31
What type of bond forms between amino acids?
Peptide bonds (covalent)
32
What is the primary structure for protein?
The sequence of amino acids bonded by covalent peptide bonds
33
What is the secondary structure for protein?
α-helix - hydrogen bonds every 4th peptide bond between carboxyl + amine group β-pleated sheet - protein folds and polypeptide chains are parallel H bonds broken by high temp and ph changes Fibrous (e.g. collagen + keratin)
34
What is the tertiary structure for protein?
Additional bonds: Hydrogen, disulphide, ionic and weak hydrophobic interactions Globular (e.g. hormones + enzymes)
35
What is the quaternary structure for protein?
>1 polypeptide chain working together as a functional macromolecule e.g. haemoglobin
36
What is the difference between globular and fibrous protein?
Globular - roughly circular, physiological function, soluble, e.g. haemoglobin, enzymes etc. Fibrous - long strands, structural function, insoluble, e.g. collagen, keratin etc.
37
What is the difference in structure between collagen and haemoglobin?
Collagen - 3 p.p chains (triple helix), long, thin and insoluble Haemoglobin - 4 p.p chains (2 alpha, 2 beta), spherical and soluble
38
What is the test for proteins?
Biuret Solution needs to be alkaline - add sodium hydroxide solution Few drops of copper sulphate Positive test = blue to lilac/purple
39
What are enzymes?
Biological catalysts which speed up the rate of chemical reactions without being used up or changed
40
What is the structure of enzymes?
3D tertiary, globular protein
41
Describe induced fit
Enzymes are specific to substrates When the enzyme and substrate bind they form an enzyme substrate complex - enzyme is altered so active site fits around substrate
42
What are the factors that affect the rate of enzyme-controlled reactions?
Temperature pH Enzyme concentration Substrate concentration Concentration of competitive + non-competitive inhibitors
43
How does temperature affect reactions?
Lower temps. mean molecules move slower (less kinetic enrgy) and collide less frequently so bonds have difficulty forming Higher temps. mean denaturation occurs, bonds break and tertiary structure changes permanently
44
How does pH affect reactions?
Enzymes denature at extreme pH changes below or above optimum pH, this causes shape of active site to alter Meaning they can't form enzyme substrate complexes
45
How does enzyme/substrate concentration affect reactions?
Rate of reaction increases as there's more active sites for substrates to bind to, if too much substrate concentration becomes limiting factor More enzyme-substrate complexes are formed, if too much enzyme concentration becomes limiting factor
46
What is DNA?
Deoxyribonucleic acid codes for the sequence of amino acids in the primary structure of a protein
47
What is the structure of a DNA nucleotide?
Deoxyribose (pentose sugar) Nitrogenous base (A, T, C, G) Phosphate
48
What are the nitrogenous bases?
Adenine + Thymine Guanine + Cytosine
49
How is a polynucleotide made?
Condensation reaction between deoxyribose sugar and phosphate group Creates phosphodiester bond Strong covalent bonds ensure genetic code isn't broken down
50
What is the structure of a polynucleotide?
Sugar-phosphate 'backbone' - strong covalent bonds
51
What is the structure of DNA complementary pairs?
Adenine and thymine form 2 hydrogen bonds Guanine and cytosine form 3 because it's more stable and have a greater resistance to denaturation
52
How does the structure of DNA relate to it's function?
Weak hydrogen bonds for easy unzipping (DNA helicase) Stable structure due to backbone + double helix
53
What is RNA?
Polymer of a nucleotide formed of a ribose, a nitrogenous base and phosphate group
54
What are the nitrogenous bases for RNA?
Adenine + Uracil Guanine + Cytosine
55
What is the function of RNA?
Copy and transfer the genetic code from DNA in the nucleus to the ribosome (transcription + translation)
56
What are the three types of RNA?
mRNA (messenger) tRNA (transfer) rRNA (ribosomal)
57
What is mRNA?
Copy of a gene from DNA, created in the nucleus and leaves to carry copy of genetic code to a ribosome in the cytoplasm Short lived as its only temporarily needed Every 3 bases in sequence codes from a specific amino acid (codons)
58
What is tRNA?
Found in cytoplasm and in a cloverleaf shape held by hydrogen bonds Attaches to amino acid and transfers to ribosome to create polypeptide chain Specific amino acids attach to specific tRNA molecules - determines by 3 bases on tRNA (anticodon) complementary to 3 bases on mRNA
59
What is the differences between DNA and RNA?
DNA - contains thymine and deoxyribose, larger and double stranded RNA - contains uracil and ribose, shorter and single stranded
60
What is the process of DNA replication? (simplified)
1) DNA helicase unzips DNA (3' to 5') by breaking hydrogen bonds between complementary pairs 2) Primase makes the primer as a starting point for polymerase 3) DNA polymerase replicates DNA molecules to build a new strand of DNA 4) Ligase glues the DNA fragments together
61
What is the structure of ATP?
Ribose Adenine Three phosphate groups Bonded by a condensation reaction with ATP synthase Hydrolysed by ATP hydrolase
62
How does ATP release energy?
ATP is hydrolysed (ATP hydrolase) to form ADP and a phosphate molecule (Pi)
63
How is hydrolysis of ATP used in cells?
To provide energy for other reactions To add phosphate to other substances and make them more reactive
64
What is the role of ATP?
Immediate source of energy Poor long-term storage of energy
65
What are some properties of water?
Surface tension, Density, Solvent, High specific heat capacity, Cohesion and Adhesion
66
What is the difference between cohesion and adhesion?
Cohesion - like molecules attract each other Adhesion - Different molecules attract each other

Biology (3 decks)

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