Topic 4: structure + function of macromolecules

Question 1

Give the 4 biological macromolecules

Answer 1

1) Carbohydrates
2) Lipids
3) Protiens
4) Nucleic acids

Question 2

Define biomolecule

Answer 2

• Chemical molecule = structural/functional component of living organism
• Synthesis of biomolecules mostly = C + H
• Also O + N + S + P

Question 3

Define polymer

Answer 3

• Long molecule consisting of small building block = monomers
• 3/4 classes = polymers = Carbs + Proteins + Nucleic acid

Question 4

What are the subunits of the macromolecules?

Answer 4

• Monosaccharides > Carbohydrates
• Fatty acids > Lipids
• Amino acids > Proteins
• Nucleotides > Nucleic acid

Question 5

Describe the condensation reaction

Answer 5

• Dehydration reaction
• 2 monomers bond through loss of H2O = Form polymers
• Enzymes speed up dehydration

Question 6

Describe the hydrolysis reaction

Answer 6

• Reverse of condensation
• Disassembles polymer > monomer by adding H2O

Question 7

Describe carbohydrates

Answer 7

• (CH2O)n
• AKA sugars
• Monosaccharides = simple sugars
  1) Glucose
  2) Fructose
  3) Galactose
• Disaccharides = 2 monosaccharides
  1) Maltose
  2) Sucrose
  3) Lactose
• Oligosaccharides = 20-30 monosaccharides
• Polysaccharides = carb polymer
  1) Starch
  2) Glycogen
  3) Cellulose

Question 8

Describe monosaccharides

Answer 8

• Glucose = C6H12O6 = most common
• Fuel for cells + raw material for building
• Classified by = location of carbonyl group + number of carbons in skeleton
• If C=O at end of sugar = aldose
• If C=O middle of sugar = ketose
• Linear but may form rings in aqueous solution

Question 9

Describe disaccharides

Answer 9

• Formed by condensation reaction to join 2 monosaccharides = covalent bond = glycosidic linkage
• Glucose + glucose = maltose
• Glucose + galactose = lactose
• Glucose + fructose = sucrose

Question 10

Describe polysaccharides

Answer 10

• Have storage + structural roles
• These are determined by monomers + position of glycosidic linkages
• Starch + Glycogen = made of glucose + for storage
• Cellulose + Chitin = structural

Question 11

What are the 2 glycosidic linkages?

Answer 11

1) α-linkage = OH group of C2 same side as OH group on C1
2) β-glucose = OH group on C2 different side than C1
- α = helical
- β = linear

Question 12

Describe starch

Answer 12

• Storage of glucose in plants
• Plants store excess starch in chloroplasts + amyloplasts
• 2 polysaccharides = amylose + amylopectin
• Amylose = 1-4 glycosidic linkage = unbranched
• Helical due to α-linkage
• Amylopectin = 1-4 + 1-6 glycosidic linkage = branched

Question 13

Describe glycogen

Answer 13

• Storage of glucose in animals
• Animals/humans store glycogen in liver + muscle cells = cytosolic granules
• α-glucose = helical
• Has 1-4 + 1-6 glycosidic linkage = branched = enzyme accessible

Question 14

Describe cellulose

Answer 14

• Component of plant cell wall
• Unbranched β-glucose polymer = linear
• Humans can not digest = passes through digestive tract as insoluble fiber
• Herbivores = symbiotic relationship with microbes in stomach to break down cellulose

Question 15

Describe chitin

Answer 15

• Component of exoskeleton of arthropods + fungal cell walls
• Used to make surgical thread
• β - glucose = linear

Question 16

Describe lipids

Answer 16

• Doesn’t have polymers
• Hydrophobic = consist if hydrocarbons = non-polar covenant bonds
• Fats + Phospholipids + Steroids

Question 17

Describe fats

Answer 17

• Triglycerides = storage = 1 glycerol 3 fatty acids
• Hydrophobic
• Condensation reaction between glycerol + each fatty acid= ester linkage
• Function = energy storage
• Humans store fat in adipose cells = adipose tissue cushions vital organs + insulates body

Question 18

Describe fatty acids

Answer 18

• Structure = R-COOH
• R = long hydrocarbon chain
• Fatty acids differ in length + number/location of double bonds
• Saturated > no =
• Unsaturated > 1 or more =
  SATURATED:
• Max amount of H
• CH3(CH2)nCOOH
• Mostly found in animals
• Solid at room temp = butter
• Diet rich in saturated fats = contribute to CVD = plaque deposits
• Directly increase LDL bound bad cholesterol
  UNSATURATED:
• Found in plants + fish
• Liquid at room temp = oil
• Signals liver = take up cholesterol from blood = improve cholesterol levels
• Reduce LDL bound bad cholesterol + maintain HDL good cholesterol

Question 19

Describe phospholipids

Answer 19

• Have phosphate group instead of 3rd fatty acid
  1) Phosphoglyceride = glycerol + 2 fatty acid + phosphate + organic molecule
  2) Phosphospingolipids = sphingosine + 1 fatty acid + phosphate + organic molecule
• Function = components of biological membranes
• Amphipathic molecule = hydrophilic head + hydrophobic tail

Question 20

Give some common membrane phospholipids

Answer 20

• Phosphatidyl-choline = glycerol + choline
• Phosphatidyl-ethanolamine = glycerol + ethanolamine
• Phosphatidyl-serine = glycerol + serine
• Phosphatidyl-inositol = glycerol + inositol
• Sphingomyelin = sphingosine + choline

Question 21

Describe the bilayer

Answer 21

• When phospholipids exposed to water = assemble in bilayer = hydrophobic tails interior and hydrophilic heads exterior
• Found in cell membranes = main component

Question 22

Describe steroids

Answer 22

• Lipids made of carbon skeleton of 4 fused rings
• Cholesterol = steroid in animal cell membrane + precursor for hormones
• Steroid hormones = androgens + estrogens

Question 23

Describe health risks of cholestrol

Answer 23

• High level in blood = CVD
• In blood bound to lipoproteins = low density / high density
• Lipoproteins recognized by receptor on plasma of liver cells = cholesterol released into liver via receptor-mediated endocytosis
• HDL bound cholesterol = good = protein > cholesterol = travels fast in blood + deposited directly to liver
• LDL bound cholesterol = bad = cholesterol > protein = travels slow in blood = leaves pieces around = plaque

Question 24

Describe proteins

Answer 24

• 50% dry mass of cells
• Functions= structural support + storage + transport + cellular communication + movement + defense against foreign substances
• Polypeptide = polymer of amino acids
• Protein = 1> polypeptides = each has unique linear sequence of amino acids
• Amino acids linked by covalent bond = peptide bond between carbonyl of 1 + amino of other via condensation reaction

Question 25

Define enzyme

Answer 25

- Protein that acts as catalyst = speed up chemical reactions

Question 26

Describe amino acids

Answer 26

H NH3-C-COOH R - Have carboxyl group + amino group - Different properties due to differing R groups - 3 types = non-polar + polar + electrically charged

Question 27

What are the non-polar amino acids?

Answer 27

- Gly - Ala - Val - Leu - Ile - Met - Phe - Trp - Pro

Question 28

What are the polar amino acids?

Answer 28

- Ser - Thr - Cys - Tyr - Asn - Gln

Question 29

What are the electrically charged amino acids?

Answer 29

ACIDIC - Asp - Glu BASIC - Lys - Arg - His

Question 30

Describe protein structure + function

Answer 30

- Machines can determine structure = X-ray crystallography - Functional proteins contain more than 1 polypeptide - Sequence of amino = 3D structure = function - Primary structure = unique sequence of aminos - Secondary structure = either coiling / folding of polypeptide chain = α-helices / β-pleated sheets - Tertiary structure = 3D structure determined by interaction in R group - Quaternary structure = multiple polypeptides bind

Question 31

What types of interactions take place in the tertiary structure?

Answer 31

- Disulphide bonds = between 2 S in S-H groups in R group - H-bonds - Van der Waals - Ionic - Hydrophobic

Question 32

Explain protein folding chaperones

Answer 32

- Proteins go through several intermediate states = stable conformation - Chaperonins = proteins that assist + maintain folding of proteins - Location = cytosol + mitochondria + ER

Question 33

Explain sickle cell disease

Answer 33

- Slight change in primary structure = affects protein structure + ability to function - Inherited blood disorder - Due to substitution of a single amino in haemoglobin in RBC - Shape deformed = unable to carry oxygen

Question 34

Describe haemoglobin

Answer 34

- Globular protein = 4 polypeptides = 2 alpha + 2 beta

Question 35

Explain protein conformation

Answer 35

- Conformation depends on physical + chemical environment of protein - Denature = loss of conformation due to unraveling = loss of function = biologically in active DENATURE FACTORS - pH change - Salt concentration change - Temp change

Question 36

Describe nucleic acids

Answer 36

- Store + transmit hereditary info - Nucleotide structure = phosphate group + pentose sugar + nitrogenous base - Nitrogenous bases = A G C T/U - Sugars = deoxyribose/ ribose - Polymer = polynucleotide = goes from 5' to 3' - Connected with a phosphodiester bond = OH 3' + phosphate 5' 2 TYPES: 1) Deoxyribonucleic acid = DNA - Stores info for protein synthesis - Directs RNA synthesis - Directs protein synthesis through mRNA 2) Ribonucleic acid = RNA

Question 37

Define gene

Answer 37

- Unit of inheritance - Amino acid sequence for polypeptide - Made of DNA = nucleic acid

Question 38

Describe a DNA double helix

Answer 38

- 2 anti-parallel polynucleotide strands = double helix - Strands run in opposite directions = 5'>3' + 3'>5' - Held together by H-bonds between bases - Sugar+phosphate backbone - Complementary base pairs = AT + CG

Question 39

Explain DNA replication

Answer 39

- Copy all DNA molecules into a 2nd set - Required before cell division - 2 strands separate = H-bonds break = each stand is template for complementary copy