IB Biology Review Chapter 5: Macromolecules 8. Outline the

1
IB Biology Review

• Chapter 5 Macromolecules

2
Vocabulary

• Macromolecule
• term used to describe large molecules such as
  carbohydrates, lipids, proteins, and nucleic
  acids
• Monomer
• the repeating unit molecules of polymers
• Polymer
• a long chainlike molecule consisting of
  repeating building-block molecules linked by
  covalent bonds
• includes proteins, carbohydrates, and nucleic
  acids

3
What are the four groups of macromolecules?

• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids

4
Examples of Monomers

• What are the monomers of
• Carbohydrates
• Simple sugars (monosaccharides) like glucose and
  fructose make polysaccharides
• Proteins
• 20 different amino acids form polypeptides
• Nucleic Acids
• Nucleotides (A, T, G, C, and U) form DNA and RNA

5
How are monomers linked and unlinked?

• Linked by condensation/dehydration reaction
• A molecule of water is removed to form a bond
• Anabolic reaction
• Unlinked by hydrolysis reaction
• A molecule of water is added to break a bond
• Catabolic reaction

6
Two Types of Covalent Bonds that Join Monomers

• Saccharide bonds join two adjacent
  monosaccharides
• Peptide bonds join two adjacent amino acids

7
MC-1.Which of the following reactions occurs when
a dipeptide is formed from amino acids?

• A. hydrolysis
• B. denaturation
• C. condensation
• D. oxidation
• Correct answer C

8
Special Types of Bonds

• Two monosaccharides are joined by a
• saccharide bond
• Two amino acids are joined by a
• peptide bond

9
DNA Structure

• 1. Alternating sugar and phosphate molecules
• 2. Bases are towards center (A/T) (G/C)
• 3. Hydrogen bond connects adjacent base pairs
• 4. Double helix structure (twisted ladder of
  polynucleotides)

2
1
4
3
10
DNA Nucleotide Structure
Single nucleotide subunit

• Deoxyribose (sugar) molecule binds to phosphate
  at the Carbon III and V positions

11
MC-2. What is the composition of the backbone of
DNA?

• A. alternating sugar and phosphate
  molecules
• B. complementary base pairs
• C. alternating sugar and base molecules
• D. a polysaccharide
• Correct answer A

12
Structure of Ribose and Glucose

• Ribose has five carbon molecules
• Glucose has six carbon molecules
• Be able to draw these structures!

13
IB Required Monosaccharides

• IB wants you to be able to list the following
  monosaccharides
• Glucose
• Ribose
• Fructose
• Glyceraldehyde
• Galactose
• Monosaccharides always have a 121 carbon
  hydrogen oxygen ratio
• Example Glucose is C6H12O6

14
IB Required Disaccharides

• IB wants you to be able to list the following
  disaccharides
• Sucrose (glucose and fructose) table sugar
• Lactose (glucose and galactose) milk sugar
• Maltose (glucose and glucose) starch in
  seeds

15
IB Required Polysaccharides

• IB wants you to be able to list the following
  polysaccharides
• Cellulose cell walls
• Glycogen energy storage in animals
• Starch energy storage in plants

16
Structure of Fatty Acids

• IB needs you to know this structure
• Where n stands for the different number of carbon
  molecules that can be added or removed to change
  the length of the chain

17
Structure of Fatty Acids

• Saturated Fatty Acids
• Have no double carbon bonds in any of three tails
• Usually solid at room temperature
• Example butter
• Unsaturated Fatty Acids
• Have at least one double carbon bond in tails
• Usually liquid at room temperature
• Example cooking oil
• Which is better for you?
• Unsaturated fatty acids

18
Phospholipid Structure

• Molecules in the phospholipid bilayer in cell
  membrane

19
Lipid Function

• Energy storage / energy supply
• Hormone production
• Cushioning / protection
• Insulation
• Constituent of cell membrane (part of
  phospholipid bilayer)

20
Energy Storage

• Carbohydrates
• Stored as glycogen in animals (in liver)
• Stored as starch in plants (in roots)
• More easily digested than lipids so energy can
  be released more quickly
• Lipids
• Stored as fat in animals
• Long-term energy storage
• More energy per gram than carbohydrates

21
Health Risks of Lipids

• Saturated fatty acids cause high cholesterol
• Athersclerosis / narrowing of (lumen of) arteries
• Hypertension / high blood pressure
• Obesity / overweight

22
Amino Acid Structure

• Twenty different amino acids
• All share the same base
• What differs in each amino acid is R or the
  side chain

23
Protein Structure

• Primary Structure
• The unique sequence of amino acids, each linked
  together by a peptide bond
• Secondary Structure
• The Beta-pleated sheets and Alpha-helix
  structures
• Tertiary Structure
• in globular proteins involves the folding of
  polypeptides. This folding pattern is stabilized
  by several types of bonds including hydrogen
  bonds and ionic bonds
• Quaternary Structure
• of proteins is the linking together of two or
  more polypeptide subunits. An example of this
  is hemoglobin which has 4 subunits
• Example Hemoglobin has four subunits

24
Protein Function

• A proteins shape is the key to its function
• Know at least four functions and an example
• Hormones Insulin helps regulate blood sugar
• Enzymes Catalase catalyzes breakdown of hydrogen
  peroxide waste in blood
• Transport Proteins Ion channels and proton pumps
  for active transport in cell membrane
• Structural Proteins Collagen, keratin, tubulin,
  fibroin
• Defense Antibodies are proteins
• Receptors Hormone receptor or neurotransmitter
  receptor on cell surface

25
MC-3. Which is not a primary function of protein
molecules?

• A. hormones
• B. energy storage
• C. transport
• D. structure
• Correct answer B

26
MC- 4. Which of the following are connected by a
hydrogen bond?

• A. the hydrogen and oxygen atoms of a water
  molecule
• B. base pairs of a DNA molecule
• C. two amino acid molecules of a dipeptide
• D. two glucose molecules in a disaccharide
• Answer B

27
1. Draw a diagram of the molecular structure of a
portion of DNA. (4 marks)
IB Exam Question

• sugar-phosphate backbone
• bases toward centre
• AT, GC base pair
• hydrogen bonds labelled
• twisted ladder
• two polynucleotides (two strands shown)

28
2. To which parts of the deoxyribose molecule do
phosphates bind in DNA? (1
mark)
IB Exam Question

• A. I and V
• B. III and V
• C. II and III
• D. III and IV
• Correct answer B

29
3. Which molecules represents ribose? (1 mark)
IB Exam Question

• Correct answer D

30
4. Outline how monosaccharides are converted into
polysaccharides. (2 marks)
IB Exam Question

• condensation
• involves the removal of water to join
  monosaccharides together
• catalysed by enzymes
• consists of many monosaccharides linked
  (glycosidic) to make polysaccharide

31
5. Describe the use of carbohydrates and lipids
for energy storage in animals. (5
marks)
IB Exam Question

• Answers must discuss both carbohydrates and
  lipids to receive full marks.
• carbohydrates
• stored as glycogen (in liver)
• short-term energy storage
• more easily digested than lipids so energy can be
  released more quickly
• more soluble in water for easier transport
• lipids
• stored as fat in animals
• long-term energy storage
• more energy per gram than carbohydrates
• lipids are insoluble in water less osmotic effect

32
6. Draw the structure of a fatty acid.
(1
mark)
IB Exam Question
OR
33
7.
IB Exam Question

• Correct answer D

34
8. Outline the production of a dipeptide by a
condensation reaction. Include the structure of a
generalized dipeptide in your answer. (5
marks)
IB Exam Question

• carboxyl / COOH group of one amino acid reacts
  with amine /
• NH2 group of another
• water / H2O is eliminated
• These steps can be shown
• diagrammatically, e.g.
• peptide / covalent bond is produced
• diagram of dipeptide, with peptide bond shown
  e.g.
• Award 1 if the two amino acids forming the
  dipeptide are shown correctly. The radicals can
  be shown as R or H. Award the second mark if the
  C-N bond is labeled as peptide bond or dipeptide
  bond. The label can include the H bonded to the N
  and the O double bonded to the C.

35
9. List four functions of proteins, giving an
example of each. (4 marks)
IB Exam Question

• Name of function and named protein must both be
  correct for the mark.
• storage zeatin (in corn seeds) / casein (in
  milk)
• transport hemoglobin / lipoproteins (in blood)
• hormones insulin / growth hormone / TSH / FSH /
  LH
• receptors hormone receptor / neurotransmitter
  receptor / receptor in chemoreceptor cell
• movement actin / myosin
• defence antibodies / immunoglobin
• enzymes catalase / RuBP carboxylase
• structure collagen / keratin / tubulin /
  fibroin
• electron carriers cytochromes
• pigments opsin
• active transport sodium pumps / calcium pumps
• facilitated diffusion sodium channels /
  aquaporins

36
10. Explain the significance of polar and
non-polar amino acids. (5 marks)
IB Exam Question

• Non-polar amino acids have non-polar (neutrally
  charged) R groups. \
• Polar amino acids have R chains with polar groups
  (charged either positive or negative).
• Proteins with a lot of polar amino acids make
  the proteins hydrophyllic and therefore able to
  dissolve in water.
• Proteins with many non-polar amino acids are
  more hydrophobic and are less soluble in water.
• With these abilities, proteins fold themselves so
  that the hydrophilic ones are on the inner side
  and allows hydrophilic molecules and ions to pass
  in and out of the cells through the channels they
  form.
• These channels are vital passages for many
  substances in and out of the cell.

37
11. Outline the difference between fibrous and
globular proteins, with reference to examples of
each protein type. ( 4 marks)
IB Exam Question

• Fibrous proteins are in their secondary
  structure, which could be in the alpha helix or
  beta pleated forms.
• They are made of a repeated sequence of amino
  acids that can be coiled tightly around in a
  pattern that makes it a very strong structure.
• Two examples are keratin (in hair and skin) and
  collagen (in tendons, cartilage, and bones).
• Globular proteins are in their tertiary or
  quaternary structure, which is folded, creating a
  globular, three-dimensional shape.
• An example of globular proteins are all enzymes

38
12. State one function of glucose and glycogen in
animals, and cellulose and starch in
plants. ( 4 marks)
IB Exam Question

• Glucose Energy for Cellular respiration
• Glycogen Energy from this polysaccharides is
  stored in the liver of animals
• Cellulose Provides strength to cell walls
• Starch Energy from this polysaccharide is
  stored in roots of plants

39
13. List several examples each of
monosaccharides, disaccharides and
polysaccharides ( 6 marks)
IB Exam Question

• Monosaccharides Glucose, Fructose (fruit
  sugar) , Lactose (milk sugar), Ribose (in RNA)
• Dissacharides Sucrose (Glucose and
  Fructose), Maltose (Glucose and Glucose)
• Polysacchrides Starch (plants) , Glycogen
  (animals), and Cellulose (plants)

40
Chapter Five Quiz

• Excellent multiple choice quiz on Campbell
  Biology textbook CD or website
• Go to Chapter 5 The Structure and Function of
  Macromolecules -gt Activities Quiz
• Use this to study!