IB Biology - Carbohydrates and Lipids B1.1

Covalent bond

sharing of a pair of electrons between 2 adjacent atoms

The amount of bonds carbon atoms can form

4

Macromolecules

Molecules composed of large number of atoms

Main classes of macromolecules in living organisms

Carbohydrates, Lipids, Proteins, Nucleic Acids

How are macromolecules made

By linking subunits (monomers) into a chain (polymer)

Condensation reaction

Chemical process that links a monomer onto the end of a polymer by removing a hydroxyl group (OH) and a hydrogen (H)

What is created during a condensation reaction

a construction of a macromolecule, removal of a simpler molecule (H2O)

Glycosidic bond

the bond resulting from condensation reaction in carbohydrates

Is energy required for the production of macromolecules? What energy?

Yes. ATP.

Disaccharide + Examples

2 monosaccharides linked together through a glycosidic bond. Lactose, sucrose, maltose

Polysaccharide + Examples

Chain of monosaccharides. Glycogen, starch, cellulose

Glucose

Monosaccharide used to make the polysaccharides glycogen, starch, and cellulose

Structure of glucose

1 hydroxyl group (OH) and 1 hydrogen (H) attached to the first Carbon. 6 carbons total. Approximate formula: (CH2O)n

Glucose features?

• Soluble in aqueous soulutuons: polar + hydrophillic (easy transport)

• Chemical stability: strong covalent bonds- useful with storage

• ATP released when oxidised

Hydrolysis Reaction

Reaction that deconstructs polymers into monomers by adding split water molecules

Monomer of Carbohydrate

Monosaccharide

Monomer of Lipid

Glycerol and fatty acids

Monomer of Protein

amino acid

Monomer of nucleic acid

Nucleotide

How many carbon atoms can a monosaccharide have?

3-7 carbon atoms

Pentose

Monosaccharide with 5 carbon atoms

Hexose

Monosaccharide with 6 carbon atoms

Starch and glycogen

Polysaccharides made of glucose that store energy

Starch stores energy in

plants

Glycogen:

Polysaccharide

• animal

• A Glucose

• 1-4 and 1-6 bonds

• branches every 10 subunits- high free ends where glucose can be broken off and hydrolysed

  • can be broken down quicly supplying metabollic needs

  • liver +muscles contain glycogen granules

alpha-glucose

1 hydrogen (H) on top

beta-glucose

1 hydroxyl group (OH) on top

2 types of starch

1. Amylose (unbranched)
2. Amylopectin (branched)

Amylose:

Polysaccharide - Starch

• plant

• A Glucose

• 1-4 bonds

• compact structure so decreased digestion

Amylopectin:

Polysaccharide - Starch

• plant

• A Glucose

• 1-4 and 1-6 bonds

• Insoluble

• Branches per 20 subunits- increased terminal glucose molecules - increased hydrolysis

Cellulose

Polysaccharide

• plants cell wall

• B glucose

• 1-4 Bonds

• flips itself to form glycosidic bonds- allows hydrogen bonds for form between strands

  • forms microfibrils with tensile strength

Why is cellulose an effective structural protein?

• chemically inert

• strong

• insoluble

• elastic

Microfibrils

Bundles of cellulose molecules arranged in parallel that form the base of the cell wall

Microfibrils as the base of the cell wall is good because

It has high tensile strength. It is made of strong covalent bonds.

Compare and contrast condensation and hydrolysis

Same:

• both involve water

• both require enzymes

• both are metabollic

Diff.:

• condenstaion releases water, hydrolysis adds

• Cond.= anabolic, Hydro. = catabolic

• Cond. uses ATP, Hydro. releases ATP

• Cond. endothermic, Hydro. Exothermic

Lipids + Examples

Diverse group of macromolecules in organisms that dissolve in non-polar solvents. Fats, oils, waxes, steroids

Are all lipids hydrophopic?

No. Sparingly soluble in aqueous (water-based) solvents

Amphipathic

Having both hydrophobic and hydrophilic properties

Triglyceride

Combination of 3 fatty acids with 1 glycerol

How many water molecules are produced through the production of a triglyceride?

3

Ester bond

linkage formed between fatty acid and glycerol

How many ester bonds in a triglyceride?

3

How many ester bonds in a phospholipid?

2

Are triglycerides hydrophilic, hydrophobic, or amphipathic?

Hydrophobic

Phospholipid

Combination of 2 fatty acids with 1 glycerol and a phosphate group

Are phospholipids hydrophilic, hydrophobic, or amphipathic?

Amphipathic (hydrophilic phosphate group)

What nicknames are used to refer to the parts of a phospholipid?

"Phosphate head", "Hydrocarbon tails"

Fatty acids

an unbranched chain of carbon atoms with hydrogen atoms covalently bonded

Name for the chain of a fatty acid

hydrocarbon chain

Around how many carbon atoms in a fatty acid?

14-20

Saturated fatty acid

A fatty acid with single bonds between all of its carbon atoms. It contains as much hydrogen as it possibly could.

Unsaturated fatty acid

A fatty acid with one or more double bonds. It contains less hydrogen than it possibly could.

Monounsaturated

1 double bond

Polyunsaturated

more than 1 double bond

Appearance of a saturated fatty acid

Straight chain

Appearance of a monounsaturated fatty acid

One kink

Appearance of a polyunsaturated fatty acid

More than one kink (curve)

Purpose of triglycerides

used for energy storage and insulation in plants and animals

Adipose tissue

groups of cells that store triglycerides as fats

Storage and USES of lipids in animals:

Stored in adipose tissue

• subcutaneous fats + under the skin

• visceral fats = around major organs

  • protection

Use:

• Seals + walruses have blubber whoch traps heat - insulator

• camel hump- source of water

• longterm energy source: lipid rich yolks for hen eggs

Properties of Triglycerides that make them good for long-term storage

• Chemically stable- cant respire anaerobically

• more compact as not associated with water molecules

• Release 2X the amount of energy in cell respiration than carbohydrates.

• storage in specialised adipose tissue
  

Metabollic water:

• water produced due to respiration

• not ingested as water but as other compounds that get respired

• forms part of the dietry water intake

What animals need thermal insulation

Animals that maintain higher body temperatures than the temperature of their environment.

Name of adipose tissue in marine mammals

Blubber

Storage and uses of lipids in plants:

• in seeds

• to provide enrgy for growing seedling plant

• olives, sinflowers, coconust

What are phospholipids usually surrounded by

aqueous solution

The double structure of the phospholipid bilayer is formed by

Hydrocarbon tails being attracted to each other

Steroids

a group of lipids

Steroids identifying features

4 fused rings of carbon atoms. 3 cyclohexane (6-sided) rings and 1 cyclopectane (5-sided) ring. 17 carbon atoms in total.

Are steroids hydrophobic, hydrophilic, or amphipathic

Hydrophobic

Can steroids pass through the phospholipid bilayer by simple diffusion? Why?

Yes. They are non-polar.