B1.1: Carbohydrates And Lipids

Question 1

Chemical properties of carbon - bio molecules

Answer 1

In all four major categories:
Carb, lipids, proteins, nucleic acids

4 electrons on outer shell
-> allow large stable molecules

Carbon -> arrange themselves to form a huge variety of chemical compounds:
Bond to other atoms
- long branched chains (glycogen)
- long straight chain molecule (cellulose)
- cyclic single rings (thymine, uracil…)
- multiple rings (adenine, guanine)
- tetrahedral structure (different 3D shape, different properties)

Double and triple bonds -> unsaturated compounds

Question 2

What are some common functional groups?

Answer 2

OH (hydroxyl)
COOH (carboxyl)
NH2 (amino/amine)
H2PO4 (phosphate)

Question 3

What is a monomer?

Answer 3

Smaller units from which larger molecules are made

Question 4

what is a polymer?

Answer 4

molecules made from a large number of monomers joined together in a chain
-> polymerization

Question 5

What is a macromolecule?

Answer 5

Very large molecules

1000+ atoms -> high molecular mass

polymers can be macromolecules, but not all macromolecules are polymers
polymers must have repeating subunits

Form by condensation reaction

Question 6

Formation of polysaccharide

Answer 6

formed when two hydroxyl groups on different monosaccharides interact to form a strong covalent bond called a glycosidic bond

Question 7

Formation of polypeptide

Answer 7

formed when two amino acid monomers interact to form a strong covalent bond called a peptide bond

Question 8

How are polymers digested?

Answer 8

Hydrolysis reaction (breaking down with water)

Covalent bonds in macromolecules -> broken when water added
-> the -H and -OH from the water molecule are used to form the functional groups of the products

Question 9

Examples of hydrolysis reaction

Answer 9

• hydrolysis of glycosidic bonds in poly- or disaccharides to produce monosaccharides
• hydrolysis of peptide bonds in polypeptides to produce amino acids
• hydrolysis of ester bonds in triglycerides to produce three fatty acids and glycerol

Question 10

Saccharide:
Bond type
General formula
Properties

Answer 10

Glycosidic bond (condensation reaction)

CnH2nOn

Colorless crystalline molecules
Soluble in water

Question 11

Différent types of monosaccharides

Answer 11

Formed from varying numbers of C atoms

Triose -> 3 C
Pentose -> 5 C
Hexose -> 6 C

Question 12

What is glucose?

Answer 12

Basic hexose monosaccharide sugar molecule that is used in respiration to produce ATP
Chemical store of energy
Formed in photosynthesis

C6H12O6

Question 13

What is the difference between alpha and beta glucose?

Answer 13

Alpha -> OH on C1 below

Beta -> OH on C1 above

Question 14

Properties of glucose

Answer 14

• stable structure due to covalent bonds
• soluble in water due to polar nature
• easily transportable due to water solubility
• source of chemical energy when bonds are broken

Question 15

What is ribose?

Answer 15

Basic monosaccharide pentose sugar

Found in RNA
a similar version in DNA
-> deoxyribose: has H in place of one of the OH

Question 16

What is maltose?

Answer 16

• maltose (malt sugar) is formed from two alpha glucose molecules joined by a 1-4 glycosidic bond
  
  • plants

Question 17

What is sucrose?

Answer 17

• sucrose (table sugar) is formed from alpha glucose and fructose joined by an alpha 1-4 glycosidic bond
  
  • plants

Question 18

What is lactose?

Answer 18

• lactose (milk sugar) is formed from galactose and alpha glucose joined by a beta 1-4 glycosidic bond
  
  • animals

Question 19

What are polysaccharides used as?

Answer 19

Structure or energy source
-> able to do both bc of differences between a and b bonds

Starch (plants -> energy)
Glucose (plants -> energy)
Glycogen (humans -> storage)

Question 20

Why are carbs good for both energy storage and structure? (Using examples)

Answer 20

Ex: starch and glycogen -> energy storage
Compact
Insoluble
-> soluble molecules will dissolve in cell lowering the water potential and causing water to move into cell -> too much water -> animal cell burst

Ex: cellulose -> structure
Strong and durable
Insoluble and slightly elastic
Chemically inert

Question 21

Properties and uses of starch

Answer 21

Major carb storage molecule in plants
Usually stored as intracellular starch grains in organelles -> plastids
-> chlorophyll/amyloplast

Starch produced from glucose -> photosynthesis

Broken down during respiration -> energy -> source of carbon from producing other molecules

Question 22

Structure of starch

Answer 22

2 different structural units:

Amylose (10-30%)
Glucose molecules joined by a 1-4 glycosidic bonds
Unbranched structure -> compact helical structure -> resist digestion

Amylopecitin (70-90%)
Glucose molecules joined by a 1-4 glycosidic bonds
Also contains more a 1-6 glycosidic bonds
-> results in highly branched structure
-> many terminal glucose -> easily hydrolyzed (easy take or add)

Question 23

Properties and uses of cellulose

Answer 23

Plant cell walls - most abundant organic polymer

Very strong, prevents cell from bursting when excess water

Long chains of b glucose molecules joined by beta 1-4 glycosidic bonds

Glucose chains -> rope-like microfibrils -> layered to form network

Question 24

Structure of cellulose

Answer 24

polysaccharide made up of many beta glucose molecules

glucose molecules are linked by beta 1-4 glycosidic bonds
-> to from glycosidic with b glucose -> every alternate must be inverted

Long straight unbranched chains

Alternate pattern -> good tensile strength (structure)

Question 25

Properties and uses of glycogen

Answer 25

Animals store carb as glycogen Stored in small granules in muscle and liver Less dense and more soluble than starch -> broken down quicker -> higher metabolic requirements

Question 26

Structure of glycogen

Answer 26

A glucose joined by 1-4 and 1-6 bonds Similar structure to amylopectin -> more a 1-6 glycosidic bonds -> MORE branches

Question 27

What is glycoprotein?

Answer 27

Carb + protein (via covalent bond)

Question 28

Uses of glycoproteins

Answer 28

Type of protein found in plasma membrane -> shorty chain of monosaccharides attached to it -> oligosaccharide (oligo - few) Displayed on the outside of cell and allows other cells to recognize them Receptor molecules: Cell recognition/identification Cell signaling molecules Endocytosis Cell adhesion and stabilization

Question 29

Example of glycoproteins

Answer 29

ABO BLOOD GROUPS Gp-> act as antigens -> can identify cells as either self or non-self - blood type A individuals have type A glycoprotein antigens - blood type B individuals have type B glycoprotein antigens - blood type AB individuals have both types of glycoprotein antigens - blood type O individuals have neither Blood transfusion -> wrong type -> antibodies don’t recognize and clump -> block blood vessels

Question 30

Examples of lipids

Answer 30

Fats Oils Waxes Steroids Cholesterol

Question 31

What is a lipid?

Answer 31

diverse group of compounds that are insoluble in water but soluble in organic solvents (ex: ethanol) most common: triglycerides (sometimes known as true fats or neutral fats) 3 fatty acid chains (has HC (saturated or unsaturated) chain and can be any length) 1 glycerol Organisms -> energy source 2x of carbs 38KJ/g

Question 32

What effects lipid solubility?

Answer 32

Structure Lipids -> hydrocarbon molecules -> non-polar covalent bonds Nonpolar -> lipids are insoluble in water/polar solvents In living organisms -> improved bu combining lipid molecules with other molecules (glycolipids, lipoproteins)

Question 33

What is the role of lipids in humans/mammals?

Answer 33

Adipose tissue Insulation -> mammals have it under skin to reduce heat loss - adipose cell shrink when fat is respired - seals + walruses -> endotherms -> thick adipose issue (blubber) -> trap heat generated by respiration Protection -> around delicate organs (kidneys) cushion impact - subcutaneous fats -> below skin - visceral fats -> major internal organs

Question 34

The role of lipids in plants?

Answer 34

Seeds -> evolved to store fats -> energy from growing seedling plant olives, sunflowers, nuts, coconuts and seeds are good examples of crops whose oils are harvested for edible oil production by humans

Question 35

Why is lipid good as long term storage?

Answer 35

Add 1/6 as much mass as carbs Fats -> stored as pure droplets - whereas 1g of glycogen + 2g water Lipids -> respired -> water produced (lot compared to carbs) - metabolic water -> can be used like drinking water Ex: camel -> hump has lipid rich storage organ Birds -> egg lipid rich yolk (energy and water) Insoluble -> not transported around the body easily -> remains in storage cell

Question 36

Formation of triglycerides

Answer 36

Esterification -> an ester bond forms when the hydroxyl group of a glycerol molecule bonds with the carboxyl group of a fatty acid (-OH → -COOH) Ester bond formed when condensation reaction -> 1 triglyceride, 3 water

Question 37

Formation of phospholipids

Answer 37

Formed from glycerol and fatty acids 2 fatty acid + Phosphate ion + glycerol Phosphate -> polar = soluble in water/hydrophilic Phospholipids -> amphipathic -> both hydrophobic and hydrophilic regions - can form mono layers or bilayers when in water

Question 38

What is a saturated fatty acid?

Answer 38

Only contains single bonds between carbon atoms Molecule straight (stearic acid) Each carbon in HC tail (- final one) -> bonded to 2 H atoms can pack together tightly → + mp, solid at room temp, used as storage

Question 39

What is a unsaturated fatty acid?

Answer 39

Contains double bonds between carbon atoms -> kink in the chain Cannot pack tightly -> liquid -> lower mp (oils) HC tail doesn’t contain max number of H atoms possible -> at least 1 double bond Monounsaturated fats -> 1 double bond Polyunsaturated fats -> more that one

Question 40

What is the difference between cis and trans fatty acids?

Answer 40

Depends on arrangement of atoms/groups around a double bond in an unsaturated fatty acid Cis -> greatest kink, chains that are unable to pack tightly together Bonds H on the same side of the C double bond Liquid lipid trans -> one bond on top, on the bottom Pack closer -> the kink of the bonds cancel out -> straighter Mimic saturated fats -> same health risks Usually created Solid lipid

Question 41

How are membranes formed?

Answer 41

Hydrophilic phosphate head bonds with 2 hydrophobic fatty acid tails - the phosphate head  is polar, so is hydrophilic and therefore soluble in water - the fatty acid tail is nonpolar, so is hydrophobic and therefore insoluble in water Placed in water -> phosphate head towards water, fatty acid tails away from water -> phospholipid monolayer Phospholipid mixed with mater -> bilayer - because amphipathic -> barrier to most water soluble substances -> nonpolar fatty acids prevent polar from passing through (no leaks)

Question 42

Steroids and passing through the phospholipid bilayer

Answer 42

Small nonpolar -> soluble in lipid bilayer -> can cross membrane Larger nonpolar -> can enter the cell due to hydrophobic properties (ex: steroid hormones) - and their lipid structure - can easily travel into and out of cell and nuclei Steroids: Contain cholesterol (lipid) Have 4 fused rings of carbon atoms Ex: oestradiol and testosterone (produced by gonadal tissue in reproductive organs)