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IB HL Biology > B.1.1 Molecules - CARBOHYDRATES & LIPIDS > Flashcards

B.1.1 Molecules - CARBOHYDRATES & LIPIDS Flashcards

1
Q

Outline the number and type of bonds carbon can form with other atoms

A

Carbon can form FOUR covalent bonds due to having 4 valence electrons

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2
Q

Outline the cause and consequence of covalent bonds between atoms

A

CAUSE:
1. Atoms want to gain stability by forming a full outer shell of valence electrons
2. Atoms share electrons between them

CONSEQUENCE:
1. Formation of diverse compounds upon which life is based
2. Covalent bonds are the strongest bonds found in biological molecules

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3
Q

What are the common functional groups?

A
  1. Hydroxyl group (-OH)
  2. Carobonyl group (C=O)
  3. Carboxyl group (-COOH + H2O -> - COO⁻)
  4. Esters (acid + alcohol -> ester + water)
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4
Q

List four major classes of carbon compounds used by living organisms. Name their sub-units.

A
  1. Carbohydrates - monosaccharides
  2. Lipids - fats (triglycerides), glycerol, fatty acids
  3. Proteins - amino acids
  4. Nucleic acids - nucleotides (sugar + phosphate group + nitrogenous base)
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5
Q

List example molecules with the four different types of shapes of carbon compounds

A
  1. SHORT & STRAIGHT: amino acid alanine
  2. LONG & STRAIGHT: fatty acids
  3. BRANCHED: amino acid valine
  4. RING: alpha glucose
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6
Q

Define monomer and polymer

A

Monomers: small molecules which may be joined together in a repeating fashion to form more complex molecules, called polymers

Polymers: Any class of substances that are composed of macromolecules, which are multiples of monomers.

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7
Q

Describe condensation reactions. Describe anabolism.

A

Condensation reactions are chemical reactions in which two molecules combine to form a larger one, with a simultaneous elimination of a smaller molecule (water).

ANABOLISM is the synthesis of complex molecules from simpler molecules including the formation of macromolecules from monomers by condensation reactions.

CHARACTERISTICS:
1. Macromolecules are made from monomers
2. Water is released
3. A new covalent bond is formed
4. requires energy, endothermic (in the form of ATP)
5. requires specific enzymes

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8
Q

Outline the condensation reactions that form 3 different types of macromolecules

A
  1. POLYSACCHARIDES
    - monosaccharide monomers join together
    - glycosidic bond is formed
    - water is released
  2. POLYPEPTIDES
  3. NUCLEIC ACIDS
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9
Q

Describe hydrolysis reacitons

A

CATABOLISM is the breakdown of complex molecules into simpler molecules including the HYDROLYSIS Of macromolecules into monomers

Hydrolysis is the DIGESTION of polymer into monomers with the requirement of specific ENZYMES

  1. Requires enzymes that are specific to the molecules they are breaking down
  2. Macromolecules are broken into monomers
  3. Hydrolysis occurs, water is used to lyse/break the macromolecule
  4. Releases energy, exothermic
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10
Q

Identify pentose and hexose carbohydrates

A

Hexose – party hat man!

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11
Q

Outline the properties of glucose referring to solubility, transportability, stability, and energy yield from oxidation

A

SOLUBILITY:
- highly soluble
- hydrophilic
- forms hydrogen bonds

TRANSPORTABILITY:
- transports through the body via the bloodstream
- transport proteins like glucose transporters (GLUTs)
- hormone insulin regulates glucose uptake

STABILITY:
- relatively stable
- glucose can tus be later used without degradation

ENERGY YIELD FROM OXIDATION:
- glycolysis: glucose partially broken down -> ATP + pyruvate
- pyruvate is oxidised through citric acid cycle & oxidative phosphorylation

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12
Q

Compare the structure and function of amylose, amylopectin, and glycogen

A

GLYCOGEN:
1. 1’-4’ AND 1’-6’ glycosidic linkages
2. Made by animals and some fungi, found in liver & muscles
3. Polyssacharide formed by monosaccharide alpha-glucose via condensation reactions
4. Compact structure allows for large volume of glucose that acts as energy storage compound in cells
5. Insoluble and doesn’t effect osmotic potential or intake of water

STARCH - AYMLOPECTIN:
1. 1’-4’ AND 1’-6’ glycosidic linkages
2. ONLY branching/helical molecules
3. Polyssacharide formed by monosaccharide alpha-glucose via condensation reactions
4. Stored in root cells/leaves (temporary)/ amyloplast (plastid) as energy storage
5. Hydrophilic but insoluble due to size, doesn’t affect osmotic balance

STARCH - AMYLOSE:
1. ONLY 1’-4’ glycosidic linkages
2. Linear AND helical molecule
3. Polyssacharide formed by monosaccharide alpha-glucose via condensation reactions
4. Stored in root cells/leaves (temporary)/ amyloplast (plastid) as energy storage
5. Hydrophilic but insoluble due to size, doesn’t effect osmotic balance

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13
Q

Discuss the benefit of polysaccharide coiling and branching during polymerisation

A
  1. Compact/dense storage
  2. Efficient use of space
  3. Rapid energy release
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14
Q

Explain how condensation or hydrolysis of alpha-glucose monomers build or mobilise energy stores

A

CONDENSATION:
1. glycogen formation in animals for energy stores
2. starch formation in plants for energy stores

HYDROLYSIS
1. glycogen breakdown via hydrolysis
- Enzyme glycogen phosphorylases cleave alpha-1,4-glycosidic bonds that release glucose-1-phosphate
- molecules convert into glucose-6-phosphate
- enters glycolysis for energy production as part of cellular respiration
2. Starch undergoes hydrolysis
- Enzyme amylase cleaves alpha-1,5- glycosidic bonds in both amylose and amylopctin
- glucose moleules can be used for energy or other metabolic processes

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15
Q

Compare the structure of alpha-glucose and beta-glucose

A

Glucose’s two incomers have a difference in the orientation in the (-OH) hydroxyl group that is connected to the first carbon atom (on the right).

Alpha: on the bottom as HO

Beta: on the top as OH

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16
Q

Describe the structure and function of cellulose !!!!

A

STRUCTURE:
1. polyssacharide made of beta glucose monomers via condensation reactions
2. 1’-4’ glycosidic linkaes
3. Straight/unbranched cellulose fibrils linked via hydrogen bonds to form cellulose fibres

FUNCTION
1. Long chains of cellulose fibrils result in insoluble cellulose fibres
2. Tensile strength as a result of hydrogen bonds
3. Rigid structure -> resists osmotic potential

17
Q

Discuss the consequences of the strength of cellulose in the plant cell wall

A
  1. structural integrity/rigid
  2. cell expansion & growth
  3. vascular tissue support
18
Q

State the function of glycoproteins in the cell membrane

A

Glycoproteins are a sugar + protein

FUNCTION:
1. receptors for hormones, chemical signalling molcules
2. assists in binding cells together
3. cell to cell recognition

CELL TO CELL RECOGNITION
1. located on the outside of the cell
2. hydrophilic carbohydrate group associated with water
3. determines self from non-self

Antigens: molecules that produce an immune response
Antibodies: proteins that bind antigens because of the immune response

19
Q

Explain why lipids are hydrphobic

A
  1. Hydrocarbon chains (fatty acids) or rings (steroid)
  2. doesn’t associate with water or hydrophilic or polar molecules
  3. Orients away from water
20
Q

Outline the structure and function of fats, oils, waxes, and steroids

A

They are all triglercides – glyerol + 3 fatty acids -> ester bond + H20

OILS: liquid triglycerides @ room temperature

WAXES: esters of long chains fatty acids and long chain alcohols
- solid @ room temperature
- higher melting points

STEROIDS: different class of lipids and include molecules like cholesterol, hormones, and vitimin D

21
Q

Explain the condensation reaction connecting fatty acids and glycerol to form a triglyceride

A

Fatty acids are long hydrocarbon chains with a carboxyl group (-COOH) at one end. Glyercol is a three-carbon alcohol with three hydroxyl (-OH) groups.

  1. Removes a hydroxyl group from glyerol + hydrogen atom from the carboyxl group of a fatty acid -> releases water molecule (H20)
  2. Remaining oxygen from glycerol hydroxyl of and carboxyl group combine to form an ester linkage
  3. An ester linkage is formed, and is covalent bond between oxygen of glycerol and carbon of fatty acid)
22
Q

Explain the condensation reaction connecting fatty acids, glycerol, and a phosphate group to form a phospholipid. Describe the nature of phospholipids.

A

Amphipathic !!!!!! – contains both hydrophilic and hydrophobic properties

Phospholipids are a class of lipids that have a hydrophilic head and hydrophobic tails. This forms a lipid bilayer that constitutes cell membranes.

Glycerol is a three-carbon alcohol with 3 hydroxyl groups (-OH)
Fatty acids are long hydrocarbon chains with 1 carboxyl group (-COOH) at the end
A phosphate group is a functional group with a central phosphorus atom bonded to oxygen

  1. 2 fatty acids connect to glycerol through ester linkages -> releases 2 H2O
  2. Phosphate group added to the remaining hydroxyl group of glycerol – attached via phosphodiester bond (replaces fatty acids) – acts as hydrophilic phosphate head
23
Q

Define organic as it is applied to compounds that make up life. Identify the exceptions.

A

Organic molecules based on carbons are:

  1. carbohydrates
  2. lipids
  3. proteins
  4. nucleic acids

Molecules that are NOT organic are carbon dioxide, carbon monoxide, or hydogen carbonates

24
Q

State 4 examples of monosaccharides

A
  1. Glucose
  2. Fructose (hexose)
  3. Galactose (hexose)
  4. Ribose (pentose)
25
Q

Define disaccharide. State 3 examples and their subunits

A

A disaccharide is a type of carbohydrate composed of 2 monosaccharides units linked through a glycosidic bond via condensation reaction.

  1. Sucrose: glucose + fructose
  2. Lactose: glucose + galactose
  3. Maltose: glucose + glucose
26
Q

Describe the properties of carbohydrates. What are the different types of their subunits?

A

CARBOHYDRATES:

  1. organic compounds that are formed from various combinations of simple (monosaccharides) or complex (polysaccharides) sugars
  2. carbon-based
  3. repeating units of CH2O
  4. ring structures

MONOSACHARRIDES: alpha glucose, beta glucose & ribose
POLYSACCHARIDES: amylopectin, amylose, glycogen, cellulose

27
Q

Describe the properties of lipids. What is an example of this, and what are their subunits?

A

LIPIDS:
1. nonpolar molecules
2. not soluble in water
examples: cholesterol, phospholipids, & triglycerides

TRIGLYCERIDES:
1. subunits: glycerol + 3 fatty acid molecules
2. length of fatty acid chain is variable
3. may be saturated or unsaturated

28
Q

Describe the properties of proteins. What is the difference between peptides, polypeptides, and proteins? What are amino acids molecules made of?

A

PROTEINS:
1. made of amino acid molecules
2. contain carbon, hydrogen, oxygen, and nitrogen (sometimes sulfur)
3. complex biomolecules which are composed of one or more polypeptide chains folded

Dipeptide: 2 amino acids linked by a peptide bond
Peptide: 2+ amino acids linked by peptide bonds
Polypeptides: longer chains of amino acids w/ 3D structure
Proteins: 1+ polypeptides w/ 3D structure

Amino acids: amino group + carboxyl group + r group

29
Q

Describe the properties of nucleic acids. What are the subunits? What is the subunit made of? What are some examples of nucleic acids?

A

NUCLEIC ACIDS:
1. contains carbon, hydrogen, oxygen nitrogen, and phosphorus
2. Made of subunits called NUCLEOTIDES
3. Nucleotides made of sugar + base + phosphate group

Examples: RNA, DNA

30
Q

Describe saturated and unsatruated fatty acids.

A

SATURATED:
1. Single bonds between carbons
2. Straight, no bend
3. Allows for right packing between fatty acid molecules

UNSATURATED:
1. mono-unsaturated (one) or poly-unsaturated (many) double bonds between carbons
2. can either be trans - straight
3. or CIS - bent

31
Q

Describe the difference between cis and trans double bonds/fatty acids

A

CIS:
1. hydrogens on the same side of the double bond
2. bent shape
3. loosely packed
4. common in nature
5. low melting temperatures/liquid @ room temp
6. lowers LDL, lowers risk of heart attack & atherosclerosis

TRANS:
1. hydrogens on opposite side
2. straight shape
3. tightly packed
4. less common
5. high melting temperature/solid @ room temp
6. increases LDL, increases risk of heart attack & atherosclerosis

32
Q

Outline how triglycerides allow for energy storage and thermal insulation.

A

Lipids or triglycerides in adipose tissue are used fro long term energy storage and thermal insulation.

ENERGY STORAGE:
1. insoluble and do not effect osmotic balance of cells or tissues
2. fats/lipids are stored as triglyerides in adipose tissue/blubber
3. contains 2x amount of energy as carbohydrates per gram and 2x as energy storage efficent than starches

THERMAL INSULATION
1. lipids are buoyant
2. provides thermal insulation
3. prevents heat loss

IB HL Biology (11 decks)

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