Theme B: B1 Molecules - B1.1 Carbohydrates and Lipids Flashcards
macromolecules
Large, complex molecules composed of smaller subunits (monomers) joined together through covalent bonds. These include carbohydrates, proteins, lipids, and nucleic acids.
monomers
Small, basic molecular units that can bind together to form larger macromolecules (polymers) through covalent bonds. Examples of monomers include amino acids (which form proteins), nucleotides (which form nucleic acids), monosaccharides (which form carbohydrates), and fatty acids and glycerol (which form lipids).
hydrolysis reaction
A chemical reaction in which a water molecule is used to break the bonds between monomers in a polymer. This process is the reverse of condensation reactions. Hydrolysis is important for the digestion and breakdown of macromolecules
condensation reaction
A chemical reaction where two monomers are joined together to form a larger molecule (polymer), with the release of a water molecule. This process is the reverse of hydrolysis. Condensation reactions are essential in the formation of macromolecules.
peptide bond
A covalent bond formed between the amine group (-NH₂) of one amino acid and the carboxyl group (-COOH) of another through a condensation reaction, releasing a molecule of water. Peptide bonds link amino acids together to form polypeptides and proteins.
pentose monosaccharide
carbon backbone is composed of 5 carbons. E.g. Ribose. chemical formula: C5H10O5
functional groups
A specific group of atoms within a molecule that determines the molecule’s characteristic chemical reactions and properties. Examples include hydroxyl or alcohol (-OH), carboxyl (-COOH), amino (-NH₂), and phosphate (-H₂PO₄) groups.
Hexose monosaccharide
carbon backbone composed of 6 carbons. E.g. glucose. chemical formula: C6H12O6
glycogen
a polysaccharide made of glucose monomers bonded in a similar pattern as in amylopectin, hence it uses 1-6 linkages though its branching is more numerous. Many animals store excess glucose as glycogen
Glycogen reserves are kept in the liver and muscle tissue.
summary:
source: animal
subunit: alpha glucose
bonds: 1-4 and 1-6
branches: yes
shape: numerous branching
Cellulose
Structure of cellulose:
* 1-4 carbon linkages between beta-glucose
* The condensation reaction that binds the beta-glucose molecules requires every second one to be upside down compared to the glucose it is bonding to, orienting the hydroxyl (OH) group of carbon 1 with the hydroxyl group of carbon 4.
* Results in very linear polymer without branches (visually like a very long, thin fibre)
* These fibres run parallel to each other and form a multitude of hydrogen bonds with adjoining fibres
* This pattern continues as bundles of beta-glucose molecules form even larger bundles held together by crosslinking attractions of hydrogen bonds
* Result is a very stable cellulose molecule
Function of cellulose:
To act as a structural molecule in nature (e.g. in cell walls - estimated to be most abundant organic molecule on Earth)
It’s strong and insoluble in water, where its fibres allow water and other substances to pass freely into and out of plant cells
NOT considered a storage molecule because very few organisms produce enzyme cellulase needed to digest cellulose.
summary:
source: plant
subunit: beta glucose
bonds: 1-4
branches: no
shape: very long fibres running parallel to each other.
amylose
(categorised as a starch) uses 1-4 carbon linkages between alpha-glucose molecules. when 100s of glucose molecules are bonded by only 1-4 linkages the molecule will be linear but in a helix shape. (unbranched).
summary:
source: plant
subunit: alpha glucose
bonds: 1-4
branches: no
shape: spiral linear shape
amylopectin
(categorised as a starch) uses alpha 1-6 linkages which creates branches.
starch (why is it a good energy store)
a polysaccharide made of hundreds of glucose monomers (essentially a polymer of glucose). Properties of starch that make it a good energy store in plants:
1. Very large molecules, thus not readily water soluble.
2. Low solubility means a plant can easily store starch.
3. Large but compact, when a plant is photosynthesising and producing lots of glucose, it can add more glucose molecules to amylose or amylopectin by condensation reactions: When the plant needs to use its reserves, hydrolysis reactions are used to break glucose molecules away form starch
amylose and amylopectin
conjugated molecule
A molecule composed of two or more different types of molecules or chemical groups covalently bonded together. Examples include glycoproteins (proteins with carbohydrate groups), glycolipids (carbohydrate group and lipid) and lipoproteins (lipids combined with proteins).
antigens
Molecules on the surface of red blood cells that can trigger an immune response if they are foreign.
triglycerides
Lipids known as triglycerides contain 1 glycerol molecule and 3 fatty acids
Formed by condensation reactions: 1 glycerol + 3 fatty acids → 1 triglyceride + 3 water
phospholipids
A type of lipid consisting of a glycerol backbone, two fatty acid tails (hydrophobic), and a phosphate group with an additional polar (hydrophilic) group (this is a phospholipids variable R group). They are key components of cell membranes, forming a bilayer structure.
fatty acids
Long hydrocarbon chains with a carboxyl group (-COOH) at one end. They can be saturated (no double bonds) or unsaturated (one or more double bonds) and are key components of lipids like triglycerides and phospholipids.
saturated fatty acids
fatty acids that contain single bonds between the carbons. This means that all the other carbon bonds are to hydrogens (except for the carboxyl group). In other words, the molecule is saturated with hydrogens.
Relatively high melting points
Solid at room temperature
Triglycerides containing only saturated fatty acids are called “fats” and are often use by animals to store excess energy
monounsaturated fatty acids
with one double bond between 2 of the carbon in the hydrocarbon chain of the molecule (location of the bond can vary). making them slightly less staurated with hydrogens.
Triglycerides with one or more monounsaturated fatty acids have a lower melting point than saturated fatty acids
typically liquid (oil) at room temperature (found in olive oil, avocado, and nuts)
Some animals and many plants store energy in this form
polyunsaturated fatty acids
Polyunsaturated fatty acids: with more than one double bond in the hydrocarbon chain (no. and location may vary) making them less saturated with hydrogen.
Triglycerides composed of polyunsaturated fatty acids also have relatively low m.p
Liquid (oil) at room temperature
More plants store energy in this form
adipose tissue
A type of connective tissue that stores fat in the form of triglycerides. It serves as an energy reserve, provides insulation, and protects organs. Adipose tissue is found under the skin (subcutaneous) and around internal organs (visceral). in artic animals (walruses, seals, whales) they have a thick layer of the tissue known as blubber.
endotherms
Organisms that regulate their body temperature internally, maintaining a constant temperature regardless of environmental conditions. They generate heat through metabolic processes. Examples include mammals and birds.
amphipathic
Molecules that have both hydrophilic and hydrophobic regions. A common example is phospholipids, which have a hydrophilic head and hydrophobic tails, making them essential in forming cell membranes.
hormones
chemical messenger molecules that are produced by a variety of glands in the body.
steroids
Steroids are a group of lipids, including hormones, that are derived from cholesterol.
oestradiol
A steroid hormone, classified as an estrogen, primarily produced in the ovaries. Oestradiol is derived from cholesterol and is part of the steroid hormone family, which also includes other hormones like testosterone and cortisol.
testosterone
A steroid hormone primarily produced in the testes in males (and in smaller amounts in females’ ovaries and adrenal glands).
carbohydrate subcategories
monosaccharides (e.g. glucose, ribose) disaccharides (e.g. lactose) polysaccharides (e.g. starch, glycogen, cellulose)
lipid subcategories
triglycerides (e.g. fat stored in adipose cells) phospholipids (e.g. cell membrane) steroids (e.g. some hormones like testosterone and oestradiol).
monosaccharides
General pattern for the chemical formula of monosaccharides (excluding modified ones like deoxyribose):
CnH2nOn
universal blood donors
people with blood type O can donate blood to anyone
universal blood recipients
people with blood type AB can recieve blood from anyone
