Macromolecules Flashcards
What are macromolecules?
Large biological molecules essential for life, including proteins, lipids, carbohydrates, and DNA
What are proteins composed of?
Proteins are macromolecules composed of amino acids covalently linked by peptide bonds
What are the six roles of proteins in cells?
- Structural components
- Catalysis of reaction
- Transport
- Movement
- Storage
- Signalling
- Gene regulation
What determines a protein’s structure?
Amino acid sequence and bonding interactions, including covalent peptide bonds and non-covalent interactions
What are the four levels of protein structure?
- Primary
- Secondary
- Tertiary
- Quaternary
What is the primary protein structure?
Linear sequence of amino acids
What is the secondary protein structure?
Alpha helices and beta sheets
What is the tertiary protein structure?
3D folding due to bonding interactions
What is the quaternary protein structure?
Association of multiple polypeptides
What assists proteins in folding?
Chaperone proteins help proteins fold into their lowest energy conformation
What are protein domains?
Independently folded regions within a protein, each with specific functions
What are fibrous proteins and what is an example of it?
Extended structural
Keratin
What are globular proteins and what is an example of it?
Compact functional
Enzymes
How are extracellular proteins stabilised?
By disulfide bonds
What is a ligand in protein binding?
A molecule that binds to a protein at a specific binding site, affecting function
What are three examples of protein function related to binding?
- Antibodies
- Enzymes
- Motor proteins
What interactions influence protein folding?
Hydrophobic and hydrophilic interactions play a key role in protein folding
What are the four major macromolecules?
- Proteins
- Lipids
- carbohydrates
- DNA
What is the biological significance of lipids?
- Store chemical energy
- Form cell membranes
- Act as hormones
- Provide waterproofing
What are the key characteristics of lipids?
- Water insoluble
- Oily/greasy
- Composed of fatty acids
What are triacylglycerols?
The most abundant lipids in the cells
What are triacylglycerols composed of?
Glycerol esterified with three fatty acids
What are triacylglycerols used for?
For fat storage in animals and plants
Why are triacylglycerols important in energy storage?
They yield twice the energy per gram compared to carbohydrates
What are the two types of triacylglycerols?
Simple - three of the same fatty acid
Mixed - two or more different fatty acids
What are sphingolipids?
Membrane lipids with a polar head and two non polar tails containing sphingosine instead of glycerol
What are steroids and what is their most abundant form?
- Fat-soluble molecules with four fused rings
- Cholesterol is the most abundant and a precursor for steroid hormones
What are lipoproteins and what is their function?
Complexes that transport water insoluble lipids in blood, consisting of polar lipids, sterols and polypeptides
What are the four classes of lipoproteins?
- Chylomicrons
- Very low density lipoprotein
- Low density lipoprotein
- High density lipoprotein
What is the relationship between lipoproteins and atherosclerosis?
High VLVL and low HDL levels are associated with an increased risk of atherosclerosis
What are waxes and what are their functions?
Esters of fatty acids and long chain alcohols providing lubrication, waterproofing and pliability for skin, feathers, fur and hair
What are trans fats and why are they harmful?
Trans fats are artificially hydrogenated fats that increase shelf life but raise the risk of heart disease by lowering HDL levels
What are mucopolysaccharides?
Glycoproteins with a higher percentage of carbohydrate than protein
What is an oligosaccharide?
A short chain of monosaccharides
Why must animals cleave sucrose before absorbing it?
Sucrose is not directly absorbable and must be broken down by sucrase/invertase in the small intestine
What are the storage polysaccharides in plants and what do they consist of?
Starch - amylose and amylopectin
What are the storage polysaccharides in animals and what do they consist of?
Gylcogen - branched polysaccharide
What is cellulose?
A fibrous water insoluble polysaccharide forming plant cell walls made of unbranched glucose chains
What is peptidoglycan?
A bacterial cell wall component made of peptide and polysaccharide targeted by penicillin to inhibit bacterial growth
What is heparin?
A mucopolysaccharide found in arterial blood vessels that inhibits blood clotting
What is the glycemic index?
A ranking of carbohydrates based on their impact on blood glucose levels
Why does DNA form a double helix?
The sugar phosphate backbone is hydrophilic while the bases are hydrophobic causing the helical structure
