Biomolecules Flashcards
What are the four main classes of biomolecules?
Sugars; nuceleotides; fatty acids; amino acids.
Sugars (Ex, poly., funct.)
Example = glucose Polymer = glycogen Function = energy storage
Nuceotides (Ex, poly., funct.)
Example = ATP Polymer = DNA Function = carries genetic information
Fatty acids (Ex, poly., funct.)
Example = stearic acid Polymer = triacylglycerols Function = long term energy storage
Amino acids (Ex, poly., funct.)
Example = alanine Polymer = proteins Function = enzymes etc.
Give an example of a cell with a glycosylated cell surface protein
RBC’s in ABO blood groups
Aldose
A sugar with a carbonyl group at the end of the carbon chain.
Ketose
A sugar with a carbonyl group in an intermediate carbon in the chain.
What forms can sugars come in, structurally?
Linear or ring
How do ring-shaped sugars form from linear sugar
Nucleophilic attack by the lone pair of electrons on the oxygen in the -OH on the penultimate carbon atom in the chain on the carbon atom in the carbonyl group. This carbon atom then is the anomeric carbon atom.
What are the a and B forms of a sugar?
a-sugars have the -OH group on the anomeric carbon facing down; B-sugars have the -OH group on the anomeric carbon facing up.
Monosaccharide examples
Glucose, fructose, galactose
Disaccharide examples
Maltose = glucose + glucose Sucrose = glucose + fructose Lactose = glucose + galactose
Polysaccharide examples
Glycogen = branched glucose polymer consisting of a(1,6) and a(1,4) glycosidic bonds. Amylose = linear glucose polymer made up of a(1,4) glycosidic bonds.
How is glycogen digested in the diet?
Salivary amylase causes hydrolysis at random a(1,4) glycosidic bonds.
Pancreatic amylase then produces a mixture of glucose monosaccharides and maltose disaccharides. Then maltase hydrolyses the a(1,4) glycosidic bonds to produce glucose which is then digested.
How is glycogen digested in the liver?
Glycogen phosphorylase hydrolyses terminal a(1,4) glycosidic bonds forming glucose-1-phosphate
What enzyme is involved in the catabolism of glycogen in the liver?
Glycogen phosphorylase
How does lactose intolerance work?
Normal lactose digestion in the small intestine; then undigested lactose in the large intestine broken down by bacteria - excess CO2 and metabolites produced cause bloating and diarrhoea.
What is the difference between deoxyribose and oxyribose sugars in nucleotides?
The presence of an -H instead of an -OH group on the second carbon.
What is the backbone in DNA made up of?
Alternating sugar and phosphate molecules
What are the classes of RNA?
mRNA = copy of a gene - template for protein synthesis; produces in transcription (its a copy, so was transcribed) tRNA = carries aa's to ribosome in translation rRNA = constituent of ribosomes
Examples of lipids?
Triacylglycerols
Fatty acids = long chain c’acid
Phospholipids
Amphipathic
Has a polar group at one end and a non-polar group at the other
How does the body get cholesterol
Made de novo by the body but also from diet.
What is cholesterol used for in the body?
Regulates membrane fluidity - regulated arrangement of the polar heads of phospholipids in the membrane and so stabilises them.
Also is a precursor of steroid hormones like testosterone.
What are essential amino acids?
Amino acids that humans cannot produce de novo (lack enzymes); so must be acquired in diet: I - Isoleucine V - valine H - histadine M - methionine L - lysine K - leusine F - phenylalanine T - threonine W - tryptophan
At what pKa does the carboxyl group on an amino acid ionise?
2.3
At what pKa does the amino group on an amino acid ionise?
9.8
What neurotransmitters can be synthesised from what amino acids?
Tyrosine (Tyr, Y) = epinephrine; dopamine
Histidine (His, H) = histamine; Tryptophan = serotonin
