Biomolecules (Week 4) Flashcards
What are the four kind of biomolecules?
-Proteins -Carbohydrates -Lipids -Nucleic Acid
What are polymers?
Polymers are long molecules constructed by the repetition of simple units called monomers.
What are macromolecules?
Macromolecules are polymers with molecular weight exceeding 1000.
What is the reaction from which macromolecules are usually formed?
Condensation reactions assemble polymers from monomers forming a covalent bond and releasing water. (energy is added to the system)
What is the reaction from which macromolecules are usually broken down?
Hydrolisis breaks down polymers to their simple units by adding water to the system (energy is released)
What is the general formula of carbohydrates?
Cx(H2O)y. The carbon atoms are bonded with both hydrogen atoms and hydroxyl groups.
What are the three roles of carbohydrates?
1- They are a source of energy 2- They can transport energy in complex organisms 3- The serve as carbon skeleton for other molecules.
What are the 4 different kind of carbohydrates according to the number of monomers?
1-Monosaccharides 2-Disaccharides 3-Oligosaccharides 4-Polysaccharides
Describe monosaccharides
They are single and simple sugar used to assemble larger polymers.
How are monosaccharides divided according to the number of carbon atoms?
-3 carbon sugars (Glyceraldehyde) -Pentoses: They have 5 carbon atoms -Hexoses: Structural isomers with 6 carbons and general structural formula C6H12O6.
What is the two possible structural configuration of monosaccharides?
-Straight chain -Ring (Cyclic)
Describe the cyclic structure of monosaccharides
The ring structure is more common and stable. It’s formed when the hydroxyl group of the fifth carbon reacts with the carbonyl group. It shows a novel functional group: the hemiacetal group.
What is a glycosidic link?
A glycosidic link is the result of a condensation reaction between a hydroxyl group on one sugar and a hydroxyl group on another sugar.
What are disaccharides?
Two simple sugars linked by covalent bonds (Glycosidic linkages).
What are oligosaccharides?
Polymers of 3 to 20 simple sugars.
What are the two characteristics of oligosaccharides?
They may have additional functional groups which give them special properties and they may be covalently bonded to proteins and lipids on the cell surface acting as recognition signals.
What are polysaccharides?
Polymers of hundreds or thousands of monosaccharides.
What are the three different kind of polysaccharides?
-Starch -Glycogen -Cellulose
Describe starch:
Is a polysaccharide of glucose linked by α-glycosidic linkages. It’s the principal energy storage in plants.
Describe glycogen:
Is a polysaccharide of glucose and the form of energy storage in animals. Is water-insoluble and resist osmotic pressure.
Describe cellulose:
Is a polysaccharide of glucose with β-glycosidic linkages, thus is more stable and an excellent structural component. Is the major component of plant cell wall.
Why are glycogen and cellulose good at storing energy?
Because they can both be hydrolized readily into glucose monomers which is then broken down to release energy.
State the three different types of carbohydrates that can be obtained when a functional group is added:
1-Sugar phosphate 2-Amino sugar 3-Chitin
Describe sugar phosphate
A phospate group is added to an hydroxyl group.
Describe amino sugars:
An hydroxyl group is replace with an amino group.
Describe chitin:
A polymer of N-acetylglucosamine.
What are lipids?
Hydrocarbons insoluble in water because they are non-polar.
Describe steroids:
Tetracyclic compounds made up of a series of alkyl rings linked by shared carbon.
What are triglycerides?
Compound composed of the three carbon alcohol glycerol linked to three fatty acids via ester linkages.
What are fatty acids?
They are long nonpolar hydrocarbon chains and have an acidic polar carboxyl group.
How is the ester linkage formed?
Through a condensation reaction between the carboxyl group of the fatty acid and a hydroxyl group of the glycerol.
What are the three different types of fatty acids?
1-Saturarted 2-Monounsaturated 3-Polyunsaturated
Describe saturated fatty acids:
The alkyl chain contains only C-C single bonds and it’s a straight line. They pack together tightly due to Van der Waals forces and thus they’re solid at room temperature and have higher melting points. Animal fats.
Describe monounsaturated fatty acids:
Their alkyl chain contains one C=C double bond that causes the structure to bend.
What’s a phosphodiester group?
Is a phosphate group modified by the addition of different substituent group.
Why are phospholipids amphipathic?
Because the two fatty acids tails are hydrophobic (repel water and tend to aggregate) while the phosphate functional group has a negative electric charge thus it’s hydrophilic.
What happens to phospholipids in an aqueous environment?
They tend to form a lipid bilayer with hydrophilic heads pointing outward. The water is excluded from the hydrophilic core.
What are glycolipids?
Lipids that contain a sugar group instead of a fatty acid.
What are carotenoids?
Lipids that act as light absorbing pigments.
What are Vitamins?
Small molecules that cannot be synthetized by the body and must be acquired in diet.
What are waxes?
Highly nonpolar and impermable compound that are plastic at room temperature.
Why are the chains of fatty acids hydrophobic?
Because they contain C-H and C-C bonds which have low electronegativity and are nonpolar.
What are nucleic acids?
Polymers of four different kinds of nucleotide specialized in the storage and transmission of genetic information.
What is a nucleotide?
A unit of the polynucleotide composed of a nucleoside (a sugar and an amino base) and a phosphate group.
What are the two kinds of bases?
Pyrimidines (CUT the Pie) and Purines (Pure As Gold).
What is DNA?
Deoxyribonucleic acid, a polynucleotide that encodes hereditary information and passes it from generation to generation.
State all the characteristics of DNA:
1- Its pentose sugar is deoxyribose. 2-It’s double-stranded and the two strands form a double helix and are antiparallel (they run in opposite direction).
How is genetic information encoded in the DNA?
Is encoded as the sequence of bases.
Describe complementary base pairing:
Thymine will always pairs with Adenine, forming two hydrogen bonds. Guanine will always pair with Cytosine forming three hydrogen bonds.
State all the characteristics of RNA;
-Its pentose sugar is ribose. -It has Uracil as a base instead of Thymine. -RNA is single-stranded.
What are the two possible ways in which complementary base pairing can occur in RNA?
1- Between different regions of the same RNA polymer. 2-Between RNA and DNA (Adenine will pair with both thymine and uracil).
What’s the difference between ribose and deoxyribose?
Deoyribose sugar differs from Ribose sugar in Lacking an Oxygen atom at the 2nd carbon position.
Describe the backbone of DNA and RNA:
Is a chain of sugars and phosphate groups linked by phosphodiester linkages.
What’s a phosphodiester linkage?
The phosphate group links carbon 3’ of one sugar to carbon 5’ of another sugar).
What are the two functions of DNA that constitute the central dogma of molecular biology?
1- DNA can repdroduce itslef (Replication). 2- DNA copies its information into RNA (transcription) and RNA can specify a sequence of amino acids in a polypeptide (translation).
What are the other roles for nucleotides?
-ATP (Energy transducer in biochemical reactions) -GTP (Energy source in protein synthesis) -cAMP (Essential to the action of hormones and transmission of information in the nervous system).
