Chapter 5 - The Structure And Function Of Large Biological Molecules Flashcards
Three classes of macromolecules
Proteins
Carbohydrates
Nucleic acids
The most important large molecules in living things
Proteins
Lipids
Carbohydrates
Nucleic acids
Polymers
Chain-like molecules (macromolecules). Long molecules consisting of many similar or identical building blocks linked by covalent bonds
Monomers
The repeating units that serve as the building blocks of polymers
Enzymes
Specialized macromolecules that speed up chemical reactions (chemical mechanisms that cells are and break down polymers)
Dehydration reaction
Reaction in which two molecules are covalently bonded to each other, with the loss of a water molecule (Monomers connected to these)
How monomers attach to polymers?
The polymer and monomer contribute a part of the water molecule lost and attach to each other covalently
Hydrolysis
Polymers are disassembled to monomers
How polymers break apart?
A water molecule is added making the polymer split and having the hydroxyl group attach to one side and the hydrogen to another
What is the hydroxyl group?
The attached part to the OH
Carbohydrates
Sugars and polymers of sugars
Monosaccharides
Simple carbohydrates ; generally have molecular formulas that are some multiple of the unit CH2O
Carbonyl group
Attached to CO
2 classifications of sugar
Aldose (aldehyde)
Ketose (ketone)
Which sugar is an aldose and which is a ketose?
Aldose - Glucose (CO at end of carbon skeleton)
Ketose - Fructose (CO within carbon skeleton)
Hexoses
6-carbon skeleton (Glucose, Fructose)
Pentoses
5-carbon skeleton (Ribose, Ribulose)
Trioses
3-carbon skeleton (Glyceraldehyde, Dihydroxyacetone)
Source of diversity for simple sugars
Spatial arrangement of their parts around asymmetric carbons
Disaccharide
Two monosaccharides joined by a glycosidic linkage
Glycosidic linkage
Covalent bond formed between two monosaccharides by a dehydration reaction
Polysaccharides
Macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages
Storage polysaccharide
Stored sugars for later use
Starch
Plants storage for glucose
Glycogen
Polymer of glucose and branched extensively
Cellulose
Major component of the tough walls that enclose plant cells
What configuration is starch glucose monomers in?
Alpha configuration (helical)
What configuration is cellulose glucose monomers in?
Beta configuration (straight)
What do the differing glycosidic linkages do?
Gives the molecules distinct shapes
Chitin
Carbohydrate used by anthropoids for their exoskeleton
Only class of large molecules that doesn’t contain true polymers and isn’t considered a macromolecule?
Lipids
What kind of molecules are lipids?
Hydrophobic
What is fat?
Large molecules assembled from smaller molecules by dehydration reactions
What two kinds of smaller molecules construct fat?
Glycerol and fatty acids
Glycerol
Is an alcohol, each of its three carbons bears a hydroxyl group
Fatty acid
Long carbon skeleton, usually 16 to 18 carbon atoms in length. One end is carboxyl and rest is part of a hydrocarbon chain
Reason why fats are hydrophobic
The nonpolar C-H bonds in the hydrocarbon chains
What gives the name fatty acids?
The carboxyl group
What are required to create a fat?
Three fatty acids and a glycerol molecule through ester linkage
What is ester linkage
A bond formed by a dehydration reaction between a carboxyl group and a hydroxyl group
What is the fat called with red fatty acids and a glycerol molecule linked?
Triacylglycerol
Saturated fats
Fats that are solid and have no double bonds with carbon atoms in the chain
Unsaturated fats
A liquid that consists of one or more carbon atoms double bonded in the chain, causing a kink. (Cis)
What causes Trans fat?
The addition of hydrogen to make the unsaturated fat to a saturated (solidified) form causes it to be both saturated and unsaturated with a Trans double bond
How is fat important to humans and not plants?
Plants are immobile and use starch as it’s energy storage. Although 1 gram of fat stores twice as much energy as a polysaccharide, plants don’t need it like mobile mammals do such as humans
Phospholipid
Essential for cells because they are major constituents of cell mem- branes. Two fatty acids attached to glycerol
What differences do the head and tails of the phospholipids have?
The head is hydrophilic and has an affinity for water while the tails are hydrophobic
Difference between hydrophobic and hydrophilic?
Hydrophobic - nonpolar
Hydrophilic - polar
What is steroids
A lipid characterized by a carbon skeleton consisting of four fused rings
What is cholesterol?
Type of steroid crucial to animals (cell membrane and sex hormones)
Importance of proteins
Account for more than 50% of the cell’s dry mass
Instrumental in almost everything organisms do
Catalysts
Chemical agents that selectively speed up chemical reactions without being consumed by the reaction
The similarity between all proteins?
They all come from the same set of 20 amino acids, linked in unbranched polymers
What is a polypeptide?
Polymer of amino acids (bond between amino acids is peptide bond)
What is a protein?
Biologically functional molecule made up of one or more polypeptides, each shaped to a three dimensional figure
What is a carboxyl group?
CO double bond and also COH bond (C attaching to both)
What is an amino acid?
Organic molecule with an amino group and a carboxyl group
Functions of proteins
Enzymatic - acceleration of chemical reactions
Storage - store amino acids
Hormonal - coordination of organisms activities
Motor - movement
Defensive - protection against disease
Transport - transport of substances
Receptor - response of a cell to chemical stimuli
Structural - support
How does an amino acid become a polypeptide?
An amino acid is a monomer. This monomer connects to another amino acid through a peptide bond. This peptide bond is when the carboxyl group of one amino acid is bonded with the amino group of the acid and undergoing dehydration reaction to become linked, thus creating polypeptides with multiple amino acids
Where do the amino acids chain start?
Amino group side (N-terminus)
What is so important about protein shape?
It is important for so many things because it is like a puzzle piece fitting to other cells and parts by having that specific shape. This is all achieved by the specific side chain and number of polypeptides a protein has
Four levels of protein structure
Primary
Secondary
Tertiary
Quaternary
Primary structure
Sequence of amino acids
Secondary structure
Coiled or folded in patterns that contribute to the protein’s overall shape
How are secondary structures formed?
Through the hydrogen bonds in the polypeptide backbone (not side chain)
Alpha helix
Delicate coil held together by hydrogen bonding every fourth amino acid
Beta pleated sheet
Two or more segments of the polypeptide chain lying side by side (called β strands) are connected by hydrogen bonds between parts of the two parallel segments of the polypeptide backbone
Tertiary structure
Overall shape of a polypeptide resulting from interactions between the side chains (R groups) of the various amino acids
Hydrophobic interaction
Amino acids with hydrophobic (nonpolar) side chains usually end up in clusters at the core of the protein, out of contact with water. Thus, a “hydrophobic interaction” is actually caused by the exclusion of nonpolar substances by water molecules. Once nonpolar amino acid side chains are close together, van der Waals interactions help hold them together. Meanwhile, hydrogen bonds between polar side chains and ionic bonds between positively and negatively charged side chains also help stabilize tertiary structure
Disulfide bridges
Covalent bonds further reinforcing the shape of a protein
Quaternary structure
Overall protein structure that results from the aggregation of these polypeptide subunits
Denaturation
Proteins break their shape due to environmental changes around them
Chaperonins
Protein molecules that assist in the proper folding of other proteins
Ways to see shapes of protein
X-Ray crystallography
NMR spectroscopy
Bioinformatics
Nucleic acids
Polymers made of monomers called nucleotides
DNA
Genetic material that organisms inherit from their parents
RNA
Interacts with the cell’s protein-synthesizing machinery to direct production of a polypeptide, which
folds into all or part of a protein
What composes a nucleotide?
Five-carbon sugar (pentose)
Nitrogenous base
One or more phosphate groups
Two families of nitrogenous bases
Pyrimidine
Purines
Pyrimidine?
One six-membered ring of carbon and nitrogen atoms
Members of pyrimidine
cytosine (C)
thymine (T)
uracil (U)
Members of purines
adenine (A)
guanine (G)
