Omics-C3 Flashcards
Teaching
What is Dehydration Synthesis (Condensation Reaction)?
Monomers are linked together to form polymers through the removal of water molecules. For example, glucose molecules combine to form starch via this process.
Proteins: Polymers
Lipids: Generally not polymers
Carbohydrates: Some are polymers (polysaccharides), while others are not (simple sugars)
What is Hydrolysis?
The process where water is added to break the bonds in a polymer, breaking it down into its monomer units.
What are the three classification of carbohydrates?
Carbohydrates are classified as monosaccharides (single sugars), disaccharides (two sugars), and polysaccharides (many sugars).
What do carbohydrates do? give 3 common examples of carbohydrates.
They serve as energy sources and provide structural support in organisms (e.g. Cellulose). Common examples include glucose, starch, and glycogen.
The ____ bond is the linkage between carbohydrate molecules formed during dehydration synthesis.
glycosidic (covalent chemical bonds that link ring-shaped sugar molecules to other molecules)
What are lipids and what do they include?
Lipids are hydrophobic molecules that include fats, oils, waxes, phospholipids, and steroids.
What are Triglycerides composed of? what do they do?
Triglycerides (The main constituents of fats and other lipids) are composed of glycerol and three fatty acids, and they serve as long-term energy storage.
What do phospholipids do?
Phospholipids form the structural foundation of cell membranes. They have a hydrophilic head and hydrophobic tails.
Steroids like ____ play a role in membrane fluidity and are precursors for steroid hormones.
cholesterol
cholesterol is essential for the structure, elasticity and the various functions of cell membranes.
Proteins are made up of ____ linked by ____
amino acids
peptide bonds
A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule(–CO–NH–), releasing a molecule of water (H2O).
Proteins have four levels of structure:
primary (which is: ____ ), secondary (which are: ____ and ____ ), tertiary ( ____ ), and quaternary (____).
sequence of amino acids
alpha helices and beta-pleated sheets
3D folding
multiple polypeptide chains interacting
Summary
Primary Structure
Definition: The primary structure of a protein is the linear sequence of amino acids in a polypeptide chain, held together by peptide bonds.
Significance: This sequence is determined by the gene encoding the protein and is crucial because the specific order of amino acids determines how the protein will fold into its higher structures. A small change in the sequence (mutation) can affect the protein’s function.
Example: Insulin has a specific primary structure, and any change in the sequence of amino acids can lead to ineffective insulin or diseases like diabetes.
Secondary Structure
Definition: The secondary structure refers to local folding of the polypeptide chain into regular structures. These structures are stabilized by hydrogen bonds between the backbone atoms of the amino acids (not the side chains).
Types:
Alpha-Helix (α-Helix):
A coiled, spring-like structure formed by hydrogen bonding every fourth amino acid.
The hydrogen bonds occur between the oxygen of the carbonyl group of one amino acid and the hydrogen of the amine group of another amino acid.
Example: The α-helix is common in many proteins, such as keratin, which is found in hair.
Beta-Pleated Sheet (β-Sheet):
Consists of strands of the polypeptide lying side by side, forming a sheet-like structure.
The strands can run parallel or antiparallel, and they are stabilized by hydrogen bonds between the backbone atoms.
Example: Fibroin, the protein in silk, has a high proportion of β-sheets, giving silk its strength and flexibility.
Tertiary Structure
Definition: The tertiary structure is the overall 3D shape of a single polypeptide chain. It is formed by the folding and bending of the polypeptide, stabilized by interactions between the side chains (R groups) of the amino acids.
Forces and Interactions that stabilize tertiary structure include:
Hydrophobic interactions: Nonpolar side chains tend to cluster in the interior of the protein, away from water.
Hydrogen bonds: Form between polar side chains.
Ionic bonds: Form between positively and negatively charged side chains (salt bridges).
Disulfide bridges: Covalent bonds between the sulfur atoms of two cysteine residues (—S—S—), providing extra stability.
Van der Waals forces: Weak attractions between atoms at short distances.
Significance: The 3D shape of the protein is crucial for its biological function. If the tertiary structure is disrupted (denatured), the protein can lose its function.
Quaternary Structure
Definition: The quaternary structure exists in proteins that are made up of two or more polypeptide chains (subunits). These subunits can be identical or different and are held together by the same forces that stabilize tertiary structure (hydrogen bonds, ionic bonds, hydrophobic interactions, etc.).
Significance: The arrangement of subunits is crucial for the function of the protein. Some proteins only become functional when all subunits are assembled into the quaternary structure.
Example: Hemoglobin, the protein that carries oxygen in red blood cells, has a quaternary structure made up of four subunits (two alpha chains and two beta chains).
Proteins perform a variety of functions, including:
1) ____
2) ____
3) ____
catalyzing reactions (enzymes)
transporting molecules ( hemoglobin)
providing structural support (keratin)
Nucleic acids (____ and ____) are polymers made of nucleotide monomers. Each nucleotide contains a ____ group, a ____, and a ____ base.
DNA
RNA
phosphate
sugar
nitrogenous
What is the importance of phospholipids in cell membranes?
Phospholipids form a bilayer that makes up the cell membrane, with hydrophilic heads facing outward and hydrophobic tails facing inward, creating a barrier that protects the cell.
How do nucleotides form nucleic acids?
Nucleotides form nucleic acids (DNA and RNA) through a process called polymerization, where individual nucleotides are linked together via phosphodiester bonds to form long chains.
the phosphate group of one nucleotide forms a covalent bond (specifically a phosphodiester bond) with the sugar (the 3’ hydroxyl group of the ribose or deoxyribose) of another nucleotide. This linkage creates the backbone of the nucleic acid.
Structure of a Nucleotide:
Each nucleotide consists of three components:
Nitrogenous Base: This can be a purine (adenine [A], guanine [G]) or a pyrimidine (cytosine [C], thymine [T] in DNA, and uracil [U] in RNA).
Pentose Sugar: This is either deoxyribose in DNA or ribose in RNA.
Phosphate Group: One or more phosphate groups attached to the 5’ carbon of the sugar.
A phosphodiester bond forms between the phosphate group of one nucleotide and the hydroxyl group (-OH) on the 3’ carbon of the sugar (deoxyribose in DNA or ribose in RNA) of another nucleotide.
This bond links the 5’ carbon of one sugar (via the phosphate group) to the 3’ carbon of the next sugar.
