Biological Molecules Flashcards
Front: What makes water a polar molecule?
Back: Water is polar due to the electronegativity difference between oxygen and hydrogen, leading to unequal sharing of electrons.
Front: What bonds are crucial for water’s properties?
Back: Hydrogen bonds are crucial for water’s unique properties.
Front: What causes the dipole moment in water?
Back: The unequal sharing of electrons and the partial charges on oxygen (
δ
−
) and hydrogen (
δ
+
) create a dipole moment in water
Front: Why does oxygen attract electrons more strongly than hydrogen?
Back: Oxygen is more electronegative than hydrogen, so it attracts electrons more strongly, leading to a partial negative charge on oxygen.
Front: What is the bond angle in a water molecule?
Back: The bond angle in a water molecule is approximately 104.5°.
Front: What kind of molecule is water classified as due to its uneven electron distribution?
Back: Water is classified as a polar covalent molecule.
Front: What is hydrogen bonding in water?
A type of weak bond between the
δ
+
hydrogen atom of one water molecule and the
δ
−
oxygen atom of another water molecule.
Responsible for many unique properties of water.
Front: Why is water considered a universal solvent?
Water’s polar nature allows it to dissolve a wide range of substances.
Interacts with polar and charged particles, making it a versatile and essential solvent in biological systems.
Front: What role does water play in biological transport?
Facilitates movement of ions, nutrients, and waste within living organisms. Because of
Its ability to dissolve charged molecules
Front: How does water’s dipole nature affect its properties?
The dipole nature enables water to form hydrogen bonds.
Contributes to its high surface tension, boiling point, and its capabilities as a solvent.
Front:
Name three common monosaccharides
Glucose, Galactose, Fructose
What are two key properties of monosaccharides?
Monosaccharides are sweet and soluble in water
What polymers are made up of glucose subunits?
Starch and glycogen are polymers made of glucose subunits
What are disaccharides made of
Two monosaccharides joined together (e.g., sucrose = glucose + fructose).
How are the two monosaccharides in disaccharides joined
They are joined in a condensation reaction, removing a molecule of water.
What type of bond links the two monosaccharides
A glycosidic bond.
What is a 1-4 glycosidic bond?
It is when carbon 1 of one molecule is attached to carbon 4 of another
How can the glycosidic bond be broken?
By hydrolysis, which is the splitting of molecules with the addition of water.
In what process does hydrolysis occur in disaccharides?
During digestion in the gut and when stored carbohydrates are broken down to release sugars.
What is a common characteristic of most disaccharides?
They are sweet
What is a common characteristic of most disaccharides?
They are sweet
Amylopectin Structure
Chains linked with α-1,4 glycosidic bonds
Branches with α-1,6 glycosidic bonds every 20-30 monomers
Branched and coiled, compact shape
Amylopectin Function
The branching chains have lots of terminal glucose molecule that can be broken off rapidly when energy is needed
Glycogen Structure
Composed of α-1,4 and α-1,6 glycosidic bonds
Branches more frequently every 8-12 residues
Forms compact granules for storage
Glycogen Function
Primary carbohydrate energy storage in animals
Quickly hydrolyzed for rapid energy release
Regulates glucose concentration levels in cells
Describe the properties of polysaccharides
A: Not sweet, difficult to dissolve, and are macromolecules.
Q: What are the components of starch?
A: Made of 30% amylose and 70% amylopectin.
Describe the structure of amylose
Unbranched chains with α-1,4 glycosidic bonds, forming a helical shape
How is glucose released from amylose?
Enzymes release glucose by working from each end of the amylose molecule
What is the primary energy-related function of lipids in animals?
They are an important source of energy and energy storage, containing more energy per gram than carbohydrates or proteins
Describe the function of lipids in nerve cells.
They form a fatty sheath that insulates nerves, helping electrical impulses travel faster.
Q: What is the composition of fats and oils?
A: Fats and oils are made up of fatty acids and glycerol.
Q: What is the chemical formula for glycerol?
C₃H₈O₃
Q: What are fatty acids made of?
A: A long hydrocarbon chain and a carboxylic group (-COOH).
Q: What are the two main types of fatty acids?
Saturated and unsaturated.
Q: Describe the structure of saturated fats.
A: They have the maximum number of hydrogen atoms, no double bonds, and long, straight chains.
Q: Why are saturated fats solid at room temperature?
A: Because their straight chains allow them to pack closely, creating strong intermolecular bonds.
What is the chemical structure of stearic acid?
CH
3
(
CH
2
)
16
COOH
- A long hydrocarbon chain with a carboxylic acid group.
Q: What is formed when a fatty acid joins with a glycerol molecule
Mono-, di-, or triglycerides through a process called esterification.
What is esterification?
A condensation reaction where an ester bond is formed by removing water when a fatty acid reacts with glycerol.
Q: What elements do proteins contain?
Carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur.
How are proteins formed?
By condensation reactions between amino acids.
What is the basic structure of an amino acid?
An amino group (-NH₂), a carboxyl group (-COOH), and a side chain (R group).
What type of reaction forms peptide bonds?
Condensation reaction.
What is the bond formed between amino acids called?
A: Peptide link.
What does the primary structure of a protein refer to?
The sequence of amino acids in its molecules.
What is the secondary structure of a protein?
The repeating pattern in the structure of peptide chains, such as an alpha helix or beta-pleated sheet, held together by hydrogen bonds.
Which bonds are responsible for maintaining the secondary structure of proteins?
Hydrogen bonds.
What does the tertiary structure of a protein refer to?
The three-dimensional (3D) folding of the secondary structure.
What types of bonds are involved in stabilizing the tertiary structure of proteins?
Hydrogen bonds
Disulfide bonds
Ionic bonds
Van der Waals forces
Provide an example of a protein with a quaternary structure and how it’s formed
Hemoglobin, consisting of four polypeptide chains held around a non-protein heme group.
🌟 Hydrogen Bonds
Form between oxgens in carboxyl groups (COOH) and hydrogens in amino groups (NH₂).
Weak individually, strong collectively.
Important for folding and coiling polypeptide chains.
🔗 Sulfur Bridges (Disulfide)
Form when 2 cysteine or methionine are close together
Result in strong covalent bonds.
Holed polypeptide structure
➕➖ Ionic Bonds
Occur between positively and negatively charged side chains.
Buried deep in proteins, very strong.
🧵 Fibrous Proteins
Little tertiary structure; long parallel chains.
Cross-linkages create fibers.
Insoluble in water, extremely tough.
Examples: keratin, collagen, spider webs.
🌐 Globular Proteins
Complex tertiary and quaternary structures.
Folded into spherical (globular) shapes.
Ionic properties; form colloids in water.
What are conjugated proteins?
Proteins that join with another molecule called a prosthetic group.
What is one function of glycoproteins?
Carbohydrates help them to hold on to lots of water, makes them less likely to be broken down by protein-digesting enzymes
What is the structural feature of collagen?
Collagen has a unique triple-helical structure.
What is the basic structural unit of collagen called?
A tropocollagen molecule.
How many polypeptide chains form a tropocollagen molecule?
Three polypeptide chains (alpha chains).
What stabilizes the helical structure of collagen?
Hydrogen bonds and covalent cross-links such as hydroxylysine and lysine.
What is the structural composition of hemoglobin?
It is a tetrameric protein with four subunits.
What are the globin chains in adult hemoglobin?
Two alpha (α) globin chains and two beta (β) globin chains
What is the role of iron ions in heme groups?
To bind and transport oxygen.
What change occurs in hemoglobin when oxygen binds?
It undergoes a change from a Tense (T) state to a Relaxed (R) state, increasing oxygen affinity.
What change occurs in hemoglobin when oxygen binds?
It undergoes a change from a Tense (T) state to a Relaxed (R) state, increasing oxygen affinity.
