Funbio 2

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Questions and Answers

What is the role of tyrosinase in protein synthesis?

Tyrosinase is an enzyme that links together amino acids in the correct sequence to build proteins.

How do digestive enzymes like amylase function in the body?

Amylase breaks down complex carbohydrates into simpler sugars during digestion.

Explain the significance of the Lock & Key model in understanding enzyme function.

The Lock & Key model illustrates that the active site of an enzyme is specifically shaped to fit a particular substrate, facilitating the reaction.

What distinguishes enzymes from other biological catalysts?

Enzymes are specific helpers to specific reactions and are not changed by the reaction, allowing them to be reused. Signup and view all the answers

Give an example of an enzyme and its corresponding substrate it acts upon.

Sucrase is an enzyme that breaks down the substrate sucrose into glucose and fructose. Signup and view all the answers

What is the primary advantage of the zigzag structure in chain proteins?

The zigzag structure makes chains strong and flexible, although not elastic. Signup and view all the answers

Define tertiary structure in proteins.

Tertiary structure refers to the complete 3D conformation of a protein, including its backbone atoms and side chains. Signup and view all the answers

What characterizes quaternary structure in proteins?

Quaternary structure is characterized by the association of several protein chains, each with its own primary, secondary, and tertiary structures. Signup and view all the answers

How does the amino acid sequence influence a protein's conformation?

The amino acid sequence dictates how a protein folds into a single stable conformation. Signup and view all the answers

What role do molecular chaperones play in protein folding?

Molecular chaperones assist in the conformational folding or unfolding of large proteins. Signup and view all the answers

What happens during protein denaturation?

Denaturation disrupts hydrogen and ionic bonds, leading to unfolding and loss of biological activity. Signup and view all the answers

What determines the biological role of a protein?

The entire protein structure, including its 3D configuration, determines its biological role. Signup and view all the answers

Describe the function of enzymes in biological processes.

Enzymes speed up metabolic reactions necessary for processes like respiration and digestion. Signup and view all the answers

What are the two functional groups present in all amino acids?

The two functional groups present in all amino acids are the amino group (-NH2) and the carboxyl group (-COOH). Signup and view all the answers

Describe the primary, secondary, and tertiary structures of proteins.

The primary structure is the linear sequence of amino acids, the secondary structure includes alpha helixes and beta sheets formed by hydrogen bonds, and the tertiary structure is the three-dimensional folding of the protein due to interactions between side chains. Signup and view all the answers

What roles do molecular chaperones play in protein synthesis?

Molecular chaperones assist in the proper folding of proteins and prevent aggregation during synthesis. Signup and view all the answers

How do enzymes function as specialized proteins in the body?

Enzymes act as catalysts that speed up biochemical reactions without being consumed in the process, lowering the activation energy required. Signup and view all the answers

What element makes proteins nitrogen-rich compared to other biological molecules?

The presence of nitrogen in the amino acids that form proteins makes them nitrogen-rich. Signup and view all the answers

What role do the R groups play in amino acids?

The R groups, or side chains, determine the identity, polarity, and chemical reactivity of each amino acid, influencing protein structure. Signup and view all the answers

What distinguishes non-polar amino acids from polar amino acids?

Non-polar amino acids are hydrophobic and have no charge on their R group, while polar amino acids contain groups like hydroxyl or amide that can participate in hydrogen bonding. Signup and view all the answers

Why are proteins considered the most abundant organic molecules in living systems?

Proteins make up about 50% of the cellular dry weight and perform essential structural and functional roles in every cell. Signup and view all the answers

What are the two classifications of polar amino acids based on the charge of their R groups?

Polar amino acids can be classified into those with positive R groups and those with negative R groups. Signup and view all the answers

Describe the process of how a peptide bond is formed between two amino acids.

A peptide bond is formed by removing a water molecule from an amino group of one amino acid and a carboxyl group of another amino acid. Signup and view all the answers

What are the four levels of protein structure?

The four levels of protein structure are primary, secondary, tertiary, and quaternary structures. Signup and view all the answers

How does the primary structure of a protein influence its overall function?

The primary structure, or unique sequence of amino acids, largely determines the protein's function by influencing its shape and interactions. Signup and view all the answers

What is the role of hydrogen bonding in the formation of secondary structures in proteins?

Hydrogen bonding stabilizes the secondary structure by allowing amino acids to fold into structures like a-helices and β-sheets. Signup and view all the answers

What characterizes the a-helix structure in proteins?

The a-helix is characterized by hydrogen bonds forming between the carboxyl oxygen of one amino acid and the hydrogen of another amino acid four residues down the chain. Signup and view all the answers

Explain the difference between the a-helix and β-sheet secondary structures.

The a-helix forms a spiral shape stabilized by hydrogen bonds along the same chain, while β-sheets are formed by hydrogen bonds between different polypeptide chains or regions of the same chain. Signup and view all the answers

What is the significance of the rigid nature of peptide bonds in protein structure?

The rigidity of peptide bonds helps maintain the structural integrity of proteins while allowing rotations of adjacent R groups for flexibility. Signup and view all the answers

Study Notes

Biological Molecules: Proteins

Proteins are derived from the Greek word proteios, meaning "holding first place".
They are the most abundant organic molecules in living systems. Over 100,000 different proteins exist.
Proteins are present in every part of a cell and make up approximately 50% of the cellular dry weight.
Proteins are fundamental for structure and function in life. They significantly influence a cell's appearance and functions.

Learning Outcomes

Describe amino acid structure and the characteristics of the peptide bond.
Explain polypeptide primary, secondary, and tertiary structure.
Describe the role of structural and functional domains in protein tertiary structure.
Explain the role of molecular chaperones in protein synthesis.
Explain the role of enzymes in the body.

Proteins

Proteins are polymers of amino acids.
Amino acids contain two functional groups; an amino group (-NH2), and a carboxyl group (-COOH).
Out of approximately 300 amino acids found in nature, only 20 are considered standard amino acids, appearing repeatedly in proteins.

Amino Acids - Building Blocks

Amino acids are organic compounds.
They are the basic building blocks of proteins, repeatedly occurring in their structure.

Amino Acid Structure

All amino acids have a similar structure.
They are known as alpha-amino acids as both carboxyl and amino groups are bonded to the alpha carbon.
The alpha carbon also bonds to a R-group (side chain), which varies for each of the 20 amino acids.

Classification Based on Polarity

Nonpolar: Hydrophobic; lack charge on their R-groups.
Polar: Possess groups like hydroxyl and amide; participate in hydrogen bonding within protein structure. Lack charge on their R-groups.

Classification Based on Polarity (Electrically Charged)

Positive charge: Polar amino acids with positive R-groups. (e.g., Lysine, Arginine, Histidine)
Negative charge: Polar amino acids with negative R-groups. (e.g., Aspartic Acid, Glutamic Acid)

Peptide Bond

A covalent bond that connects amino acids.
Formed by removing a water molecule from the amino group of one amino acid and the carboxyl group of the adjacent amino acid.
Creates a dipeptide, and extends to form polypeptides, and ultimately proteins (starting from the N-terminus).

Protein Structure

Proteins have four levels of organization:
- Primary: Amino acid sequence.
- Secondary: Hydrogen bonding between amino acids results in structures like alpha-helices and beta-sheets.
- Tertiary: Interactions among side chains fold the protein into a 3D structure.
- Quaternary: Several polypeptide chains associate to form a larger structure.

Primary Structure

The linear sequence of amino acids in a protein is its primary structure.
This structure heavily influences the protein's function.
Example: The first six amino acids in hemoglobin.

Secondary Structure

Forming hydrogen bonds, the primary structure organizes into a compact structure.
The alpha-helix and beta-sheet (parallel or antiparallel) are the most common structures.
Keratin is an example.

Tertiary Structure

The interactions between side chains bring about the protein's 3D conformation.
Hydrogen and ionic bonding influence this process.
RNA is one example.

Quaternary Structure

Multiple polypeptide chains bond to form a complex structure.
This interaction involves hydrogen bonds and Van der Waals forces between nonpolar side chains.
Hemoglobin is an illustration.

Why Do Proteins Have Different Conformations?

The amino acid sequence dictates the protein's conformation.
Proteins normally fold into a single stable conformation initially.
Environmental factors, like pH and temperature, can cause slight changes or even denaturation (unfolding). Denaturation disrupts hydrogen and ionic bonds, which often leads to a change in shape and loss of biological activity.

Molecular Chaperones

Specialized proteins that aid in protein folding or unfolding.
Facilitate and regulate protein conformational changes.
Assist in the correct folding of proteins during or after synthesis.

What Determines a Protein's Biological Role/Activity?

The entire protein's structure defines its role.
Different protein regions can have varying functions.
Variations in amino acid sequence, and the resulting 3D structure, define protein specialization.

Function of Proteins

Enzymes: Speed up biochemical reactions. Examples include amylase (digestion) and diastase (starch to maltose conversion).
Transport: Carry molecules. Examples include hemoglobin (oxygen transport), and albumin (lipoproteins transport).
Storage: Store molecules. Examples include ferritin (iron).
Others: Defensive, hormonal, structural, to name a few.

Enzymes

Enzymes are proteins that speed up metabolic reactions.
Each enzyme catalyzes a specific reaction.
Enzymes are reusable.
Enzymes are needed in small quantities, typically converting thousands of molecules per second.
Enzyme functions are dependent on their shape and the ‘lock and key’ interactions with the substrate.

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Description

Test your knowledge on the structure and function of proteins with this quiz. Covering topics such as amino acid structure, protein synthesis, and the role of enzymes, this quiz will help reinforce your understanding of these essential biological molecules.