Proteins AP Biology

Summary

Proteins are complex organic macromolecules built from sequences of 20 different amino acids, each with a unique R group. Amino acids join via dehydration synthesis, forming polypeptide chains. These chains fold into specific 3D shapes through interactions among R groups, resulting in secondary and tertiary structures. Some proteins, like hemoglobin, achieve quaternary structure by combining multiple polypeptides. Protein shape dictates function, allowing them to serve various roles in cells, including structural, communicative, metabolic, and transport functions.

Takeaways

• 🧬 Proteins are organic macromolecules made from sequences of amino acids.
• 🌿 Amino acids in proteins contain carbon, hydrogen, oxygen, and nitrogen.
• 🔬 There are 20 different amino acids, each with a unique R group.
• 🔗 Amino acids have a central carbon atom bonded to a hydrogen atom, a carboxyl group, and an amino group.
• 💧 Dehydration synthesis forms covalent bonds between amino acids, resulting in a polypeptide chain.
• 🧩 The primary structure of a protein is its specific sequence of amino acids in a polypeptide chain.
• 🌀 Secondary protein structure involves alpha helices and beta sheets formed by hydrogen bonding.
• 🔄 Tertiary structure arises from interactions among R groups, leading to the protein's unique 3D shape.
• 🔄 Quaternary structure occurs when two or more polypeptides join to form a functional protein.
• ⚛️ Proteins perform diverse functions such as cell structure, communication, metabolism, defense, and transport.

Q & A

What are proteins made of?

Proteins are organic macromolecules built from a sequence of amino acids, which are covalently bonded together.

What elements do amino acids and proteins contain?

Amino acids and proteins contain the elements carbon, hydrogen, oxygen, and nitrogen.

How many different amino acids are there and what makes each unique?

There are 20 different amino acids, each made unique by their variable region of atoms called an R group.

What is the general structure of an amino acid?

An amino acid contains a central carbon atom bonded to a hydrogen atom, a carboxyl group, and an amino group. Additionally, each amino acid has a variable region called an R group.

What reaction joins amino acid monomers, and what does it produce?

The reaction that joins amino acid monomers is called dehydration synthesis, which involves the loss of water and the formation of a covalent bond, producing a polypeptide.

What is the primary structure of a protein?

The primary structure of a protein is a linear chain of amino acids covalently bonded together, forming a polypeptide.

What are the secondary structures in proteins, and how are they formed?

Secondary structures in proteins include alpha helices and beta sheets, which are formed by hydrogen bonding between the backbone of the polypeptide.

What determines the tertiary structure of a protein?

The tertiary structure of a protein is determined by interactions among the R groups of amino acids, including polar, nonpolar, and ionic interactions.

What is quaternary protein structure?

Quaternary protein structure occurs when two or more polypeptides join together to form a functional protein.

Why is the shape of a protein important?

The shape of a protein determines its biological function. Proteins must have specific 3D shapes to perform various functions such as cell structure, communication, metabolism, defense, and transport.

What is an example of a protein with quaternary structure?

Hemoglobin, a protein found in red blood cells that functions in oxygen transport, is an example of a protein with quaternary structure, made from four polypeptides.

Outlines

00:00

🔬 Introduction to Proteins and Amino Acids

Proteins are organic macromolecules composed of amino acids covalently bonded together. Each amino acid contains carbon, hydrogen, oxygen, and nitrogen. Despite the 20 different types of amino acids sharing a general structure, the R group varies for each, giving them unique properties. The reaction joining amino acids, known as dehydration synthesis, forms a polypeptide chain. Polypeptides have directionality, with new amino acids added to the free carboxyl terminus. The sequence of amino acids in a polypeptide determines the primary structure of the protein. Functional proteins have distinct three-dimensional shapes.

05:02

🧬 Protein Structures and Their Functions

Secondary protein structure involves the polypeptide folding into alpha helices and beta sheets due to hydrogen bonding. Tertiary structure results from interactions between R groups, determining the protein's unique 3D shape and function. Proteins' shapes are crucial for their diverse roles, such as enzymes, hormones, receptors, and transport channels. Additionally, some proteins have a quaternary structure, where multiple polypeptides join to form a functional protein, like hemoglobin in red blood cells. The specific sequence and interactions of amino acids dictate the final structure and function of proteins.

Keywords

💡Proteins

Proteins are organic macromolecules that are essential for various biological functions. They are built from a sequence of amino acids that are covalently bonded together. In the video, proteins are described as having a primary structure, which is a linear chain of amino acids, and higher levels of structure that contribute to their function. The diversity of proteins is highlighted, emphasizing their role in cell structure, communication, metabolism, defense, and transport.

💡Amino Acids

Amino acids are the building blocks of proteins. There are 20 different amino acids, each with a unique R group. Amino acids contain the elements carbon, hydrogen, oxygen, and nitrogen. They have a central carbon atom bonded to a hydrogen atom, a carboxyl group, and an amino group. The video script explains how amino acids are joined together through dehydration synthesis to form polypeptides, which are the basis of protein structure.

💡Dehydration Synthesis

Dehydration synthesis is the chemical reaction that joins amino acids together to form proteins. In this process, a water molecule is lost as the free carboxyl group of one amino acid reacts with the free amino group of another, creating a covalent bond. This reaction is fundamental to the formation of polypeptide chains, which are the linear sequences of amino acids that make up proteins.

💡Polypeptide

A polypeptide is a linear chain of amino acids that are covalently bonded together. It is formed through dehydration synthesis and represents the primary structure of a protein. The script mentions that polypeptides have a specific directionality, with the first amino acid indicated by the free amino terminus and new amino acids being added to the free carboxyl terminus.

💡Primary Structure

The primary structure of a protein refers to its linear sequence of amino acids. Each polypeptide has a unique sequence that determines its identity and function. The video script explains that the primary structure is essential for understanding how proteins are built from their basic units, the amino acids.

💡Secondary Structure

Secondary structure in proteins refers to the general patterns that the polypeptide chain folds into, such as alpha helices and beta sheets. These structures are formed due to hydrogen bonding between the backbone of the polypeptide. The video script illustrates how these patterns contribute to the overall shape and stability of the protein.

💡Tertiary Structure

Tertiary structure is the three-dimensional shape that a protein takes after the polypeptide has folded and twisted into its final form. This structure results from interactions between the R groups of the amino acids. The video script emphasizes that the tertiary structure is crucial for the protein's function, as it determines how the protein interacts with other molecules in the cell.

💡Quaternary Structure

Quaternary structure is the highest level of protein structure, where two or more polypeptides come together to form a functional protein. The video script uses the example of hemoglobin, a protein in red blood cells that transports oxygen, to illustrate how multiple polypeptides can combine to create a complex protein with a specific function.

💡R Group

The R group is the variable part of an amino acid that makes each of the 20 amino acids unique. It is attached to the central carbon atom and determines the chemical properties of the amino acid. The video script explains that R groups can be polar, nonpolar, or ionic, and their interactions play a crucial role in determining the protein's tertiary structure.

💡Hydrophilic and Hydrophobic

Hydrophilic refers to molecules that are attracted to water, while hydrophobic refers to molecules that repel water. In the context of the video script, amino acids with polar and ionic R groups are hydrophilic and interact readily with the water-based environment of a cell. In contrast, nonpolar amino acids are hydrophobic and tend to be found in the interior of proteins, away from the aqueous environment.

💡Function of Proteins

Proteins perform a wide variety of functions in cells, as highlighted in the video script. They are involved in cell structure, communication, metabolism, defense, cell transport, and more. The script emphasizes that the diverse shapes and structures of proteins, determined by their amino acid sequences and R group interactions, are crucial for their specific biological functions.

Highlights

Proteins are organic macromolecules, built from a sequence of amino acids, covalently bonded together.

Amino acids and therefore the proteins they build contain the elements carbon, hydrogen, oxygen, and nitrogen.

There are 20 different amino acids, but they share the same general structure.

Amino acids contain a central carbon atom bonded to a hydrogen atom, a carboxyl group, and an amino group, with a variable region called an R group.

The R group is what makes each of the 20 amino acids unique.

The reaction that joins amino acid monomers occurs between the free carboxyl group of one amino acid and the free amino group of another, forming a covalent bond through dehydration synthesis.

A linear chain of amino acids covalently bonded together is called a polypeptide.

Polypeptides are built with a specific directionality, starting with a free amino terminus and adding new amino acids to the free carboxyl terminus.

The sequence of amino acids in a polypeptide represents the primary structure of a protein.

Secondary protein structure involves the polypeptide spiraling and folding into alpha helices and beta sheets due to hydrogen bonding.

Tertiary structure results from R group interactions, causing the protein to bend, fold, and twist into a unique 3D shape.

R groups can be polar, nonpolar, or ionic, and their interactions determine the unique folding pattern of a protein.

Some proteins have a quaternary level of structure, where two or more polypeptides join together to form the final functional protein.

The tertiary shape of a protein determines its biological function.

Proteins perform a variety of functions, including cell structure, communication, metabolism, defense, and transport.

Transcripts

proteins are organic macromolecules

built from a sequence of amino acids

covalently bonded together

amino acids and therefore the proteins

they build contain the elements carbon

hydrogen oxygen and nitrogen

there are 20 different amino acids but

they share the same general structure

amino acids contain a central carbon

atom bonded to a hydrogen atom a

carboxyl group and an amino group

additionally each amino acid has a

variable region of atoms called an R

Group the R Group is what makes each of

the 20 amino acids unique

here are four different amino acids the

r groups are highlighted in red

let's look at how the structure of amino

acids allows for the building of complex

proteins

the reaction that joins amino acid

monomers occurs between the free

carboxyl group of one amino acid and the

free amino group of another

in the reaction water is lost and a

covalent bond is formed this is called

dehydration synthesis

a linear chain of amino acids covalently

bonded together is called the

polypeptide

polypeptides are built with a specific

directionality

directionality refers to the fact that a

molecule has distinct ends and that

reactions between molecules occur in

distinct positions

the first amino acid of the polypeptide

is indicated by the free aminotterminus

new amino acids are always added to the

free carboxyl terminus

each polypeptide is built from a

specific sequence of amino acids a

polypeptide is referred to as the

primary structure of protein

while primary structure is a linear

chain of amino acids functional proteins

have distinct 3D shapes

let's simplify our model to see how this

polypeptide takes shape

in secondary protein structure the

polypeptide Spirals and folds into

General patterns called Alpha helices

and beta sheets

these folds and twists are the results

of hydrogen bonding between the backbone

of the polypeptide

in tertiary structure the protein

continues to bend fold and twist into a

unique 3D shape

tertiary structure results from R Group

interactions the folding that takes

place depends on the sequence and

properties of the r groups in the

polypeptide

the atoms found in R groups determine

the unique chemical properties of each

amino acid R groups can be polar

nonpolar or ionic

amino acids with ionic and polar R

groups are hydrophilic and readily

interact with the water-based

environment of a cell

nonpolar amino acids are hydrophobic

in tertiary structure not only do R

groups interact with the cell

environment they also interact with each

other

polar R groups are attracted to other

polar R groups and charged R groups but

repel nonpolar groups

are groups with opposite charges attract

but R groups with the same charge do not

our group interactions determine the

unique folding pattern that gives a

protein its 3D shape

let's color code these amino acids by

chemical properties of their R groups to

imagine how they might interact

notice the nonpolar hydrophobic amino

acids found in the interior of the

protein while polar and ionic R groups

are interacting with each other and the

aqueous environment

some proteins have a quaternary level of

structure quaternary structure is when

two or more polypeptides join together

to build the final functional protein

an example of a protein with quaternary

structure is hemoglobin a protein found

in red blood cells that functions in

oxygen transport it is made from four

polypeptides

the tertiary shape of a protein

determines its biological function

proteins are the most diverse organic

molecule functioning in cell structure

communication metabolism defense cell

transport and more

to summarize amino acids are the

building blocks of proteins there are 20

different amino acids each with a unique

R Group amino acids contain the elements

carbon hydrogen oxygen and nitrogen

amino acids can be polar nonpolar or

ionic

dehydration synthesis forms covalent

bonds The Joint amino acids into

polypeptide Chains new amino acids are

always added to the free carboxylent

each polypeptide has a unique sequence

of amino acids and represents the

primary structure of a protein

secondary protein structure involves

Alpha helices and beta sheets due to

General hydrogen bonding

tertiary structure is the result of our

group interactions tertiary structure

determines a unique 3D shape of a

protein

the shape of a protein determines its

function

proteins are incredibly diverse and

perform a variety of functions examples

in cells include enzymes hormones

receptors and transport channels