of all living things, cells.

These incredible packages of organelles

and subcellular components

carry out a variety of functions in the body,

like taking in nutrients,

converting them into energy,

and working with other cells to produce things

that the body needs.

Each cell is essentially like its own little mini factory,

with complex processes occurring within the cell

to carry out specific functions.

Okay, so when we zoom into the cell to figure out

how exactly these cell processes are carried out,

one of the star players

is a class of biological macromolecules known as proteins.

Proteins carry out

many incredibly important tasks in the cell,

such as providing structural support,

aiding in chemical reactions

and even building or repairing the cell.

We can imagine proteins as a chain of amino acids,

kind of think of them as like beads on a bracelet

that fold and twist into distinct three-dimensional shapes.

The structure of a protein

along with the chemical properties of its amino acid,

evidently, determine its function.

Does it form a round, globular sphere

that can attach and interact with other compounds?

Or does it twist into long and narrow strands

that can provide structural support?

The huge variety of structures

that proteins can take on

leads to the wide range of cellular functions

that they can carry out.

Okay, so now that we've talked about proteins,

let's zoom back out

to analyze how different types of cells come together

to carry out a variety of functions in an organism.

This is where cell specialization comes into play,

which is the process by which a cell takes on

a specific structure and function.

So to better help understand this concept,

let's consider a movie theater analogy

where the movie theater is your body.

There is the cashier that handles all the money,

the snack vendor who handles out popcorn and snacks

and even the ticket operator

who directs you to the proper screenings.

In this analogy,

each person has their own distinct functions

in what they handle,

like money or popcorn or tickets.

In a similar way,

the body is also composed of specialized cells

with unique roles,

such as red blood cells that carry oxygen in the blood,

muscle cells that contract and relax

or even nerve cells that carry signaling messages

throughout the body.

Now, remember how I told you about proteins before?

Well, cell specialization is largely based

on which proteins are present or absent in the cell.

It is a cell's unique combination of proteins

that determine which functions can be carried out.

But no cell works alone,

because teamwork makes the dream work.

Groups of specialized cells

that carry out specific functions for the organism

are organized into tissues.

Looking back at our movie theater analogy,

there are multiple people within each department

that work together to help the theater function efficiently.

Similarly, our specialized cells work together

as tissues to help the organism function.

The red blood cells make up the blood,

a connective tissue

that moves important substances throughout the body.

The muscle cells help make up muscle tissue

which helps the body move

and neurons or nerve cells make up nervous tissue

that helps the organism process information.

So what are the key takeaways about cell specialization?

Number one, cells are the fundamental unit of life.

They're the smallest structural

and functional unit of an organism.

Number two, proteins help carry out cell processes.

Number three, specialized cells carry out

specific functions in an organism.

Think of the movie theater analogy

where each person has its own specific role.

And number four, groups of specialized cells

come together as tissues

to carry out one or more specific functions

for the organism.