Text reads: The Mysteries of Life with Tim and Moby.

Question

An animation shows a boy, Tim, and a robot, Moby, in their attic. They're building a toy dinosaur out of blocks.

Tim: Hey, I need one of those eight-by-two pieces.

Moby rummages in their toys. He holds up a green block. It has four dots arranged in a two-by-two array.

Tim: No… no, eight-by-two.

Moby finds a different block. It's still a two-by-two piece.

Tim: Eight dots long and two dots wide.

Moby puts down the green block and picks up a letter. He hands the letter to Tim, who reads from it.

Tim: Dear Tim and Moby, My sister said my body is made of cells. Is that true, and what are cells, anyway? From, Jenny.

Tim: Well, your sister is right. You are made of cells. She's made of cells, too. In fact, all living things are made of one or more cells. If you could look at yourself through a microscope, you could see that you're divided into millions of tiny… mm, tiny sections.

An animation shows a piece of skin viewed through a microscope. It looks like many little shapes squished together. Each shape has a dot in the center of it.

Tim: These sections are called cells, and they’re the basic unit of life. They come in lots of types and live with other cells like them in groups called tissues.

The animation expands to show dozens of identical cells. They form a tissue.

Tim: When two or more tissues combine, they form organs, like the heart and brain.

The animation expands again to show that the tissue is part of the liver. The liver is shown inside the silhouette of a human.

Tim: Every single part of your body is really millions of cells working together.

Images of many other organs appear inside the person's body.

Moby: Beep?

Tim: Each cell is basically a sac of jelly-like fluid called cytoplasm. The sac surrounding it is called the cell membrane.

An animation shows a single cell. A section of the cell is removed to reveal its interior. The cytoplasm and cell membrane are visible.

Tim: It lets good stuff in and keeps bad stuff out. Floating around in the cytoplasm are organelles.

In the animation, several objects in the cytoplasm light up. These are the organelles.

Tim: Just like the body has organs for different functions, the cell has organelles for all its functions.

The animation shows the image of the body and the image of the cell side-by-side.

Tim: Like, mitochondria extract energy from nutrients.

Two mitochondria in the cell light up. They are shaped like small beans.

Tim: And ribosomes create proteins, molecules used to build pretty much everything in the body.

The ribosomes in the cell light up. They look like flecks of pepper in the cytoplasm.

Tim: Then there’s the nucleus, which is kind of like the cell's brain. It’s a membrane pouch that holds an organism’s genetic material: the biological instructions passed down from its parents.

The nucleus in the center of the cell lights up.

Tim: These instructions are encoded in a substance called DNA.

An animation shows the DNA inside the nucleus. It is shaped like a double-helix.

Tim: In plants and animal cells, DNA is contained in a nucleus. We call these kinds of cells eukaryotic.

An animation shows a close-up of a human's skin. The skin's cells all have a nucleus. The image of a strand of DNA is inside each nucleus.

Tim: The other type of cell, prokaryotic, has no nucleus. Genetic information in prokaryotic cells just sort of floats free in the cytoplasm.

An animation shows an oval-shaped cell. A tail wiggles to make the cell move. Genetic material can be seen inside the cell. It does not have a nucleus.

Tim: Most prokaryotes are single-celled bacteria, like Lactobacillus acidophilus, which is used to make yogurt.

An animation shows a group of oval-shaped cells. The animation reveals they're inside of a yogurt container.

Moby: Beep?

Tim: Nope, not all cells look like these. In any given organism, different cells carry out very specialized functions. As a result, they can look very different. Some types of bone cells are star-shaped.

An animation shows a eukaryotic bone cell. It has a spiky shape.

Tim: Muscle cells have to be stretchy.

An image of a thin muscle cell appears.

Tim: Nerve cells can be over a meter long, so they can carry signals across the body.

An image of a long and wiry nerve cell appears. It has a tree-like structure on both ends.

Tim: This bacterium has little hairs growing out of its membrane to help it move around.

An image of a pill-shaped bacterium appears. It has a variety of short and long hairs protruding from its body.

Tim: Red blood cells are sort of shaped like little bowls.

An animation shows red blood cells floating through veins and arteries.

Tim: And plant cells have a rigid cell wall that maintains their shape.

An animation shows a collection of green plant cells. Each has organelles surrounded by a cell wall.

Tim: You have about 40 trillion eukaryotic cells in your body—and about as many prokaryotic cells. Your intestines and other body parts are home to all kinds of helpful bacteria.

An animation reveals the inside of a human's digestive system. Many types of bacteria move around inside it.

Moby: Beep!

Tim: Laugh all you want, but humans like me couldn’t live without them.

Moby: Beep.

Tim: Okay, whether they’re eukaryotic or prokaryotic, almost all cells have the ability to divide. In eukaryotes, the process is called mitosis. The cell makes a copy of its nucleus… then its cell membrane splits to form two separate cells.

An animation shows a cell with a nucleus. The nucleus copies itself. Then the cell splits. The resulting cells are identical.

Tim: This is how you grow.

Moby: Beep.

Moby points his finger at the dinosaur that Tim was building. A beam of light hits the dinosaur. It splits into two identical dinosaurs.

Tim: Hey… hey cut that out.

Moby beams his finger-laser at Tim. It creates two, identical Tims.

Tim One: Holy cats!

Tim Two: I'm beside myself.

Tim One: What are we gonna do?

Both Tims point to each other.

Both Tims: Twice as much homework! Jinx!

The Tims high five. Moby shakes his head.

make an observation on this and correlate it to the question, "where do cells come from"

Answer 1

In the dialogue between Tim and Moby, we learn about the fundamental characteristics of cells, including their structure, functions, and types. Tim explains that all living things are made of cells, which are considered the basic unit of life. He emphasizes how these cells can exist as individual units or work together in groups to form tissues and organs.

When addressing the question, "Where do cells come from?" Tim clarifies that cells have the ability to divide. He describes the process of mitosis, wherein a eukaryotic cell duplicates its nucleus and then divides, resulting in two identical cells. This process is fundamental to growth and reproduction in multicellular organisms.

Thus, we can observe that cells originate from pre-existing cells through division. This notion, often summarized by the principle "Omnis cellula e cellula" (all cells come from cells), reflects the continuity of life at the cellular level. It illustrates that rather than simply appearing or spontaneously generating, cells are produced as a result of previous cells dividing. This understanding not only answers the question of where cells come from but also reinforces the interconnectedness of living organisms and the fundamental processes that sustain life.