Types of Cells | Don't Memorise

Summary

This educational script differentiates between plant and animal cells, highlighting key features such as cell walls, chloroplasts, and vacuoles. It explains that plant cells have a cell wall and a central vacuole, while animal cells lack these and have smaller, dispersed vacuoles. The script further clarifies that both plant and animal cells are eukaryotic, possessing a true nucleus, contrasting with prokaryotic cells found in lower organisms like bacteria, which lack a defined nucleus and membrane-bound organelles.

Takeaways

• 🌿 Plant cells have a well-defined cell wall, while animal cells lack a cell wall and only have a cell membrane.
• 🍃 Chloroplasts, which are unique to plant cells, are absent in animal cells.
• 💧 Plant cells contain a large central vacuole, whereas animal cells have many small vacuoles scattered throughout the cytoplasm.
• 🧬 Prokaryotic cells lack a well-defined nucleus and have a nucleoid instead, which is a region with genetic material but without a membrane.
• 🔬 Eukaryotic cells, which include both plant and animal cells, have a true nucleus and membrane-bound organelles.
• 🔬 The term 'prokaryotic' suggests a primitive type of cell structure, while 'eukaryotic' indicates a more complex cell with a nucleus.
• 🌱 The presence of a cell wall and chloroplasts are key features that distinguish plant cells from animal cells.
• 🌡 The shape of plant cells is defined by their cell walls, giving them a more rigid structure compared to the flexible shape of animal cells.
• 🧐 The classification of cells into prokaryotic and eukaryotic is based on the presence or absence of a nucleus and membrane-bound organelles.
• 📚 Cells of lower organisms, such as bacteria, are classified as prokaryotic, while higher organisms have eukaryotic cells.

Q & A

What is the primary difference between plant and animal cells in terms of cell structure?

The primary difference is that plant cells have a cell wall, while animal cells do not. Plant cells also have a well-defined shape due to the cell wall, whereas animal cells lack a proper shape because they do not have a cell wall.

What is the function of the chloroplast in plant cells?

Chloroplasts are the organelles in plant cells that are responsible for photosynthesis, the process by which plants convert light energy into chemical energy.

How do vacuoles differ in plant and animal cells?

In plant cells, there is typically one large central vacuole that can occupy most of the cell space, while in animal cells, there are numerous small vacuoles scattered throughout the cytoplasm.

What is the significance of the cell wall in plant cells?

The cell wall in plant cells provides structural support and protection, and it also helps maintain the cell's shape.

Why do animal cells not have a defined shape?

Animal cells do not have a cell wall, which is responsible for providing structure and maintaining shape in plant cells. Without a cell wall, animal cells are more flexible and can change shape.

What is the difference between prokaryotic and eukaryotic cells in terms of nucleus structure?

Prokaryotic cells lack a well-defined nucleus and have a nucleoid, which is an area with genetic material but without a membrane. Eukaryotic cells have a true nucleus with a membrane that encloses the genetic material.

Which type of cells are considered to be more primitive, prokaryotic or eukaryotic?

Prokaryotic cells are considered more primitive because they lack a well-defined nucleus and have simpler organelles.

Are all plant and animal cells classified as eukaryotic cells?

Yes, both plant and animal cells are classified as eukaryotic cells because they have a true nucleus and membrane-bound organelles.

What are some examples of organisms that have prokaryotic cells?

Lower organisms such as various bacteria have prokaryotic cells.

How does the organization of genetic material differ between prokaryotic and eukaryotic cells?

In prokaryotic cells, the genetic material is found in a nucleoid, which is not membrane-bound and has a less organized structure. In eukaryotic cells, the genetic material is contained within a well-defined nucleus with a membrane.

Outlines

00:00

🌿 Differences Between Plant and Animal Cells

This paragraph introduces the differences between plant and animal cells. It explains that plant cells have a cell wall, chloroplasts, and a large central vacuole, whereas animal cells lack a cell wall and have smaller, scattered vacuoles. The paragraph also clarifies that cells are classified into broader categories: prokaryotic and eukaryotic cells. It contrasts prokaryotic cells, which lack a well-defined nucleus and membrane-bound organelles, with eukaryotic cells that have a true nucleus and membrane-bound organelles. The paragraph concludes by identifying animal cells, including the one discussed, as examples of eukaryotic cells.

Keywords

💡Cell Wall

The cell wall is a rigid outer layer found in plant cells, providing structural support and protection. In the video, the presence of a cell wall is highlighted as a key distinguishing feature between plant and animal cells. Plant cells have a well-defined cell wall, which gives them their shape, while animal cells lack this structure, resulting in a more flexible and irregular form.

💡Chloroplast

Chloroplasts are organelles unique to plant cells that are responsible for photosynthesis, the process by which plants convert sunlight into energy. The video emphasizes that chloroplasts are absent in animal cells, making them exclusive to plant cells and a critical component for plant survival and growth.

💡Vacuole

A vacuole is a membrane-bound organelle found in both plant and animal cells that serves various functions, including storage and waste management. The video points out that plant cells have a large central vacuole that can take up most of the cell's volume, pushing other organelles to the side, while animal cells contain many smaller vacuoles scattered throughout the cytoplasm.

💡Prokaryotic Cells

Prokaryotic cells are a type of cell that lack a nucleus and membrane-bound organelles. The term 'prokaryotic' is derived from 'pro' meaning primitive and 'karyon' meaning nucleus. In the video, it is explained that prokaryotic cells, such as those found in bacteria, have a nucleoid instead of a nucleus, which is a region with genetic material but without a membrane.

💡Eukaryotic Cells

Eukaryotic cells are cells with a true nucleus and membrane-bound organelles. The video clarifies that both plant and animal cells are examples of eukaryotic cells, which have a more complex structure compared to prokaryotic cells. Eukaryotic cells are characterized by having a well-defined nucleus and other organelles enclosed within membranes.

💡Nucleoid

The nucleoid is a region in prokaryotic cells that contains the genetic material of the cell. Unlike a true nucleus, the nucleoid is not enclosed by a membrane. The video uses the nucleoid to illustrate the structural simplicity of prokaryotic cells compared to eukaryotic cells, which have a well-defined nucleus.

💡Cell Membrane

The cell membrane is a thin, flexible barrier that surrounds all cells, controlling the movement of substances in and out. The video mentions that while plant cells have a cell membrane, they also have a cell wall for additional support. Animal cells, however, only have a cell membrane, which contributes to their lack of a fixed shape.

💡Cytoplasm

Cytoplasm is the jelly-like substance within a cell, where most of the cell's functions occur. The video describes how in animal cells, vacuoles are scattered throughout the cytoplasm, in contrast to the large central vacuole found in plant cells, which can occupy a significant portion of the cell's space.

💡Organelles

Organelles are specialized structures within cells that perform specific functions. The video explains that in eukaryotic cells, organelles are membrane-bound, while in prokaryotic cells, they are not. This distinction is important for understanding the complexity and organization of cellular components.

💡Genetic Material

Genetic material, such as DNA and RNA, carries the instructions for an organism's growth, development, and reproduction. The video highlights that in prokaryotic cells, genetic material is found in the nucleoid, which is less organized than the nucleus where genetic material is housed in eukaryotic cells.

💡Cell Classification

Cell classification is the process of categorizing cells based on their structure and function. The video explains that cells are broadly classified into prokaryotic and eukaryotic cells, with further distinctions made between plant and animal cells within the eukaryotic category. This classification system helps in understanding the diversity and complexity of life.

Highlights

Plant and animal cells can be distinguished by their characteristics.

Plant cells have a well-defined cell wall, while animal cells do not.

Animal cells have a cell membrane, which is also present in plant cells.

Plant cells have a defined shape due to the presence of a cell wall.

Animal cells lack a proper shape because they do not have a cell wall.

Chloroplasts are present in plant cells and are absent in animal cells.

Plant cells contain a large central vacuole, whereas animal cells have numerous small vacuoles.

The central vacuole in plant cells can occupy most of the cell space.

Animal cells have smaller vacuoles scattered throughout the cytoplasm.

Cells are broadly classified into Prokaryotic and Eukaryotic cells.

Prokaryotic cells lack a well-defined nucleus and have a nucleoid instead.

Eukaryotic cells have a true nucleus and membrane-bound organelles.

Animal cells are examples of Eukaryotic cells.

Plant cells are also categorized as Eukaryotic cells.

Prokaryotic cells are found in lower organisms, such as bacteria.

The classification of cells is not based solely on plant and animal cells.

Prokaryotic cells have genetic material in the form of a nucleoid, not a nucleus.

Eukaryotic cells have a complex structure with a nucleus and membrane-bound organelles.

Transcripts

Here are two cells on your screen.

Can you tell me which one is a plant cell

and which is an animal cell by merely glancing at them ?

Don’t worry !

It’s not that difficult !

Plant and animal cells can be distinguished

from each other by merely looking at them.

The presence and absence of a few characters

are enough to let us know the differences.

Let us go through the differences one by one.

If we travel from outside of the cell to the inner core,

then the first difference we find

is the presence and absence of cell wall.

Plant cells have a proper, well-defined cell wall.

On the other hand,

animal cells do not have a cell wall at all !

They just have the cell membrane

which is also a part of the plant cell !

It is due to the cell wall

that the plant cells obtain this proper defined shape.

On the other hand, animal cells

do not have a proper shape because they lack cell wall.

The next obvious difference

is the presence of chloroplast in the plant cell.

This, as we have already studied,

is the exclusive organelle for plant cell.

It is absent in animal cells.

Can you now help me with the third difference ?

That’s right !

The presence of vacuoles.

Both plant and animal cells contain vacuoles.

However, in plant cells,

the vacuole is a large one located at the center.

While in animal cells,

there are numerous small sized vacuoles.

The central vacuole can occupy majority of the

cell space pushing other organelles to the periphery.

The case of animal cells is slightly different.

Here, the vacuoles are much smaller in size

and they are scattered throughout the cytoplasm.

Apart from these,

there are several other differences in these two cells.

But we will have a look at them in our higher grades.

For now, you tell me,

is classification of cells done only on these basis ?

Are there only two types of cells ?

Plant cells and animal cells ?

Think for a moment !

The answer is a definite no !

This was just the difference between plant and

animal cells.

This is not the way cells are classified.

Then how do we classify the cells ?

Cells are broadly classified in two major types.

Prokaryotic cells and Eukaryotic cells !

Here are the two types we are referring to !

This is a typical prokaryotic cell

and this is a eukaryotic cell.

Let us begin understanding the

difference between the two !

To begin with,

the name prokaryotic helps us know its structure.

The term “Pro” indicates primitive

and the term “karyon” refers to a kernel

which means “nucleus” in this case.

So do these cells have a primitive type of nucleus ?

Well, these cells do not actually have a

proper well-defined nucleus.

Can you see these thread like structures scattered

in the cytoplasm ?

This is nothing but the genetic material named nucleoid.

The nucleoid is analogous to the nucleus in our cells.

It has strands of DNA, RNA

and it carries the genetic information of the cell.

The only difference is that the nucleoid does not have a

compact shape and mainly lacks a proper membrane.

The next obvious difference is that the organelles

are also not membrane bound.

That means the prokaryotic cell does not have

well defined membranes for the different organelles.

On the other hand, the eukaryotic cell,

which means cell with a true nucleus has well defined,

membranes for nucleus as well as the other organelles.

There are several other features

but we will not get into their details for now.

Tell me one thing…

Doesn’t this look like an animal cell ?

Yes it does !

That is because this IS an animal cell !

So is animal cell an example of eukaryotic cell ?

Yes it is !

Both plant and animal cells

can be included in the category of eukaryotic cells.

So which cells will be in the prokaryotic type ?

Cells of lower organisms

like various bacteria have prokaryotic cells !