Cells Review

Cells Part 1

​All living things have these in common:

​1. Have a metabolism (meaning they do chemical reactions)

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​2. Maintain homeostasis (keep themselves balanced)

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​3. Reproduce (and pass on traits to offspring)

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​4. Grow and develop

​One more thing: all living things are made of cells!

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​The cell is the smallest thing that has all four of the characteristics of life.

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​Cells have a metabolism, they maintain homeostasis, they reproduce, and they grow and develop.

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​Cell Theory

​Cell theory states three things:

​1. All living things are made of cells.

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​2. The cell is the smallest unit of life.

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​3. Cells come from other cells.

Multiple Choice

Which of the following is NOT a characteristic of living things?

• The ability to reproduce.

• Having a metabolism (using energy).

• The ability to think.

• Growth and development.

Multiple Choice

Which of the following is NOT a part of cell theory?

• Cells come from other cells.

• Cells are the smallest unit of life.

• All living things are made of cells.

• Some living things are not made of cells.

​Cells and Organelles

​Cells are made of even smaller parts called organelles.

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​Organelle is a word that means "little organ".

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​So, just like your body has organs like your heart and lungs, cells have organelles like the nucleus and the mitochondria.

​Types of Cells

​There are two main types of cells:

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​1. Prokaryotic Cells

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​2. Eukaryotic Cells​

Prokaryotic Cells

​Prokaryotic cells are mostly bacteria.

They are ALWAYS unicellular.​

​They NEVER have a nucleus.

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​​They DO have DNA, a cell membrane, ribosomes, and cytoplasm.​

​They may also have a cell wall for protection and a flagella (a tail that helps them move).

Prokaryotic Cells

​They may also have a cell wall for protection and a flagella (a tail that helps them move).

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​Prokaryotic cells are usually much smaller and simpler than eukaryotic cells.

Eukaryotic Cells

Eukaryotic cells can be further divided into plant cells and animal cells.

​Eukaryotic cells can be unicellular or multicellular.

ALL eukaryotic cells have:

A nucleus​​

​Membrane-bound organelles

As well as DNA, ribosomes, a cell membrane, and cytoplasm

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Multiple Choice

The two main types of cells are:

• Prokaryotic and bacterial

• Eukaryotic and plant

• Prokaryotic and eukaryotic

• Plant and animal

Multiple Choice

Which type of cells have a nucleus? (Remember: "euks have nukes, pros have no")

• Bacterial cells

• Eukaryotic cells

• Prokaryotic cells

• All cells

Multiple Choice

Which is bigger: a cell or an organelle?

• A cell

• An organelle

Multiple Choice

What does the word "organelle" mean?

• Cell

• Organ

• Little organ

• Little cell

Multiple Choice

Which is NOT a characteristic of a bacterial (prokaryotic) cell?

• Has DNA

• Has a cell membrane

• Has mitochondria

• Has ribosomes

Multiple Choice

Which is NOT a characteristic of a bacterial (prokaryotic) cell?

• Multicellular

• May have a cell wall

• Has DNA

• Is alive

Multiple Select

Choose the characteristics of a eukaryotic cell (There are 3 correct answers. Please choose all 3.)

• Has a nucleus

• Has membrane-bound organelles

• Smaller and simpler than prokaryotic cells

• Lacks a nucleus

• May be unicellular or multicellular

Multiple Select

Choose the characteristics that are shared by ALL cells, whether they are prokaryotic or eukaryotic. (There are 4 correct answers. Choose all 4.)

• Have DNA

• Have a cell membrane

• Have a nucleus

• Have ribosomes

• Have cytoplasm

Cell Membrane

​All cells, whether prokaryotic or eukaryotic, have a cell membrane.

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A cell membrane is like the cell's skin. It keeps the cell's insides in, and keeps other things out.

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​A cell membrane can also let certain things pass through (if the cell needs them.)

Membrane-bound organelles

​Membrane-bound organelles are just organelles with a membrane around them.

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​The organs in your body, like your heart and brain, have membranes around them. These membranes are like tiny versions of skin.​

​The organelles in a eukaryotic cell also have membranes around them.

Nucleus

The nucleus is a very important membrane-bound organelle. The nucleus is like the brain of a eukaryotic cell. It acts as the cell's control center.

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​The nucleus contains the DNA, or genetic material, of the eukaryotic cell.

Mitochondria

​The mitochondria is the powerhouse of the cell. It provides energy for cell.

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​The mitochondria also has its own DNA, separate from the DNA of the cell!​

Mitochondria are found in all eukaryotic cells, whether plant or animal.​

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Other Organelles

​There are many other membrane-bound organelles.

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These include: the endoplasmic reticulum, the Golgi apparatus, vacuoles, chloroplasts, and lysosomes.

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​Some of these organelles, like chloroplasts, are only found in plant cells.

Multiple Choice

What does it mean for an organelle to be membrane-bound?

• The organelle has its own membrane (like a little skin around it)

• The organelle has its own nucleus (like a little brain)

• The organelle is a cell all on its own

• The organelle is bigger than a cell

Multiple Choice

Which organelle produces energy for the cell?

• The nucleus

• The cell membrane

• The Golgi apparatus

• The mitochondria

Multiple Choice

Which organelle keeps the insides of the cell in and acts like the skin of the cell?

• The nucleus

• The cell membrane

• The Golgi apparatus

• The mitochondria

Multiple Choice

Which organelle is the control center of the cell, contains the DNA, and acts as the brain of the cell?

• The nucleus

• The cell membrane

• The Golgi apparatus

• The mitochondria

Plant cells vs Animal cells

​There are two types of eukaryotic cell: plant cells and animal cells.

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Both plant cells and animal cells have a nucleus, a cell membrane, ribosomes, and many of the same organelles.

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​For example, both plant and animal cells have mitochondria to produce energy.

Plant cells vs Animal cells

​However, there are important differences between plant and animal cells.

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​Plant cells have a cell wall outside of their cell membrane. This cell wall offers protection and support.

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​Plant cells also have a much larger central vacuole to store food and water.

Plant cells vs Animal cells

Perhaps the most important difference between plant and animal cells is how they get food.

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​Plant cells have organelles called chloroplasts. Chloroplasts produce food from sunlight and water in a process called photosynthesis.

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​Animal cells lack chloroplasts, so they cannot create their own food.

Chloroplast DNA

Recall that earlier we said mitochondria have their own DNA, completely separate from the cell's DNA.

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​Chloroplasts also have their own DNA!

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​The fact that mitochondria and chloroplasts have their own DNA has lead to . . .

Endosymbiotic Theory

According to endosymbiotic theory, mitochondria and chloroplasts were once independent, prokaryotic cells.

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​However, at some point they were absorbed by other cells. They continued living and reproducing inside those other cells.

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​That is why cells today have mitochondria and chloroplasts!

Multiple Choice

The two types of eukaryotic cells are:

• Plant and bacterial

• Plant and animal

• Prokaryotic and eukaryotic

• Animal and bacterial

Multiple Select

What kind of cells have mitochondria?

(There are two correct answers. Choose both correct answers.)

• Plant cells

• Animal cells

• Bacterial cells

• Prokaryotic cells

Multiple Select

What do plant cells have that animal cells do not have? 

(There are three correct answers. Choose all three.)

• Cell Walls

• Central Vacuole

• Mitochondria

• Chloroplasts

• Cell Membrane

Multiple Choice

What is the purpose of chloroplasts?

• To produce energy

• To contain the cell's DNA

• To produce food

• To store food and water

Multiple Choice

What is the purpose of a central vacuole?

• To produce energy

• To contain the cell's DNA

• To produce food

• To store food and water

Multiple Choice

What is the purpose of a cell wall?

• To protect and support the cell

• To contain the cell's DNA

• To produce food

• To store food and water

Multiple Select

Which two organelles have their own DNA?

• Mitochondria

• Vacuoles

• Chloroplasts

• Cell Wall

Multiple Choice

According to endosymbiotic theory, why do mitochondria and chloroplasts have their own DNA?

• They are independent prokaryotic cells

• They just do

• They were once independent prokaryotic cells

• They do not have their own DNA

Multiple Choice

According to endosymbiotic theory, how did cells come to have mitochondria and chloroplasts?

• They generated them spontaneously

• They produced them over time

• Larger cells absorbed them

• They just do