chapter 3 cell structure and function section 1: discovering cells what are cells? how did the...
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Chapter 3 Cell Structure and Function
Section 1: Discovering Cells
What are cells?How did the invention of the microscope contribute to knowledge about living things?What is the cell theory?How are the cells of multicellular organisms organized?
Chapter 3 Cell Structure and Function
What Are Cells?
All living things are made up of cells.
Cells have many similarities between different species.
• Example: Mitochondria can be found in the cells of humans, dogs, spiders, trees, etc.
Cells are the basic unit of structure and function in all living things.
Chapter 3 Cell Structure and Function
Cell Structure
Cells form parts of your organs.
It gives your body its’ shape, size, strength.
Chapter 3 Cell Structure and Function
Cell Function
Cells perform all of an organism’s tasks and functions.
» obtain oxygen and food
» get rid of wastes
» allow you to grow and repair.
Chapter 3 Cell Structure and Function
Cell SizeMost cells are so small they are microscopic.
• Microscopic: can only be seen by the human eye with the help of a microscope.• Approximately 100,000 skin cells fit in a square centimeter.• Approximately 250 million red blood cells are found in a drop of blood.
Chapter 3 Cell Structure and Function
Development of the Cell Theory
The cell theory states the following:
• All living things are composed of cells.• Cells are the basic units of structure and function in living things.• All cells are produced from other cells.
Chapter 3 Cell Structure and Function
Unicellular vs. Multicellular
Unicellular, or single-celled, organisms include bacteria, the most numerous organisms on Earth.
Multicellular organisms, like this dog, are composed of many cells.
Unicellular
Multicellular
Chapter 3 Cell Structure and Function
Advantages of Being Multicellular
In multicellular organisms, cells are often organized into tissues, organs, and organ systems.
This allows our cells to perform specialized and unique tasks.
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End of Section: Discovering Cells
Chapter 3 Cell Structure and Function
What role do the cell wall and cell membrane play in the cell?What is the role of the nucleus in the cell?What organelles are found in the cytoplasm and what are their functions?How do cells differ?
Section 2: Looking Inside Cells
Chapter 3 Cell Structure and Function
Organelles (and other Cell Structures)
Organelle: a tiny structure that has a specific function inside the cell,
floating in the cytoplasm
Found in BothPlant and Animal Cells
Found Only inPlant Cells
Found Only inAnimal Cells
nucleus cell wall lysosomes
cell membrane chloroplasts vacuoles
(several small)
cytoplasm vacuole (one large)
endoplasmic reticulum
ribosomes
Golgi body
mitochondria
Chapter 3 Cell Structure and Function
Plant and Animal Cells
Chapter 3 Cell Structure and Function
Cell Membrane
What is it?
The “skin” of the cell, helping form a boundary that separates the inside of the cell from the outside.
Why does the cell need it?
To control what substances are allowed to enter or leave the cell.
Where can it be found?
In both plant and animal cells.
NOT an
organelle
Chapter 3 Cell Structure and Function
Cell Wall
What is it?
A rigid layer of cellulose that surrounds the cell membrane. Although it is very strong, it still allows materials like water and oxygen to pass through.
Why does the cell need it?
It helps to protect and support the cell.
Where can it be found?
In plant cells only.
NOT an
organelle
Chapter 3 Cell Structure and Function
Nucleus
What is it?
The “control center” of the cell. It contains thin strands of DNA called chromatin that direct all of the cell’s activities.
Why does the cell need it?
The cell would not know how to function without the nucleus.
Where can it be found?
In both plant and animal cells.
Chapter 3 Cell Structure and Function
Cytoplasm
What is it?The area between the cell membrane and the nucleus. Contains a gel-like fluid that is constantly moving inside the cell.
Why does the cell need it?Allows organelles to move around the inside of the cell. Also, the fluid helps regulate the cell’s temperature and pH level.
Where can it be found?In plant and animal cells.
NOT an
organelle
Chapter 3 Cell Structure and Function
MitochondriaWhat is it?The “powerhouses” of the cell because they convert food molecules to energy the cell can use to carry out its functions (also called “cellular respiration”).
Why does the cell need it?Without it, cells wouldn’t have the energy to function.
Where can it be found?In both plant and animal cells.
Chapter 3 Cell Structure and Function
Endoplasmic Reticulum (E.R.)
Where can it be found?In plant and animal cells.
What is it?Moves materials throughout thecell. When covered with ribosomes,it is called “Rough E.R.”. Without ribosomes, it is called “Smooth E.R.”.
Why does the cell need it?Ribosomes help make proteins, hormones, and other materials.The E.R. helps move thesematerials to specific placesafter they have been made.
Chapter 3 Cell Structure and Function
RibosomesWhat is it?Tiny “protein factories” that are found floating in the cytoplasm or attached to the E.R.
Why does the cell need it?Ribosomes read the message encoded in the cell’s DNA and translate these codes into proteins, hormones, and other structures. Without ribosomes, the DNA would be useless.
Where can it be found?In both plant and animal cells.
Middle School Version
Medical School Version
Chapter 3 Cell Structure and Function
Golgi bodiesWhat is it?The “post office” of the cell. The Golgi bodies receive proteins and other newly formed materials from the E.R., package them, and distribute them to other parts of the cell.
Why does the cell need it?Without it, many proteins would be incomplete or lost.
Where can it be found?In both plant and animal cells.
Chapter 3 Cell Structure and Function
ChloroplastWhat is it?Green organelles that capture sunlight and convert it into sugar, which is used as a food source.
Why does the cell need it?Without it, plants would not have a food source. Also, animals depend on plants for food, either because they eat plants, or they eat other animals (which eat plants).
Where can it be found?In plant cells only.
Chapter 3 Cell Structure and Function
VacuoleWhat is it?Storage area of the cell. Mostly stores water, but sometimes stores food and waste.
Why does the cell need it?Allows the cell to store materials. In plants, the vacuole gives the cell internal pressure (like air inflating a balloon).
Where can it be found?In animal cells, there are several tiny vacuoles. In plant cells, there is only 1 large vacuole (called “the central vacuole”).
Animal Cell
Plant Cell
Chapter 3 Cell Structure and Function
Lysosomes
What is it?
The “clean-up crew” of the cell. Contains chemicals called enzymes that break down large food particles, trash, and even old organelles.
Why does the cell need it?
Without it, the cell would become cluttered with food particles that are too big for the mitochondria, toxic trash, and dead organelles.
Where can it be found?In animal cells only.
Chapter 3 Cell Structure and Function
End of Section: Looking Inside Cells
Chapter 3 Cell Structure and Function
What are elements and compounds?How is water important to the function of cells?What are the functions of carbohydrates, lipids, proteins, and nucleic acids?
Section 3: Chemical Compounds in Cells
Chapter 3 Cell Structure and Function
Elements
An element is any substance that cannot be broken down into simpler substances.
Examples include carbon (C), nitrogen (N), hydrogen (H), and oxygen (O).
Chapter 3 Cell Structure and Function
CompoundsCarbon dioxide, which is found in gas bubbles, is a chemical compound made up of 1 carbon and 2 oxygen atoms. So is water (2 hydrogen and 1 oxygen).
Chapter 3 Cell Structure and Function
Organic and Inorganic Molecules
Inorganic Molecules: do not contain carbon (C); water (H20) and “breathable” oxygen (O2) are important inorganic molecules needed by living organisms.
Organic Molecules: contain carbon; includes carbohydrates, lipids, proteins, and nucleic acids.
Chapter 3 Cell Structure and Function
Carbohydrates
Provides quick energy for the cell.
Plants make “carbs” in the form of sugars and starches.
The cellulose in a plant cell wall is a type of “carb”.
Chapter 3 Cell Structure and Function
Lipids
Provides slow-burning energy for the cell.
Cells can store lipids to save energy for future use.
Makes up most of the cell membrane.
Found in fats, oils, and waxes.
Chapter 3 Cell Structure and Function
Proteins
Provides structures (like
muscles) and chemicals (like hormones and enzymes) for
your body.
Found in meat, eggs, fish,
nuts, and beans.
Proteins are actually made up of tiny molecules called amino acids.
Chapter 3 Cell Structure and Function
Nucleic Acids
Contains the instructions that cells need to do their job and stay “alive”.
2 types of nucleic acids:
• DNA (instructions that can be passed on from parent to child)
• RNA (help make proteins).
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End of Section: Chemical
Compounds in Cells
Chapter 3 Cell Structure and Function
How do most small molecules cross the cell membrane?Why is osmosis important to cells?What is the difference between passive and active transport?
Section 4: The Cell in Its Environment
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A Selective Barrier
The cell membrane protects the contents of the cell and helps control the materials that enter and leave.
Chapter 3 Cell Structure and Function
Diffusion
In diffusion, molecules move from an area of HIGHER concentration to an area of LOWER concentration.
Chapter 3 Cell Structure and Function
Osmosis
In osmosis, water diffuses through the cell membrane using the power of diffusion.
Chapter 3 Cell Structure and Function
Osmosis
The picture in the middle shows blood with equal amounts of salt inside and outside the cell. As a result, water moves evenly inside and outside.
Chapter 3 Cell Structure and Function
Osmosis
The picture on the left shows blood surrounded by excessive salt. Water is attracted to this, so it leaves the cell and the cell shrivels like a raisin.
Chapter 3 Cell Structure and Function
Osmosis
The picture on the right shows a cell that is filled with salt. Water is attracted to this, so the cell swells up with water.
Chapter 3 Cell Structure and Function
Passive and Active Transport
Passive and active transport are two methods that allow materials (like food and waste) to pass through the cell membrane.
Active transport requires the cell to use its own energy, while passive transport does not.
Chapter 3 Cell Structure and Function
End of Section: The Cell in Its Environment