chapter 3 cell structure and function chapter preview 3.1 discovering cells 3.2 looking inside cells...

Chapter 3 Cell Structure and Function

Chapter Preview

3.1 Discovering Cells

3.2 Looking Inside Cells

3.3 Chemical Compounds in Cells

3.4 The Cell In Its Environment

Table of Contents


Chapter Preview Questions

1. In a microscope, an image is focused by

a. the eyepiece lens and the mirror.

b. the objective lens and the mirror.

c. the eyepiece lens and the objective lens.

d. the objective lens and a concave lens.



2. An electron microscope uses a beam of electrons

instead of

a. slides.

b. lenses.

c. mirrors.

d. light.



3. Cells break down carbohydrates to get ____ for life processes.

a. energy

b. food

c. oxygen.

d. carbon dioxide



3. Cells break down carbohydrates to get ____ for life processes.

a. energy

b. food

c. oxygen

d. carbon dioxide



4. Cells in green plants make

a. food and carbon dioxide.

b. water and carbon dioxide.

c. food and oxygen.

d. water and carbon dioxide.


You hear that a pinch of soil may contain millions of organisms.

What optical tools would you use to see these organisms and to study their structure?

What is the structure of a cell?


Prefix Meaning Example Word

chlor- green chloroplast A cellular structure that captures energy from sunlight

Prefixes


Prefixes


cyto- cell cytoskeletonThe framework inside a cell



multi- many multicellularHaving many cells

Prefixes



uni- one unicellularHaving one cell

Prefixes


Apply It!

1. A chloroplast is a structure in plant cells. What color do you think achloroplast is?

green

2. What clue within the word cytoplasm lets you know that the word hassomething to do with cells?

the prefix cyto-


End of Chapter Preview


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?


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.


An Overview of CellsKey concept: Cells are the basic units of structure and

function in living things.Examples of function: obtaining oxygen, getting rid of waste,

obtaining food, growing, and more…Cells function similarly in all organisms, they carry out the

basic processes of life in similar ways.Cells are so small they are measured in micrometers

The invention of the microscopeMade it possible to discover and Learn about cells


Unicellular and Multicellular

Unicellular, or single-celled, organisms include bacteria, the most numerous organisms on Earth. Multicellular organisms are composed of many cells.

Unicellular

Multicellular


Multicellular Organisms

Categorized into:

1) Tissues

- Similar cells that work together for specific function

2) Organs

- Made of different tissues that work together

- Ie. Brain

3) Organ Systems

-A group of organs that work together to perform a major function

-Ie. Cells, tissues, and organs


First Observations of Cells

1590ish invention of the microscopeKey concept: The invention of the

microscope made it possible for people to discover and learn about cells.

Robert Hooke•one of first people to observe cells•built his own microscope- one of the best of his time•observed cork which looked like small rectangular rooms they called cells


First Observations of Cells

Anton van LeeuwenhookDutch businessman

Built simple microscopes in his spare time

Looked at drops of lake water, scrapings from teeth and gums, water from rain gutters

Animalcules- means “little animals,” small organisms that moved that he found in things like lake water


Development of the Cell Theory

Schleiden- all plants are made of cellsSchwann- all animals are made of cellsVirchow- new cells are formed only from

cells that already exist


Cell Theory

An explanation of the relationship between cells and living things

i. All living things are made of cells.

ii. Cells are the basic units of structure and function

iii. All cells are produced from other cells


Unicellular and Multicellular

Unicellular- single celledMulticellular- many cellsKey concept: “In multicellular

organisms, cells are often organized into tissues, organs, and organ systems.

Tissue- a group of singular cells that work together

Organs- is made up of different kinds of tissue

Organ system- a group of organs wanted to what those


Links on Cell Theory

Click the SciLinks button for links on the cell theory.


End of Section: Discovering Cells


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


Plant and Animal Cells


Cell Wall

The cell wall is a rigid layer of nonliving material that surrounds the cells of plants & some other organisms.A plant’s cell wall helps to protect & support the cell.The cell wall is made of a strong, flexible material called cellulose, & many materials can pass through it.


Plant and Animal Cells Activity

Click the Active Art button to open a browser window and access Active Art about plant and animal cells.


Cell MembraneIn cells that do not have cell walls, the cell membrane is the outside boundary that separates the cell from its environment. (Barrier-like a window Screen)All cells have cell membranes.In cells with cell walls, the cell membrane is located just inside the cell wall. The cell membrane controls what substances come into & out of a cell. (ie. Food & oxygen)*In plant cells and animal cells


Nucleus

The nucleus is the cell’s control center, directing all of the cell’s activities.


Nuclear Envelope

The nucleus is surrounded by a protective membrane called the nuclear envelope.

Materials pass in & out of the nucleus through small openings, or pores, in the nuclear envelope.


Chromatin

Directs the Nucleus

Strands that contain the genetic material, the instructions for directing the the cell’s functions.


Cytoplasm

The cytoplasm is the region between the cell membrane & the nucleus.

Many cell organelles are found in the cytoplasm.


Mitochondrion

Mitochondria are known as the “powerhouses” of the cell because they convert energy in food molecules to energy the cell can use to carry out its functions.


Endoplasmic ReticulumThe endoplasmic reticulum is similar to the system of hallways in a building. Proteins and other materials move throughout the cell by way of the endoplasmic reticulum. The spots on this organelle are ribosomes, which produce proteins.


Endoplasmic Reticulum

Passageways called the endoplasmic reticulum carry proteins & other materials from one part of the cell to another.


Ribosomes

Small, grainlike bodies called ribosomes function as factories to produce proteins.

In plant and animal cells.


Golgi BodyThe Golgi bodies receive proteins and other newly formed materials from the endoplasmic reticulum, package them, and distribute them to other parts of the cell.


Chloroplasts

The Golgi Bodies release materials outside the cell.

In plants, & some other organisms, large, green structures called chloroplasts capture energy from sunlight & use it to produce food for the cell.


Vacuoles

Large water-filled sacs called vacuoles are the storage areas of cells.

A vacuole stores food & other materials needed by the cell.


Lysosomes

Small, round structures called lysosomes contain chemicals that break down certain materials in the cell.


Organelles

Inside a cell are tiny structures called organelles, which carry out specific functions within the cell.The nucleus is a large, oval structure that acts as the “brain” of the cell.You can think of the nucleus as the cell’s control center, directing all of the cell’s activities.


The Cytoplasm and Organelles

Click the Video button to watch a movie about cytoplasm and organelles.


Bacterial Cells

Bacterial cells are smaller & different from plant & animal cells.

While a bacterial cell does have a cell wall & a cell membrane, it does not contain a nucleus.

The bacterial cell’s genetic material, which looks like thick, tangles string, is found in the cytoplasm.

Bacterial cells contain ribosomes, but none of the other organelles found in plant & animal cells


Cell DiversityThe Variety is cell structure in cells reflects differences in cell

function.

A cells structure is complementary to it’s function

Example- Red blood cell shape to fit through tiny vessels


End of Section: Looking Inside Cells


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


An element is a pure substance where all the atoms in a sample of matter have the same identity, and cannot be broken down into simpler substances. For example all of the elements in the periodic table.

Compounds are made from atoms of two or more elements that are combined chemically. Smallest unit of a compound is a molecule.


Elements and CompoundsCarbon dioxide, which is found in gas bubbles, is a chemical compound. So is water.


Most chemical reactions that take place within cells could not take place without water.

Many compounds in living things contain the element carbon, Compounds that do not contain carbon are called inorganic compounds. Water

and sodium chloride are familiar examples of inorganic compounds.

Has to have Carbon to be organic


Compounds in Bacteria and Mammals

All cells contain carbohydrates, lipids, proteins, and nucleic acids, as well as water and other inorganic compounds. But do all cells contain the same percentages of these compounds? The graph compares the percentage of some compounds found in a bacterial cell and a cell from a mammal.



Red bars represent percentages of compounds in bacterial cells; blue bars represent percentages of compounds in mammalian cells.

Reading Graphs:

What do the red bars represent? What do the blue bars represent?



About 70%; the percentages are the same.

Interpreting Data:

What percentage of a mammalian cell is made up of water? How does this compare to the percentage of water in a bacterial cell?



Proteins

Interpreting Data:

Which kind of compound–proteins or nucleic acids–makes up the larger percentage of a mammalian cell?


Compounds in Bacteria and MammalsDrawing Conclusions:

In general, how do a bacterial cell and mammalian cell compare in their chemical composition?

They are similar, though mammalian cells have a lower percentage of nucleic acids, and bacterial cells have a lower percentage of lipids and fewer proteins.


Carbohydrates, Lipids & Energy

Carbohydrate- energy-rich organic compound made up of carbon, hydrogen, and oxygen.

-Provide energy for the cell

- components for cell parts (cellulose-plants)

Lipids- energy-rich organic compounds made up of carbon, hydrogen, and oxygen

- Provide energy to the cells

- make up most of the cell membrane


Proteins

Proteins- Large organic molecules made up of carbon, hydrogen, oxygen, nitrogen, and, in some cases, sulfur.

Foods- Meat, eggs, fish, nuts, beans

Made up of amino acids (20 but many due to combinations)

Enzyme- A type of protein that speeds up a chemical reaction in living things.


Links on Proteins

Click the SciLinks button for links on proteins.


Nucleic Acids

Very long organic molecules made up of carbon, oxygen, hydrogen, nitrogen, and phosphorus.

Contain the instructions that cells need to carry out all functions of life.

Types:

DNA- genetic material that carries info. About an organism and is passed from parent to offspring

- Found in chromatin in the nucleus

RNA- role in production of proteins

- Found in the cytoplasm as well as the nucleus


End of Section: Chemical

Compounds in Cells


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


A Selective Barrier

The cell membrane protects the contents of the cell and helps control the materials that enter and leave.


The Cell in its Environment

1. Selective Permeability – This means that some substances are allowed into a cell and others are not. Permeable means to “pass through”.


Diffusion

In diffusion, molecules move from an area of higher concentration to an area of lower concentration.


Ratios The concentration of a solution can be expressed as a ratio. A ratio compares two numbers. It tells you how much you have of one item in comparison to another. For example, suppose you dissolve 5 g of sugar in 1 L of water. You can express the concentration of the solution in ratio form as5 g:1 L, or 5 g/L.

Practice Problem

Suppose you dissolve 7 g of salt in 1 L of water. Express the concentration of the solution as a ratio.

7 g:1 L or 7 g/L


Osmosis

In osmosis, water diffuses through a selectively permeable membrane. (Movement of water by diffusion)


Passive and Active TransportPassive and active transport are two processes by which materials pass through the cell membrane. Active transport requires the cell to use its own energy, while passive transport does not.


The Cell in its Environment

2. Two ways substances move in and out of cells – Passive and Active Transport


The Cell in its Environment3. Passive Transport – Movement of material through a cell membrane

where energy is not required

a. Diffusion – the movement of molecules from an area of higher concentration to an area of lower concentration. Example: pond water organisms survive because oxygen in the pond water is at higher levels than inside the organism


More on Cellular Transport

Click the PHSchool.com button for an activityabout cellular transport.


End of Section: The Cell in Its Environment


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chapter 3 cell structure and function chapter preview 3.1 discovering cells 3.2 looking inside cells...

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