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Cell Structure and Function
Discovering Cells
Looking Inside Cells
Chemical Compounds in Cells
The Cell in Its Environment
Table of Contents
Cell Structure and Function
What is a Cell?
*A cell is the basic
unit of life.
*All life activities
take place inside
cells.
Cell Structure and Function
Discovery of Cells
*Robert Hooke—first man to see cells (1663) -looked at thin slices of cork -saw empty boxes and called them cells -never realized that cells are living things
Cell Structure and Function
*Anton van Leeuwwenhoek
-father of microbiology
(1600’s)
-improved and developed
many types of microscopes
-discovered microscopic, one
celled organisms and called
them “animalcules”,
meaning “little animals”.
Cell Structure and Function
*Matthias Schleiden (1838)
-stated all plants are
made of cells
*Theodor Schwann (1839)
-stated all animals are
made of cells
Cell Structure and Function
*Rudolph Virchow (1855)
-stated all cells come
from other cells.
*The work of these men
led to the “Cell Theory”
Cell Structure and Function - Discovering Cells
The cell theory states:
1. All living things are
made of cells.
2. Cells are the basic units of
structure and function in
living things.
3. All cells come from other
cells.
Cell Structure and Function
SequencingConstruct a flowchart showing how the work of Hooke, Leeuwenhoek, Schleiden, Schwann, and Virchow contributed to scientific understanding of cells.
Discovering Cells
Hooke sees cells in cork.
Leeuwenhoek sees many one-celled organisms.
Schleiden concludes that all plants are made of cells.
Schwann concludes that all animals (and all living things) are made of cells.
Virchow proposes that new cells form only from cells that already exist.
- Discovering Cells
Cell Structure and Function
Links on Cell Theory
Click the SciLinks button for links on the cell theory.
- Discovering Cells
Cell Structure and Function
End of Section:Discovering
Cells
Cell Structure and Function
Eukaryotic vs. Prokaryotic
*All cells are either eukaryotic or prokaryotic.
-Eukaryotic cells —complex cells with a nucleus. All animal and plant cells are eukaryotic.
-Prokaryotic cells—simple cells without a nucleus. All bacteria and cyanobacteria (blue-green bacteria) are prokaryotic.
Cell Structure and Function
Structure of Animal CellsAnimal cells are typical eukaryotic cells.
Most contain the following structures:
*Cell Membrane
-Surrounds the cell
-Has pores
-Controls what gets
in and out
Cell Structure and Function - Looking Inside Cells
*Nucleus—control center of cell
-directs all of the cell’s activities
Nuclear Envelope
Nucleolus
Chromatin
Pores
Cell Structure and Function
*Cytoplasm—gel-like material inside the cell.
*Organelles—many tiny structures inside the cell. Each has its own job to do.
-Organelles include:
Cell Structure and Function
1.Mitochondria—“powerhouses” of the cell because they convert energy in food molecules to energy the cell can use to carry out its functions.
- Looking Inside Cells
Cell Structure and Function
2. Endoplasmic reticulum —folded tube
like membranes that move materials
throughout the cell.
3. Ribosomes—small protein factories
found on the “er” or in the cytoplasm
- Looking Inside Cells
Ribosomes
Endoplasmic reticulum
Cell Structure and Function
4. Golgi bodies —packaging centers that wrap up and package proteins and send them to other parts of the cell or out of the cell.
- Looking Inside Cells
Golgi Body
Cell Structure and Function
5. Lysosomes—garbage
collectors that contain
enzymes used to break down
large molecules and old cell
parts.
Cell Structure and Function
6. Vacuoles—sacs that store water, dissolved material or waste products. They are larger in plant cells than in animal cells.
Cell Structure and Function
Structure of Plant Cells
*Plant cells contain all the same structures and organelles as animal cells plus a few more.
Plant cells can do everything that animal cells can do plusmake food.
Cell Structure and Function
-Cell wall—a ridged structure outside the cell membrane made of cellulose. It supports and protects the plant cell.
-Chloroplasts—tiny disks that contain chlorophyll. Photosynthesis takes place here.
-Larger Vacuoles—to store water
Cell Structure and Function
Plant and Animal Cells
- Looking Inside Cells
Cell Structure and Function
Cell Variety
*Cells differ in size, shape, and
function. They will not all look like the
diagrams.
Cell Structure and Function
*Examples:
-Nerve cell—0ne meter long with many extensions: carries impulses to the brain.
-Red Blood Cell—microscopic, round and flexible: carries oxygen throughout the body.
Cell Structure and Function
Structure of Bacteria Cells*Bacteria cells have no nucleus and no
membrane-bound organelles. -They are prokaryotic. -Their parts include:
Capsule Cell wall Cell membrane Cytoplasm DNA floating in cytoplasm Ribosomes
Some have flagella
Cell Structure and Function
Diagram of a Bacteria Cell
Cytoplasm
DNA
Capsule
Cell wallCell Membrane
Ribosomes
Flagella
Cell Structure and Function
Plant and Animal Cells Activity
Click the Active Art button to open a browser window and access Active Art about plant and animal cells.
- Looking Inside Cells
Cell Structure and Function
Before you read, preview Figure 12. Then write two questions you have about the illustrations in a graphic organizer like the one below. As you read, answer your questions.
Q. How are animal cells different from plant cells?
A. Plants cells have a cell wall and chloroplasts, which animal cells to not have.
Q. What do mitochondria do?
A. Mitochondria convert energy in food molecules to energy the cell can use.
Plant and Animal Cells
- Looking Inside Cells
Previewing Visuals
Cell Structure and Function
The Cytoplasm and Organelles
Click the Video button to watch a movie about cytoplasm and organelles.
- Looking Inside Cells
Cell Structure and Function
Specialized Cells
Click the Video button to watch a movie about specialized cells.
- Looking Inside Cells
Cell Structure and Function
End of Section:Looking Inside
Cells
Cell Structure and Function
What are Cells Made Of?
*Cell Chemistry begins with atoms:
-Atom—basic units of matter
-Elements—any substance that
cannot be broken down into
simpler substances (made of
only one type of atom)
Cell Structure and Function
-All known elements are listed on
the Periodic Table of the Elements
Cell Structure and Function
-The elements found in living cells
include mostly carbon, hydrogen,
nitrogen, oxygen, phosphorus
and sulfur: (CHNOPS)
Cell Structure and Function
Molecules and Compounds *Atoms combine to form molecules.
-Molecules—two or more atoms bonded together (different or
same) Ex: H2O O2 NaCl -Special molecules made of different elements only are called
compounds Ex: H2O CO2
Cell Structure and Function - Chemical Compounds in Cells
Carbon dioxide, which is found in gas bubbles, is a chemical compound. So is water.
Cell Structure and Function
-When just the right molecules and
compounds get together in just
the right way, cells are formed.
-Compounds in living organisms
are classified as either organic or
inorganic.
Cell Structure and Function
*Organic compounds contain the
elements; carbon and hydrogen.
*They make up foods and cell membranes.
*Four basic groups:
Cell Structure and Function
1.Carbohydrates—make up 1% of a cell; contain carbon, hydrogen, and oxygen; used for energy; examples are sugars and starches; most important carbohydrate for living things is glucose.
Cell Structure and Function
2. Lipids—make up 10% of a cell;
contain carbon, hydrogen and
oxygen; store and release
energy; found in cell membranes;
examples are fats, oils and waxes.
Cell Structure and Function
3. Proteins—make up 15% of a cell;
made of amino acids that contain
carbon, hydrogen, oxygen and
nitrogen; used to build cell parts
and for growth and repair of cell;
examples are enzymes.
Cell Structure and Function
4. Nucleic Acids—make up 4% of a cell; contain carbon, hydrogen, oxygen, nitrogen, and phosphorus; carry genetic information; found in chromosomes, mitochondria, chloroplasts, and nucleus; examples are DNA and RNA
Cell Structure and Function
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.
- Chemical Compounds in Cells
Cell Structure and Function
Compounds in Bacteria and Mammals
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?
- Chemical Compounds in Cells
Cell Structure and Function
Compounds in Bacteria and Mammals
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?
- Chemical Compounds in Cells
Cell Structure and Function
Compounds in Bacteria and Mammals
Proteins
Interpreting Data:
Which kind of compound–proteins or nucleic acids–makes up the larger percentage of a mammalian cell?
- Chemical Compounds in Cells
Cell Structure and Function
Compounds in Bacteria and Mammals
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.
Drawing Conclusions:
In general, how do a bacterial cell and mammalian cell compare in their chemical composition?
- Chemical Compounds in Cells
Cell Structure and Function - Chemical Compounds in Cells
*Most inorganic compounds are made from elements other than carbon. Example: Water
-water makes up two-thirds of your body
-70% of a cell’s cytoplasm is water -many substances must be dissolved in water in order to be used by cells.
Cell Structure and Function
Type of Compound
Elements Functions
As you read, compare and contrast carbohydrates, proteins, and lipids in a table like the one below.
Carbohydrate Carbon, hydrogen, oxygen
Store and provide energy and make up cellular
parts
Protein Carbon, hydrogen, oxygen, nitrogen, and
sometimes sulfur
Make up much of the structure of cells and speed up chemical
reactions
Lipid Carbon, hydrogen, oxygen
Store energy
- Chemical Compounds in Cells
Comparing and Contrasting
Cell Structure and Function
Links on Proteins
Click the SciLinks button for links on proteins.
- Chemical Compounds in Cells
Cell Structure and Function
End of Section:Chemical
Compounds in Cells
Cell Structure and Function
Cell Transport
*The cell membrane controls what gets in and out of the cell. This is called Cell Transport.
-Substances pass through pores.-The membrane is selectively-permeable (meaning only molecules of a certain size can get through).
Cell Structure and Function - 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.
Cell Structure and Function
Types of Transport
*Passive Transport —cell uses
no energy to move materials into or out
of the cell.
-Two types of Passive Transport:
1. Diffusion
2. Osmosis
Cell Structure and Function
*Diffusion is a type of passive transport in which molecules move from high to low concentration.
-Oxygen and carbon dioxide move
into a cell by diffusion.
-Molecules move through tiny pores in
the cell membrane.
-Diffusion requires no energy from the
cell.
Cell Structure and Function
Cell Structure and Function
Diffusion
In diffusion, molecules move from an area of higher concentration to an area of lower concentration.
- The Cell in Its Environment
Cell Structure and Function
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
- The Cell in Its Environment
Cell Structure and Function
*Osmosis is a type of passive
transport in which water moves
from high to low concentration.
-Plants get water into their roots
by osmosis.
-Osmosis also requires no energy
from the cell.
Cell Structure and Function
Cell Structure and Function
Osmosis
In osmosis, water diffuses through a selectively permeable membrane.
- The Cell in Its Environment
Cell Structure and Function
Equilibrium
*Both diffusion and osmosis will continue until the cell reaches a point where the concentrations are equal both inside and outside the cell. This is called equilibrium.
Cell Structure and Function
*Active Transport —cell must
use energy to move substances
in or out.
-Cell will move things from low to
high concentration.
-Transport proteins are needed.
Cell Structure and Function
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
Cell Structure and Function
Endocytosis—process used by cells to move very large substances into the cell.
Cell Structure and Function
Exocytosis —process used by cells to move very large substances out of the cell.
Cell Structure and Function
Cell Structure and Function
Building VocabularyA definition states the meaning of a word or phrase. After you read the section, reread the paragraphs that contain definitions of Key Terms. Use all the information you have learned to write a definition of each Key Term in your own words.
Key Terms: Examples:
- The Cell in Its Environment
selectively permeable The cell membrane is selectively permeable, which means that some substances can pass through the membrane while others cannot.
diffusion Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration.
osmosis Osmosis is the diffusion of water molecules through a selectively permeable membrane.
Key Terms: Examples:passive transport
active transport
The movement of dissolved materials through a cell membrane without using cellular energy is called passive transport.
Active transport is the movement of materials through a cell membrane using cellular energy.
Cell Structure and Function
More on Cellular Transport
Click the PHSchool.com button for an activityabout cellular transport.
- The Cell in Its Environment
Cell Structure and Function
End of Section:The Cell in Its Environment
Cell Structure and Function
types
typesmade ofincludeinclude
Graphic OrganizerOrganic
Compounds
Carbo-hydratesLipids Proteins
StarchesAmino acids
SugarsFats, oils, and waxes DNA
Nucleic acids
RNA
Cell Structure and Function
End of Section:Graphic Organizer
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