CELLSChapter 3

Organism

• an individual living thing EX. - kitten, corn plant, worm

There are 5 features all organisms (living things)

MUST have to be considered living things

list of the 5 features all organisms have in common

•1. Organisms are made of one or more cells. Cells are the smallest units of organisms that carry on the functions of life.

•2. Organisms use energy. • Organisms use energy every second of

every day through all phases of life. EX. movement

• 3. Organisms respond to changes in their environment. A response is a reaction to a stimulus. A stimulus is anything that causes an organism to respond.

Adaptation• Characteristic an organism has that

makes it better able to survive in its environment.

• Organism that are able to respond to changes around them often survive longer than those that are unable to.

Homeostasis

• The ability to maintain steady conditions no matter what is going on inside or outside the organism. EX. the human body’s temperature remains ~98.6ºF no matter what the external temperature (for a period of time)

4. Organisms Reproduce

• Most organisms produce offspring similar to themselves to ensure the survival of the species. Copies of nonliving things can be produced, but not by other nonliving things.

5. Organisms Grow & Develop

• Development - all changes that living things undergo. Changes occur throughout an organisms entire life.

• Lifespan - length of time an organism is expected to live.

Bacteria

• Bacteria is the smallest living organisms that satisfy all 5 criteria.

Viruses - NOT LIVING

• Viruses cannot reproduce on without a host cell - viruses cannot reproduce on their own. Thus, viruses are nonliving things.

Abiotic

non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems.

Biotic

Biotic describes a living or once living component of a community; for example organisms, such as plants and animals.

Bioticor Abiotic

TWO CELL TYPES

• There are two basic types of cells.

• PROKARYOTIC CELLS

• EUKARYOTIC CELLS

PROKARYOTIC CELLS

• PROKARYOTIC CELLS - are cells that have NO membranes around their nuclear materials.

• Prokaryotic cells - have no membrane bound organelles

• EXAMPLE - bacteria cells

• they have a very different reproductive system then eukaryotic cells have (not meiosis or mitosis)

• they generally feel slimy to the touch

Eukaryotic cells

• EUKARYOTIC CELLS are cells that have a nucleus with a membrane around it.

• EXAMPLE - animal and plant cells

• have membrane bound organelles

• reproduce by meiosis and mitosis

Cell Structures

• There are many structures and organelles inside a cell. We are going to study the following cell parts.

cell membrane endoplasmic reticulum (ER)

mitochondria

cytoplasm ribosomes lysosomes

nucleus Golgi bodies vacuoles

Cell Membrane

• Cell membrane is the structure that forms the outer boundary of the cell and allows only certain materials to move into and out of the cell.

• Double layer of fats & proteins (lipid bilayer)

Cell Membrane (cont’d)

• The cell membrane described as POROUS - it has tiny holes in it to allow the movement of materials into and out of the cell.

• Also described as SELECTIVELY PERMEABLE - Not all materials will move freely across this membrane.

• Selectively permeable - means it allows only certain materials in and out of the cell.

• Impermeable - means it allows nothing in (like a concrete wall around the cell)

• Permeable - means it would allow everything in - toxins, poisons, etc.

CYTOPLASM

• Cytoplasm is a gel-like material inside the cell membrane that fills most of the cell. It stores many of the cell’s building materials. (serves as a shock absorber for the cell parts)

• In eukaryotic cells organelles are found in the cytoplasm.

Organelles

• The term organelle comes from Latin meaning “small organ”.

• It is used to describe the structures inside the cell.

• Every organelle inside the cell has a unique function.

Nucleus• LARGEST ORGANELLE

• Responsible for directing all the activities of the cell.

• Contains the genetic blueprints for the operations of the cell in the form of chromatin.(3c on your paper)

Nucleus Ongoing• Contains the genetic blueprints for the

operations of the cell in the form of chromatin.(3c on your paper)

• Chromatin is made up of proteins and DNA (deoxyribonucleic acid). When a cell is ready to divide the chromatin thickens and is referred to as a chromosome.

• The chromosomes store instructions for all of the cell functions. Contains the cell’s DNA.

Nucleus Still• The nucleus is separated from the

cytoplasm by a NUCLEAR MEMBRANE. (3A on your picture)

• Nuclear membrane may also be referred to as a nuclear envelope.

• The nuclear membrane regulates the movement of materials into and out of the nucleus.

Nucleus cont’d

• The nucleus contains a structure called a nucleolus.

• The nucleolus (3 B on your sheet) makes parts for the ribosomes. The nucleolus makes sure the ribosomes are always working.

Endoplasmic Reticulum

• a folded membrane that moves materials around the cell.

• a network of canals that lead from the nuclear membrane to the cell membrane.

• Important in the transport and storage of substances.

there are 2 types of endoplasmic reticulum

• rough & smooth

• ROUGH - ribosomes are attached

• SMOOTH - no ribosomes are attached

Ribosomes• these are small structures in the cell that are

responsible for the manufacturing of proteins.

• Ribosomes make proteins.

• Proteins take part in nearly every cell activity. They are the building blocks of the cell.

• Ribosomes are found attached to the ER and scattered throughout the cytoplasm.

Golgi bodies

• Golgi bodies are packaging and secreting organelles of the cell. They move proteins to the outside of the cell.

Mitochondria• Mitochondria (mitochondrion plural) are

organelles where food molecules are broken down and energy is released. this structure is often called the “POWERHOUSE OF THE CELL”.

• all energy in the universe is stored in chemical bonds - the body breaks down the chemical bonds and releases energy - this happens in the mitochondria of the cell.

Lysosomes• known as “ the garbage disposal of the

cell” - it contains chemicals that digest wastes and worn-out cell parts.

• when a cell dies these lysosomes release chemicals that act quickly to break down the cell.

• In a healthy cell, the membrane around the lysosome keeps it from breaking down the cell itself.

Vacuoles

• clear storage structures in the cell

• They may store food, water, or waste products.

• In both plants and animals cells, a filled vacuole provides support.

How do plant and animal cells differ?

• Plant cells have two more parts - a cell wall and chloroplast.

Cell Wall - found only in plant cells

• A cell wall is a rigid structure outside the cell membrane that supports, protects, and give the plant cell its shape.

• Cellulose is the carbohydrate the cell wall is made of. (It is a nonliving structure.)

Plant cells contain chloroplast which contain chlorophyll

• Chloroplast are organelles in a plant cell that trap the sun’s energy.

• In the chloroplast light energy is changed into chemical energy in the form of a sugar called glucose. This process is called photosynthesis.

Remember Chlorophyll

• Chlorophyll is the green pigment found in the chloroplast - function is to trap the sun’s energy.

• It gives the plant it’s green color.

• Photosynthesis cannot take place without chlorophyll present.

Equation for Photosynthesis

• CO₂ + light energy + H₂0 ⇔ C₆H₁₂O₆ + O₂

• KNOW THIS EQUATION

DIFFERENCES AMONGST CELLS

• Shapes - cells come in different shapes

• Sizes - cells come in a variety of sizes

• Functions - cells differ in the jobs they perform

• Living arrangement - unicellular or multicellular

Single cell organism

• unicellular organism• EX: bacteria

Many Celled Organism

• Multicellular organism - in a many celled organism (multicellular organism) cells do not work alone, they depend on other cells to carry out its functions.

Cell Organization

• Cells organize themselves into tissues, tissues organize themselves into organs, and organs into organ systems, and organ systems organize themselves to form organisms.

What is a typical cell made of? •water (70%) - there are many water molecules in the cell’s cytoplasm.

•proteins (15%) - proteins are complex compounds made up of long chains of amino acids. There are 20 different amino acids that combine in different combinations to form various proteins. Proteins give each cell its distinctive characteristics.

•DNA (4%) - Deoxyribonucleic acid is found in the nucleus and it contains all of the instructions for building new cells.

•carbohydrates (1%) - These supply much of the cell’s energy. The smallest carbohydrates are sugars. sugar + sugar = starch

•fat (10%) - store extra energy for the cell There are 2 kinds of fats oil and wax.

Antonie van Leeuwenhoek

• mid 1600’s

• Dutch fabric merchant

• made first simple microscope

• found things in pond water that no one had ever seen

Robert Hooke

• discovered first cells (from cork plant)

• cork cells( little boxes - resembled jail cells)

• 1665 - he was an English scientist

Theodore Schwann

• concluded that all animals were made up of cells

Mathias Schleiden

• used a microscope to study plant parts. He determined plants were made up of cells.

Rudolph Virchow

• hypothesized that cells divided to form new cells

Theory

• A theory is basically accepted to be true - it has been repeatedly tested and has never been proven false.

Cell Theory

• developed by several scientist Rudolph Virchow, Theodore Schwann, Mathias Schleiden, along with Robert Hooke

• the importance of their work wasn’t realized until 200 years after they died.

• The above named scientist, along with others, provided evidence to develop the cell theory.

Parts of the Cell Theory• 1. All organisms are made of one or

more cells

• 2. The cell is the basic unit of organization in organisms.

• 3. All cells come from other cells.

• ***this is one of the most important theories in the study of science.

Microscope

• an important tool that aids scientists in their study of the cell.

• microscopes have one or more lenses that make an enlarged image of an object

Light Microscopes

• SIMPLE or COMPOUND depending on the number of lenses they have.

• SIMPLE - similar to a magnifying glass - only 1 lens

• COMPOUND - combination of two or more lenses which give you a larger image. Compound light microscope - lets light pass through an object and then through two or more lenses

brightfield/darkfield microscope

• another name for a light microscope

• It is called this because the image is viewed against a bright background.

Phase contrast microscope

• emphasizes slight differences in a specimen’s capacity to bend light waves, thereby enhancing light and dark regions w/o the use of stains

Scanning Electron Microscope

• sweeps a beam of electrons over a specimen’s surface, causing other electrons to be emitted from the specimen.

• Electron microscopes are used to view objects too small to be seen with a light microscope.

Atomic force microscope

• it has a diamond tipped probe that moves across the surface of a specimen

VIRUSES

• a strand of hereditary material surrounded by a protein coating.

• Viruses DO NOT have a nucleus or other organelles.

• Viruses lack a cell membrane.

• Viruses are too small to be seen by a light microscope.

• Viruses were only discovered after the invention of the electron microscope

VIRUSES

• attack all living cells

• cannot move by themselves

• can be carried by wind, ingested, or inhaled

• must attach to the host cell in an exact place in order to enter the host cell

Host Cell

• Viruses require a host cell in order to reproduce ( make a copy of itself)

• Once inside a host cell a virus can become ACTIVE or LATENT

An Active Virus

• enters the host cell and makes more copies of itself

• this destroys the host cell. EXAMPLE : cold, chicken pox

Latent Virus

• enters the host cell then the hereditary material can become part of the host cell’s hereditary material.

• a latent virus can become active at any time.

• EXAMPLE: of a latent virus becoming active - cold sore on your lip

Vaccines

• used to fight viruses

• made from weakened virus particles that are unable to cause disease anymore

• EXAMPLE: mumps, chicken pox, polio, rabies

Interferons• Proteins

made by the body to protect cells against viruses

Antibiotics

• Not helpful in getting rid of viruses.

• Antiviral drugs may be given to infected patients to help fight a virus.