The CELL

• Cells Were discovered by Robert Hooke. He observed the slices of cork from the bark of an oak tree-dead plant cells.

• Anton Van Leeuwenhoek was the first person to observe living cells.

• Observations and conclusions of scientists from the late 17th century to the time of scientists, Schwann, Schleiden, and Virchow, are summarized into the Cell Theory.

Three parts of the cell theory:1. All living things are made of one or more cells.2. The cell is the basic unit of structure

and function in organisms.3. All cells come from pre-existing cells.

= Life

1. There are two cell types:1.) Prokaryote-the simplest cells

* Small, simple and lack membrane-bound organelles. *They have no nucleus. *DNA is found floating in the cytoplasm.

Prokaryotic cells contain:*cell wall*cell or plasma membrane*cytoplasm*ribosomes

Example:* BACTERIA is the only example!* Many bacteria have flagella, which are long, threadlike structures

that protrude from the cell’s surface and enable movement.* A bacterium’s flagella rotates, propelling a bacterium through its environment.* Pili- Many species of bacteria have pili (singular, pilus). Pili are small

hair-like projections that emerge from the cell. These outgrowths assist the bacteria in attaching to other cells and surfaces, such as teeth, intestines, and rocks. Without pili, many disease-

causing bacteria lose their ability to infect because they're unable to attach to host tissue.

State Test Question

In prokaryotic cells, the DNA is found—

A.floating in the cytoplasm.

B.attached to the ribosomes.

C.surrounded by the nuclear membrane.

D.contained in the vacuole.

State Test Question

• Which of the following are prokaryotes?

A.Protists

B.Plants

C.Fungi

D.Bacteria

2. Eukaryote

*Large, complex and contain membrane bound organelles such as a nucleus.

* Example: Plants, Fungi, and Animals

* Eukaryotic cells have a nucleus which is an internal compartment that houses the cell’s DNA. Other internal compartments, called organelles, enable eukaryotic cells to function in ways different from bacteria.

* An organelle is a structure that carries out specific activities in the cell.

– Many single-celled eukaryotes use flagella for movement. Short hair like structures packed in tight rows, called cilia, protrude from the surface of some eukaryotic cells. Flagella or cilia propel some cells through their environment.

– In other cells, cilia and flagella move substances across the cell’s surface.

» Example: Cilia on cells found in the human respiratory system sweep mucus and other debris out of the lungs.

State Test Question

• What type of cell is pictured below?

A.Prokaryote

B.Eukaryote

C.Plant

D.Animal

State Test Question

• Which of these types of cell has a nuclear membrane?

A. Spirillum

B. Coccus

C. Liver

D. Bacillus

State Test Question

• Coded information for heredity and protein production is contained in DNA found in the eukaryotic cell structure called the—

A. nucleus.

B. plasma membrane.

C. endoplasmic reticulum

D. Golgi apparatus.

CiliaFlagella

State Test Question

• What structure could a cellular organism use to move through its environment?

A.Flagellum

B.Cell wall

C.Mitochondrion

D.Lysosome

Cell Size and Shape:

• The symbol “” stands for the prefix micro.

• A micrometer (m) is a unit of linear measurement equal to one-millionth of a meter, or one-thousandth of a millimeter.

• Cell size and organelle size is measured in micrometers (m). This means that they are microscopic.

• Most cells are cubical or spherical. A cell’s shape can determine its function or job.

Both Animal and Plant Cells Contain These Organelles:

1. Cell Membrane– The cell membrane is primarily composed of

phospholipids. – Various proteins are located in the lipid bilayer of a cell

membrane. • Small protein molecules found on the cell membrane called

glycoproteins act as receptors to “recognize self” – bringing other cells/proteins together for structure & support.

– A phospholipid is a lipid made of a phosphate group (head) and two fatty acids (tails).

• A phospholipid “head” is polar, and its two fatty acid “tails” are nonpolar.

– Transport proteins aid in the movement of substances into and out of the cell.

– It surrounds and protects the cell, while only allowing certain substances to pass in and out of the cell.

– The cell membrane allows the cell to remain separate from the environment.

State Test Question

Which of the following is usually measured in micrometers?

A. Specimen mass

B. Organelle length

C. Tree height

D. Sound intensity

Both Animal and Plant Cells Contain these Organelles:

• Cell Membrane Cont.– It is a Selectively permeable membrane, which means it

keeps out some molecules, but allows others to pass through.

– The cell membrane regulates or controls what comes into and out of the cell, like gases, nutrients and wastes.

• Small molecules like H2O, CO2,O2 and soluble end products of digestion pass through easily.

• Large molecules like glucose and ions do not pass through easily. Larger molecules need help getting across the membrane by aid of the transport proteins.

– This control keeps the cell alive and well. If it wasn’t selectively permeable everything on the outside would come into the inside.

State Test Question

The unique properties of a cell membrane arise from the arrangement of two layers of organic molecules called—

A.cellulose.

B.nitrates.

C.nucleic acids.

D.phospholipids.

State Test Question

• The part of a eukaryotic cell that allows it to remain separate from the outside environment is the—

A. cell membrane.

B. ribosome.

C. cytoplasm.

D. golgi vesicles

Both Animal and Plant Cells Contain These Organelles

• 2. Cytoplasm– A fluid-like material that fills the space

between the cell membrane and the nucleus.– Contains the organelles

• **The cytoskeleton (in the cytoplasm) is a web of protein fibers that holds the cell together and keeps the cell membrane from collapsing or folding.

State Test Question

• Animal cells maintain their shape by having—

A. cytoskeletons.

B. cell walls.

C. cytoplasm.

D. chromosomes.

State Test Question

• Which of the following structures would you expect to find when examining a bacteria cell?

• A cellulose cell wall

• Chromosomes within a nucleus

• A phospholipids cell membrane

• Cytoplasmic organelles

Both Animal and Plant Cells Contain These Organelles

• 3. Nucleus– The control center of “brain” of the cell (Most functions of a

eukaryotic cell are controlled b the cell’s nucleus).– The nucleus directs cell activities and stores DNA.– Stores DNA which forms long strands called chromatin.

(Chromatin is made of DNA and proteins that become chromosomes during cell division.” **Chromosomes carry the genes (DNA and are in the nucleus of eukaryotic cells**

– The nucelus is surrounded by a double membrane called the nuclear envelope or membrane. The nuclear envelope is made of two bilayers that separate the nucleus form the cytoplasm.

– Substances that are made in the nucleus include ribosomal proteins and RNA, which move into the cytoplasm through nuclear pores.

State Test Question

• The structure shown below is found in what part of a eukaryotic cell?

A.Cytoplasm

B.Nucleus

C.Golgi apparatus

D.Smooth endoplasmic reticulum

Both Animal and Plant Cells Contain These Organelles

• 4. Nucleolus– Dense struc-

tures inside the

nucleus.– Stores RNA

that forms

ribosomes.

Both Animal and Plant Cells Contain These Organelles

• 5. Ribosomes– Tiny “dot” organelles located on the rough

ER and throughout the cytoplasm. – They are the site of protein synthesis.– A cell makes proteins on ribosomes. The

building of proteins from amino acids occurs on the cell’s ribosomes.

– Some ribosomes float freely in the cytoplasm, while others are attached to the endoplasmic reticulum.

State Test Question

• The building of proteins from amino acids occurs on the cell’s—

A.membrane.

B.ribosomes.

C.nucleus.

D.centriole.

State Test Question

• Peptide bonds between amino acids are formed PRIMARILY on the cell’s—

A.mitochondria.

B.lysosomes.

C.ribosomes.

D.membrane.

State Test Question

• Which of the cellular structures labeled below is responsible for protein synthesis?

A.Cell membrane

B.Nucleus

C.Ribosomes

D.Golgi apparatus

Both Animal And Plant Cells Have These Organelles

• 6. Endoplasmic Reticulum– Materials can be moved around within a cell by using

the endoplasmic reticulum. The rough ER helps transport the proteins that are made by its attached ribosomes. As each protein is made, it crosses the ER membrane and enters the ER. The portion of the ER that contains the completed protein then pinches off to form a vesicle.

– A vesicle is a small, membrane-bound sac that transports substances in cells. By enclosing certain proteins inside vesicles, the eukaryotic cell keeps these proteins separate from proteins that are produced by free ribosomes in the cytoplasm.

– Proteins must enter the endoplasmic reticulum to be transported to other parts of the cell.

State Test Question

• Which of the structures below transports material within the cell?

A.Ribosomes

B.Endoplasmic reticulum

C.Nucleus

D.Mitochondria

Both Animal And Plant Cells Have These Organelles

• Endoplasmic Reticulum Cont.

– A membrane system of folded sacs and tunnels that functions as an intracellular highway (a path for molecules to move from one part of the cell to another) The canals of the ER connect the cell membrane with the nuclear membrane.

– Two Types of ER:– 1. Rough ER

» Has ribosomes on the membrane and helps transport the proteins that are made by its attached ribosomes.

» A vesicle is a small, membrane-bound sac that transports substances in cells. By enclosing certain proteins inside the vesicles, the eukaryotic cell keeps these proteins separate from proteins that are produced by free ribosomes in the cytoplasm.

– 2. Smooth ER» It lacks ribosomes (appearing smooth) and produces

certain lipids.

State Test Question

• Proteins must enter the endoplasmic reticulum to be—

A.transported to other parts of the cell.

B.used in building new strands of RNA.

C.synthesized into genetic codes.

D.excreted as waste material.

Both Animal And Plant Cells Have These Organelles

• 7. Golgi Apparatus– Vesicles that contain newly made proteins move

through the cytoplasm from the ER to an organelle called the golgi apparatus.

– It is stacks of flattened membranes with vesicles that packages and assembles many cell products. The Golgi Apparatus serves as the packaging and distribution center.

– It receives, chemically modifies, and repackages proteins into forms the cell can use, expel, or keep stored. The modified proteins are then enclosed in new vesicles that bud from the surface of the golgi apparatus.

– Some of these vesicles include lysosomes.

Both Animal And Plant Cells Have These Organelles

• 8. Mitochondria – They are called the “powerhouse” of the cell

because it produces energy (ATP). – They are the site of aerobic cellular

respiration.

A cell that requires a lot of energy, like a muscle cell, would contain large numbers of mitochondria.

State Test Question

• Endoplasmic reticulum is to mitochondrion as road is to—

A.control center.

B.generator.

C.storage tank.

D.toll gate.

=

Mitochondria Power

Both Animal And Plant Cells Have These Organelles

• 9. Vacuole– Small, fluid-filled structures that store

materials like food, enzymes, and other materials needed by the cell.

– **Plant Cell have a single large vacuole.**

State Test Question

• Golgi apparatus is to vacuole as packaging is to—

A.protecting.

B.storing.

C.absorbing.

D.hydrating.

Found In Animal cells Only

• 10. Centrioles –have asters– Tiny, cylindrical structures that are found in

pairs near the nucleus.– They are involved in cell division.

Found in Animal cells:

• 11. Lysosomes– Small spherical or- ganelles that contain digestive enzymes.– They teak care of for- eign particles enter- ing the cell and “di- gest” worn out cell parts. (extremely rare

plants)

Found In Plant Cells Only• 12. Chloroplasts

– Small green pigmented structures that contain chlorophyll.

– It is the site of photosynthesis.

Found in Plant Cells Only

• 13. Cell Wall– The cell wall consists of a mixture of proteins

and carbohydrates, including the polysaccharide cellulose. A polysaccharide is also known as a sugar.

– Structure found outside of the cell membrane in plants that provides strength and rigidity, but does not affect passages of materials in and out of the cell

**Plant cells have a LARGE vacuole that stores water which can occupy most of the space in a plant cell.**

State Test Question

Which of the following organelles are NOT found in both animal and plant cells?

A.Mitochondria

B.Cell membrane

C.Chloroplasts

D.Vacuoles

State Test Question

• When viewed under a microscope, a cell has several structures visible, including a membrane-bound nucleus, a cell wall, and several mitochondria. What type of cell is it?

A. Bacterial cellB. ProkaryoteC. Plant cellD. Animal cell

State Test Question

• All of the following statements about plant and animal cells are accurate EXCEPT—

A.plant cells have a cell wall, but animal cells do not.

B.animal cells have mitochondria, but plant cells do not.

C.animal cells have centrioles, but plants cells do not.

D.both plant and animal cells are eukaryotic.

State Test Question

• When viewed through a microscope, which of the following would indicate that a sample contained eukaryotic cells?

A.Cell wallsB.ChloroplastsC.Single-celled organismsD.Nuclei

State Test Question

• The cell shown below is NOT an animal cell because—

• it has a membrane-bound nucleus.

• it has a cell wall.

• it contains mitochondria.

• it is too large.