CellsCells

Mr. HunterKennedy H.S.

Mr. HunterBiology

11/15/2012

• Objective(s)• SWBAT• Describe the function of the plasma membrane • Describe function and location of various organelles• Answer vocab / review questions

• Bell Ringer: What are the two components of the phospholipids of the cell membrane?

The Discovery of The Cell

• All living things are made up of one or more cells.

• A cell is the smallest unit that can carry on all the processes of life.

Looking at cellsLooking at cells

Microscopes Reveal Cell StructureMicroscopes Reveal Cell Structure

Most cells are too small to see with the Most cells are too small to see with the naked eye. Scientists became aware of naked eye. Scientists became aware of cells only after microscopes were cells only after microscopes were invented in the 1600s.invented in the 1600s.

A.A. Robert HookeRobert Hooke used a crude microscope used a crude microscope to observe a thin to observe a thin slice of corkslice of cork in 1665. in 1665. He saw many small boxes which He saw many small boxes which reminded him of the small rooms in reminded him of the small rooms in which monks lived, so he called them which monks lived, so he called them cellscells. He observed plant cells.. He observed plant cells.

B.B. 10 years later a scientist, 10 years later a scientist, Anton vanAnton van LeeuwenhoekLeeuwenhoek used a microscope to used a microscope to view pond water. view pond water. He observed many He observed many small living creatures. He named them small living creatures. He named them animalculesanimalcules (tiny animals). They were (tiny animals). They were singled-cell organisms.singled-cell organisms.

The Cell – Theory and The Cell – Theory and FeaturesFeatures

A.A. In 1838, the German botanist In 1838, the German botanist MattiasMattias SchleidenSchleiden concluded that cells concluded that cells compose every part of the plant.compose every part of the plant.

B.B. A year later, the German zoologist A year later, the German zoologist Theodore SchwannTheodore Schwann claimed that claimed that animals are also made of cells.animals are also made of cells.

C.C. In 1858, In 1858, Rudoloph VirchowRudoloph Virchow, a German , a German physician, determined that cells come physician, determined that cells come from other cells.from other cells.

D.D. The works of these three scientist form The works of these three scientist form the the Cell TheoryCell Theory

1.1. All living things are made of one or All living things are made of one or more cells.more cells.

2.2. Cells are the basic units of structure Cells are the basic units of structure and function in organisms.and function in organisms.

3.3. All cells arise from existing cells.All cells arise from existing cells.

The Cellular Basis of Life

• All living things share several basic characteristics:

• Organized parts• Obtain energy• Perform chemical reactions• Change with time• Respond to environment• Reproduce• Maintain homeostasis• Share a Common History

Cell Diversity

• Cells are very different in terms of their shapes and functions.

• A cell’s function can influence its physical features

Cell Size

• Cells differ in shape and size.• Some cells may be seen by the

naked eye, such as a giraffe’s nerve cell ( 6 & ½ ft long) or a human egg cell (the size of a period at the end of sentence in your text book)

• A cell’s size is limited to its outer surface area to inner volume ratio.

• Nutrients, Oxygen and Waste produced must pass through the cell at its surface.

Surface Area

Surface Area

Volume

Volume

Two Basic Types of Cells

• Prokaryotes• Single Cell• Lack membrane bound

nucleus – control center of the cell / contains DNA

• Lack membrane bound organelles – specialized bodies with specific jobs

• DNA is found in nucleoid region

• Eukaryotes• Made of one or more cells• Nucleus and membrane

bound organelles present• Larger than prokaryotic

cells• More complex structure

Eukaryotic and Prokaryotic Cells

Cellular Organization

• Over time, cells began to form groups that function together.

Colonial organism: • Collection of genetically

identical cells that live together in a connected group.

• Few activities are coordinated.

Plasma Membrane

• The plasma membrane (cell membrane) has several functions.

• Selective access• Separation of internal and external

environments• Means of waste removal• Environmental interactions

• Fluid Mosaic Model – The membrane behaves more like a liquid than a solid.

• It is a pattern (mosaic) of lipids and proteins.

Cell Organelles• Organelle= “little organ”• Found only inside

eukaryotic cells• Organelles are

structures that have specific jobs within cells

• All the stuff in between the organelles is cytosol

• Everything in a cell except the nucleus is cytoplasm

Cell Membrane• Boundary of the cell• Made of a phospholipid bilayer

Nucleus• Control center of the

cell• Contains DNA• Surrounded by a double

membrane• Usually the easiest

organelle to see under a microscope

• Usually one per cell

Cytoskeleton• Acts as skeleton and

muscle• Provides shape and

structure• Helps move organelles

around the cell• Made of three types of

filaments

Endoplasmic Reticulum

• A.k.a. “ER”• Connected to nuclear

membrane• Highway of the cell• Rough ER: studded with

ribosomes; it makes proteins

• Smooth ER: no ribosomes; it makes lipids

Ribosome• Site of protein synthesis• Found attached to

rough ER or floating free in cytosol

• Produced in a part of the nucleus called the nucleolus

That looks familiar…what is a That looks familiar…what is a polypeptidepolypeptide??

Golgi Apparatus• Looks like a stack of

plates• Stores, modifies and

packages proteins• Molecules transported

to and from the Golgi by means of vesicles

Lysosomes• Garbage disposal of

the cell• Contain digestive

enzymes that break down wastes

Which organelles do lysosomes work with?

Mitochondria• “Powerhouse of the

cell”• Cellular respiration

occurs here to release energy for the cell to use

• Bound by a double membrane

• Has its own strand of DNA

Chloroplast• Found only in plant cells• Contains the green

pigment chlorophyll• Site of food (glucose)

production• Bound by a double

membrane

Cell Wall• Found in plant and

bacterial cells• Rigid, protective barrier• Located outside of the

cell membrane• Made of cellulose (fiber)

Vacuoles• Large central vacuole

usually in plant cells• Many smaller vacuoles

in animal cells• Storage container for

water, food, enzymes, wastes, pigments, etc.

What type of microscope may have been used to take this picture?

Centriole• Aids in cell division• Usually found only in

animal cells• Made of microtubules

Where else have we talked about microtubules?

Eukaryotic and Prokaryotic Cells

Quick Review• Which organelle is the control center of the cell?

• Which organelle holds the cell together?

• Which organelles are not found in animal cells?

• Which organelle helps plant cells make food?

• What does E.R. stand for?