Cell Structures!

October 11th, 2012

The Cell: The Basic Unit of Life All living organisms on Earth are made up of small

units called cells All of the macromolecules that we have studied about

so far (proteins, lipids, carbohydrates and nucleic acids) are small molecules that are part of cells

There are many different kinds of cells. Humans may have more than a 100 different kinds!

When looking through his microscope, Matthias Schleiden discovered that every part of the plant cell he

was looking at was made up of small tiny cells. Theodor Schwann discovered that every part of an animal

he looked at through his microscope was made of cells!Later, Rudolf Virchow (another scientist) added that all

cells arise from other cells

The Cell Theory! All living things are made of cells. Cells are the basic units of structure and

function in living things. Living cells come only from other living cells.

Why are Cells so small? Most plant and animal cells are very small!

Ranging from 10 and a 100 micrometers Cells must constantly interact with their

environment, gases and food molecules must be absorbed and waste products must be eliminated.

Inside the cell, there are many small organelles. All of these organelles need access to the cell membrane (surface of the cell) to get food or other necessities. If a cell’s surface area gets larger, then so does the volume. It will come to a point where there just isn’t enough cell membrane to give service to the inside of the cell!

Eukaryotes Vs. ProkaryotesEukaryotic cells have a nucleus,

organized organelles, they are larger than prokaryotic cells and are multi-cellular

Prokaryotic cells do not have a nucleus, no organelles and they are all unicellular

Prokaryotic Cells Bacteria and Archaebacteria (ancient bacteria,

that still exist today) are prokaryotic cells No nucleus No membrane bound organelles Unicellular – single-celled organisms

What are Protists? Protists are a diverse group of organisms that

cannot be classified as animals, plants or fungi They consist of multicellular or unicellular

organisms such as amoebae, red algae, dinoflagellates, diatoms and euglena

Eukaryotic Cells – The “Classic” Cell

Most living organisms have eukaryotic cells (including humans, animals, fungi, protists and plants)

Membrane-bound nucleus and organelles Usually multi-cellular – many cells! Larger than prokaryotic cells Eukaryotic cells are divided into compartments

and each of these compartments have different functions and are called organelles

What are Organelles? Organelles are specific compartments within a cell There are many types of organelles in eukaryotic

cells Prokaryotic cells do not have organelles

What are Cytoplasmic Organelles? Membrane-bound organelles within

the cytoplasm of a cell Organelles include:-Nucleus-Vacuole-Vesicles-Endoplasmic reticulum-Golgi Complex-Lysosomes-Mitochondria-Chloroplasts

What is a Vacuole?Vacuoles are little pockets in the cytoplasm

of a cell where a cell stores foodFound mainly in plants – they are smaller in

animalsPlant cells store starch molecules and water

in vacuolesVacuoles help keep plant cells rigid and fullMembrane surrounding vacuole is called

tonoplast

Vesicles – Travel Cellular HighwaysVesicles are found in both plant and

animal cells Primary role is to transport materials

throughout the cell and keep the different areas of the cell in contact

Ribosomes Not considered to be classic organelles Ribosomes are small particles that manufacture proteins They connect one amino acid to another in order to create a

long chain which will become a protein. This process is called protein synthesis

They are located on the endoplasmic reticulum or they are free-floating within the cytoplasm

Unit Test Tomorrow!

Unit Test will cover: All material on PowerPoints All supplementary material in

textbook Chemical Fundamentals

(acids/bases, isotopes, radioisotopes, bonding, etc;), Chemicals of Life (macromolecules), Enzymes, Cellular Respiration and Photosynthesis