Download
1 / 15
150 likes | 197 Views
Prokaryotic & Eukaryotic Cells. As you have already learned, everything is made up of living cells. And the cells themselves are made up of many different parts . There are many different cells that do many different things, but all of these cells fall into one of the two main categories:
E N D
As you have already learned, everything is made up of living cells. • And the cells themselves are made up of many different parts . • There are many different cells that do many different things, but all of these cells fall into one of the two main categories: • Prokaryotic cells & • Eukaryotic cells
What the words mean Prokaryotes Eukaryotes Eu = true Karyose = kernel, the nucleus So eukaryotes are the cells with a true nucleus Ex. Found in animals, plants, and fungi (yeast) • Pro = before • Karyose = kernel, which represents the nucleus • So prokaryotes occurred before cells with a nucleus • Ex. Bacteria
What they have in common • DNA • Cell (plasma) membrane • Ribosomes • Simple in Prokaryotic, complex in Eukaryotic • Cytoplasm • Allow the flow of nutrients and wastes to enter and leave the cell • Have similar metabolic ( life processes) like photosynthesis and respiration • Require a supply of energy • Made from the same basic chemicals • Carbohydrates, proteins, nucleic acid, fats, minerals, and vitamins
Differences • That’s what they have in common, but there are significant differences too. • The two main ones are age and structure.
Age Differences • Scientists believe that prokaryotic cells (in the form of bacteria) were the first life forms on earth. They are considered “primative” and originated 3.5 billion years ago. That is 2 billion years before eukaryotic cells and billions of years before our earliest ancestor, the hominids. • 4.6 billion years ago – Earth was formed • 3.5 billion years ago – the first life arose: prokaryotic bacteria • 1.5 billion years ago – eukaryotic cells arose • 500 million years ago – multi-celled eukaryotes arose • 3 million years ago – our earliest ancestor, the hominids, appeared
Structural Differences • Eukaryotic cells contain two important things that prokaryotic cells do not: • A nucleus • Membrane bound organelles
DNA • Although both contain DNA: • The DNA in eukaryotic cells in in the membrane bound nucleus • The DNA in prokaryotic cells floats around in the cell in what we call a • Nucleoid – not a real structure, just a word to describe the inside of the cell where the nuclear material sits
Organelles • The organelles in eukaryotic cells allow them to perform more complex functions than prokaryotic cells. • Prokaryotic cells do not have organelles like eukaryotic cells. • Both have ribosomes, but they are much more complex in Eukaryotic cells.
Chloroplasts and mitochondria • Evidence suggests that chloroplasts and mitochondria were once bacteria that developed a symbiotic relationship with cells that have a nucleus • Chloroplasts and mitochondria have their own DNA that is not a part of the cells. • Yes, plants have both chloroplasts and mitochondria.
Size • Eukaryotic cells are about 10 times larger than prokaryotic cells.
Cell Wall Both have a cell wall, but they are made up of different substances. Well, eukaryotic plant cells do.
Flagella & Cilia • Flagella and cilia are the structures that help cells move. • Eukaryotic flagella are more complex than prokaryotic flagella.
New Discoveries • Until recently, it was thought that only eukaryotic cells existed in multi-celled groups like in organs and tissue. Recent discoveries suggest that some prokaryotic cells do too. • This is just one more example of how new discoveries are always changing what we know – or think we know. • But that is what makes science so exciting! • http://www.ted.com/talks/lang/eng/bonnie_bassler_on_how_bacteria_communicate.html
