Presentation on theme: "Cell Theory and Prokaryote vs. Eukaryote"— Presentation transcript:
1Cell Theory and Prokaryote vs. Eukaryote Characteristics #1 of Living Things:-Living things are organized
2What is a Cell? Cell – Basic unit of living things. Organisms are either:Unicellular – made of onecell such as bacteria and amoebas.ORMulticellular – made ofmany cells such as plantsand animals.
3Multicellular Organization tissueorganorganismA group of similar cells is called a tissue.A group of similar tissues is called an organ.A group of organs working together form anorgan system or organism
4Scientists to Remember Anton van Leeuwenhoek (1674)Father of MicroscopySaw tiny living things in pond water.
5Scientists to Remember Robert Hooke (1665) – Observed “cells” in corkNamed box-shaped structures as “cells”
6Other Scientists Matthias Schleiden (1838) – Plants are made of cells. Theodor Schwann (1839) – Animals are made of cells.Rudolf Virchow (1855) – New cells come from existing cells.Janet Plowe (1931) – Cell membrane is a physical structure.Lynn Margulis (1970) – Organelles were once free-living cells.
7Cell TheoryConfirmed discoveries that all scientists believe to be true about cells:All organisms (living things) are composed of one or more cells.The cell is the basic unit of (life) structure and organization of organisms.All (new) cells come from preexisting cells.
8MicroscopesLight Microscope – magnifies tiny organisms up to 1,000 times.-Uses light and lenses.-We use these.Electron Microscope – magnifiesup to a million times.-Uses electrons.
9The Discovery of Cells Prokaryotic before nucleus Eukaryotic true
10Eukaryotes Has a nucleus with a nuclear envelope Bigger and more complex than prokaryotesHave membrane bound Organelles (golgi, ER, lysosomes…etc)DNA – double-stranded and forms chromosomes (highly organized)Can be unicellular OR multicellular organismsSexual Reproduction by MeiosisEx: animals, plants, fungi
11Prokaryotes NO nucleus NO membrane bound organelles (just ribosomes) ALL are unicellularSmaller than eukaryotic cellsForerunner to eukaryotic cells (smaller and more simple)DNA – single strand and circularAsexual Reproduction by Binary FissionEx: ALL Bacteria
12Similarities Both have ribosomes Contain all four macromolecules lipids, carbohydrates, proteins, and nucleic acidsBoth have ribosomesBoth have DNASimilar MetabolismBoth can be unicellularHave cell/plasma membranes or cell wall
15Eukaryotic Cell Reproduction Note that mitosis is also valuable for repairing damaged tissue, replacing worn out cells, growing, and developing, not just asexual reproduction. Mitosis: cell reproduction for growth and replacement of cells. This makes identical copies (clones)Meiosis: cell reproduction for the production of gametes, such as egg and sperm (sex cells)
16How did organelles evolve? Biologists generally believe that eukaryotes evolved from prokaryotes.In 1981, Lynn Margulis popularized the “endosymbiont theory.”
17Endosymbiotic TheoryThe Endosymbiotic Theory states that present day eukaryotic cells evolved from the uniting of several types of primitive prokaryotic cellsSome organelles (mitochondria and chloroplasts) might have been were originally prokaryotes that were involved in a symbiotic relationship
18Endosymbiotic Theory A prokaryote ancestor “eats” a smaller prokaryote The smaller prokaryote evolves a way to avoid being digested, and lives inside its new “host” cell kind of like a pet.
20Endosymbiotic TheoryThe small prokaryotes that can do photosynthesis evolve into chloroplasts, and “pay” their host with glucose.The smaller prokaryotes that can do aerobic respiration evolve into mitochondria, and convert the glucose into energy the cell can use.Both the host and the symbiont benefit from the relationship
21Endosymbiotic TheoryChlorella are tiny green cells that live inside some amoeba... endosymbiosis may still be evolving today!