Characteristics 1 of Living Things Living things are organized What is a Cell Cell Basic unit of living things Organisms are either Unicellular made of one cell such as ID: 685559
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Slide1
Cell Theory and Prokaryote vs. Eukaryote
Characteristics
#1 of Living Things:
-
Living things are organizedSlide2
What is a Cell?
Cell
– Basic unit of living things. Organisms are either:Unicellular – made of one cell such as bacteria and amoebas. ORMulticellular – made of many cells such as plants and animals.Slide3
Multicellular Organization
cell
tissue
organ
organism
A group of similar cells is called a
tissue
.
A group of similar tissues is called an
organ
.
A group of organs working together form an
organ system
or
organismSlide4
Scientists to Remember
Anton van Leeuwenhoek
(1674)
Father of MicroscopySaw tiny living things in pond water.Slide5
Scientists to Remember
Robert Hooke
(1665) – Observed “cells” in cork
Named box-shaped structures as “cells”Slide6
Other 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.Slide7
Cell Theory
Confirmed 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. Slide8
Microscopes
Light Microscope
– magnifies tiny organisms up to 1,000 times.
-Uses light and lenses. -We use these.Electron Microscope – magnifies up to a million times. -Uses electrons.Slide9
The Discovery of Cells
Prokaryotic
before
nucleus
Eukaryotic
true
nucleusSlide10
Eukaryotes
Has a
nucleus
with a nuclear envelopeBigger 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, fungiSlide11
Prokaryotes
NO
nucleusNO 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 BacteriaSlide12
Similarities
Contain all four macromolecules
lipids
, carbohydrates, proteins, and nucleic acidsBoth have ribosomesBoth have DNA
Similar MetabolismBoth can be unicellular
Have cell/plasma membranes or cell wallSlide13
Eukaryote VS. Prokaryote PictureSlide14
Prokaryotic Cell Reproduction Binary FissionSlide15
Eukaryotic Cell 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)Slide16
How did organelles evolve?
Biologists generally believe that eukaryotes evolved from
prokaryotes.
In 1981, Lynn Margulis popularized the “endosymbiont theory.”Slide17
Endosymbiotic Theory
The
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 relationshipSlide18
Endosymbiotic 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.Slide19
Endosymbiotic
Theory
Endo = inside
Symbiont = friendSlide20
Endosymbiotic Theory
The
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 relationshipSlide21
Endosymbiotic Theory
Chlorella are tiny green cells that live inside some amoeba... endosymbiosis may still be evolving today!