B ELL R INGER A prediction or statement that can be tested is a(n) ______. a. Conclusion b. Observation c. Control d. Hypothesis 2. A sample that is treated exactly like the other experimental groups except that the variable is not applied to it is a(n) __________. a. Observation b. Variable c. Control d. Hypothesis 3. What is the only difference between the control group and the experimental group in a controlled experiment? a. The test b. The prediction c. The variable d. The hypothesis

A GENDA Standard Cell Theory Notes Endosymbiotic Theory Video Eukaryotic/Prokaryotic Venn Diagram Independent Whole class

S TANDARD Students will analyze the nature of the relationships between structures and functions in living cells Explain the role of cell organelles for both prokaryotic and eukaryotic cells, including the cell membrane, in maintaining homeostasis and cell reproduction.

B EFORE W E G ET G OING … A theory in everyday language implies that something is unproven or speculative A theory in science is A widely accepted explanation of things observed in nature It must be supported by evidence (including evidence gained through experimentation and observation)

C ELL T HEORY Some random cell facts: The average human being is composed of around 100 Trillion individual cells It would take as many as 50 cells to cover the area of a dot on the letter “i” Red blood cells

D ISCOVERY OF C ELLS 1665 – English scientist, Robert Hooke, discovered cells while looking at a thin slice of cork. He described the cells as tiny boxes or a honeycomb He thought that cells only existed in plants and fungi

A NTON VAN L EUWENHOEK 1673 – used a handmade microscope to observe pond scum and discovered single-celled organisms He called them “animalcules” He also observed blood cells from fish, birds, frogs, dogs, and humans Therefore, it was known that cells are found in animals as well as plants

Y EAR G AP ? Between the Hooke/Leuwenhoek discoveries and the mid 19 th century, very little cell advancements were made. This is probably due to the widely accepted traditional belief in “spontaneous generation” Example Maggots from rotting meat

M ATTHIAS S CHLEIDEN 1838 – concluded that all plant parts are made of cells He was a German botanist

T HEODOR S CHWANN 1839 – concluded that all animal tissues are composed of cells He was a German physiologist and close friend of Schleiden

L OUIS P ASTEUR Disproved spontaneous generation

R UDOLF V IRCHOW 1858 – studied cellular pathology and concluded that cells must arise from preexisting cells “Where a cell exists, there must have been a preexisting cell.” He was a German physician

T HE C ELL T HEORY 3 Basic Components: All organisms are composed of one or more cells. The cells is the basic unit of life in all living things. All cells are produced by the division of preexisting cells. Roundworm embryo undergoing cell division

T HE M ODERN I NTERPRETATION OF C ELL T HEORY All known living things are made up of one or more cells All living cells arise from preexisting cells through division The cell is the fundamental unit of structure and function in all living organisms The activity of an organism depends on the total activity of independent cells Energy flow occurs within cells Cells contain hereditary information which is passed from cell to cell during cell division All cells are basically the same in chemical composition in organisms of similar species

W HY IS C ELL T HEORY I MPORTANT ? Helps us to differentiate between living and non-living things. Unifies all living things – no matter how different one organism is from the next they are both composed of cells Foundational for biology! Onion cells Mouse kidney cells

P ROKARYOTES The first organisms on Earth May have lived 3.5 billion years ago and for millions of years they were the only organisms on Earth Eukaryotes evolved from prokaryotes, but how? Endosymbiotic theory E. coli, prokaryote Amoeba, eukaryote

P ROKARYOTIC /E UKARYOTIC V ENN D IAGRAM Use Chapter 7 in your textbook to complete a Venn Diagram comparing and contrasting prokaryotic and eukaryotic cells Work for minutes on your own, then we will fill out a class Venn diagram based on your input