1. Pick up your science journal Announcement: Learning portfolio
1.5 The origin of cells
Pick up your science journal
Announcement: Learning portfolio

3. EQ: How do we know how life began?

4. 1.5.1 Cells can only be formed by the division of pre existing cells
Louis Pasteur made a nutrient broth by boiling water containing yeast and sugar
Swan-necked flask
Omne vivum ex vivo (All life from life)

5. 1.5.2 The first cells must have arisen from non-living material

6. 1.5.2 Recipe for the origin of life
The synthesis of simple organic molecules (amino acids) from inorganic molecules (water, carbon dioxide, ammonia)
The assembly of these molecules into polymers (e.g. polypeptides from amino acids)
Formation of polymers that can self-replicate to allow for inheritance of characteristics
Development of membranes with internal chemistry different from their surroundings

7. 1.1.2 Cells carry out all functions necessary for life
growth: an irreversible increase in size
homeostasis: keeping conditions inside the organisms within tolerable limits
metabolism: chemical reactions inside the cell, including cell respiration to release energy
nutrition: obtaining food, to provide energy and the materials needed for growth
reproduction: producing offspring either sexually or asexually
sensitivity: perceiving and responding to changes in the environment
Image source:

8. The cell theory All living things are made of one or more cells
The cell is the smallest unit of life
All cells come from pre-existing cells

9. Learning Portfolio September 8th
Pick up your science journal
Submit your cell theory lab.

10. 1. Announcements: Resources, Quiz (1.5 & 1.2)
Cell Size
1. Announcements: Resources, Quiz (1.5 & 1.2)

11. 1.5 Endosymbiotic theory
Theory that chloroplasts and mitochondria were once free living prokaryotes that were engulfed by larger prokaryotes and survived to evolve into modern organelles

12. 1.5 Endosymbiotic Theory Mitochondria and chloroplasts:
Both have a double membrane (the second outer membrane from the host, the eater)
Have a look of naked DNA, lacking histone proteins
Divide by binary fission
Small 70S ribosomes (not 80S eukaryotic ribosomes)
Structure and biochemistry of chloroplasts similar to cyanobacteria

13. 1.1 Cell size molecules: ~ 1 nm cell membrane thickness: ~ 10 nm
viruses: ~ 100 nm
bacteria: ~ 1 µm
organelles: up to 10 µm
eukaryotic cells: up to 100 µm

14. 1.1 Why is the cell small?

15. 1.1 Why is the cell small? Surface area determines rate of exchange
Volume determines metabolism
As cell size increases, volume increases proportionally faster than SA => SA: V ratio decreases
Low SA reduces rate of exchange while high V increases metabolic demands
Cell cannot meet needs of metabolic demands

16. Cell size
Stephen Taylor (i-biology)

18. To do today Magnification & Cell Size worksheet Resources:
(slide number 25 – 36)

19. Stephen Taylor (i-biology)

20. Stephen Taylor (i-biology)

21. Stephen Taylor (i-biology)

22. Stephen Taylor (i-biology)

23. Stephen Taylor (i-biology)

24. Stephen Taylor (i-biology)

25. 1.1 Stem Cells & Cell Division
Submit your cell size worksheet
Checkpoint: Learning Portfolio

26. 1.1 Why do cells look so different?
Stem cells = Cells that retain capacity to divide and differentiate along different pathways
multicellular organisms can differentiate into a variety of interdependent cell types
each specialized to carry out a subset of functions  greater efficiency
cellular differentiation
achieved through differential gene expression
all cells in an organism have identical DNA

27. 1.1 Stargardt’s disease
Junvenile Macular Degeneration

28. Tumors Tumors are result of uncontrolled cell division
Apoptosis = programmed cell death
Apoptosis?

29. 1.1 Lymphoma
Blood cell tumors that develop from lymphcytes

34. Science of perception: Law of closure

35. ATM, floppy disk, hard drive

37. 1.7 Systems biologists “Whole is greater than the sum of its parts”
Put together the parts that make up a system and then observe the properties of that 'emerge' from the system
“Emergent properties”: occurrence of unexpected characteristics or properties in a complex system
Reductionism = reduce phenomenon to its constituent parts.
Smallest parts are predictable then the system as a whole is predictable.
No new properties will arise from the sum of the parts

38. What do the components of the watch do individually?
What do they do when they are put together in the right way?
William Paley: Complexity of X necessitates a designer (as a watch)