1. Cell structure and function

2. Cell Theory: All living things are made of cells
Cells are the basic unit of structure and function in an organism (basic unit of life)
Cells come from the reproduction of existing cells.

3. Cell sizes and types Cells can only be observed under microscope
Three Basic types of cells include:
animal plant bacteria

4. Number of cells
Although ALL living things are made of cells, organisms may be:
Unicellular – composed of one cell
Multicellular- composed of many cells

5. Prokaryote bacteria cells Eukaryote animal cells
Types of cells
Prokaryote bacteria cells
Eukaryote animal cells
Eukaryote plant cells

6. Prokaryotes Cells that lack a nucleus and membrane-bound organelles
Ex: bacteria
Simplest type of cell
Single, circular piece of DNA

7. Eukaryotes
Cells that HAVE a nucleus and membrane-bound organelles
Ex: protists, fungi, plants, and animals
More complex type of cells

8. ATP Cell Jobs make proteins make energy build more cells
proteins control every cell function
make energy
for daily life
for growth
build more cells
growth
reproduction
repair
ATP

9. Limits to cell size Lower limit Upper limit most bacteria
1-10 microns
Upper limit
eukaryotic cells
microns
diameter of human hair = ~20 microns

10. Why are cells small? Surface area to volume ratio
V increases faster than SA
Large cells cannot move material in & out fast enough to support life
square - cube law
As cell gets larger, volume increases cubically, but surface area only increases by the square.
The volume of the cell is demanding… it needs exchange. The surface area is the exchange system… as cell gets larger, the surface area cannot keep up with demand.
Instead of getting bigger, cell divides -- mitosis.
s:v
6:1

11. How to get bigger? Become multicellular (cell divides) aa O2 aa aa aa
NH3 O2 CH
CHO aa O2 CH
CHO
CO2
Larger organisms do not generally have larger cells than smaller organisms — simply more cells
What’s challenges do you have to solve now?
how to bathe all cells in fluid that brings nutrients to each & removes wastes from each aa
NH3
CHO CH O2 aa

12. The Cell: Nucleus, Ribosomes

13. Nucleus Function contains DNA
some genes located in mitochondria & chloroplasts

14. Nucleus structure double membrane  nuclear envelope
Pores (membrane fused) allow materials to pass through
What kind of molecules need to pass through?
RNA

15. Nucleus structure DNA organized into fibers called chromatin
chromatin fibers coil up as separate chromosomes prior to division

16. Nucleolous
produces ribosomes from rRNA & proteins

17. The Cell: Mitochondria & Chloroplasts

18. Overview
Mitochondria & chloroplasts are organelles that convert energy to a form that cells can use for work
mitochondria: from glucose to ATP
chloroplasts: from sunlight to ATP & carbohydrates
ATP = active energy
carbohydrates = stored energy
ATP +
ATP

19. Mitochondria & Chloroplasts
Similarities to each other (and bacteria)
transform energy (generate ATP)
double membranes = 2
semi-autonomous  move, change shape, divide
have their own ribosomes, DNA & enzymes

20. Mitochondria Function cellular respiration generate ATP
from breakdown of sugars, fats & other fuels
in the presence of oxygen = aerobic respiration

21. Mitochondria Structure 2 membranes
smooth outer membrane
highly folded inner membrane
cristae
fluid-filled space between 2 membranes
internal fluid-filled space
mitochondrial matrix
DNA, ribosomes & enzymes
Why 2 membranes?
increase surface area for membrane-bound enzymes that synthesize ATP

22. Dividing Mitochondria
DIVIDE like bacteria
REMEMBER ENDOSYMBIOSIS

23. Mitochondria Almost all eukaryotic cells have mitochondria
number of mitochondria is correlated with aerobic metabolic activity
more activity = more energy needed = more mitochondria
What cells would have a lot of mitochondria?
active cells:
• muscle cells
• nerve cells

24. increase surface area for membrane-bound enzymes that synthesize ATP
Chloroplasts
Structure
2 membranes
outer membrane
inner membrane
internal fluid-filled space = stroma
DNA, ribosomes & enzymes
thylakoids = membranous sacs where ATP is made
grana = stacks of thylakoids
Why internal sac membranes?
increase surface area for membrane-bound enzymes that synthesize ATP

25. Who else divides like that?
Chloroplasts
Function
photosynthesis
generate ATP & synthesize sugars
transform solar energy into chemical energy
produce sugars from CO2 & H2O
Semi-autonomous
moving, changing shape & dividing
can reproduce by pinching in two
Who else divides like that?
bacteria!

26. Mitochondria & chloroplasts are different from other organelles
not part of endomembrane system
Grow & reproduce  semi-autonomous
Proteins from ribosomes
Contain circular chromosome directs synthesis of proteins produced by own internal ribosomes
Who else has a circular chromosome bound within a nucleus?
bacteria

27. Endosymbiosis theory
Mitochondria & chloroplasts were once free living bacteria that were engulfed by ancestral eukaryote
Endosymbiont
cell that lives within another cell (host)
partnership
evolutionary advantage for both
one supplies energy
the other supplies raw materials & protection
LICHENS = fungi & algae
Lynn Margulis
From hypothesis to theory!
Paradigm shifting ideas in evolutionary biology.