Transcript Tour of the Cell

Tour of the Cell
Part 2
AP Biology
2007-2008
From food to making Energy
 Cells must convert incoming energy to
forms that they can use for work
mitochondria:
ATP
from glucose to ATP
 chloroplasts:
from sunlight to ATP & carbohydrates

 ATP = immediate energy
 carbohydrates = stored energy
ATP
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Mitochondria & Chloroplasts
 Important to see the similarities

transform energy
 generate ATP
double membranes = 2 membranes
 semi-autonomous organelles

 move, change shape, divide

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internal ribosomes, DNA & enzymes
Lynn Margulis
U of M, Amherst
Membrane-bound Enzymes
glucose + oxygen  carbon + water + energy
dioxide
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C6H12O6 +
6O2  6CO2 + 6H2O + ATP
Membrane-bound Enzymes
carbon + water + energy  glucose + oxygen
dioxide
light  C H O + 6O
6CO
+
6H
O
+
6 12 6
2
2
2
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energy
Mitochondria are everywhere!!
animal cells
plant cells
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Cells gotta live!
 What jobs do cells have to do?

building proteins
 proteins control
every cell function

make energy
 for daily life
 for growth

build more cells
 growth
 reproduction
 repair
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Cytoskeleton
 Function

structural support
 maintains shape of cell
 provides anchorage for organelles
 protein fibers


microfilaments, intermediate filaments, microtubules
motility
 cell locomotion
 cilia, flagella, etc.

regulation
 organizes structures
& activities of cell
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Cytoskeleton
 actin
 microtubule
 nuclei
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Centrioles
 Cell division
in animal cells, pair of centrioles
organize microtubules
 guide chromosomes in mitosis

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Cell Size
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2007-2008
Limits to cell size
 Lower limit

smallest bacteria
 mycoplasmas
 0.1 to 1.0 micron (µm = micrometer)

most bacteria
 1-10 microns
 Upper limit

eukaryotic cells
 10-100 microns
 micron = micrometer = 1/1,000,000 meter
Biology
APdiameter
of human hair = ~20 microns
What limits cell size?
 Surface to volume ratio

as cell gets bigger its volume increases
faster than its surface area
 smaller objects have greater
ratio of surface area to volume
Why is a huge
single-celled
creature not
possible?
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s:v
6:1
~1:1
6:1
Limits to cell size
 Metabolic requirements set upper limit
in large cell, cannot move material in &
out of cell fast enough to support life
aa
aa
What process is this?
CH
NH3
aa

CHO
O2
CH
aa
CO2
CO2
CHO
CH
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aa
aa
O2
CO2
CHO
O2
NH3
CHO
O2
NH3
O2
NH3
CO2
CH
aa
What’s the solution?
How to get bigger?
 Become multicellular (cell divides)
But what challenges do you have to solve now?
CO2
CO2
aa
aa
CO2
CHO
NH3
CH
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CO2
O2
NH3
aa
aa
CO2
NH3
CO2
CO2
NH3
NH3
CO2
CH
NH3
NH3
CO2
CHO
O2
NH3
CO2
O2
CH
aa
O2
NH3
CHO
CO2
aa
Cell membrane
 Exchange structure

plasma membrane functions as
selective barrier
 allows passage of O2 & nutrients IN
 allows passage of products & wastes OUT
Phospholipid
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Membrane
proteins
Cholesterol
Any Questions??
AP Biology
2007-2008