Lecture 2: Natural Selection
Thursday, 19 March 2015 11:01 a.m.
Describe the theory of evolution via Natural Selection
1. Variation (individuals vary from one another)
2. Inheritance (parents pass on traits to their offspring)
3. Selection (some variants reproduce more than others)
4. Time (long periods of it)
Describe the history of the idea of Natural Selection
Darwin observed that
1. Individuals in a population vary in heritable characteristics
2. Organisms produce more offspring than the environment can support (so the ones that do
end up surviving have favourable traits)
From these, he inferred that
1. Individuals more suited to the environment leave more offspring
2. Over time, favourable traits accumulate in the population
Explain the idea of sexual selection
We/mates select for DNA which effects the phenotype, not just the physical trait.
"Natural selection arising through preference by one sex for certain characteristics in individuals of
the other sex i.e. females choosing mates based on their characteristics."
In other words - individuals with certain inherited characteristics are more likely to obtain mates
e.g. the strongest, fittest, one with largest tail (peacock)
CELL STRUCTURE AND DIVERSITY Page 1
,Lecture 3: Basics of Cell Science
Thursday, 19 March 2015 11:02 a.m.
Describe the different techniques used to study cells
Two types of microscope - light and electron
Two types of electron microscope - transmission and scanning
1. Transmission Electron Microscopes
- TEM
- Magnify up to 100,000x
- Looks at internal structures, like a slice or a plane - looks at internal ultrastructure
- 2 dimensional
- Sample must be dead
2. Light Microscopes
- Only living tissue
- Magnify up to 1000-1400x
3. Scanning Electron Microscopes
- SEM
- Magnify up to 100,000x
- Can't penetrate the sample
- Can produce a 3D image
Define the basic characteristics of living cells
All cells, both prokaryotes and eukaryotes have:
1. Membranes to hold them in
2. Chromosomes to store genetic information like DNA or RNA
3. Cytosol fluid for dissolving ions
4. Ribosomes to make proteins
Outline the biological classification of organisms
Domains: Archaea, bacteria and eukarya
(Eukarya) Kingdoms: Plantae, animalia, fungi (little plants) and protists (little animals)
CELL STRUCTURE AND DIVERSITY Page 2
,Describe the basic difference between prokaryotes and eukaryotes
Eukaryotes - membrane enclosed nucleus and organelles, around 10-100 micrometres
Prokaryotes - lacking membrane enclosed nucleus and organelles and much smaller, less than 5 micrometres
n.b. Sizes of things:
size of plant cell 20x30 micrometres
size of animal cell 20 micrometres
size of bacteria cell 1 micrometre
Size of DNA 2nm
Size of ribosome 25nm
Size of eukaryotes 10-100 micrometres
Size of prokaryotes >5 micrometres
Outline the 'spontaneous generation' and 'germ' theories for the origin of microorganisms
Spontaneous Generation
Spontaneous generation was a theory that germs just appeared under certain conditions, out of nowhere, say, if you left a pie ce of meat
out that flies and maggots would just 'appear' on it.
CELL STRUCTURE AND DIVERSITY Page 3
, Louis Pasteur disproved this and proved germ theory; that they are present in cases of disease and cause it.
"The germ theory of disease states that some diseases are caused by microorganisms. These small organisms, too small to see wi thout
magnification, invade humans, animals, and other living hosts. Their growth and reproduction within their hosts can cause a d isease."
Pasteur developed a special flask. It had a curved neck that allowed air in, but would trap any microorganisms and not let them
contaminate his findings.
Germ theory says that diseases are caused by microorganisms, which who's growth and reproduction within their host causes a d isease.
Disproving spontaneous generation:
CELL STRUCTURE AND DIVERSITY Page 4
Thursday, 19 March 2015 11:01 a.m.
Describe the theory of evolution via Natural Selection
1. Variation (individuals vary from one another)
2. Inheritance (parents pass on traits to their offspring)
3. Selection (some variants reproduce more than others)
4. Time (long periods of it)
Describe the history of the idea of Natural Selection
Darwin observed that
1. Individuals in a population vary in heritable characteristics
2. Organisms produce more offspring than the environment can support (so the ones that do
end up surviving have favourable traits)
From these, he inferred that
1. Individuals more suited to the environment leave more offspring
2. Over time, favourable traits accumulate in the population
Explain the idea of sexual selection
We/mates select for DNA which effects the phenotype, not just the physical trait.
"Natural selection arising through preference by one sex for certain characteristics in individuals of
the other sex i.e. females choosing mates based on their characteristics."
In other words - individuals with certain inherited characteristics are more likely to obtain mates
e.g. the strongest, fittest, one with largest tail (peacock)
CELL STRUCTURE AND DIVERSITY Page 1
,Lecture 3: Basics of Cell Science
Thursday, 19 March 2015 11:02 a.m.
Describe the different techniques used to study cells
Two types of microscope - light and electron
Two types of electron microscope - transmission and scanning
1. Transmission Electron Microscopes
- TEM
- Magnify up to 100,000x
- Looks at internal structures, like a slice or a plane - looks at internal ultrastructure
- 2 dimensional
- Sample must be dead
2. Light Microscopes
- Only living tissue
- Magnify up to 1000-1400x
3. Scanning Electron Microscopes
- SEM
- Magnify up to 100,000x
- Can't penetrate the sample
- Can produce a 3D image
Define the basic characteristics of living cells
All cells, both prokaryotes and eukaryotes have:
1. Membranes to hold them in
2. Chromosomes to store genetic information like DNA or RNA
3. Cytosol fluid for dissolving ions
4. Ribosomes to make proteins
Outline the biological classification of organisms
Domains: Archaea, bacteria and eukarya
(Eukarya) Kingdoms: Plantae, animalia, fungi (little plants) and protists (little animals)
CELL STRUCTURE AND DIVERSITY Page 2
,Describe the basic difference between prokaryotes and eukaryotes
Eukaryotes - membrane enclosed nucleus and organelles, around 10-100 micrometres
Prokaryotes - lacking membrane enclosed nucleus and organelles and much smaller, less than 5 micrometres
n.b. Sizes of things:
size of plant cell 20x30 micrometres
size of animal cell 20 micrometres
size of bacteria cell 1 micrometre
Size of DNA 2nm
Size of ribosome 25nm
Size of eukaryotes 10-100 micrometres
Size of prokaryotes >5 micrometres
Outline the 'spontaneous generation' and 'germ' theories for the origin of microorganisms
Spontaneous Generation
Spontaneous generation was a theory that germs just appeared under certain conditions, out of nowhere, say, if you left a pie ce of meat
out that flies and maggots would just 'appear' on it.
CELL STRUCTURE AND DIVERSITY Page 3
, Louis Pasteur disproved this and proved germ theory; that they are present in cases of disease and cause it.
"The germ theory of disease states that some diseases are caused by microorganisms. These small organisms, too small to see wi thout
magnification, invade humans, animals, and other living hosts. Their growth and reproduction within their hosts can cause a d isease."
Pasteur developed a special flask. It had a curved neck that allowed air in, but would trap any microorganisms and not let them
contaminate his findings.
Germ theory says that diseases are caused by microorganisms, which who's growth and reproduction within their host causes a d isease.
Disproving spontaneous generation:
CELL STRUCTURE AND DIVERSITY Page 4
