WEEK 1 - Introduction to cell biology
Learning Outcomes
1. Explain cell theory and its consequences
2. Interpret the concept of 'life' and the requirements for life to exist
3. Appreciate the supposed origins of life, the tree of life, and
common ancestry
4. Understand the concept of heredity, in both Prokaryotes and
Eukaryotes
5. Appreciate how different microscopes can inform us about cell
biology
Overview:
1. Cell theory
2. Requirements for life
3. Heredity
4. The tree of life
5. Scale and magnification
6. Types of microscopes
1 – Cell theory
Postulates of original cell theory:
- All living things are made up of cells
- The cell is the most basic unit of life
- All cells arise form preexisting cells
2 – Requirements for life
Some are more important than others
(Mrs GREN)
- Movement
- Respiration
- Sensitivity – maybe not as important as some bacteria can live in
extreme environments
- Growth
- Reproduction – essential, without it, no life would exist
- Excretion
- Nutrition
Out of bones, bacteria, DNA, viruses, crystals and memes, viruses are not
alive. An active metabolism is a sign of life, viruses without cells don’t
have this requirement.
, Crystals aren’t alive but they can grow, they require nourishment and
have sensitivity and can reproduce but they don’t have internal
metabolism, and they can’t control movement.
Bones are alive when inside a living thing. They have lots of active tissues
in them.
DNA itself isn’t alive but inside an organism it is, DNA is a requirement of
life
How did life start:
In hydrothermal vents, where a lot of archaea are found, without light as
slight would have damaged things. They have the right conditions for
early versions of life.
In stromatolites, formed from cyanobacteria. They have been present for
years.
The beginning of life is likely to remain a speculative topic as we can’t
retrieve intact organic samples from the beginning of life
There are only two requirements of life:
1- A molecule that can speed up its own creation
2- A catalyst that can make mistakes
Autocatalysis:
Autocatalysis – a reaction where one of the products is a catalyst for itself
But what organism can simply make copies of itself, without extra help -
RNA
Ribozymes can make copies of itself. They are enzymes made up of RNA
and often act on RNA
The original autocatalyst was possibly a proto-RNA (something that came
before RNA)
- Evidence for this – scientists think RNA came before proteins and
are confident about this
- We don’t know of a way that proteins can be made without RNA,
which means RNA must have come first.
- RNA is seen universally in all life so it should predate, meaning it
must have been first
- DNA replication wouldn’t occur without some catalytic properties.
DNA can’t perform its own catalysis
- RNA can do catalysis, and it stores information
Learning Outcomes
1. Explain cell theory and its consequences
2. Interpret the concept of 'life' and the requirements for life to exist
3. Appreciate the supposed origins of life, the tree of life, and
common ancestry
4. Understand the concept of heredity, in both Prokaryotes and
Eukaryotes
5. Appreciate how different microscopes can inform us about cell
biology
Overview:
1. Cell theory
2. Requirements for life
3. Heredity
4. The tree of life
5. Scale and magnification
6. Types of microscopes
1 – Cell theory
Postulates of original cell theory:
- All living things are made up of cells
- The cell is the most basic unit of life
- All cells arise form preexisting cells
2 – Requirements for life
Some are more important than others
(Mrs GREN)
- Movement
- Respiration
- Sensitivity – maybe not as important as some bacteria can live in
extreme environments
- Growth
- Reproduction – essential, without it, no life would exist
- Excretion
- Nutrition
Out of bones, bacteria, DNA, viruses, crystals and memes, viruses are not
alive. An active metabolism is a sign of life, viruses without cells don’t
have this requirement.
, Crystals aren’t alive but they can grow, they require nourishment and
have sensitivity and can reproduce but they don’t have internal
metabolism, and they can’t control movement.
Bones are alive when inside a living thing. They have lots of active tissues
in them.
DNA itself isn’t alive but inside an organism it is, DNA is a requirement of
life
How did life start:
In hydrothermal vents, where a lot of archaea are found, without light as
slight would have damaged things. They have the right conditions for
early versions of life.
In stromatolites, formed from cyanobacteria. They have been present for
years.
The beginning of life is likely to remain a speculative topic as we can’t
retrieve intact organic samples from the beginning of life
There are only two requirements of life:
1- A molecule that can speed up its own creation
2- A catalyst that can make mistakes
Autocatalysis:
Autocatalysis – a reaction where one of the products is a catalyst for itself
But what organism can simply make copies of itself, without extra help -
RNA
Ribozymes can make copies of itself. They are enzymes made up of RNA
and often act on RNA
The original autocatalyst was possibly a proto-RNA (something that came
before RNA)
- Evidence for this – scientists think RNA came before proteins and
are confident about this
- We don’t know of a way that proteins can be made without RNA,
which means RNA must have come first.
- RNA is seen universally in all life so it should predate, meaning it
must have been first
- DNA replication wouldn’t occur without some catalytic properties.
DNA can’t perform its own catalysis
- RNA can do catalysis, and it stores information
