Lecture 2 Flashcards
Who advanced neuroscience the most
Darwin
All animals in the world have a lot in common as they are all descended from a common ancestor
Timeline of universe
13.7 billion years old
tjhis is the oldest light we can see
this light originated from a space, 46 billion years away from us (cos universe is expanding)
Atoms and molecules
all matter is made of atoms
elements consist only of one of these atoms
118 elements
The air we breathe is 99% N2 and O2
Usually form molecules
Chemical reactions
is when a chemical bond is formed, broken or modified. Living things regulate these reactions to do things
Ions
If a molecule or atom has a charge, it is called an ion
Cations positive
Anions negative
Ions often form ionic bonds with each other
Atoms held together with ionic bonds are called salts and dissolve in water
Evolution
earth is 4.5 billion years ago
life created in primordial soup in the first billion years
CHNOPS
The main elements of cells are
59% Hydrogen 25% Oxygen 11% Carbon 4% Nitrogen 2% Others
Origin of life
Lightning hits soup with water (essential for life) and many chemical compounds
By chance, lighting causes chemical reactions
Blob of oil engulfs DNA
Creates the first cell, ancestor of all life
Could self-replicate
Molecules of life
CHNOPS come together to make
Water H2O
Sugar (rings of carbons)
Lipids (long, hydrocarbon chains
Nucleic acids
Amino acids
Chains of life
Almost everything in life chemically is a chain
shains of sugars = carbohydrate
Chains of nucleic acids = chromatin (or folded, chromosomes)
Lipids form sheets ehich make all membranes and vesicular membranes
The molecular composition of cells
70% water
15% sugars
10% lipids
15% nucleic acids
50% AAs
10% other organic molecules
RNA enzymes
refers to ribonucleic acids
String RNA together, it folds up
Sometimes these have enzymatic activity
Some can self-replicate
The first self replicating molecule was RNA
Phospholipd bilayer
Strands of fat with a phosphate cap
Lipids avoid water, phosphate is drawn to it
Thus forms bi-layers
Under some conditions, form micelles (balls) and explode and reform , forming liposomes.
The cell membrane is essentially a liposome
The interior is full of salt water
RNA to DNA
RNA is not stable
It was replaced by DNA. DNA has no enzymatic activity and is more stable.
RNA is not abundant (not many types). There is a greater abundance of AAs so we use them to make enzymes etc
RNA based enzymes probably started to incorporate proteins and eventually were replaced by them
over the last 3.5 billion years (4 things)
All instructions of life stored as DNA\
Sections of DNA are transcribed into RNA
RNA gets translated into proteins
Protein catalyses chemical reactions
Transcription
Where the gene is switched on
RNA polymerase attaches to the gene (DNA)
Moves along DNA making a strand of mRNA from free bases present in the nucleus
DNA code determines the order in which RNA bases are attached
This is then processed which involves adding and removing sections of RNA
Note these genes can be read in alternative ways which can result in different forms of the same protein (isoforms). Several isoforms are made from the same gene.
Translation
The mRNA leaves the nucleus and goes to a ribosome
There are 20 AAs
tRNA takes these AAs to the ribosome the mRNA is read 3 bases at a time, each coding for an AA
tRNA delivers this AA
The AA is added to the growing chain
When this is finished, it folds into a complicated 3D shape
in this way RNA is translated at the ribosome
The prokaryotic cell
Consists of a plasma membrane, cytoplasm, chromatin (loose strings of DNA) and ribosomes (nucleic acid - mostly RNA - and proteins)
Proteins
are what does things in cells
Enzymes
Receptors
Myotubules, messengers, transport and storage
Eukaryote origins
1 billion years after life, prokaryotes existed
There were larger and smaller ones
The large ate the small
One day a small one had a defense that allowed tit to survive in the larger cell
One time, a symbiotic relationship formed and the small cell became dedicated to metabolizing sugar
The first mitochondria
ATP
power source
When ATP binds with a protein, releases a phosphate. The energy of ATP>ADP changes the shape of the protein
The eukaryotic cell
Nucleus
Membrane bound
No chromatin, tightly folded chromosomes
Mitichondria have their own DNA
ER, golgi body
Lysoosomes
Eukaryotic Cell body (SOMA)
is where the nucleus is located
A nerve cell is defined by where the soma is located (eg a hippocampal neuron)
Cell membrane defines the boundary
Microtubules
proteins
roads
kenisins walk along them
globular heads act as feet
one binds with tubule, the other ATP and uses its energy to flip them over thus appears to walk
Each has a neck attached to cargo
They can carry much bigger cargo than them but still get blocked by cellular components sometimes so use multiple at once
Typically take stuff from cell body to periphery
100 steps/8nm per secons
Multicellular organisms
One day cells did not divide fully and stuck together
DNA codes for when to switch on or off expression
Eg if cold, bind here, if not, dont
SO binding points are turned on or off
Cells specialise too eg if your cell is on the edge, become hard etc
Animal studies
because all have a common ancestor, you can study animals nerve systems
Giant squid = action potential (Nobel in 1963)
Sea Slug = learning and memory (2000 Nobel)
Brains in mammals
Brain structure is similar in mammals
40% of mammals are rodents, 20 are bats
Rodents are evolutionary closer to humans so we use them
justification for animal studies
1 - mental disease is real, the ends justify the means
2 - no one is cruel. No one enjoys it, you stomach it
3 - must have ethics board approval. Always checks and balances
Evolution of the human brain
Great apes and us share 98.8 % of DNA
Research on them is not allowed
Still there is a massive cognitive difference between them and us and we do not know why.
Maybe it is the pattern of expression
Birth and the brain
The human brain develops after birth. Production of new neurons almost ceases but those present grow and establish connections with each other. Other brain cells that support neurons proliferate
4x more massive from birth to 20. 1400g
neoteny extended youth
Fermi Paradox
40 billion planets like earth in the milky way
13 billion years old so some earth like planets are much older
if interstellar travel is possible, even the slow kind within the reach of earth it would take 5-50 million years to colonize the galaxy
There are 2 trillion galaxies in the known universe
So… Where is everybody?
