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Lecture

NEUR 2600 Lecture Notes - Semipermeable Membrane, Human Genome Project, Fluid Compartments

by

Department
Neuroscience
Course Code
NEUR 2600
Professor
Ian Whishaw

Page:
of 2
The parts of a cell
1.
The sequence of action by a cell to produce and export a protein
2.
The four kinds of proteins active in and around the cell membrane
3.
Things you need to know:
Cell structure
1.
Cell function
2.
The Cell
2 hemispheres
3 levels of function (spinal brain, brain stem, the brain)
4 lobes (frontal, temporal, parietal, occipital)
5 types of neurons, 5 types of glial cells
Uses electrons instead of light
-
Electron Microscope
Unless the cell wants it to
Some things get through, others don't
Phospholipid molecule
One layer phospholipid cells facing out to extracellular fluid
Heads are charged and are attracted towards the water
Water molecules are repelled by the tails of phospholipid molecules and so the
membrane is impermeable to water
Doesn't allow water to go through because fatty tails are hydrophobic
Other faces intracellular
A cell membrane is a bilayer
Hydrophobic - water heating
Hydrophilic - water loving
Phospholibid bilayer
Properties that make it semi-permeable:
Semipermeable
-
Goes into membrane, attaches to tails of bilayer, moves all around the membrane
Many flourescent dies incorporate into the cell membrane because fatty
-
Without interference
Isolates the activity of the cell from the ECF
Membranes can be considered as walls that partition a cell into rooms that provide biochemical privacy
-
Properties of a cell membrane
One of each pair from father + mother
Autosomes - sex chromosomes
Chromo = color
Chromosome
-
Nucleus
-
Nuclear membrane
-
Endoplasmic reticulum
-
Golgi bodies
-
Microtubules
-
Cell membrane
-
Cell Structure
Proteins formed in the ER enter the Golgi bodies, where they are wrapped in a membrane and given a shipping
address
1.
Continue from powerpoint...
2.
Cell Function - making a protein
Each gene makes one protein
We're interest in channels, gates, pumps and transmitters
20 to 25 thousand genes
-
The Genome War - James Shreeve
3 billion base pairs
-
The Human Genome Project
20 000 genes, implies 20 000 primary proteins
Infinite number of proteins
20 000 primary proteins is what we really mean
Proteins can be cut in half or combined
One gene produces one protein
-
The function of the cell is to produce proteins
Adenine (a) binds with thymine (t)
Guanine (g) binds with cytosine (c)
Each chromosome is a double-stranded molecule of DNA
-
Two backbones made of sugar and phosphate groups bound together by bases
Deoxyribonucleiuc acid - DNA
-
Genes represent the code for a protein
Hydrophilic
Hydrophobic
Extracellular Fluid
Intracellular fluid
Cell Function
January-28-13
8:20 AM
Brain and Behavior Page 1
Bases are the code
Two backbones made of sugar and phosphate groups bound together by bases
DNA uncoils to expose a gene, a sequence of nuceotide bases that encodes a protein
1.
One strand of the gene serves a template for transcribing a molecule of mRNA
2.
Copying as in hand copying a typed text, DNA to mRNA
Transcription - gene to mRNA - base to base
Ribose (sugar) instead of deoxyribose
Uracil instead of thymine
mRNA
The mRNA leaves the nucleus and comes in contract with ribosome in the endoplasmic
reticulum
3.
As a ribosome moves along the mRNA, it translates the bases into a specific amino acid chain,
which forms the protein
4.
Copying from one language to another, mRNA to protein
Translation - mRNA to protein - base to amino acid
8 essential amino acids cannot be synthesized.
20 Standard Amino Acids
A short chain is sometimes called a peptide, a long chain a polypeptide chain
Proteins are important because their shapes can do interesting things
Protein is a chain of amino acids
-
20 000 genes = 20 000 proteins
Primary structure
Alpha Helix
Result of hydropen bonds
Beta pleated sheet
Secondary structure -> start to coil, fold
Some proteins are complete
Tertiary structure
Quaternary structure
Packaging and addressing
Every membrane is an address
Each protein gets put in a vesicle on its own
Wraps a membrane around it
Steps
Shape is everything
Have a shape, their shape can change, and can do specific tasks
Proteins are important because their shapes can do interesting things
Why do we care?
Golgi body
-
Directs the vesicles about where it should go
"Highway"
Microtubules
-
Exocytosis
Others re exported and also do useful things
-
Impermeable -> semi-permeable membrane
-
Some proteins are embedded in the membrane where they do useful things.
Cell Function
Channels
1.
Ions can cross a cell membrane through the appropriately shaped channel
-
Gates
2.
And prevents the passage one or both gates are closes
A gated channel allows the passage of substances when gates are open
-
Pumps
3.
A pump changes cell to carry substances across a cell membrane
-
Messengers (transmitters)
4.
Proteins:
http://en.wikipedia.org/wiki/SETI_Institute
http://en.wikipedia.org/wiki/Human_Genome_Project
Brain and Behavior Page 2