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Lecture Notes MBOC1 2021
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Lecture notes molecular biology of the cell 1
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Lecture 1Chapter 1 Cells and Genomes
Chapter 2 Cell Chemistry and Bioenergetics
Cells contain four major families of small organic molecules:
Sugar: Glucose almost always has a closed ring. Small differences in sugars make only minor
changes in the chemical properties. But they are recognized by different enzymes and other
proteins and therefore can have major biological effects. As soon as one sugar is linked to
another you have the alfa or beta form as soon as you close it the alfa or beta form is frozen.
Fatty acid: Carboxylic acids with long hydrocarbon tails. Some have one or more double
bonds in their hydrocarbon tail and are unsaturated, these are liquid and healthier. Fatty
acid that are saturated have no double bonds and are solid. Fatty acids are stored as an
energy reserve through an ester linkage to glycerol, which makes it a triglyceride.
Phospholipids are the major constituents of cell membranes. Fatty acids have a hydrophilic
head and a hydrophobic tail. Lipids are defined as the water-insoluble molecules in cells that
are soluble in organic solvents. 2 common types of lipids are steroids and polyisoprenoids.
Isoprene is the building block of many steroids.
Nucleotide: These are the building blocks for nucleonic acids. You
have pyrimidine (uracil, cytosine, thymine) which has one ring and
the purine (adenine, guanine) which has two rings. A base + sugar is
called a nucleoside. The base is often linked with sugar (in ribose
form) and phosphate, this together is a nucleotide. Nucleotides are
the subunits of nucleic acids. Nucleotides are joined together by a
phosphodiester linkage between 5’ and 3’ carbon atoms to form
nucleic acids.
Amino acid: The general formula of an amino acid: R is commonly
one of 20 different side chains. Amino acids have a – and + side.
Amino acids are very hydrophilic, they like to be in water, they are
,polar. A peptide is some amino acid formed together, you have an amino terminus (N-
terminus) and a carboxyl terminus (C-terminus). There is no rotation around the C-N
bond of the peptide bond. This is a peptide bond →
Subunits can form covalent bonds which makes it to macromolecules, these macromolecules
can form noncovalent bonds which makes it to macromolecular assemblies.
DNA molecules were neglected by researchers because they thought DNA were very simple
molecules. James Watson and Francis Crick discovered the structure of DNA. Now we know
DNA is very important.
The tree of life has three primary branches: bacteria,
archaea, and eukaryotes.
Eukaryotic cells may have originated as predators.
Modern eukaryotic cells evolved from a symbiosis.
Mitochondria comes from aerobic bacterium that has
been indulged somewhere in the evolution. A chloroplast also has its own DNA. A
photosynthetic bacterium went into the eukaryotic cell.
The human genome project: In the cell there are 23 chromosomes pact into a nucleus. Each
chromosome contains a long coil of DNA. DNA has 4 kind of building blocks. RNA polymerase
copies the information into a messenger molecule. Messenger RNA travels out into the
cytoplasm. The ribosome reads the messenger RNA and makes amino acids. There are about
30.000 human genes.
The use of data from the humas genome project:
- Determining novel targets for medicines.
- Detection of hereditary disorders → prenatal diagnosis.
- Track down individual differences in response to medicines → personalized
medicine.
Pharmacogenomics is about the issue; why drugs work better in some patients than in
others.
, Lecture 2
Chapter 3 Proteins
Proteins are the highest portion of the macromolecules of the cell. Proteins are crucial for
the living cells.
People who don’t have the human growth hormone suffer from dwarfism. But people want
to fight dwarfism so, they use the human growth hormone as a medicine. Now this product
is made by genetic engineering but earlier the Human Growth hormone was distracted from
the pituitary glance from the brains of people who died, people became sick after a few
years.
The EMA and FDA are organizations that are approving drugs. When the active ingredient
ends with -mab it is a monoclonal antibody. Proteins are drug targets, so they are very
important. NME: New molecular entity, new drug products containing as their active
ingredient a chemical substance marketed for the first time.
The carbon atom from the amino acid is a chiral atom which means it has a
mirror image. There is a L form, and a D form Proteins consist exclusively of L-
amino acids. This is important for the form and shape of the protein. The
nonpolar side chain stays at one side and the polar side chain stays at the other
side and they fold together. →
There are 20 amino acids, there are 4 families:
- Acidic: Aspartic acid and Glutamic acid, at a neutral pH they donate a proton and
leave behind a negative o.
- Basic: Lysine, Arginine, Histidine, at a neutral pH they accept a proton and are
positive charge. Histidine’s often function as switches in proteins because the pK is
around 6.5.
This table shows at what pH the acids donate a
proton and at what pH the base accept a proton.
- Uncharged polar: Asparagine, Glutamine, Serine, Threonine, Tyrosine, they are polar
but not charged.
- Nonpolar (hydrophobics): All the other amino acids. Two cysteine side chains can
form a disulfide bond.
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