Molecular & Cell Biology Exam 1

BCOR 2500 Lectures 1-7

What is cellular reprogramming and why is it important

Can now reprogram adult somatic cells to become neurons in hopes of one day being able to replace parts of the brain like we replace parts of our cars.

E. Coli

Bacteria, easy to keep with a short life cycle and a simpler genome. Gave us an understanding for how DNA replication, gene expression and protein synthesis work.

Yeasts

Simplest eukaryotes,

Shared characteristics with E.coli: easy to keep, short life cycle, larger genome than e. coli but simpler than humans.

Shared characteristics with humans: distinct nucleus, genomic DNA organized in 16 linear chromosomes, contains organelles

C. elegans

Nematode (eukaryotic and multicellular), small number of genes and cells that have been mapped out, good to study animal development and cell differentiation, can use mutations to study developmental abnormalities (similar genes have been found in humans)

Drosophila melanogaster

Fruit fly, genome larger than c. elegans, easy to maintain, short reproductive cycle. Good to study the molecular mechanisms of development. Similar genes and mechanisms exist in humans

Arabidopsis thaliana

Simple plant, small genome, easy to grow and maintain. Methods for molecular genetic manipulations are available, identification of genes involved in plant development.

Zebrafish

Vertebrate, easy to maintain, reproduce rapidly, embryos develop outside the mother and are transparent. Several molecular techniques available to map mutations.

Mouse

mammal, more complex than other models, many mutations identified, several mutant mice available. More applicable to medicine: similar genomes, mutations in homologous genes result in similar phenotypes.

Cell culture

allows for controlled manipulations, makes it easier to study signaling mechanisms. Primary cultures vs immortal cell lines.

HeLa cell line

Henrietta Lacks, first human cell line derived from a cervical cancer tumor. Important for the development of the polio vaccine and used around the world today.

Viruses

Intracellular parasites that cannot replicate on their own. Smaller and simpler genomes, can be studied in cultured cells. Discovered that some cancers are caused by viruses

How did biomolecules form (3)

Reducing environment, energy, liquid water

What does the RNA World Hypothesis state

The first cell was an enclosed bit of self-replicating RNA in a phospholipid bilayer.

Eventually DNA replaced RNA as the genetic material

Supporting observations for the RNA world hypothesis

Forms spontaneously, RNA can self-replicate, RNA car form enzymes (rRNA, tRNA)

Evolution of Metabolism

The first cells got energy straight from their surroundings. Later, cells started using ATP to store and use energy. O2 built up in atmosphere → cells begin using O2 to make energy more efficiently

Evolution of Cells

Hypothesized that the primordial cell gave rise to 2 varieties of prokaryotes (before nucleus): archaebacteria and bacteria.

Eukaryotes likely arose from an endosymbiosis

Supporting factors: Mitochondria and chloroplasts are prokaryote sized, have their own circular DNA and ribosomes

Covalent bonds

Strongest interaction between atoms

Can form single, double, or triple bonds

Can be polar or nonpolar

What makes carbon special?

Can engage 4 bonds with tetrahedral shape

Double bonds are planar

Can bond with itself to form chains or rings

Can bond with many other atoms

Carbon will form the backbone or organic molecules in living matter

Ionic bonds

Ions held together by attraction of opposite charges

“give and take” of electrons (forms cations and anions)

Hydrogen bonds

Noncovalent bond between a +H and -N/O/F

Weaker than the other bonds but incredibly important in cells.

Hydrophilic

Can form hydrogen bonds with water molecules, polar molecules, and surrounds charged ions

Hydrophobic/Lipophilic

Molecules without charged groups are poorly soluble in H2O and associate closely with each other instead

Amphipathic

Molecules having regions with both properties

1st Law: Conservation of ENergy

The total energy of a system and its surroundings is constant

2nd Law: Entropy increases over time

A system will change spontaneously to a state of greater disorder

Catabolic reactions (catabolism)

Downhill reactions. Breakdown of complex molecules into simpler ones and release energy that was used to form them

Anabolic reactions (anabolism)

Uphill reaction. Link simple molecules to form complex molecules. Anabolic reactions require energy to form bonds within the smaller molecules.

How do polymers form

A dehydration reaction (condensation) that occurs when 2 monomers bond together through the loss of a water molecule.

How are polymers broken down

Hydrolysis, a reaction that is essentially the reverse of the dehydration reaction: it needs water

Carbohydrates

Simple sugars, provide energy

C_n(H₂O)_n

C = 3-7

Name 3 monosccharides

Glucose, fructose, galactose

Oligosaccharide

2-10 monomers

Polysaccharide

more than 10 monomers

What are complex sugar carbohydrates useful for (3)

Energy storage (hydrolyse starch and glycogen)

Structure: cellulose, bacteria can break down.

Signaling: attach to proteins inside cell/on surface like an address

What lipid is used for energy storage and why/how

Triacylglycerides (Triglycerides): 3 fatty acids linked by a glycerol, insoluble in water. Clump together as fat droplets.

Fatty Acids

Fatty acids: long hydrocarbon chains, carboxyl group is polar, Nonpolar C-H bonds

Principle component of cell membranes

Phospholipids

What are phospholipids

2 C-H chains with a polar head group.

Acyl chains can be held together with glycerol or serine (sphingolipids)

Amphipathic = ideal for cell membranes

What lipids are used for signaling

Glycolipids, cholesterol

Glycolipids

Similar to phospholipids, head contains carbohydrate, cellular recognition

Cholesterol

The C/H chain is formed into a multi-ring structure. Also used in hormones (signaling)

end. slide 41 lecutre 2