Sept 24th - Cells, genomes, and model organisms

• cell: the fundamental unit of life

            - morphically & structurally diverse and share common features

1) adaptation

2) complexity & organization

3) growth, development, and death

4) interactions - cell environment

5) energy acquisition

6) transmission of genetic information between generations

7) homeostasis

• common ancestry contributes to cellular unity

            - LUCA (origin of life)

            - vertical transmission of genomes sends information from parent to progeny to multicellular organism

            - 4 bases: optimal number of bases to construct nucleotides; two would be too few for what genetic information could code for & eight would be too costly (energetically)

            - 2 strands: two strands will code for different genetic information

• DNA genomes are replicated semi-conservatively

• central dogma

            - genetic information is transferred in multiple forms

            - proteins do the work both structurally & functionally

• a genome contains all an organism’s genetic information, but genes aren’t uniformly active

            - differences in cell morphology and behavior emerge depending on which genes are active

            - for cells to get energy, hydrophobic and nonpolar / uncharged molecules pass through the lipid bilayer

• information transfer is not perfect — alterations are the basis of evolution

            - genomic differences

            - radiation, oxidants, and radicals in DNA replication alter genetic sequences

            - mutations (some parts of the genome are more likely to mutate than others)

            - new genes are generated from existing genes: 1) mutation 2) gene duplication 3) DNA segment shuffling 4) horizontal DNA transfer