Living systems store , retrieve , transmit and respond to information essential to life processes.

1. Living systems store, retrieve, transmit and respond to information essential to life processes. Big Idea #3

2. Biotechnology makes it possible engineer heritable changes But errors or mutations may occur despite repair enzymes Mutations MAY alter cellular activities and phenotypes store, retrieve, transmit, and respond Genetic Information is passed through DNA Genetic Variation is caused by sexual reproduction, Conjugation in bacteria, and lysogenesis in viruses DNA is copied during Interphase for identical cells and asexual reproduction Meiosis creates gametes which are fussed together for genetic variation Changes in phenotype and environment can result in mutations in DNA Cell Signaling RTR Mendel described a model of genetics Transmission of nonheritable information influences behavior within and between cells, organisms and populations. But most traits don’t follow this pattern

3. DNA, and in some cases RNA, is the primary source of heritable information. • Genetic information is transmitted through DNA • Prokaryotes have circular chromosomes; Eukaryotes have linear chromosomes • History: • Structure (Watson/Crick, Wilkins, and Franklin) • Experiments (Avery, Hershey/Chase)

4. Replication is semiconservative • Requires leading and lagging strands (ALL built 5-3) • Enzymes: DNA polymerase, ligase, RNA polymerase, helicase, and topoisomerase

5. DNA and RNA • Made of nucleotides, covalent bonds • DNA- deoxyribose; RNA- ribose • DNA- Thymine; RNA- Uracil • DNA double stranded; RNA single

6. mRNA, tRNA, rRNA, and RNAi • Transcription- RNA polymerase builds mRNA • Initiation, Elongation, Termination • Post Transcription modification • Poly-A tail, GTP cap, Excision of introns • Translation occurs in the ribosome.

7. Steps to understand in Translation • The mRNA interacts with the rRNA of the ribosome to initiate translation at the (start) codon. • The sequence of nucleotides on the mRNA is read in triplets called codons. • Each codon encodes a specific amino acid, which can be deduced by using a genetic code chart. Many amino acids have more than one codon. • tRNA brings the correct amino acid to the correct place on the mRNA. • The amino acid is transferred to the growing peptide chain. • The process continues along the mRNA until a “stop” codon is reached. • The process terminates by release of the newly synthesized peptide/protein.

8. Phenotypes are determined by protein activities • Enzymatic reactions • Transport by proteins • Genetic Engineering allows us to manipulate DNA • Electrophoresis, plasmid-based transformation, PCR

9. In eukaryotes, heritable information is passed to the next generation via processes that include the cell cycle and mitosis or meiosis plus fertilization. • Interphase • Growth, DNA synthesis, preparation for Mitosis • Cell Cycle is regulated by checkpoints (MPF) • Cyclin and CDK control the cell cycle • Cells may enter no division stage when it specializes, but it can reenter the cell cycle when given appropriate cues. Nondividing cells may exit the cell cycle; or hold at a particular stage in the cell cycle.

10. Mitosis passes a complete genome from the parent of offspring (replication, alignment, separation) • Mitosis occurs after DNA replication • Cytokinesis • Growth, repair, and asexual reproduction • Meiosis, a reduction division, increase variation • Homologous chromosomes pair, separate independently and create gametes • Fertilization involves the fusion of two gametes

11. The chromosomal basis of inheritance provides an understanding of the pattern of passage (transmission) of genes from parent to offspring. • Segregation and Independent Assortment can be applied to genes on different chromosomes • Terms to know: Monohybrid , dihybrid, sex-linked, linked genes • Disorders: • Sickle cell, Tay-Sachs, Huntington’s • Xlinked, Trisomy 21, Klinefelters • Ethical, social, and medical issues • Reproductive issues and ownership of genetic info

12. The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. • Many traits are from MANY genes • Sex linked recessive traits are always expressed in males • Nonnuclear inheritance • Mitochondrial DNA is transmitted form the egg

13. Gene regulation results in differential gene expression, leading to cell specialization. • DNA sequence used for regulation • Promoter, terminator, enhancer • Bacteria and viruses • Inducers turn on gene expression • Repressors inhibit gene expression • Regulatory proteins stimulate (positive control) and inhibit by (negative control). Binding! • Some genes are always turned on like Ribosomal genes

15. Eukaryotes • Transcription factors bind to promoter region to start transcription • Activators (increase expression) some are repressors (decrease expression) • Gene expression accounts for phenotypic differences with similar genes

16. A variety of intercellular and intracellular signal transmissions mediate gene expression. • Cytokines- cell replication • Mating pheromones in yeast • Levels of cAMP in bacteria

17. Changes in genotype can result in changes in phenotype. • May lead to the amount of protein produced • Mutations may be positive/negative/neutral depending on environmental context • Mutations ( random change in genome) • Mutations may change phenotype or fertility • Changes in genotype lead to natural selection • Antibiotic resistance mutations, pesticide mutations, sickle cell heterozygous advantage • Selection results in evolutionary change!

18. Biological systems have multiple processes that increase genetic variation. • The imperfect nature of DNA replication and repair increase variation (Mutation) • Transformation, transduction, conjugation, and transposition • Sexual reproduction in eukaryotes • Crossing over, independent assortment, random fertilization

19. Viral replication results in genetic variation, and viral infection can introduce genetic variation into the hosts. • Viral replication is • Highly efficient allowing for rapid evolution • RNA viruses lack replication error-checking mechanisms thus • Related viruses can combine info if they infect the same host • HIV has rapid evolution *retrovirus/reverse transcriptase • Transduction and Transposons in incoming DNA

20. Lytic vs. Lysogenic

21. Cell communication processes share common features that reflect a shared evolutionary history. • Stimulatory or inhibitory signals from other cells, organisms, or the environment start signal transduction (ligand, light wave) • Bacteria use quorum sensing • In multicellular organism signal transduction pathways coordinate the activities in the cell that support function of the organisms. • Epinephrine=glycogen breakdown in mammals • Temperature=sex determination in some vertebrates • DNA repair mechanisms

22. Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling • Cell-to-cell • Immune cells interact by cell-cell contact, antigen-presenting cells (APCs), helper T-cells and killer T-cells. • Plasmodesmatabetween plant • Short Distance • Neurotransmitters • Plant immune response • Morphogens in embryonic development • Long distance • Insulin, HGH, Thyroid, testosterone, estrogen

23. Signal transduction pathways link signal reception with cellular response. • Rectption: ligand binds to receptor protein • G-protein • Ligand-gated ion channels • Receptor tryosine kinases • Transduction: signal converted to cellular response • Signaling cascades, amplification • Response: response to the msg • Protein synthesis, protein modification,

24. Changes in signal transduction pathways can alter cellular response. • Signal transduction is blocked • Diabetes, heart disease, cancer, • Effects of neurotoxins, poisons, pesticides • Drugs

25. Individuals can act on information and communicate it to others. • Organisms exchange information in response to internal change and external cues. This may result in reproductive success • Fight of flight • Predator warning • Plant-plant interactions due to herbivory • Different mechanisms • Visual, audible, tactile, electrical and chemical signals, find food, establish territory • Bees dance, birds song, packing behavior, coloration • Response to communication lead to natural selection

26. Animals have nervous systems that detect external and internal signals, transmit and integrate information, and produce responses. • Cell body, axon, dendrites, synapse, myelin sheath • The structure allows for detection, generation, transmission, and integration of signal information

27. Action potential • Maintained by Na/K+ • Membranes are polarized by electrical potentials (Na+ and K+ channels)

28. Neurotransmitters are chemical messengers: acetylcholine, epinephrine, norepinephrine • The response may be stimulatory or inhibitory