BIO 151 1st Edition Lecture 16 Outline of Last Lecture 1. Mutations2. Nonsense mutations create new stop codons in DNA template for mRNA, make abnormally short proteins3. DNA nucleotide sequence contains information for...4. Mutations can remove or create new splice sites in DNA template for mRNA5. DNA arrangements can change gene expression6. Simplifying part of the central dogma - DNA replication via polymerase chain reaction (PCR)7. PCR geometrically amplifies DNA between the 2 primers, but need both DNA and a protein (DNA polymerase)8. RNA World Hypothesis9. Self-Replicating DNAOutline of Current Lecture 1. Assume early cell has membrane DNA to RNA to protein2. Eukaryotes have membrane-bound "organelles"3. Evolution of eukaryotes4. Prokaryotes vs. eukaryotes5. Mitochondria6. Chloroplasts7. Endosymbiant8. Endocytosis9."Semi-autonomous" organelles10. Some cells have true bacterial endosymbionts11. Nucleus12. Protein import into nucleus13. Endomembrane system for secreted and transmembrane proteins, carbohydrates, lipids14. Endoplasmic Reticulum (ER)15. Smooth ER16. Rough ER17. "Processing" of proteins in ER and Golgi18. Vesicle formation and trafficking Current Lecture Assume early cell has membrane DNA to RNA to protein:- something like modern prokaryote- next big steps: -metabolic diversity how to get energy (photosynthesis, etc.)-prokaryotes to eukaryotesEukaryotes have membrane-bound "organelles":- prokaryotes - 3.4 billion years ago- eukaryotes - 1.3 - 1.8 billion years ago- infolding of plasma membrane to make nucleus, endomembrane?- What about other organelles?Prokaryotes vs. eukaryotes:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- eukaryotic cells - most are larger, more complex than prokaryotesSemi-Autonomous organelles:- where most of the ATP comes from in most eukaryotic cells- the energy to make ATP comes from catabolic reactions that are exergonic- ATP hydrolysis provides the energy for cellular processes that are endergonicMitochondria:- in almost all eukaryotes- produce ATP from carbohydrates, fats, etc.Chloroplasts:- in plants and some protists (single-celled eukaryotes)- produce ATP and carbohydrates from sunlight = photosynthesisEndosymbiant:- theory for semi-autonomous organelles- symbiosis - organisms living together in direct and intimate contact- endosymbiant - one living inside (endo) otherEndocytosis: - pinching off captures substance from outside cell"Semi-Autonomous" Organelles:- mitochondria and chloroplasts contain DNA in small circular chromosomes - replicates, transcribed into RNA- have ribosomes that resemble bacterial ribosomes- other biochemical similarities to specific modern bacteria- they reproduce in cells by fission- circular DNA in mitochondrion (mtDNA has transcription units for):-2 bactera-like ribosomal rRNAs-22 transfer RNAs- 13 protein-coding genes, all for components helping to make ATP- all other genes for making mitochondria reside in cells- nucleus - moved from endosymbiant to host over time?Some cells have true bacterial endosymbiants:- Rickettsia bacteria live only inside eukaryotic cells- cause many diseases: typhus, Rocky Mountain spotted fever, etc.- produce energy similarly to mitochondriaNucleus:- chromatin strands of chromosomes- nucleolus - site(s) of rRNA synthesis, assembly of large and small ribosomal subunits- nuclear envelopes - 2 lipid bilayers- inner and outer nuclear envelopes perforated by nuclear "pores"Protein import into nucleus:- import protein - shuttles back and forth in "pore" - more like active transport- nuclear localization (import) signal sequence = amino acid sequence that allows protein to bind nuclear import protein- mRNA export from nucleus: binds export proteins that contain nuclear export signal sequences- different adaptors for ribosome subunits, tRNAsEndomembrane system for secreted and transmembrane proteins, carbohydrates, lipids:- endoplasmic reticulum - Golgi apparatusEndoplasmic Reticulum (ER):- network of membrane-enclosed tubes, discs- continuous with outer nuclear envelope- rough ER has ribosomes, smooth ER does notSmooth ER:- synthesis of many molecules, including some lipids and carbohydrates- storage of substances, including Ca2+ release from ER plays role in muscle contraction, other eventsRough ER:- transmembrane and secreted proteins made by ribosomes outside rough ER- secretion signal sequence allows insertion through protein in ER membrane- secreted proteins move from ER to Golgi apparatus = stack of flattened membrane-bound discs- more processing, carbohydrate formation- molecules move from cis layer to trans layer?"Processing" of proteins in ER and Golgi:- some cleaved to make smaller polypeptides- some linked to other proteins- some linked to other molecules, especially carbohydrates = glycosylationVesicle formation and trafficking:- membrane vesicles can fuse with or pinch off from cell membrane- but can also happen with intracellular membranes of ER, Golgi, etc.- movement to and from ER and Golgi via transport and secretory vesicles and