BILD 3 Notes - Lecture 9 PDF

BILD 3: Midterm 2 (Notes) Distinguishing & Categorizing Species ○ Traits that are shared due to COMMON ANCESTRY are used to CLASSIFY organisms. They are put into GROUPS that will reflect their EVOLUTIONARY HISTORY. Hatch Marks ○ These represent a CHA...

BILD 3: Midterm 2 (Notes) Distinguishing & Categorizing Species ○ Traits that are shared due to COMMON ANCESTRY are used to CLASSIFY organisms. They are put into GROUPS that will reflect their EVOLUTIONARY HISTORY. Hatch Marks ○ These represent a CHARACTER that is SHARED by the group to the RIGHT of the mark. Taxonomic Methods ○ Taxonomy will incorporate MULTIPLE METHODS for identifying and describing NEW species. The Polyphasic Approach ○ This approach to taxonomy will use THREE METHODS: Method 1: Phylogenetic Analysis Method 2: Genotypic Analysis Here, you will look at the GENOTYPES and the DNA itself. Method 3: Phenotypic Analysis Here, you will look at OBSERVABLE CHARACTERISTICS that are PRESENT in the organisms. Phylogenetic Analysis ○ This is a scientific method that will study the EVOLUTIONARY RELATIONSHIPS between ORGANISMS and TRAITS. Example: Dog/Cat/Bat/Wolf They are all MAMMALS, but since they look so DIFFERENT, no one would have noticed. The PHENOTYPIC analysis would help differentiate between them, but it would not tell us about their COMMONALITY. How To Build A Tree ○ Step 1: Align The Sequences The DNA sequences will be put together in rows, and they will look for the DIFFERENCES. ○ Step 2: Make A Distance Matrix They are all compared with each other and it is used to identify how many DIFFERENCES are in the sequences. A “---” = NO DIFFERENCE. ○ Step 3: The tree is constructed by adding NODES to join LINEAGES. The nodes are meant to join LINEAGES with the FEWEST DIFFERENCES. Differences are how organisms in a population will DIVERGE from one another, and this will come from MUTATIONS. 1 & 2 = SISTER TAXA 3 & 4 = SISTER TAXA BILD 3: Lecture 9 (Notes) Analogous Structures ○ These are structures that are SIMILAR but the creatures are NOT closely related. Example 1: (Shark Vs. Dolphin) Similarities: ○ Dorsal Fins ○ Streamlined Body ○ Flippers Differences: ○ Sharks are FISHES but a dolphin is a MAMMAL, but people would not know this based on EXTERNAL APPEARANCES. Convergent Evolution ○ Sugar Gliders are Australian Marsupials that SUPERFICIALLY RESEMBLE the Flying Squirrel, a North American EUTHERIAN. Marsupial: Their EMBRYONIC DEVELOPMENT is done OUTSIDE of the uterus (Kangaroo). Eutherian: Their EMBRYONIC DEVELOPMENT is done INSIDE the UTERUS. Three Domain System ○ In the late 1970s, there was a SCIENTIST who found THREE DOMAINS in the Tree of Life: BACTERIA, ARCHAEA, and EUKARYA. He claimed that there were 3 MAIN DOMAINS in the TREE OF LIFE. There was a division where BACTERIA/ARCHAEA were considered the same thing: PROKARYOTES. Prokaryotes: NO NUCLEUS/NUCLEAR MEMBRANE Eukaryotes: YES NUCLEUS Ribosomal Subunits ○ Dogma: DNA —> RNA —> PROTEIN rRNA is HIGHLY CONSERVED. The difference between the RIBOSOMAL SUBUNITS for BAE is their DIVERGED SEQUENCES. ○ The ribosomal subunits in BAE highlight that there are SMALL DIFFERENCES in the DNA sequences. Even though there are differences, they are so small that they DO NOT affect the function. There will be a MUTATION that will allow us to identify a difference. 16S rRNA = Molecular Clock  This will track the TIME of how long it takes for a cell to acquire a certain number of MUTATIONS. ○ We assume that evolution proceeds EXACTLY at the SAME SPEED per each ORGANISM. This is known as OCCAM’S RAZOR, and it is NOT ACCURATE. All trees are ESTIMATES! Eukaryotes & Ribosomal Subunits ○ Bacteria/Archaea are the ones that have 16S rRNA Eukaryotes DO NOT have 16S rRNA, because they do not have the 16S rRNA GENE. Instead, they have the 18S rRNA GENE. They can also analyze ITS, which is the DNA region between the rRNA SUBUNITS. ○ If not, then they can analyze the MITOCHRONDRIAL DNA, which is known as mtDNA. ○ The human genome has 47 PIECES, because the 47th comes from MITOCHONDRIAL DNA. Mitochondrial DNA comes from the MOTHER, so it can be used to determine the RIBOSOMAL SUBUNITS. The SPERM will only bring DNA. However, the EGG will bring MITOCHONDRIAL DNA and the regular DNA. ○ It is because the EGG is entirely made of MITOCHRONDRIAL DNA.