23. 3. Genetics and molecular similarities All organisms have DNA and share a great similarity in proteins, carbohydrates and lipids that make them up. Metabolic processes are also very similar in many ways.
33. Write a few sentences that summarize the relationship between organisms A, B, and C. Does “B” have to be extinct in order for “C” to exist? Does the common ancestor have to be extinct? Image courtesy of http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_05
45. A very brief comparison: Prokaryotes Eukaryotes Mitochondria Chloroplasts DNA 1 single, circular chromosome Many linear chromosomes 1 single, circular chromosome 1 single, circular chromosome Replication Binary Fission Mitosis Binary Fission Binary Fission Electron Transport Chain In the plasma membrane of the cell Found only in mitochondria and chloroplasts In the plasma membrane around the mitochondria In the plasma membrane around the chloroplast Size 1-10 µm 50-100 µm 1-10 µm 1-10 µm Ribosomes 70 S 80 S 70 S 80 S
Notes de l'éditeur
Example: the Afrikaner population of Dutch settlers in South Africa is descended mainly from a few colonists. Today, the Afrikaner population has an unusually high frequency of the gene that causes Huntington’s disease, because those original Dutch colonists just happened to carry that gene with unusually high frequency. This effect is easy to recognize in genetic diseases, but of course, the frequencies of all sorts of genes are affected by founder events.
Humans have probably had two major bottlenecks. One during the migration out of africa (africans are more diverse than all other races) and another at the Bering land bridge (native americans least diverse). There are many examples of founder effect in small populations
Behavioral. Not reproductive because that is when parts don’t fit and/or matings don’t make fertile offspring.
Reproductive and Behavioral…….. donkeys have 62 chromosomes, horses 64. unable to match up, hybrid is sterile. Donkey usually the male, the missing chromosomes not as imp. “Hinnies” are female donkey, male horse. More rare.
REVIEW
Stress that cladograms not only serve as a pictorial representation of lineage, but also as a snapshot in time. Be sure to introduce the term SPECIATION. The four descendents are DIFFERENT species.
Students should look at this illustration and begin to understand the concept of common ancestry. Be sure to have students justify their answer to the question.
Students should be given a few minutes to consider the answer to this question. It is useful to have each student write a one or two sentence explanation of what they are thinking AND why. The metacognitive aspect of this exercise will set the tone for the rest of the presentation.
Think-pair-share
Dolphins and sharks …
Lynn Margulis 1938- U of Chicago, U of Wisconsin, UC Berkely. Faculty at Boston University when proposed the Endosymbiotic theory, rejected by all journals While E.S. theory is widely accepted or at least plausible, she holds other various unconventional ideas (ex. About AIDS, evolution, etc)
70 S are smaller, have less amino acids/proteins, 2:1 RNA:protein ratio…. 80 S are larger, have more… 1:1 RNA:protein ratio The “S” refers to the sedimentation rate