W 7/30 exam #3 (bring cheat sheet) bonus #2 due W 8/6 optional final exam, during class time

Homologous pair of chromosomes Linkage can be used to determine distance

Some crosses do not give the expected results

By comparing recombination frequencies, a linkage map can be constructed = 17 m.u.

A much greater proportion of the two types found in the parental generation Fig 5.2

The probability of crossing over can be used to determine the spatial relationship of different genes

Double recombinants arise from two crossovers Recombinant

Double recombinants can show gene order

similar to Fig 5.3, also see Fig 5.9, and pg What is the relationship between these 3 genes? What order and how far apart?

similar to Fig 5.3 What is the relationship between these 3 genes? What order and how far apart?

Double crossover

Which order produces the double crossover?

We have the order. What is the distance?

Recombinants between st and ss: ( )/755 =14.6%

Recombinants between ss and e: ( )/755 =12.2%

stsse 14.6 m.u m.u m.u. Put it all together…

Drosophila linkage map

Linkage map of Drosophila chromosome 2

Yeast chromosome 3 physical distance linkage map Recombination is not completely random.

Alignment of physical and recombination maps

PhenotypeGenotype Genes code for proteins (or RNA). These gene products give rise to traits… It is rarely this simple.

For life to exist, the information (genes) must be passed on. {Mitosis: producing more cells} {Meiosis: producing gametes}

105 males : 100 females (live births) Why?

105 males : 100 females (live births) Why?

Is this all of your DNA?

Mitochondria have their own DNA. Fig 7.13

Endosymbiotic Theory - proposed origin of mitochondria and chloroplasts from free-living bacteria to cellular organelles Fig 7.20

Human Life Cycle Combination of two individuals DNA

mitochondria Only the egg provides mitochondria to the offspring.

Human Life Cycle In females Mom provides % and Dad provides % of DNA to offspring. … because Mom provides 100% of mitochondrial DNA

Mitochondrial DNA comparisons can be used to trace ancestry:

Tsar’s Family During the Bolshevik revolution, the Tsar’s family was captured and executed.

Tsar’s Family There are many stories about what happened to their youngest daughter Anastasia

Anna Anderson, claimed she was Anastasia

Anna Anderson claimed she was Anastasia, but tests of her mtDNA and one of Anastasia’s maternal relatives did not match.

For more info check out: Or the book “Seven Daughters of Eve” by Bryan Sykes

How do individuals and groups with different genes arise? Evolution… Does it occur? How does it occur?

Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces.

Does evolution occur?

As DNA changes; traits change. Protein

DNA is replicated semi-conservatively

When DNA is replicated, mutations occur.

CB 13.5 DNA must be replicated before it can be passed on. How it is passed on and how it gets modified impacts evolution.

Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces.

Natural Selection: Individuals that are most successful at reproducing will pass on more of their genetic information.

O O OOO O O OO OO Bacteria with mutation causing resistance Evolution: changes in DNA as information transmitted

O O OOO O O OO OO O O OOO O O OO OO Apply antibiotic X XX XXXX X XX Kills most bacteria. Except if some have mutation that allow them to be resistant. Bacteria with mutation causing resistance Evolution: changes in DNA as information transmitted

O O OOO O O OO OO O O OOO O O OO OO O Apply antibiotic X XX XXXX X XX Kills most bacteria. Except if some have mutation that allow them to be resistant. Continues to replicate Bacteria with mutation causing resistance Evolution: changes in DNA as information transmitted

O O OOO O O OO OO O O OOO O O OO OO O O OOO O O OO OO O Apply antibiotic X XX XXXX X XX Kills most bacteria. Except if some have mutation that allow them to be resistant. Continues to replicate Population of resistant bacteria Bacteria with mutation causing resistance Evolution: changes in DNA as information transmitted

Evolution: A species’ genetic component changes as the individuals reproduce due to… Non-random changes (natural selection) Random changes (genetic drift/bottleneck) Mutations add new alleles or genes

Generation 1 Generation 3 Generation 4 Generation 5 Generation 2 MutationReplicationDriftSelection Mutations are subject to Drift and Selection

Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces.

How are we related, and where did we come from?

Human DNA is divided into 46 chromosomes (23 pairs)

Mom provides % and Dad provides % of DNA to offspring. … because Mom provides 100% of mitochondrial DNA CB 13.5

Mitochondrial DNA comparisons can be used to trace ancestry:

Why use mtDNA? Fig 7.14

Non-Coding DNA is used for comparisons between individuals Fig 7.14

Why use mtDNA? Fig 7.14

Why use mtDNA? No crossing-over Fig 7.14

Why use mtDNA? No crossing-over No ends, less likely to be damaged Fig 7.14

mtDNA exists as multiple copies per cell

Fig 1 and 4 As DNA is passed on mutations take place

What happened to the Neanderthals?

What happened to the Neanderthals? Analysis of one million base pairs of Neanderthal DNA: “We have identified a 38,000-year-old Neanderthal fossil that is exceptionally free of contamination from modern human DNA.” Genetic evidence and the modern human origins debate: “At present, it is difficult to distinguish between a model of total genetic replacement and a model that includes some degree of genetic mixture.” No Evidence of Neandertal mtDNA Contribution to Early Modern Humans: “In combination with current mtDNA data, this excludes any large genetic contribution by Neandertals to early modern humans, but does not rule out the possibility of a smaller contribution.” A 28,000 Years Old Cro-Magnon mtDNA Sequence Differs from All Potentially Contaminating Modern Sequences: “The Paglicci 23 individual carried a mtDNA sequence that is still common in Europe, and which radically differs from those of the almost contemporary Neandertals, demonstrating a genealogical continuity across 28,000 years, from Cro-Magnoid to modern Europeans.”

Tbl. 1 Serre D, Langaney A, Chech M, Teschler-Nicola M, Paunovic M, et al. (2004) No Evidence of Neandertal mtDNA Contribution to Early Modern Humans. PLoS Biol 2(3): e57 PCR of mtDNA from fossils

Fig. 3 Serre D, Langaney A, Chech M, Teschler-Nicola M, Paunovic M, et al. (2004) No Evidence of Neandertal mtDNA Contribution to Early Modern Humans. PLoS Biol 2(3): e57 The four upper DNA sequences were determined in this study. Previously determined DNA sequences are shown below. Comparisons of modern human and Neanderthal mtDNA sequences

Fig. 1 Neanderthals in central Asia and Siberia. J Krause, L Orlando, D Serre, B Viola, K Prüfer, M Richards, J Hublin, C Hänni, A Derevianko, S Pääbo (18 October 2007) Nature 449, Known fossil range of Neanderthal Extension of range via mtDNA

Fig. 1 Analysis of one million base pairs of Neanderthal DNA. R Green, J Krause, S Ptak, A Briggs, M Ronan, J Simons, L Du, M Egholm, J Rothberg, M Paunovic, S Pääbo Nature (16 November 2006) 444, Contamination of Neanderthal fossils with modern DNA

Fig. 5 Analysis of one million base pairs of Neanderthal DNA. R Green, J Krause, S Ptak, A Briggs, M Ronan, J Simons, L Du, M Egholm, J Rothberg, M Paunovic, S Pääbo (16 November 2006) Nature 444, ~8% of differences between human and chimp occurred since the divergence from Neanderthal

Fig. 6 Analysis of one million base pairs of Neanderthal DNA. R Green, J Krause, S Ptak, A Briggs, M Ronan, J Simons, L Du, M Egholm, J Rothberg, M Paunovic, S Pääbo (16 November 2006) Nature 444, ~6.5 million ya ~500,000 ya

What happened to the Neanderthals?

W 7/30 exam #3 (bring cheat sheet) bonus #2 due W 8/6 optional final exam, during class time