Molec Cell Bio (Chapter 7: Evolution)

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What is the germ line?

the cell lineage in a multicellular organism that contributes to the formation of the next generation by producing gametes (sperm or eggs)

What are the two types of genetic changes that contribute to gene alteration and genome evolution?

1) Vertical transfer
2) Horizontal transfer

What is vertical transfer?

from parent to progeny. mendelian inheritance

What is horizontal transfer?

from one organism to another
-conjugation
-viral infections

-EX) conjugation, viral infections

What is conjugation?

the transfer of DNA from one bacterium to another through a sex pilus

result is genetic recombination WITHOUT reproduction

What is the difference between sex and reproduction?

Reproduction is the making of new organisms

Sex is the transfer of info from organism to another

Explain how the drosphila experiment where drosphila acquired antennaes through eyes

-alteration of regulatory sequence of Antennapedia gene
-caused insertion of mobile genetic element which caused gene to be ectopically expressed in head

What is the somatic cell line?

(body cell): any cell in a multicellular organism that is not a germ line cell

What happens if a mutation occurs in a somatic cell?

-only the progeny of that cell will be affected in the individual in which the mutation occured

What happens if a mutation occurs in a germ cell?

-the mutation will not affect the individual
-may be passed on to the next generation (may result in heritable trait)

Germline cell. Parent and offspring

*haploid germ cells: gametes (sperm or eggs)

Mutation within a gene results in what?

altered product

Mutation in regulatory region results in what?

altered expression (phenotype)

Gene duplication within a gene results in what?

new gene family

When does gene acquisition occur?

When gene is acquired from one organism to another (horizontal transfer)

Related genes may take very different developmental pathways due to differences in the what?

regulatory DNA

so you can have the same regulators, but the expression of genes will change depending on where the transcription regulator is binded

What are gene families?

-groups of genes that originate from a common ancestor
-have similarities in structure and/or function

Globin gene family

-these genes code for hemoglobin subunits
-all have same structure (three exons and two introns)
-different members expressed during fetal, embryonic, and adult stages
-some are pseudogenes (non-functional genes)

What does hemoglobin do and what is it's structure?

-transports O2 and CO2 in circulatory system
-adult version contains four subunits: two alpha, two beta
-heme group: iron-containing molecule in each globin subunit

The ordering of genes on the chromosome corresponds to the order of what?

expression (embryonic, fetal, and adult)

single regulatory region on each chromosome, located to left of each group

Different globins have different affinities for what?

O2 (alpha has higher affinity for oxygen)

What can cause misalignments and unequal crossing over within homologous chromosomes?

-short repeated sequences
-these sequences are non-coding conserved sequences scattered throughout the genome
-results in altered sizes and genetic contents

aka IR (interspersed repeats)

Short repeated DNA sequences are also known as what?

interspersed repeats

What happens if a cell division fails to occur following DNA replication in a germ line cell?

-the entire diploid set may be passed to gametes and eventually to progeny

Xenopus genus

-X. tropicalis has diploid genome
-X. laevis (huge frog): occurs when a whole genome duplication occurs, resulting in tetraploid species

Explain how the transposition of eukaryotic MOBILE GENETIC ELEMENTS can mediate the recombination of genes or regulatory requences.

-if two similar mobile genetic elements happen to insert near each other in a chromosome, transposition mechanism may use ends of two diff elements and move entire segment of chromosome between them

What can alter the tissue-specific pattern of expression of genes?

transposition of regulatory requences

Explain exon transposition of mobile genetic elements?

-if the transposed segment between two similar mobile genetic elements contains an exon, its insertion into a second gene would create a new version of that gene

see slide 19

Which has a higher affinity for oxygen? Fetal hemoglobin or maternal hemoglobin?

-fetal hemoglobin

Where do gene families originate from?

gene duplications

What are genetic changes that contribute to gene alteration and genome evolution?

1) mutation within a gene
2) mutation in regulatory region
3) gene duplication
4) horizontal and vertical transfer

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