Heredity Review

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Heredity Review
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Asexual reproduction
Hydra (related to jelly-fish
Single celled eukaryotes like this protist
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Zygote (2n) - diploid
n chromosomes
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Independent Assortment
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Codominance
Incomplete Dominance
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Epistasis
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Thomas Hunt Morgan
Discovered sex-linked traits
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• The recessive mutations s (scute bristles) and rb
  (ruby eyes) identify two linked autosomal genes
  of Drosophila melanogaster. When females
  heterozygous for these genes were crossed with
  scute bristled, ruby eyed males, the following
  classes and numbers of progeny (out of 1000) were
  obtained
• wildtype bristles, wildtype eyes 188
• scute bristles, wildtype eyes 307
• wildtype bristles, ruby eyes 313
• scute bristles, ruby eyes 192
• Based upon these results, the map distance
  between the s and rb genes is estimated to be
• A. 31.3 map units
• B. 38 map units
• C. 30.7 map units
• D. greater than 50 units because all four classes
  of offspring were observed

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DNA (pattern done by Rosalind Franklin, Model
completed by Watson and Crick)
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Promoter includes the TATA box has the core DNA
sequence 5'-TATAAA-3' or a variant, which is
usually followed by three or more adenine bases.
It is usually located 25 base pairs upstream to
the transcription site. The sequence is believed
to have remained consistent throughout much of
the evolutionary process, possibly originating in
an ancient eukaryotic organism.
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G 5 cap and Poly A tail and reomval of introns
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Conjugation
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• Histone acetylation
• Seems to loosen chromatin structure and thereby
  enhance transcription

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Evolution of Genes with Related Functions The
Human Globin Genes

• The genes encoding the various globin proteins
• Evolved from one common ancestral globin gene,
  which duplicated and diverged

Figure 19.19
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• The similarity in the amino acid sequences of the
  various globin proteins
• Supports this model of gene duplication and
  mutation

• Subsequent duplications of these genes and random
  mutations
• Gave rise to the present globin genes, all of
  which code for oxygen-binding proteins

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Genomic library
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Bands form due to SNPs -Single nucleotide
polymorphisms
A single nucleotide polymorphism (SNP, pronounced
snip), is a DNA sequence variation occurring when
a single nucleotide - A, T, C, or G - in the
genome (or other shared sequence) differs between
members of a species (or between paired
chromosomes in an individual). For example, two
sequenced DNA fragments from different
individuals, AAGCCTA to AAGCTTA, contain a
difference in a single nucleotide. In this case
we say that there are two alleles C and T