lec 11- heritable variation Flashcards
what are the major factors to evolutionary changes?
evolution, development, and gene regulation
what is the ultimate source to new variations?
mutations
even tho the life stages of the black swallowtail butterfly have the same genotype, they look different, why is that?
they have different phenotypes due to gene regulation
what is eukaryotic DNA organized into?
chromosomes which contain DNA and histone proteins
what must happen to the DNA from histones to activate and be transcribed?
it must be unwound
what are proteins and what are their structures?
-they are specific chains of amino acids that only function in the quaternary structure
-changes in quaternary structure result in modification of the function of the protein
can mutations alter amino acid sequences and proteins?
yes
what does insulin consist of?
two amino acid chains linked by 3 disulfide bridges
which species have identical insulin?
human, chimpanzees, and monkeys
which animals insulin was used first to treat diabetes and how does it differ from humans?
-pig insulin
-differs by one amino acid position while cow has 3 differences
what do chromosomes come in?
homologous pairs (maternal + paternal)
what is a karyotype?
a complete set of chromosomes of an inidvidual
what are the types of ploidy levels?
-Haploid (n)
-Diploid (2n)
-Triploid (3n)
-Tetraploid (4n)
-polyploidy more than two sets of chromosomes
what is needed for the production of proteins from DNA?
transcription and translation
what is gene expression?
process by which info from a gene is turned into a protein product
what occurs during translation?
mRNA is taken to ribosome where the tRNA carrying an amino acid binds to the start codon, it works its way down attaching more amino acids until amino acid chain is formed
how many codons are there?
64 codons of 4 nucleotides
Why are the codes for codons so redundant?
to prevent mutations, mutations are common but mostly neutral
who came up with the neutral theory and what is it?
-Motoo Kimura
-said that most evolution at the molecular level is neutral
-mutations are neutral
-came up with the molecular clock hypothesis
what is the molecular clock hypothesis?
-since neutral mutations accumulate at a constant rate, they can be used as a molecular clock to estimate evolutionary time and divergence between species
is gene expression regulated?
yes, can be turned off or on by transcription factors
why are humans and chimps so similar in genes but still different?
due to gene regulation
what do microRNA do?
-block translation into proteins by binding to specific spots on mRNA molecules
-mutation of microRNA can affect regulation in other parts of plants and animals
what does RNA splicing do?
create multiple proteins from a single gene
what is in the 1.2% of the genome that isnt coded for?
the non-coding region includes:
-RNA genes
-Psudogenes
-microsatellites
-they reflect the evolutionary history of the genome
what are mutations and their characteristics?
-errors in DNA
-usually deleterious (may become beneficial)
-or neutral
what are the 7 types of mutations?
-point mutations
-insertions
-deletions
-gene duplication
–inversion
-chromosome fusion
-genome duplication (ploidy changes)
what are some rare human point mutations?
albinism, polydactyly, piebald skin and more
what is albinism?
a recessive point mutation that blocks melanin production in melanocytes
what is melanism?
common polymorphism in mammals birds and others, causes affect in formation and distribution of melanin
why was the industrial melanism the pepper moths experienced beneficial?
the beneficial mutation allowed the moth to become darkened and match soot covered environments
did the 2a and 2b chromosome in chimps fuse in humans to become homologous?
yes
why is polypetaly mutation in salmonberry flowers beneficial?
causes red berries instead of yellow which are preferred by birds
what are somatic mutations?
mutations that affect one cell and its descendants in the body of an organism, not heritable
