ne102 3/25 lecture - genome, new genes, gene editing + CRISPR

how do genes and genomes evolve?

through the role of coding + non-coding DNA

chromosome 22

composed of two double-stranded DNA molecules, each 48M nucleotide pairs long; most of the DNA is NON coding

how did DNA changes + evolution occur

modifications in any region of a DNA molecule can change how the info stored in DNA is used → consequences on evolution + disease

germ line cells

info in germ line cells will be passed onto next generations + define their somatic/germ cell lines (gametes)

what happens when new mods occur in the DNA of germ line-cells? somatic?

mods will be passed onto next gen + will be present in their somatic/gametes. mods in somatic cells will NOT be passed on

what happens when gametes carry mods?

every time gametes carry mods in the DNA → genome + genes are changed → development/evolution

how are new genes formed?

1. point mutations (single nucleotide changes in the DNA)

2. rearrangements of DNA sequences

3. changes in protein characteristics/function/expression

4. changes in transcriptional activation

5. breaking + rejoining at intron sequence

point mutations

caused by the presence of single nucleotide changes in any one exon/intron of a gene, or a regulatory region

effects of point mutations

“new” proteins are made: in coding region, different AA can be benign (protective from disease) or toxic (causing disease); same AA = neutral/silent

lactose tolerance

point mutation in regulatory DNA of lactase gene is responsible for lactose tolerance

CRISPR

clustered regularly interspaced palindromic sequences

what is CRISPR?

specific DNA sequence found ONLY in DNA of bacteria cells; designed to integrate genetic material from viruses into bacteria DNA → bacteria kills virus

how viruses invade prokaryotic cells

bacteria infected w/ virus → viral DNA transcribed + viral proteins are made → viral DNA copied by DNA poly, multiplying them → infection

how can bacteria cells protect themselves against viral infections?

they exploit the genetic info stored in viral DNA to break down viral DNA itself by incorporating sequences of viral DNA in their own DNA to fight