Download presentation
Presentation is loading. Please wait.
1
Genomes and Their Evolution
Chapter 21 Genomes and Their Evolution
2
What you need to know: The major goals of the Human Genome Project
How prokaryotic genomes compare to eukaryotic genomes. The activity and role of transposable elements and retrotransposons. How evo-devo relates to our understanding of the evolution of genomes. The role of homeotic genes and homeoboxes.
3
Bioinformatics Use of computers, software, and math models to process and integrate data from sequencing projects
4
Human Genome Project Purpose: to sequence the entire human genome
Completed in 2003 Genomes sequenced thus far*: 58,000 prokaryotes, 2700 eukaryotes, 5300 viruses * Data as of 1/27/16
5
Human Genome Project
6
Comparing Genomes of Bacteria, Archaea, & Eukaryotes
What surprises you?
7
Human DNA 3 billion base pairs ~20,000 genes
Only 1.5% codes for proteins (or RNA) Mostly Repetitive DNA: sequences present in multiple copies
8
Video Clip: What are SNPs?
9
Transposable Elements
Make up 75% of repetitive DNA Stretches of DNA that can be moved from one location to another in genome Discovered by Barbara McClintock – corn breeding experiments 2 Types: Transposons Retrotransposons
10
Transposons Moves within genome via DNA intermediate
“cut & paste” or “copy & paste” mechanisms Requires enzyme transposase
11
Retrotransposons Move by means of RNA intermediate
Leaves copy at original site Involves enzyme reverse transcriptase
12
Choose Transposon or Retrotransposon for each statement.
“QUIZ”! Choose Transposon or Retrotransposon for each statement. ____________________ Uses a DNA intermediate ____________________ Uses reverse transcriptase ____________________ Uses a “copy paste” or “cut paste” method Transposon Retrotransposon Transposon
13
All of this adds to genetic variation!
Genome Evolution All of this adds to genetic variation! Insertion effects of transposons: Can interrupt or alter gene function Multiple copies of genes Duplication genes with related functions Genes diverge by accumulating mutations Some become nonfunctional pseudogenes Eventually, new genes with new functions can occur
14
Multigene Families Collections of 2 or more identical or very similar genes Eg. hemoglobin: -globin and -globin gene families
15
Transpositions chromosomal rearrangements
Thoughts on the Human & Mouse chromosomes? Transpositions chromosomal rearrangements Thoughts on the Human & Chimpanzee chromosomes?
16
Transposable elements contribute to evolution
Promote recombination, disrupt genes or control elements, & carry genes to new locations May be harmful or lethal, but can also have small beneficial effects Provides raw material for natural selection
17
HHMI Short Film: The Birth & Death of Genes
18
Illustrative Example: Antifreeze Gene in Fish
Antifreeze proteins (AFP): produced by vertebrates, plants, fungi, bacteria to aid survival in sub-zero environments Function: bind to ice crystals and prevent growth Antarctic fish: old protein gene transformed into a new gene with new structure/function Gene mutates duplicated divergent evolution
19
Evolutionary Development (Evo-devo)
Compares developmental processes to understand how changes can lead to evolution of organisms
20
Homeotic genes: master regulatory genes
Control placement and spatial organization of body parts Homeobox: widely conserved 180-nucleotide sequence within homeotic (Hox) genes Found in many groups (fungi, animals, plants) Hints at relatedness between all life forms
21
Conservation of homeotic genes
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.