Bacteria  Bacteria are great!  one-celled organisms  reproduce by mitosis  easy to grow, fast to grow  generation every ~20 minutes

Bacterial DNA  Single circular chromosome  only one copy = haploid  no nucleus  Other DNA = plasmids! bacteria chromosome plasmids

There’s more…  Plasmids  small extra circles of DNA  carry extra genes that bacteria can use  can be swapped between bacteria  bacterial sex!!  rapid evolution = antibiotic resistance  can be picked up from environment

How can plasmids help us?  A way to get genes into bacteria easily  insert new gene into plasmid  insert plasmid into bacteria = vector  bacteria now expresses new gene  bacteria make new protein + transformed bacteria gene from other organism plasmid cut DNA recombinant plasmid vector glue DNA

Grow bacteria…make more grow bacteria harvest (purify) protein transformed bacteria plasmid gene from other organism + recombinant plasmid vector

Biotechnology Gel Electrophoresis

Many uses of restriction enzymes…  Now that we can cut DNA with restriction enzymes…  we can cut up DNA from different people… or different organisms… and compare it  why?  forensics  medical diagnostics  paternity  evolutionary relationships  and more…

Comparing cut up DNA  How do we compare DNA fragments?  separate fragments by size  How do we separate DNA fragments?  run it through a gelatin  gel electrophoresis  How does a gel work?

Gel electrophoresis  A method of separating DNA in a gelatin-like material using an electrical field  DNA is negatively charged  when it’s in an electrical field it moves toward the positive side + – DNA        “swimming through Jello”

 DNA moves in an electrical field…  so how does that help you compare DNA fragments?  size of DNA fragment affects how far it travels  small pieces travel farther  large pieces travel slower & lag behind Gel electrophoresis + – DNA        “swimming through Jello”

Uses: Forensics  Comparing DNA sample from crime scene with suspects & victim – + S1 DNA  S2S3V suspects crime scene sample

DNA fingerprints  Comparing blood samples on defendant’s clothing to determine if it belongs to victim  DNA fingerprinting

RFLP / electrophoresis use in forensics  1st case successfully using DNA evidence  1987 rape case convicting Tommie Lee Andrews “standard” semen sample from rapist blood sample from suspect How can you compare DNA from blood & from semen? RBC?

Gene Therapy: experimenting in cystic fibrosis  In gene therapy, an absent or faulty gene is replaced by a normal, working gene.

Human Genome Project  An ongoing effort to analyze the human DNA sequence **Important because it could be used to cure genetic disorders -determines carriers of genetic conditions -Helps develop gene therapy

Cloning  A clone is a member of a population of genetically identical cells produced from a single cell.  Dolly, Cows, Cats and more.  Bring back endangered or even extinct species.  Dolly the sheep was 1 st clone!

Human Chromosomes  23 pairs of Chromosomes for a total of 46. – 1-22: autosomal – 23: sex chromosomes  Karyotypes, pictures of chromosomes, can be used to study our chromosomes.

Karyotype