HUMAN GENOME
COPY in red
Genetic Research
Do you recognize each of these
organisms? Why are they important to
geneticists?
These organisms represent a group
known as “model organisms.” By
working with them, scientists better
understand genetics.
Guinea
pigs
E. coli
Tobacco mosaic
virus
Baker’s
yeast
Wheat
Fruit flies
Studying the human genome
Imagine a small library, with only 46 books. The longest of these books would be 3340
pages, and the shortest 400 pages. The text on the page would be a normal size and
there are not any pictures. Now, shrink that library down so it would fit inside the
nucleus of a cell. That is the amount of information found in the human genome.
Do humans have the largest “library?” Not even close. The marbled lungfish has
130 000 000 000 base pairs in its genome. Humans? Just 3 200 000 000.
Dissecting Genomes
A genome is the full DNA sequence of an organism.
The smallest human chromosome contains 5 million base pairs.
In 1990, the Human Genome Project starting mapping the entire human genome with two goals in mind:
To determine the nucleotide sequence of all the DNA in human chromosomes
To identify the location and sequence of every human gene
The project explored gene functions, studied variations among human DNA, and compared human DNA to other
species.
The Human Genome Project was completed in 2003.
Some Completed Genomes
Species
Genome Size (Nucleotide
Base Pairs)
Approximate Number of
Genes
Haemophilus influenzae
(bacterium)
1.8 million
1700
Escherichia coli (bacterium)
4.6 million
4400
Saccharomyces cerevisiae
(yeast)
12 million
6200
Caenorhabditis elegans
(nematode)
96 million
19 000
Arabidopsis thaliana (mustard
plant)
125 million
25 500
Drosophila melanogaster (fruit
fly)
170 million
13 700
Oryza sativa (rice)
470 million
60 000
Mus musculus (mouse)
2.6 billion
30 000
Rattus norvegius (lab rat)
2.8 billion
25 000
Macaca mulatta (macaque)
2.9 billion
22 000
Pan troglodytes (chimpanzee)
3.1 billion
22 000
Homo sapiens (humans)
3.2 billion
21 000
Model Organisms
Comparing genes and sequences can reveal insights about different species.
The human Parkinson’s disease gene is similar to a gene for the sense of smell in rats, and a gene for learning
songs in a species of finch.
These discoveries can lead to therapies and potential cures.
Functional genomics studies the genes of model organisms.
By understanding specific genes in these organisms, the human genome can also be better understood.
Agricultural and plant genomes can reveal potential improvements for food and medicine.
The most important aspect of current research is to understand how genes and proteins work together to create
organisms.
This research has allowed us to identify the locations and functions of human genes and to further
Genetic Engineering
disorders
our understanding of genetic
The human population on Earth continues to increase, and somehow everyone
needs to eat.
How we grow and obtain our food has changed drastically over the past 100 years.
Today, large agricultural processes that utilize genetic engineering and biological
engineering are managing to keep up with feeding most of the world. It is
estimated that more than half of what we eat has been genetically modified in
some way.
Molecular biologists have only been working with genetics at the molecular level
for the past 30 years, yet their results have saved millions of lives, and have
changed many industrial processes. How are all of these changes possible using
the simple building blocks of life?
Genetically modified foods
Genetic Engineering
- intentionally producing new genes and altering genomes by
substituting or introducing new genetic material
- in the technique called recombinant DNA, combines genes from
different sources, even different species, into a single DNA
- the organism most used is a simple bacterium (reproduces every
45 minutes)
Genetic Engineering
Questions
1. What is one way that recombinant DNA technology can benefit farmers?
2. How can recombinant DNA technology be used to treat diabetes?
Biotechnology refers to using living things to help
humans produce useful products. This has occurred
for thousands of years in our agricultural practices,
especially in the breeding of useful organisms.
In our modern world, there are a multitude of
examples of using biotechnology. Try the activity on
right to learn about some uses you may not have
known. Once you have finished the activity, please
answer the questions found on
the tab to the left.
Answers
1. What is one way that recombinant DNA technology can benefit farmers?
Recombinant DNA technology has been used to develop tomatoes that ripen
slowly and corn that is resistant to herbicides.
2. How can recombinant DNA technology be used to treat diabetes?
The human gene for producing insulin has been inserted into bacterial DNA. The
bacteria reproduce quickly, producing much more insulin than other methods.
Insulin is used by diabetics to control the levels of sugar in their blood.
Genetic Engineering
Genetic recombination
Genetic engineering is a branch of biotechnology that involves the
manipulation of the actual genetic material of useful organisms.
By changing or adding genes, useful traits can be added, and
detrimental traits can be removed. Soon, an entire genome could
be stitched together from pieces of genetic material.
Until that fateful day, we will continue
to use technologies such as genetic recombination, where sections
from one genetic source are added to another.
Watch how genetic recombination works in the animation on the
right.
Individual genes, or an entire genome, can be cloned.
Cloning
Cloning can refer to making copies of DNA fragments, cells, or entire
organisms.
Dolly the sheep (1997) was the first successful mammal clone.
Many other mammals have been clones in the years since.
Nuclear transplantation is one method used in animal cloning.
The nucleus from an adult cell replaces the nucleus in an egg.
If the egg begins to develop into an embryo, it is implanted into a host.
Gene Therapy
Gene therapy is used to treat genetic afflictions.
A gene is enhanced or replaced to treat a medical condition.
This allows the body to produce the missing protein that causes the condition by using the therapeutic gene.
It can be challenging to get the fixed gene to the proper location.
Viruses are sometimes used to carry and insert the gene.
Cell and tissue transplants, microscopic injections, and aerosol inhalers are also used.
Gene therapies are being developed that may help treat Huntington’s disease, skin cancer, cystic fibrosis, and
more.
Testing is difficult and time consuming; challenges include successfully delivering the new genes and long term
success.
Gene Therapy
Genetically Modified Organisms
Scientists have already created many useful organisms in their laboratories.
The bacteria C. crescentus naturally creates a biofilm to cover solid objects, and has been modified to absorb heavy
metals.
This bacterium could be used to clean lake water.
While these genetically modified organisms (GMOs) could help, they would also have unknown consequences.
A GMO is any organism that has genetically engineered
materials.
Transgenic organisms have genetic material from other
species.
GMOs have a wide range of applications in agriculture and
medicine.
GloFish, gentically engineered fish with fluorescent
jellyfish DNA, were one of the first GMOs for sale to the
public as pets.
Producing Genetically Modified Plants
Pest resistant GM crops integrate genes from (bacteria) Bacillus thuringiensis, producing a toxin that kills insect
pests.
These GM crops do not require spraying with pesticides.
Other traits biologically engineered into crop plants include resistance to herbicides and viral infections.
GM plants are often used as “factories” to produce desirable materials such as pharmaceuticals, industrial
products, and biofuels.
Transgenic safflower plants can produce human insulin for diabetics to use, replacing the difficult to refine insulin
currently produced by transgenic yeast and bacteria.
GM plants can lower production costs and increase yields.
Producing Genetically Modified Animals
Recombinant DNA is used extensively to produce vaccines and growth hormones for farm animals.
These animals themselves can become GMOs as well.
Animals are more difficult to bioengineer, as their development is much different from plants.
During in vitro fertilization, an egg is fertilized outside of the
female, the desired gene is injected into the developing
embryo, and it is then implanted into the mother to develop.
It can take many attempts before the fertilized egg will accept
DNA.
Success rates are much lower than with plants.
The first successful human in vitro fertilization (IVF)
occurred in England in 1977. Early IVF offspring were
referred to as “test tube babies.”
Producing Genetically Modified Animals
“Pharming” refers to using GMOs to producing pharmaceuticals.
In pharming, human genes are added to farm mammal genomes.
These genes then produce a particular protein, such as hormone, that is generally secreted in the animal’s milk.
This method is used when transgenic bacteria or
plants cannot produce the required protein or
substance adequately.
Often, the goal of creating GMOs is the same as
traditional breeding programs; to enhance traits
already present in the species through selective
breeding.
Researchers at the University of Guelph developed the GMO
“EnviroPig”. Enviropig wastes are much lower in phosphorous
than normal pig wastes.
Regulating the Use of GMOs
There are concerns that the use of GMOs could harm consumers or the environment.
What effect will an organism with changed genetic information have when it interacts with normal members of its
species?
Will GMOs outcompete normal individuals?
Will GMOs pass along their genetic changes if they successfully mate with wild organisms?
Could engineered genetic traits, such as pesticide resistance, spread to other species through viral transfer?
Who owns organisms with certain engineered traits?
Although few health problems have been noted, strict regulations are usually recommended for GMOs.
Testing of medicines and foods must be done to ensure safety.
Regulating the Use of GMOs
Governments and agencies around the world are attempting to make GMOs safe and properly understood.
In Canada, evaluators from the Canadian Food Inspection Agency (CFIA) and Health Canada assess the
safety of new agricultural products made with modern biotechnology.
Many countries require any food that has a GMO connection must be labelled as such.
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Producing Genetically Modified Plants
Recombinant DNA technology can be used to improve the characteristics of crop plants.
Genetically modified (GM) plants have been made to slow ripening, improve nutrition, tolerate stress, and reduce
spoiling.
GM plants have replaced traditional breeding practices, especially if the crop’s important traits are found on few genes.
GM plants are easy to grow, as an entire
new plant can often be grown from a
single adult cell.
Transgenic plants are often created by
using the bacterium Agrobacterium
tumefaciens.