6.1 Studying the Human Genome Flashcards
What is the difference between a gene and
a genome?
gene: units of inherited information that code for a specific trait or function
genome: full DNA sequence of
an organism
What were the primary goals of the Human
Genome Project?
two main goals:
first, to determine the nucleotide sequence of all the DNA in human chromosomes
second, to identify the location and sequence of every human gene
How are restriction enzymes used to
manipulate DNA?
Restriction enzymes are bacterial proteins that cut DNA wherever a particular nucleotide sequence
occurs
What are restriction fragments?
The pieces of DNA made by cutting it
with restriction enzymes are called restriction fragments
What does DNA sequencing determine?
the order of nucleotides in DNA
What fraction of the human genome contains
genes?
1.5-2%
What does the remaining 98% of the human genome contain?
repeated nucleotide sequences, regions
that regulate genes, and even DNA
sequences inserted from viruses.
Which areas of science does bioinformatics
bring together?
biology & information science
What term is used for the study of genomes?
genomics
How are DNA chips used for genetic testing?
DNA chips: small glass wafer or slide spotted with an
array of single-stranded DNA fragments.
-Some spots, for example, could contain DNA with mutations known to cause cystic fibrosis.
-used to determine whether the DNA from a particular individual contains a mutation in genes
Which species has more genes in its
genome: the mustard plant or the nematode
mustard plant
Which species has more DNA in its genome:
the rice plant or the fruit fly?
rice plant
Describe two ways in which model organisms
are used to understand the function of human
genes.
-enable scientists to follow the inheritance of genes
through many generations in a relatively short time
-Cross-species comparisons can help us understand the functions of particular genes.
For example, if a nucleotide sequence in the human
genome is similar to a particular mouse gene with a known function, this gives us insight into the function of the human sequence
Describe three benefits of having a complete
map of the human genome
-Mapping genes enables researchers to identify genes associated with diseases.
An example is Parkinson’s disease. This progressive
disease gradually destroys brain cell function, causing tremors, speech difficulties, and rigid muscles
-understand inherited disorders and their treatment.
-earlier detection of genetic predispositions to disease
What are three reasons that mice are used
as model organisms in genetic studies?
-Mouse development and genetics have been well studied
-Mice and humans have a similar number of nucleotides in their genomes and a comparable number of genes
-In most cases, for a particular human gene
a mouse counterpart can be found
Suggest one or more drawbacks to using
mice in genetic studies
-fail to accurately mimic human disease phenotypes
-poor models to study inflammation in humans, a condition present in many humans
-research mice are inbred and do not capture the genetic variation existing in human population
How are DNA sequencing and gene mapping
related?
A sequence spells out the order of every DNA base (nucleotides) in the genome, while a map simply identifies a series of landmarks in the genome (enables researchers to identify genes associated with diseases)
Should anyone have the right to own DNA
sequence data? Justify your response.
- yes, because if we privatize it, these companies will raise the price unbelievably high and make it inaccessible to people that really need it
e.g. single mom has a disease and the cure used to cost $15 and now it costs $850 per bottle. She can’t afford it now and will die
Pros & Cons of DNA chips
pros:
-gene chips could become a useful tool in personalized health care.
-knowledge about genomes can have useful applications in agriculture as well as medicine
-for example, sequencing the rice genome has led
to ways of making it a more nutritious food source.
cons:
-microarrays do not have the ability to show changes at the protein level. These changes are an important factor of toxic effects on the body.
-little research available
-results influenced by minor changes
-complex data, difficult to interpret
What is the Human Genome Project?
-determined the nucleotide sequence of all the DNA in human chromosomes, and identified the location and sequence of every human gene.
-other goals included exploring gene functions, studying variations among different people’s DNA, and comparing human DNA with DNA from other species.
What can you learn by comparing restriction fragment gels?
-can be used to identify the source of a disease outbreak
For example, if bacteria that are making people ill produce the same restriction fragments as bacteria in a food sample, the food can be identified as the source of the illness.
Why did the field of bioinformatics emerge as a science?
This area of study involves the creation,
development, and operation of databases and other computational tools to collect, organize, and interpret data.
For example, nucleotide sequences are stored in searchable databases. Researchers then use specialized computer programs to recognize and align overlapping nucleotide sequences
What are the goals of genomics?
One goal of genomics is to map the location of genes within a genome.
-Scientists use key identifier regions to map genes.
-describe and understand the pattern of gene expression
-Mapping genes enables researchers to identify genes associated with diseases
How do scientists identify gene regions in DNA?
-Scientists use key identifier regions to map genes.
-These identifiers include switches that turn genes on or off, start codons at the beginning of genes, and stop codons at the end of genes
-Some regions of genes contain the instructions for making particular proteins.
-These regions are known as coding regions.
Name two model organisms.
-Lab mouse
-E.Coli
-Nematode
-Baker’s yeast
-Fruit fly
by working with model organisms scientists better understand _______
genetics
why do we use model organisms?
Shorter life cycle
Cheap
Genomes have been sequenced
-e.g. mice have very similar genes to us and so we can extrapolate information in lab tests to apply to humans
give an example of an experiment where we would use a model organism
retinitis pigmentosa
Fused mutated human gene with a jellyfish gene that codes for green fluorescent protein (GFP)
Replaced light receptor gene in mouse cells grown in culture with the fused human-GFP gene
Mouse cells injected into mouse embryos, which developed into mice with new gene
If genetic treatment works, the eyes of the mice light up with GFP
retinitis pigmentosa
Disease begins in teens and progresses over years to cause blindness
cause of retinitis pigmentosa
Cause is a mutation of a gene for a light receptor pigment
gfp
green fluorescent protein
In retinitis pigmentosa, if genetic treatment works, the eyes of the mice light up with
GFP
the degree of fluorescence in the eyes by GDP indicates
how effective the treatment is
2 goals of Human Genome Project
- Determine the nucleotide sequence of all the DNA in human chromosomes
- Identify the location and sequence of every human gene
what else is part of the human genome project
Also, explore gene functions, studying variations among different people, comparing human DNA with other species
what did we discover from the human genome project
-it’s smaller than we thought
-1-2% of DNA contains genes
-98% contains “junk” DNA (regulatory sequences, repeated sequences and even old virus, Neanderthal and bacterial DNA!)
1-2% of DNA contains
genes
98% of DNA contains
“junk” DNA (regulatory sequences, repeated sequences and even old virus, Neanderthal and bacterial DNA)
DNA is long and must be ______________ before being analyzed
cut into smaller pieces
“molecular scissors” that cut DNA comes from bacterial protein called
Restriction Enzymes
Pieces of DNA made by cutting are called
Restriction Fragments
Used in paternity tests and tracing disease origin
gel electrophoresis
gel electrophoresis
-Technology that separates DNA pieces based on size
-Acts like a sieve
-DNA added to one end of the gel, electric current applied, DNA is negatively charged thus travel towards the positive end
-Larger pieces travel slower and stay at the top as they are run through a gel
Technology that separates DNA pieces based on size
gel electrophoresis
DNA sequencing definition
Determining the order of nucleotides in DNA
DNA sequencing
Determining the order of nucleotides in DNA
Double helix is separated, and one strand is used as a template
Starting at the bottom, a new nucleotide is added in each row
They are radioactively labelled, and will fluoresce in different colours
The colour sequence is recorded and converted into the DNA sequence
T = red, C = blue, G = black, A = green
bioinformatics
Science of handling and analyzing biological data
genome databases
-Many genomes have now been completed for humans and other animals, plants, and various micro-organisms.
-Stored in GenBank, a public database that can be accessed through the Internet.
-Researchers and students can search, browse, and compare DNA sequences from thousands of species.
-Can compare novel (new) DNA sequences to known genes to predict function.
-Some scientists want to own this information, and others want it to be available free of charge to everyone.
The study of genomes
genomics
goal of genomics
Goal is to map location of genes within the genome
with genomics, you can figure out _____________ and allow us to better diagnose and prevent illness
genetic causes of diseases (ex. Parkinson’s, breast cancer)
DNA chip
array of known sequences for genetic disorders placed on a glass slide 1.28cm2
application of genetics in medicine
DNA chip – array of known sequences for genetic disorders placed on a glass slide 1.28cm2
-Scans more than 400,000 probes (short DNA sequences)
-Potential for personalized healthcare, but also raises ethical concerns
applications of genetics in agriculture
-Can make food more nutritious
-eg. Sequencing rice genome allowed scientists to make it more nutritious
-Allows farmers to select “best” livestock (healthiest, most productive) for breeding
