genomes Flashcards
this increase in detail and resolution, from cytogenetic and linkage maps to physical and sequence maps.
genetic maps
[Scientists create maps of our DNA to locate genes. These maps started as rough guides (like looking at chromosomes under a microscope) and became much more detailed over time, down to the exact sequence of DNA.]
it was used to discover individual genes by beginning with a phenotype and gradually identifying a causative gene, localizing it to part of a chromosome.
positional cloning
[To figure out which genes cause specific traits or diseases, scientists looked at the symptoms first. Then, they worked step by step to narrow down the location of the responsible gene on a chromosome.]
the human genome project began in 1990 under the direction of?
DOE, department of energy
NIH, national institutes of health
Over time, technology got better and faster, speeding up the process.
How Sequencing Worked: To figure out the sequence of our DNA:
Scientists cut the genome into small pieces.
They read the sequences of these pieces.
Then, they pieced them back together like a puzzle. Two methods were used: one focused on one chromosome at a time, while the other looked at the whole genome in one go.
What We Learned from Sequencing:
Humans are very similar genetically, with only small differences.
Reading genomes helps us
1. understand family history
2. identify genes linked to diseases
3. predict how people might respond to medicines
what happens after sequencing
Once scientists could sequence entire genomes, they focused on:
improving the process
studying how people’s DNA varies
figuring out what all the genes do.
the cost ___ while the speed ____
the cost decreased while the speed increases
as researchers annotated genes with information on gene function, mode of inheritance, genotype, and frequency of variants.
what does genome sequencing do not detect
copy no. variants (extra or missing copies of genes)
mitochondrial dna
uniparental disomy (cases where a child inherits both copies of a chromosome from one parent, uniparental disomy)
gene-gene and gene-environment interactions
Missing or extra copies of genes (copy number variants).
DNA from mitochondria.
Complex inheritance patterns, like getting both chromosome copies from one parent.
it provided information on how crossing over and de novo mutations are connected
genome sequencing
it is a digital nucleic acid sequence derived from many sequences genomes that established a representative genome sequences for a species
reference genome
- like a “standard template” of human DNA.
- created by combining high-quality DNA data from a group of people to represent what the human genome generally looks like.
[Comparison: Scientists use the reference genome to compare an individual’s DNA and spot differences (like mutations or variations).
Research: Helps study how genetic variations relate to diseases or traits.
Standardization: It acts as a universal guide for genetic research, so everyone is using the same “template.”
The reference genome is like a “map” of human DNA that helps researchers find and understand differences in people’s genes.]
four types of genetic maps
Cytogenetic maps: Rough visual maps of chromosomes.
Linkage maps: Show how traits are inherited based on how often genes are passed down together.
Physical maps: More detailed maps showing distances between genes in DNA units.
Sequence maps: The most detailed maps, showing the exact order of DNA letters (A, T, G, C).
Scientists started with a visible disease or trait, tracked where it appeared in families, and then pinpointed the gene responsible by looking at DNA in that area.
positional cloning
- first human genomes were sequenced, researchers matched single genes to specific disease
-the technique began w examining a particular phenotype corresponding to a Mendelian disease in a large families
Why was there debate about sequencing human genomes?
Some researchers thought it was too expensive and complex, while others believed it was essential for progress.
Why use many copies of a genome?
To avoid mistakes. Sequencing multiple copies helps ensure the DNA sequence is accurate.
What makes genome information useful in medicine?
It should:
Be new or provide better insights than current tests.
Be accurate and reliable.
Help improve treatments or diagnoses.
