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.
it can create new combinations of genes or mutations, which can lead to variation or, in some cases, genetic disorders
Crossing over during reproduction
A study that sequences newborns’ genomes to learn how this information can guide health decisions throughout their lives while exploring the ethical and privacy challenges involved.
BabySeq project
- newborn genome sequencing initiatives
what are the 2 examples of applications of genome information
a new view of crossing over
sequencing the genomes of newborns
annotations in linguistics means
note of explanation
comment added to a text or diagram
annotations of a gene variant might include
■ the normal function of the gene;
■ mode of inheritance;
■ genotype (heterozygote, homozygote, compound heterozygote)
■ frequency of a variant in a particular population; and
■ classification as benign, likely benign, variant of uncertain significance, likely pathogenic, or pathogenic.
transitions from genetics to genomics
genome
what are the historical milestone in genome research
1920 - H. Winkler coined the term genome
- a hybrid of “gene” and “chromosomes”
-genome then denoted a complete set of chromosomes nd genes
1986 - T.H Roderick indicated the study of genomes
what are the impact on medicine and research
personalized medicine:
Doctors can tailor treatments based on a person’s unique genetic makeup.
Example: Choosing the right cancer drug based on a patient’s genes.
disease prediction and prevention:
By studying someone’s genome, doctors can predict the risk of diseases like diabetes or heart disease and suggest lifestyle changes to prevent them.
faster diagnosis:
Genomic tests help identify rare conditions quickly, especially in newborns or complex cases.
drug development:
Understanding genomes helps scientists design better, more effective drugs.
Scientists finished mapping the entire human genome, a huge leap in understanding human DNA.
Human Genome Project, 2003
pri purpose:
aimed to create a detailed instruction manual of human life to help understand health, diseases, and the genetic basis of life.
briefly explain the development of genome sequencing techniques
clone-by-clone sequencing:
- early approach involved sequencing many small, overlapping DNA fragments to reconstruct the full human genome
- researchers used restriction enzymes to cut the dna into smaller pieces, which were then sequenced and assembled into longer contiguous sequences
- time-consuming and required assembling many small pieces to get the full genome sequence
whole genome shotgun sequencing:
- new approach involved randomly fragmenting the entire genome and sequencing the fragments w/o focusing on specific chromosomes
- sequencing software then used overlaps between the fragments to assemble the full genome sequence
- faster and more efficient than the clone-by-clone approach, as it didn’t require targeted sequencing of individual chromosomes. HOWEVER, it misses some sections that the clone-by-clone detects
who unveil the “first draft” of the human genome sequences
J. Craig Venter from Celera Genomics and Francis Collins
on June 26, 2000
what are the importance of overlapping fragments
- for accurately assembling the full genome sequence
- software uses the overlaps between fragments to piece together the complete genome by recognizing sequence overlaps
- without these overlapping regions, it would be much more difficult to assemble the fragmented genome sequences into a coherent whole.
briefly explain the high genetic variability
SNPs (single nucleotide polymorphisms):
What it is: A small change in a single “letter” of the DNA code.
Example: Instead of “A,” it might be “G.”
Why it matters:
SNPs can affect traits like eye color or height.
Some SNPs increase the risk of diseases or affect how a person responds to medications.
CNVs (copy no. variants):
What it is: A section of DNA is duplicated or deleted.
Example: Instead of one copy of a gene, a person might have three, or they might be missing one.
Why it matters:
CNVs can influence traits like brain development.
Some CNVs are linked to conditions like autism or schizophrenia.
[Key Difference
SNPs: Tiny, single-letter changes.
CNVs: Bigger changes, adding or removing chunks of DNA.]
what is personalized medicine
tailors healthcare to your unique genetic makeup, lifestyle, and environment.
It’s like having a treatment plan designed specifically for you, not a “one-size-fits-all” approach.
How It Helps with Disease Prevention and Treatment
1.Disease Prevention
Predicting Risk: By looking at your DNA, doctors can identify your risk for diseases like heart disease, diabetes, or cancer.
Prevention Plan: If you’re at high risk, you can make lifestyle changes (like diet or exercise) or take preventive medicines.
- Better Treatments
Right Medicine: Your genetics can show which medicines work best for you and which might cause side effects.
Effective Care: Treatment plans are adjusted to your specific needs, improving outcomes and reducing trial-and-error.
