GENETICS - CLUTCH CH.15 GENOMES AND GENOMICSlightcat-files.s3.amazonaws.com/...clutch...genomes-and-genomics-1… · Traditional whole genome sequencing (WGS) require cellular reactions
Post on 27-Jun-2020
0 Views
Preview:
Transcript
! www.clutchprep.com
!
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
CONCEPT: OVERVIEW OF GENOMICS
● Genomics is the study of genomes in their entirety
□ Bioinformatics is the analysis of the information content of genomes
- Genes, regulatory sequences, protein binding regions, non-coding RNAs
□ Comparative genomics compares genomes of closely and distantly related species for evolution studies
□ Functional genomics uses laboratory methods to understand gene and protein functions
PRACTICE:
1. Genomics is the study of what? a. Specific genes and their activities b. The information content of a genome c. The study of genomes in their entirety d. The study of gene development
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 2
2. Which of the following is not a class of genomics? a. Bioinformatics b. Comparative genomics c. Darwinian genomics d. Functional genomics
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 3
CONCEPT: SEQUENCING THE GENOME
● Sequencing genomes uses a few main steps 1. DNA must be broken into millions of random, and overlapping segments
- Restriction enzymes are proteins that can chop the DNA at specific sequences
- Reads are what we call each of these fragments. They can range from 100-5000 bp long
EXAMPLE:
2. Sequence each read
- Pyrosequencing takes each sequence, attaches it to bead, and then amplifies it
- A machine then runs each nucleotide across the sequence one at a time
- When a nucleotide binds it releases a pyrophosphate molecule, which can be converted into a light signal
- A camera detects the light signal and determines which nucleotide caused it by complementary binding
EXAMPLE:
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 4
3. Use software to find overlapping sequences and segments
4. Overlap each segment until all of the reads are linked
- Sequence assembly is building individual reads into a consensus sequence
- Individual differences prevents any one sequence from truly representing the genome
- Requires multiple reads of each base pair
- Ex: 10-fold coverage means that each base pair is found in at least 10 reads
EXAMPLE:
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 5
Traditional vs. Next Generation Sequencing
● There are many different types of sequencing that have improved over the years □ Traditional whole genome sequencing (WGS) require cellular reactions
- DNA fragments are placed into vectors (plasmid) and grown in bacteria
- Sequence reads are obtained through isolating these sequences from vectors
- Sequence contigs is the final contingous sequence each overlapping read is arranged into
□ Next Generation WGS does not require cellular reactions
- DNA is prepared using cell-free reactions
- DNA fragments are isolated and sequenced using software and sequencing machines
- Very small reaction volumes
EXAMPLE:
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 6
Difficulties of Whole Genome Assembly
● Certain genome characteristics make sequence assembly difficult □ One difficulty is repetitive DNA sequences that are longer than the reads
- Scientists are unable to determine where the overlap starts
- Paired-end reads are pairs of sequences that are read from opposite ends of genomic inserts
- Pair-end reads may span the gap and help determine the sequence between two contigs
EXAMPLE:
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 7
Sanger Sequencing
● Sanger sequencing was one of the first methods of sequencing DNA □ Takes advantage of dideoxy nucleotides (ddNTPs) which stop elongation if they are incorporated
- Add one ddNTP type to four separate normal sequencing reactions (one for A, T, C, G) - Strand elongation will stop after a ddNTP is added, and will generate a variety of different strand lengths - Strand length and ddNTP incorporation will determine the DNA sequence
EXAMPLE:
Sequence: TATGCCGCA
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 8
PRACTICE:
1. Restriction enzymes are proteins responsible for what? a. Labeling DNA with molecular probes b. Chopping the DNA at specific sequences c. Amplifying a short DNA sequence d. Compiling paired end reads
2. What is the name of a short sequenced DNA fragment? a. Read b. Contig c. Consensus Sequence d. Overlaps
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 9
3. The purpose of a sequence assembly is to what? a. Use reads to build a conserved sequence b. Use reads to build a consensus sequence c. Use reads to form a vector d. Use reads to form a labeled sequence
4. Which of the following sequence techniques requires the use of vectors? a. Pyrosequencing b. Traditional whole genome sequencing c. Next generation whole genome sequencing d. Sanger sequencing
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 10
5. Dideoxy nucleotides (ddNTPs) are used in Sanger sequencing because they have what function? a. ddNTPs add fluorescence to the DNA sequence b. ddNTPs speed up DNA amplification c. ddNTPs stop elongation once they are incorporated into a growing sequencing reaction d. ddNTPs prevent stalling of DNA sequencing reactions
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 11
CONCEPT: GENOMIC VARIATIONS
● There are ____________________ of different variations that exist between two individual’s genomes □ Single nucleotide polymorphisms (SNPs) are single nucleotide variations
- One in every 1000 bases is altered between two individuals (Around 18 million total SNPs in humans)
- Vast majority of SNPs are in silent regions of the genome
- SNPs are identified via multiple ways
- Southern blots of restriction enzyme cut DNA will result in different DNA lengths
- Other methods include PCR, and DNA microarrays
EXAMPLE: Example of a single nucleotide polymorphism
□ Deletion-insertion polymorphisms (DIPs or In-Dels) are small deletions or insertions of genetic material
- Can _______________- from 1-517 base pairs, and there are nearly 300,000 in the human genome
- One in every 10kb of DNA differs between two individual
□ Simple sequence repeats are 1,2, or 3 base sequences repeated 15-100 times
- A CA repeat is repeated once in every 30,000 base pairs in mammalian genomes
- Arise through DNA replication errors
- Can cause serious diseases like Huntington disease
EXAMPLE: Example of CA repeats
CACACACACACACACACACACACACACA
ACCTAGTTGCAATG ACCTACTTGCAATG
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 12
□ Minisatellites are repeats of 500pb to 20kb in size that are scattered throughout the genome
- DNA fingerprint is a pattern produced by detection of a genotype (minisatellites) at unlinked loci
- DNA fingerprinting pattern is used in crime investigations to identify a suspect’s DNA
□ Large scale deletions can also differentiate human ______________________
- Copy number variants are polymorphism of up to 1mb in length
EXAMPLE: Example of a DNA Fingerprint
Crime DNA 1 2 3
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 13
PRACTICE:
1. Which of the following is NOT an example of large genomic variations between two individual genomes? a. Single nucleotide polymorphisms b. Simple sequence repeats c. Dominant and Recessive alleles d. Minisatellites
2. Which of the following genomic variations can be detected through DNA fingerprinting? a. SNPs b. Simple sequence repeats c. Large scale deletions d. Minisatellites
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 14
3. Which of the following genomic variations is most common in human genomes? a. SNPs b. Simple sequence repeats c. Large scale deletions d. Minisatellites
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 15
CONCEPT: BIOINFORMATICS
● Bioinformatics is the study of the information found within _________________________ □ What information does the genome hold?
- Genes, RNAs, binding sites for proteins, non-coding RNAs, positions for gene regulation
- Annotation marks these functional elements of the genome
EXAMPLE:
□ Bioinformatics can be used to determine protein-encoding genes from the genomic sequence:
- Proteome is the inventory of all proteins encoded by an organism’s genome
- Open-reading frames (ORFs) are sequences with characteristics of typical genes
- 5’ and 3’ end sequences, introns, exons
- Codon bias is when an organism prefers one codon over other codons for the same amino acids
- Drosophila uses UGC 73% and UGU 27% to code for cysteine
□ cDNA sequences can be used to __________________- ORFs
- cDNA is DNA reverse transcribed from RNA
- Introns are removed
- Expressed sequence tags (ESTs) are large data sets of short cDNA sequences
- Made to determine gene boundaries
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 16
EXAMPLE:
□ Bioinformatics can be used to ______________________ DNA binding sites
- Computer software searches the genomic sequence for predicted sequences (promoters, splice sites, etc)
□ Bioinformatics can be used to study evolution and DNA similarity
- BLAST searches can be used to determine if a particular sequence is similar to other known sequences
EXAMPLE:
TranscriptionStart
Start Codon
Open Reading Frame (ORF)
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 17
PRACTICE:
1. Which of the following is NOT a piece of information that bioinformatics can analyze? a. Location of DNA-Protein binding sites b. Identifying all the proteins expressed in a skin cell c. A list of all introns in the genome d. The function of one gene
2. Which of the following can be used to identify an open-reading frame? a. cDNA sequences b. Introns c. Enhancer locations d. Exons
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 18
CONCEPT: COMPARATIVE GENOMICS
● Comparative genomics is the study of genomics from an evolutionary _________________________
□ Homologs are genes that have similar DNA sequences
- Orthologs are genes inherited from a common ancestor
- Paralogs are genes related by a gene duplication
EXAMPLE:
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 19
□ Phylogeny is the evolutionary history of a group of ______________________
- Phylogenic inference infers how genes came about
- Parsimony is a principle that says to choose the simplest explanation
EXAMPLE:
1. Generally, mammals do not lay eggs, but platypuses are mammals that lay eggs. Therefore, platypuses contain
genes associated with egg yolks that other mammals do not have. Where did these genes come from?
a. Yolk genes came from a common egg-laying ancestor and other mammals lost the yolk genes.
b. Yolk genes evolved in platypuses independently of other egg-laying organisms
Humans, Mice, and Chimps
● Human genomes share similarities with other __________________________
□ Mice genomes are very similar to human genomes
- 99% of human genes have a homolog in mice
- They have 90% synteny, which is a conserved order of genes
□ Chimpanzee genomes are extraordinarily similar to human genomes
- 35 million single nucleotide difference between a human and chimp
- 3 million single nucleotide differences between two humans
- Duplications of chromosomal segments result in major difference
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 20
PRACTICE:
1. Two similar genes that arose from a gene duplication and are found in the same organism are called what? a. Homologs b. Orthologs c. Paralogs d. Metalogs
2. Synteny describes conservation of what? a. Number of genes in a species b. Number of exons in a gene c. The order of genes in a chromosomal region d. Number of chromosomes in an organism
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 21
CONCEPT: HUMAN GENOME AND MEDICINE
● The human genome project sequenced the first human ___________________-
□ Identified major components of the human genome
- Protein coding regions make up only 2% of the genome
- But, each gene can produce more than one protein
- Gene rich regions are areas that are concentrated with genes
- Gene desserts are regions without any genes
- It is 99% similar between individuals
- Copy number variations are variations in number of gene copies (due to deletion or insertion)
- Single nucleotide polymorphism are single nucleotide variations that exist between individuals
EXAMPLE:
□ Non-coding regions of the genome are just as important as ______________________ regions
- ENCODE project is the encyclopedia of DNA elements
- Records enhancers, promoters, and other regulatory regions
- Psuedogenes are sequences that resemble genes, but are nonfunctional or inactive
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 22
Transgenic Organisms and Gene Therapy
● To study human genes, scientists often use transgenic _________________________
□ Transgenic organisms are organisms that contain foreign DNA
- Gene addition is when a cloned gene is added to a cell or organism (Ex: glo fish)
- Gene knockin is when a gene addition is added to a specific site within a genome
□ Organisms can also be generated with a lack of a gene
- Gene knockout is when the gene is entirely removed or silenced
- Gene replacement is when a cloned gene replaces a normal gene in the chromosome
□ These methods create genetically modified organisms with altered genomes
- Ex: include developing mice strains of a specific disease, or providing crops with pest resistance
EXAMPLE: Knockout mouse (brown) missing gene for hair growth
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 23
● Human gene therapy uses transgenes (foreign DNA) to _________________________ a disease
□ Personal genomics involves sequencing a diseased individual’s DNA and finding a mutant gene
- Then, doctors attempt to add the correct version of the gene back into the cell
□ Gene therapy involves introducing cloned genes into human cells
- Can uses viruses that inject and incorporate DNA into the human cell
- Can use non-viral methods including liposomes, which are vesicles containing the gene of interest
□ Gene therapy is already being used for diseases like Cystic Fibrosis
EXAMPLE:
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 24
PRACTICE:
1. The human genome project discovered that protein coding regions make up what percent of the human genome? a. 1% b. 2% c. 10% d. 90%
2. Transgenic organisms are organisms that contain what? a. DNA from another organism b. RNA from another organism c. Protein from another organism
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 25
3. The purpose of human gene therapy is to what? a. Remove a mutated gene b. Remove a mutated RNA c. Remove a mutated protein d. Add a normal-functioning gene into the organism
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 26
CONCEPT: FUNCTIONAL GENOMICS
● Functional genomics is an approach used to study the function, expression, and interactions of genes and proteins
□ Many ____________________________ of functional genomics exist
- Transcriptomics is the study of the sequence and expression of RNA transcripts
- Proteomics is the study of the cellular expression of proteins
- Ineractomics is the study of physical interactions between DNA, RNA, and proteins
□ There are many __________________________ used to study functional genomics
- DNA microarrays are used to determine which genes are active in a particular cell and circumstances
EXAMPLE:
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 27
- Two-hybrid test is used to study protein interactions in live cells
EXAMPLE:
- ChIP (chromatin immunoprecipitation) is used to study protein-DNA interactions
EXAMPLE:
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 28
- Reverse genetics disrupts a gene’s sequence to analyze its function
EXAMPLE:
PRACTICE:
1. Which of the following terms describes the study of physical interactions between DNA, RNA, and Protein? a. Proteomics b. Transcriptomics c. Metagenomics d. Interactomics
GenotypePhenotype
Reverse Genetics
Forward Genetics
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 29
2. Which of the following methods is used to study protein interactions in live cells? a. DNA microarrays b. Two-hybrid test c. ChIP d. Reverse genetics
3. Which of the following methods is used to study protein-DNA interactions? a. DNA microarrays b. Two-hybrid test c. ChIP d. Reverse genetics
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 30
CONCEPT: PROTEOMICS
● Proteomics is the analysis of the cell, tissue, or organism’s _____________________________
□ Proteome describes the complete set of proteins encoded by a genome
- Due to protein processing the proteome is much larger than the number of genes
□ A variety of different methods have been developed to isolate proteins
- Gel electrophoresis separates thousands of proteins by charge
- Isoelectric focusing is when the protein migrates in the gel to the point where its charge is zero
- SDS PAGE separates proteins by mass
EXAMPLE: SDS Gels
● A variety of different _________________________ have been developed to identify proteins in a sample
□ Mass spectrometry is a method use to identify proteins
- Tandem mass spectrometry separates proteins by mass and charge
- Can be used to identify the amino acid sequence of the protein
□ Protein microarrays is a method used to detect proteins and protein-protein interactions in a sample
- Uses antibodies on a plate, and protein in the sample will bind to the antibody
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 31
EXAMPLE: Mass Spec Protein Sequencing
PRACTICE:
1. SDS-PAGE is a method used to separate proteins by which of the following characteristics? a. Mass b. Length c. Charge d. Acidity
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 32
2. Which of the following methods would be best to identify an amino acid sequence of a protein? a. Protein microarrays b. ChIP c. Tandem Mass Spectrometry d. Reverse genetics
GENETICS - CLUTCH
CH.15 GENOMES AND GENOMICS
Page 33
top related