exam 4 (ch 19-21) Flashcards
- Makes copies of DNA
- Can copy DNA when the original source is limited or impure
- Selective of specific sequences
PCR (polymerase chain reaction)
- Allows us to separate molecules of various sizes
- DNA can move between the gel molecules
- *Electrical current is used to move molecules
- *Smaller molecules are carried further
- DNA forms distinct bands that can be cut out and sequenced
Gel Electrophoresis
- Instead of relying on chain termination, the single template strand is immobilized and electronic sensors can tell which nucleotide (C, T, A, or G) is added to the strand
- Allows for faster and cheaper processing
- What do we do with the sequences?
- *Compare species’ characteristics
- *Look for mutations that lead to disease
DNA Sequencing
Genetically identical descendants of a cell or animal
Clones
DNA from 2 different sources (often different sources)
Recombinant DNA
Contain DNA that might be necessary in certain environments, but are not necessary for the normal functioning of bacteria
Plasmids
- Conducted in vivo (in life)
- Should use when you want proteins or recombinant DNA
- Positives: obtain proteins, large quantities
- Negatives: must start with high-quality DNA, difficult with mammals
Cloning
- Conducted in vitro (in a test tube)
- Should be used when you want specific sequence of DNA
- Positives: Amplifies small fragments of DNA, more selective
PCR
Using fluorescent dyes to see where genes are expressed
in situ Hybridization
Genome-wide expression studied using DNA ???
microarrays
- Useful because it examines a large number of genes from a small tissue sample
- Examines mRNA
- Detects presence (yes/no) and intensity
- Screens 1000s of genes at a time
- Developed using knowledge of the genome
- *Look for start codons to identify genes
- *Determines function of the gene
Microarrays
A plate that contains DNA
Array
Pros: new technology
Cons: Expensive, requires prior knowledge of the genome, results may be hard to interpret (don’t know the functions of all the genes)
Microarrays
Unspecialized cells that can both reproduce itself indefinitely or differentiate into specialized cells
Stem Cells
Stem cells from embryos
- Can divide indefinitely
- Pluripotent-can differentiate into a wide variety of cells
Embryonic Stem Cells
Stem cells from adults
-Can only give rise to a few different varieties of cells
Adult Stem Cells
- In 2007, obtained from skin cells
- Researchers introduced 4 ‘stem cell’ master regulatory genes
- Not exactly the same as embryonic stem cells
- May be useful to use to treat patients >they won’t reject their own cells
- May be useful to obtain cell cultures to study disease
Induced Pluripotent Stem Cells (iPS)
- Introducing genes into an afflicted individual for therapeutic purposes
- Works best if genetic disease is caused by a single, mutant gene
- Is a ‘forever fix’ only if treated cells multiply throughout the patient’s life
- Examples: LCA2, SCID (severe combined immunodeficiency), liver therapy
Gene Therapy
Many technical issues
-How can the activity of the transferred gene be controlled?
-How can we be sure that the insertions of the therapeutic gene doesn’t harm some other necessary cell function?
Many ethical issues
-‘Tampering’ with human genes
-Should we be manipulating genes in human germ lines (egg&sperm)?
Gene Therapy
- DNA testing can identify guilty or innocent individuals from blood, semen, or tissue left at crime scenes
- *Cannot tell identical twins apart
- Identify the victim of a crime
- *After the attack in 2001, 10,000 samples of victims were tested and 3,000 were identified
Forensic Evidence
Genetically modified organisms
- Most are crops: corn, soybeans, canola
- Widespread in US, Argentina, Brazil
- 80% of the world’s average devoted to crops
- Not accepted in Europe
- *Fear that crops will pass their genes to close relatives… ‘super weeds’ may arise
- *Protein products may lead to allergic reactions
GMOs
The application of computational methods to the storage and analysis of biological data
Bioinformatics
The study of whole sets of genes and their interactions
Genomics
The study of whole sets of proteins
Proteomics
- Smaller 1-6 Mb
- Fewer genes
- Higher gene density
Prokaryotic Genomes
- Larger 12-3000 Mb
- More genes
- Lower gene density
Eukaryotic Genomes
With eukaryotes, there is a lot of ?? in genome size and variation
variation
Makes RNA (mRNA, rRNA, tRNA, miRNA)
Coding Regions
Does not make RNA
- Used to be called ‘junk DNA’
- 500 regions are identical in humans, rats, and mice; suggests it has an important function
- Function is still largely unknown
Noncoding Regions
Characteristics of plant viruses?
RNA genome, Helical capsid
Symptoms of viral infections in plants?
Bleaching, brown spots, stunted growth
Research about the basic functioning and expression of genes and proteins
Basic Research
Research that solves a problem
Applied Research
The direct manipulation of genes for practical purposes
Genetic Engineering
Evolutionary developmental biology, compares developmental processes of different multicellular organisms
Evo-Devo
- Consists of genetic information and a protein coat
- Latin for ‘poison’ (causes a variety of diseases)
- Cannot reproduce without a host cell
- Much smaller than both bacteria and a cell
Virus
Used to classify viruses
- DNA or RNA
- Single-stranded or double-stranded
- Linear or circular
- 4-1000 genes
Genetic Material
Protein shell
- Comes in many shapes
- May also have viral envelopes (derived from host membrane, has host’s proteins)
Capsids
Culminates in the death (lysis) of the host cell and release of new viruses
New phage DNA & proteins are synthesizes & assembled into phages>the cell lyses, releasing phages>the phage injects its DNA> phage DNA circularizes
Lytic Cycle
Viral DNA is replicated without killing host cell
Phage DNA integrates into the bacterial chromosome, becoming a prophage>the bacterium reproduces, copying the prophage & transmitting it to daughter cells>cell division produces a population of bacteria infected with the prophage>daughter cells with prophage>phage DNA circularizes
Lysogenic Cycle
Why haven’t viruses been eliminated?
The viruses mutate at a high level; receptors that are used in viruses, humans also use for survival
A harmless variant of a pathogen that stimulates the immune system to mount defenses against the pathogen
-Available to combat: smallpox, mumps, HPV, hepatitis B
Vaccines
Cannot be used to treat viruses, only treats bacteria infections
Antibiotics
Interferes with viral nucleic acid synthesis or the assembly of viruses
Antiviral Drugs
A virus that suddenly becomes apparent
Emergent Virus
A general outbreak of a disease (localized to 1 area)
Epidemic
A global outbreak (more than 1 continent)
Pandemic
Transmitted via air/sneezing
H1N1 Influenza
Transmitted via physical contact
Zika & Ebola
RNA viruses have a high rate of mutation, influenza
Mutation of existing viruses
Dissemination increases if virus can be transferred human to human, Zika
Dissemination from a small, isolated human population
Ebola
Spread of existing viruses from animals to humans
What is a characteristic of the lytic cycle?
A large number of phages is released at a time
What property of life is shared by eukaryotes and prokaryotes, but not viruses?
The ability to process energy through metabolic reactions
Why was influenza pandemic, but zika and ebola epidemic?
Influenza can be spread in the air, so it can be spread over a greater area
Plant is infected by an external source, generally via open wounds caused by wind, injury, or herbivores (insects)
Horizontal Transmission
Viral infection passed from parent plant to offspring (via both asexual and sexual reproduction)
Vertical Transmission
Transplanting nucleus from one cell to another
Nuclear Transplantation
Heat briefly to separate DNA strands
Denaturing
Cool to allow primers to form hydrogen bonds with end of target sequence
Annealing
DNA polymerase adds nucleotides to the 3’ end of each primer
Extension
