Gene Editing Flashcards
Benefits of CRISPR-Cas9 Gene Editing
Precise as it cuts DNA at a specific location with high accuracy
Versatile as it can be used for various editing tasks such as inserting deleting or modifying genes
Efficient as it works quickly and easily compared to other gene editing tools
Germ Cell Mutation VS Somatic Cell Mutation
Somatic occurs in body cells
Germ occurs in reproductive organs
Somatic is not passed onto offspring
Germ is passed onto offspring
Somatic can lead to health issues or diseases
Germ can directly affect offspring and all cells developed from the mutated zygote
Somatic is common
Germ is rare
What is Used to Check Non-disjunction
Karyogram
Gene Knockout
Inactivating a specific gene to observe the effect of its inactivation to find out about its function
Types of Gene Mutation
Beneficial: A mutation that provides an individual with a better chance of survival and is likely to be passed onto future generations
Detrimental: A mutation that causes disease or death and is less likely to be passed onto future generations
Purpose of Gene Knockout
Study the function of genes
Study biological pathways
Study mechanisms of certain drugs
Study of embryo development
Disease research
Why are Some DNA Regions Highly Conserved
They have slower lates of mutation
Control gene expression
Code for proteins that are vital for life
Provide structural stability
Variation
The difference in phenotypes within the same species, and usually results from small differences in DNA base sequences
Mutations Classifications
Point Mutations: Base substitution
Frameshift Mutations: Insertion and Deletion
Types of Base Substitution Mutations
Silent: Does not alter the amino acid sequence of the polypeptide, and occurs because of degenerate genetic code where multiple codons code for the same amino acid, which leads it to be unchanged
Missense: Causes the expression of a different amino acid
Nonsense: Adds a stop codon to the premature protein and stops protein synthesis
Functional Requirements of Highly Conserved Sequences
Highly conserved sequences probably code for essential proteins that are critical for organisms across species, and any slight change in these sequences could be detrimental which explains their strong conservation throughout evolution
Applications of Gene Editing
Correcting genetic diseases
Developing new therapies for cancer and other illnesses
Engineering crops with desirable traits like resistance to pests or diseases
Conserved and Highly Conserved Sequences
Conserved: Identical or similar across a species or group of species
Highly Conserved: Identical or similar along long period of evolution
Ethical Considerations of Gene Editing
Very expensive which limits access to those who need them most
Can have unintended side effects due to off target edits
Editing germ cells can pass change to future generations
Role of Genes (Alleles) in Variation
Genes come in different forms called alleles which have slight variations in DNA sequences, and organisms inherit their parent’s alleles. Due to the different combinations of alleles, they will promote variation as they receive different combinations from each parent
Process of Crispr-Cas9 formation
Virus tries to invade bacteria
Bacteria fights back and grabs a fragment of virus DNA
The bacteria stores this snippet as a CRISPR sequence in its DNA
Over time, the bacteria collects many CRISPR sequences from different viruses forming a library
If the same virus attacks again, the bacteria recognizes it from its library and uses CRISPR sequence to guide Cas9 to virus’ DNA to cut the viral DNA
CRISPR Abbreviation
Clustered: The repeats are grouped together in DNA sequences
Regularly Interspaced: The repeats are separated consistently by spacers
Short: Each repeat is a relatively short sequence of DNA nucleotides
Palindromic: Each sequence has parts which can be read the same forwards and backwards
Repeats: The same base sequence occurs several times in one part of the genome
Causes of Mutation
DNA Replication might not have good proofreading
Ionizing Radiation
Viruses can integrate their genetic material into the host DNA which disrupts host genes
Exposure to environmental toxins or industrial chemicals or pollutants
Gene Mutation
A permanent random change in the base sequence of a gene, which produces a protein that has different properties
Usage of CRISPR Good Way
Scientists can make their own RNA that Cas9 can cut, using this, they can:
Insert a new piece of DNA
Remove unwanted DNA
Make slight changes to DNA
Randomness in Genetic Mutation
Uncoiled DNA has a higher probability of encountering mutations as it is more exposed
Non-coding regions also have many mutations
Mutation Hotspots are regions where mutations are more frequent. An example is when cytosine is followed by guanine: CG
