Gene Function Analysis in eukaryotes Flashcards
What did Mendel discover
Genes
What are the advantages of using pea plants for genetic analysis
hermaphroditic, lots of natural variation, reproduce by self fertilisation
Describe the haploidy/diploidy of parents and gametes
Parents are diploid, gametes are haploid
What was Mendel’s first law
Principle of segregation, alleles of genes segregate during gamete formation
What as Mendel’s second law?
Principle of independent assortment, genes controlling different characters assort into gametes independently
Describe Incomplete Dominance
heterozygous phenotype is intermediate between 2 homozygous parental phenotypes
Example of incomplete dominance
Snapdragon flower, carnation flower
Describe co-dominance
simultaneous expression of two phenotypes
Example of co-dominance
blood groups
How are genes located on the same chromosome described
linked
How can non-parental combinations of alleles occur?
crossovers between chromosomes during meiosis
What affects the rate of recombination
genetic distance between genes on the same chromosome
If genes are close together on the same gene how common is recombination
very uncommon
How are genetic pathways analysed?
Complementation tests
Describe loss of function mutations?
recessive and reduce gene function
What do complementation tests tell us?
Whether two independent recessive mutations with similar phenotypes lie in the same or different genes
Where do complementing mutations lie
different genes
where do non-complementing mutations lie
same gene
What can induce mutations (non-natural)?
X-rays, UV, chemical mutagens, and DNA mutagens
Name two alkylating agents
EMS and ENU
How do alkylating agents work
covalently modify DNA
Describe the effect of alkylating agents on DNA
Modify guanine so its unable to bond with cytosine
What do alkylating agents cause in non germline cells
tumours
How do UV, X-rays and gamma rays cause mutations in DNA
induce breaks in DNA backbone, knock off electrons and break covalent bonds
Describe the effect of UV on DNA
causes thymine to form covalent bonds with thymine, causes small deletions of insertions of nucleotides
Describe genome engineering
targets specific genes, introduces precise changes in specific DNA sequences
What is transgenesis?
Gene addition
What is knockout
Complete loss of gene function
What does gene replacement/knockout rely upon?
homologous recombination
What is the function of enzymes in genome engineering
recombine foreign DNA into genomic DNA
Describe zinc finger nucleases
Proteins that bind to specific parts of DNA
What is the function of ZFNs?
create small deletions, insertions or substitutions at site
Describe CRISPR/Cas9
bacterial immunity system against infectious bacterial virus genomes
How does CRISPR/cas9 work
uses RNA to guide nuclease to cleave a specific DNA site
Advantages of homologous recombination
very precise genome alterations like deletions, insertions and rearrangements, low frequency off target effects
Disadvantages of homologous recombination
slow
Which technique is the most precise for genome alterations
homologous recombination
What are complementing mutations?
when different homozygous recessive mutations give the same phenotype
