Genetics Flashcards
What is meiosis?
Occurs in reproductive cells. Daughter cells have half the number of chromosomes. (E.g. 23 vs 46). The cell replicates itself and then splits the DNA to form 4 gametes.
What is a homozygous gene?
2 copies of a gene that are identical
What is a heterozygous gene?
2 copies of the same gene that are different.
What is an allele?
An alternative form of the same gene located on homologous chromosomes at identical locations.
What is a genotype and phenotype?
Genotype- the genetic makeup of an organism
Phenotype- the physical characteristics resulting from the genotype
What are dominant and recessive genes?
A dominant gene is a gene that is expressed in the phenotype. The recessive gene is a gene that is masked by the other gene
What are the components of the DNA structure?
Phosphate which is connected to deoxyribose sugar which is connected to the nitrogenous bases.
What are the 4 nitrogenous bases?
T- thymine
A- adenine
C- cytosine
G- guanine
What is a chromosomal abnormality?
A mutation that occurs in the chromosomes during meiosis and results in too many or too little chromosomes.
What is a gene abnormality?
When a mutation occurs in the DNA and the gene doesn’t code for the correct amino acid/protein
What are the three ways to alter a gene?
Adding a foreign gene, altering an existing gene or deleting a gene
What is adding a foreign gene and example?
A gene from another species is inserted into the organism so the GMO expresses the traits of that species (transgenic). E.g. Glow in the dark rabbits with a gene from a jellyfish.
What is altering an existing gene?
Making the gene express in a different way or at a higher level. E.g. Making growth hormones express more so the organism grows more.
What is deleting a gene? Example
Deactivating an existing gene to prevent the expression of that trait. E.g. Deactivation of tomato ripening gene for a longer shelf life.
What is mitosis?
Cell replication in all cells except reproductive cells. The cell replicates itself and then splits to form 2 identical cells.
Who were the 4 people who helped discover DNA structure?
Rosalind Franklin *
Maurice Wilkins *
James Watson ^
Francis Crick ^
What did Franklin and Wilkins do?
They were crystallographers who took photos of DNA. Photograph 51 helped discover the DNA structure
What did Watson and Crick do?
They used photograph 51 to determine that the structure of DNA was a double helix
What did Gregor Mendel do?
He was a monk who did experiments cross breeding peas to determine patterns of inheritance and dominant and recessive genes.
What happens in DNA replication?
The double helix unzips and nucleotides from the cytoplasm join to form 2 new double helixes
What causes Down Syndrome?
It is a chromosomal abnormality that happens when meiosis doesn’t work properly and the 21st chromosome doesn’t split properly, causing someone to have 3 21 chromosomes
What are arguments for GM?
Increase in food production- improves nutrition of people
Decrease in use of pesticides
Economic benefits
What are arguments against GM?
Transgenic organisms spreading uncontrollably in the wild
Makes GM animals unhealthy
May cause resistance to pests or insects
Economic impacts/no benefits to farmers
What is gene therapy?
Where the defective gene is replaced with a properly working gene
What is the process of gene splicing?
Remove plasmid and cut it using enzyme
DNA is cut to isolate a gene
Join both to form gene
Implant gene inside bacteria to reproduce
