Genetics (Lect2) Flashcards
What is genetic variation?
The differences in DNA sequences among individuals within a population
What is evolution?
Changes happen to inherited characteristics within a population over time as a result of natural selection
What are the 3 things genetic variation can result from?
-Mutations
-Sexual reproduction: meiosis= new combo of genes
-gene flow= transfer of genes between populations through migration=new genetic material introduced
What is inheritance?
process by which genetic info is passed from parents to offspring
What is gene-environemnt interaction?
-the impact of an environmental exposure of disease risk is different for people with different genotypes OR
-the impact of a genotype on disease risk is different in people with different environmental exposures
What is DNA composed of?
-2 strands that coil around each other= double helix
-each strand= nucleotides made up of sugar, phosphate + nitrogenous base
What are genes?
-segments of DNA that contain instruction for building proteins
-varies in length
What is a trait?
any observable feature/characteristic of an organism
What is an inherited character?
produced by genes transmitted from parent to offspring
What is an oligogenic/qualitative character?
-a character controlled by only a few genes
-discontinuous variation e.g. blood type
-not influenced by environment
What is a polygenic/quantitative character ?
-a character controlled by many genes
-continuous variation e.g. weight
-influences by environment
What is a genotype?
the total genetic makeup of an organism
What is a phenotype?
all observable traits of an organism that results from the interaction of its genotype with its environment
What is an allele?
different versions of the same gene that can result in different traits
What is a mutation?
-a change in the DNA sequence of an organism
-can be beneficial, harmful or neutral
What can mutations result from?
-errors in DNA replication during cell division
-exposure to mutagens
-viral infection
What are the types of mutations?
-substitution
-inversion
-insertion
-deletion (causes large no. of genetic diseases)
What is an oncogene?
a mutated gene that has the potential to cause cancer
How does cancer arise from a oncogene?
-before oncogene becomes mutated= proto-oncogene
-mutates causing cell to divide and multiply uncontrollably
What is an exon?
-region of genome that ends up within an mRNA molecule
-some are coding (info for making a protein) others= non-coding
What does Mendelian inheritance refer to?
-how traits are passed
-focuses on traits controlled by single gene with 2 alleles
What does the pattern of inheritance of Mendelian traits depend on?
whether traits are controlled by genes on autosomes or by genes on sex chromosomes.
Representations of inheritance
