Genetic variation 2 Flashcards
What is Karyotype?
Changes affecting the number of chromosomes in an organism
What is fusion?
the joining of two chromosomes to form one
What is fisson>
The splitting of a single chromosome into two or more
What are two things to effect karyotype?
fusion and fission
How did humans evolve from chimpanzees, when they have more chromosomes than we do ?
fusion
What is aneuploidy?
- the loss or gain of an entire chromosome, making an odd number of chromosomes
- caused by nondisjunction during gamete fertilization
What is polyploidy?
- where there are more than 2 sets of homologous chromosomes
- this occurs due to a failure of reduction division in meiosis
- much more common in plants than animals
What is autopolyploidy
- where multiple chromosome sets (3+) originate from within one species
What is allopolyploidy?
- where multiples chromosomes sets (3+) originate from two or more species
- between closely related species
- essentially from hybridization
what is parthenogenesis?
- a type of asexual reproduction
- growth and development of embryo without fertilization by males
evolutionary, the only mutations that matter are…
germline mutations
what kind of effects can germ line mutations have?
- no change in phenotype (mutation does not change amino acid, ect)
- small change in phenotype (Single mutation, no major effects)
- big change in phenotype
what is a control gene?
- genes that regulate the expression of other genes
- like Hox genes or homeotic genes
What are homeotic genes? How might mutations affect homeotic genes?
- genes that regulate the development of anatomical structures
- homeotic mutations may alter multiple phenotypic characters, thus effecting survival, reproduction, fitness.m
what are some limitations to mutations?
- majority of mutations alter pre-existing traits
- they can alter developmental processes but NOT developmental foundations
- mutations are dictated by phylogenetic constraints
what is the cause of point mutations?
chance errors during DNA synthesis or during repair of damaged DNA
What is the evolutionary significance for point mutations?
it can create new alleles
What is the cause of gene duplication?
unequal crossing over during meiosis
What is the evolutionary significance for gene duplication?
extra gene is free to mutate, and perhaps gain new function
What is the cause of polyploidy?
errors in meiosis or mitosis
What is the evolutionary significance for polyploidy
can create new species
