Week 2 Flashcards
What is POLYPLOIDY?
= the addition of complete sets of chromosomes (more than 2)
- 30-35% of flowering plants are polyploid
What is ANEUPLOIDY?
= one or more individual (!) chromosomes are added or deleted
What is CHROMOSOME REARRANGEMENT?
= structural changes to chromosome; i.e. piece of chromosome is deleted, inverted, or duplicated, only structural change since chromosome number is unchanged
What is MONOPLOIDY?
= only a single one of each chromosome
- in male wasps bc males arise from unfertilized egg
What are AUTOPOLYPLOIDS?
= plants with chromosome sets that are all identical (homologous), the chromosomes are all derived from the same species
These plants usually have larger cells, thicker leaves, bigger flowers, larger plants and fruit but LESS seed production
Problems with autopolyploids?
Often sterile due to pairing problems in Meiosis 1 - they often produce unbalanced gametes
What is a 3N=33 organism?
It has 33/3=11 chromosomes with three copies of each chromosome
What are ALLOPLOIDS?
= polyploids that are the result of crosses between 2 or more species (usually related species)
Hybrids with two different sets of chromosomes are technically a different species than both parents
Problems of alloploids?
= the hybrid plant is sterile because in meiosis I the different chromosome sets (from 2 different species) cannot align since they are not homologous
- the plant can however still reproduce asexually and through nondisjunction the plant can become tetraploid (AB to AABB) and thus they can become fertile
What are AMPHIDIPLOIDS?
= functional diploids, can come from crossing of two diploid species
example: 6N=42 allohexaploid is a functional (3 x two sets of homologous chromosomes) diploid = behaves like diploid in function but technically there are three times 2 sets of homologs
