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Lecture 13
Genomes and Chromosomes
18
Biology
Undergraduate 3
11/22/2012

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Term
Name the 3 types of plant genomes
Definition
1. Mitochondrial
2. Chloroplast
3. Nuclear
Term
Which is the most conservative genome in gene sequence?
Definition
Mitochondrial (& very labile in gene arrangement; easily altered/changed)
Term
Which is the least conservative genome in gene sequence?
Definition
Nuclear (most variable)
Term
Outline the structure of a chromosome, from smallest (11nm) to largest width (1400 nm)
Definition
DNA < Chromatin beads < Chromatin fibre < Extended section < Condensed Section < Mitotic chromosome
Term
How do genomes decrease in size (3 ways)?
Definition
- polyploids "diploidizing" over time (become diploid)
- transposon excision (by translocation and deletion)
- chromosome loss (by translocation and deletion)
Term
What evidence is there for Palaeopolyploidy (genome duplications millions of years ago) in Arabidopsis ?
Definition
5 chromosomes have duplicated blocks
Term
What are the active agents of genome evolution?
Definition
Transposons
Term
What increases chromosome number?
Definition
Polyploidy
Term
What decreases chromosome number?
Definition
Translocations/deletions
Term
What does the basic number (x) represent w.r.t a chromosome number?
Definition
Number of chromosomes in the ORIGINAL genome
Term
Inversions of chromosomes cause a _______________ in gene order
Definition
reversal
Term
What is a translocation?
Definition
Attachment of one segment of a chromosome to another
Term
What are the 4 types of changes that chromosomes can undergo?
Definition
- translocation
- inversion
- deletion
- duplication

(TIDD)
Term
Imperfect chromosome pairing (at meiosis) happens most often in ____________ plants
Definition
annual
Term
What is a Karyotype?
Definition
Chromosome morphology at mitotic metaphase (number and appearance of chromosomes in nucleus of a eukaryotic cell)
Term
Define metacentric, acrocentric, and telocentric
Definition
1. Centromere is in middle of chromosome
2. Centromere is towards one end
3. Centromere is at one end (terminal end)
Term
What happens during the Revolutionary phase of Polyploid evolution? (2 things)
Definition
1. Hybridization
2. Chromosome doubling
Term
What happens during the Evolutionary phase of Polyploid evolution? (2 things)
Definition
1. Divergence
2. Diploidization (new diploid genomes)
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