lecture 21, plant DNA part 2

Question 1

what are the advantages of “selfing”?

Answer 1

• progeny 100% related to parent, but can also pollinate others
• reproduce when pollinators are rare
• fast spread through new habitat

Question 2

what are the most common transitions in flowering plant evolution?

Answer 2

evolution from outcrossing to predominant self-fertilization

Question 3

what is a diploid?

Answer 3

one copy from maternal and one from paternal

Question 4

what percentage of all known plant genera are polyploid?

Answer 4

50%

Question 5

define autopolyploidy

Answer 5

doubling of chromosome number within individual organism

Question 6

define alloploidy

Answer 6

chromosomes from closely related species

Question 7

how does autopolyploidy occur?

Answer 7

nondisjunction in meiosis followed by fertilization

Question 8

how does allopolyploidy occur?

Answer 8

autopolyploidy occurring followed by meiosis

Question 9

animal genomes are very sensitive to …

Answer 9

mutations

Question 10

what is paleo-polyploidy?

Answer 10

whole genome duplication events, followed by gene diversification and loss

Question 11

what kind of error do gametes have?

Answer 11

meiotic error

Question 12

greater genetic material leads to …

Answer 12

robustness
more gene products –> more tissue

Question 13

what does ancient genome duplication eventually lead to?

Answer 13

loss of genes, re-diploidization

Question 14

plant genomes are more …. than animal genomes

Answer 14

flexible, more resilient to chance mutations sub- and neo-functionalization of duplicated genes. grow despite genetic modification

Question 15

what are the main systems of genetic transformation?

Answer 15

• agrobacterium tumefaciens
• CRISPR/Cas9

Question 16

DNA recombination works by …

Answer 16

DNA from carrier recombines with another organism’s DNA. can be a plasmid or virus

Question 17

using recombinant DNA technology ….

Answer 17

one can insert transgenes and novel genotypes

Question 18

how does gene cloning by recombination work?

Answer 18

1. restriction enzymes cut donor/vector DNA
2. ligated
3. bacterial host is transformed with recombinant plasmid
4. bacterial cell proliferates
5. culture or plate-full of bacteria growing

BUT not all cells will contain recombinant DNA

Question 19

what is a reporter gene?

Answer 19

a gene that can be easily assayed

Question 20

what is a chimeric gene?

Answer 20

genes produced from the fusion of two or more parent genes

Question 21

traits of agrobacterium tumefaciens:

Answer 21

• soil-dwelling bacterium
• infects wide range of angiosperms; via sounds
• crown-gall tumours
• tumor-inducing (Ti) plasmid
• contains transfer DNA

Question 22

Ti plasmid:

Answer 22

• 100 genes
• T-DNA region: 20,000 bp
• Gene O: amino acid derivative
• onc region: hormone biosynthesis (grow and divide uncontrollably)
• vir region: transfer process

Question 23

what happens in transgenic plants?

Answer 23

T-DNA genes are replaced by genes of interest. genes are inserted into plant’s genome

Question 24

why is A. tumefaciens transformation a major limitation?

Answer 24

no control over location of DNA insertion in host genome and can knock out a major function, e.g. photosynthesis or a low expression region

Question 25

what is CRISPR-Cas9?

Answer 25

a prokaryotic immune system against viruses/pathogens, that uses DNA sequences from past pathogens to recognize new invaders and cleave them

Question 26

how is CRISPR/Cas9 applied to engineering?

Answer 26

• Cas9 nuclease complexed with synthetic gDNA
• cut at specific location
• edit and/or add new DNA
• using host repair system

Question 27

examples of benefits to genetic engineering in plants:

Answer 27

1. add new traits; salt / drought-tolerance
2. new flavors
3. save native species; resistance against rapidly-spreading viruses