17. Microbial Genetics

Question 1

what is a clone?

Answer 1

• population of cells that are genetically identical

Question 2

what is a genome?

Answer 2

• genes present in a cell or virus
  – bacteria usually haploid
  – eukaryotes usually diploid

Question 3

what is a genotype?

Answer 3

• specific set of genes possessed

Question 4

what is a phenotype?

Answer 4

• collective characteristics of genotype that are observable

Question 5

what are the functions and structures of genetic material?

Answer 5

• store, transmit and express genetic informations of cell/organism
• linear polymers of nucleotides in genetically determined sequence
• DNA and RNA

Question 6

what is the central dogma of molecular biology?

Answer 6

• DNA
• transcription
• RNA
• translation
• protein

Question 7

what is the structure of DNA?

Answer 7

• double stranded, double helix
• chains of nucleotides
  – nucleic acids contain non-identical monomeric units in a specific sequence
• sugar component is 5-C doxyribose
  – helps form phosphate backbone
• directionality 5’ to 3’
  – strands anti-parallel
• complimentary bas pairing
  – AT; GC

Question 8

what is the structure of RNA?

Answer 8

• sugar component is 5-C ribose
  – instead of deoxyribose
• contains base Uracil
  – instead of thymine
• RNA stranded
  – but can fold into number of shapes by base pairing between complimentary regions of the same strand
  – some viruses have dbl stranded RNA
  – tRNA
• apart from carrying information
  – structural and catalytic fxns

Question 9

what are the structural differences and simalarities between DNA and RNA?

Answer 9

• base pair vs. nucleobases
• thymine vs. uracil
• helix of sigar-phosphates

Question 10

what is gthe structure of a gene?

Answer 10

• linear sequence of nucleotides
  – fixed start and end
  – transcribed to give RNA product and encode single polypeptide, tRNA, rRNA
• prokaryotic and viral genes differe from eukaryotic
  – prokaryotic coding information is usually continuous
  – eukaryotic coding information usually have exons that are interrupted by introns

Question 11

what are the genes that encode tRNA and rRNA?

Answer 11

• DNA segments
• all rRNA transcribed as single, large precursor cut up by ribonucleases after transcription to yield final rRNA product
• 16S rRNA and 23S rRNA flanked by inverted repeats formingstem structure in RNA
• stems cleaved by RNase III, generates mature 16S and 23S
• tRNA liberated by RNase P and F
• 5S rRNA liberated by RNases E and M5