Genes and genomes

Question 1

significance of: Muller

Answer 1

showed X-rays cause mutations in genes, can be intentionally changed

Question 2

significance of: Beadle and Tatum

Answer 2

used bread mold, which when treated with X-rays could not make enzymes
- conclusion: 1 gene 1 enzyme

Question 3

define gene: technical

Answer 3

unit of heredity, from parent to offspring and determines some characteristic of offspring

Question 4

define gene: practical

Answer 4

distinct sequence of nucleotides forming part of chromosomes, which determines order of monomers and thus the polypeptide/ nucleic acid molecule the cell may synthesise

Question 5

what do genes produce?

Answer 5

• proteins

- RNA: mRNA, tRNA, rRNA

Question 6

1 gene 1 enzyme hypothesis:

Answer 6

• originally thought 1 gene, 1 protein

- central dogma of molecular biology

Question 7

outline gene structure: prokaryotes

Answer 7

• control regions

- protein coding regions

Question 8

prokaryotes: control regions

Answer 8

• determines when gene produces protein
• has promoters (region on DNA where transcription starts)
• other regulatory regions

Question 9

prokaryotes: protein coding regions

Answer 9

• start codon
• stop codon
• open reading frame (ORF)

Question 10

outline gene structure: eukaryotes

Answer 10

• control regions
• protein coding regions
• non-protein coding regions
• many eukaryotic genomes are non-protein coding

Question 11

eukaryotes: protein coding region

Answer 11

exons

Question 12

eukaryotes: non-protein coding region

Answer 12

introns

Question 13

human eg. of gene structure

Answer 13

approx. only 1.5% code for proteins

- 8% regulatory (control regions)

Question 14

alternate RNA splicing

Answer 14

• during transcription, different splicing of exons will translate into different types of proteins

Question 15

define genome:

Answer 15

the entire genetic complement of an organism

- HOWEVER genome size doesn’t correlate to species complexity

Question 16

eg. human genome features

Answer 16

• 26 000+ nuclear genomes

- mitochondrial DNA: 17 000 bp

Question 17

features: gene density prokaryotes

Answer 17

• maximise genomic territory

- gene coding regions very close, even overlap

Question 18

features: gene density eukaryotes

Answer 18

• evolved other ways for complexity:
• different gene expression
• different gene splicing
• epigenetic factors

Question 19

non- protein coding genes: features

Answer 19

• pseudogenes non-functional copies of normal genes
• introns within genes
• highly repetitive DNA sequences btw genes (satellites/ microsatellites)
• large regulatory regions (up/downstream)
• structurally: critical regions like centromeres and telomeres

Question 20

sequencing genomes:

Answer 20

• much cheaper and faster now

- takes DNA, cuts it up, assembles

Question 21

genome sequencing use:

Answer 21

• from this, can determine evolutionary relationships
• regions of similarity and difference
• genes btw species
• genes which give organisms unique characteristics