Genes, Genomes And Genomics 2 Flashcards
(18 cards)
What is the difference between genetics and genomics ?
Genetics- the study of individual genes
Genomics- the study of the entire genome
What is the C-value ?
The amount of DNA within a haploid nucleus
Measured in picograms
What is the human c-value ?
3.2pg
3.2x10^9 bp of DNA
What is the C-value paradox?
Genome size is not proportional to the apparent complexity of an organism
Similar organisms may have greatly differing genome sizes
How many genes do humans have ?
19,396
What is gene density ?
The number of genes per pg of DNA
What is an open reading frame (ORF) ?
A regional of the genome that is transcribed and has a defined star and stop codons
Describe the structure of the prokaryotic gene
It is continuous
A shine-dalgarno sequence helps align ribosome to start codon
Each polycistronic operant has a single TSS
How is transcription regulated in prokaryotes ?
By:
1. Promoter
2. Operator
3. Terminator
Describe the structure of the eukaryotic gene
It is discontinuous- contains introns and exons
Each gene has its own promoter
Also contains enhancers which can increase the expression of some genes
Has a kozac sequence (equivalent to shine dalgarno)
What are paralogues ?
Two homogenous genes arising as a result of gene duplication
What are orthologues ?
Two homologous genes arising as a result of species divergence
How do gene families arise ?
From duplication of an existing gene
What are homologues ?
Genes that share a common ancestor
What are analogues ?
Genes that share a function but not a common ancestor
What is the pribnow box ?
TATAAT
-10 position (10 bases upstream of where transcription begins)
Found in the promoter region of prokaryotic genes
How many bp are introns ?
100-2000bp
Average 200-500
What is the initiator ?
Simplest functional promoter
Initiates transcription on its own
Usually found on the TSS
