Lecture 5 - Genome Anatomy Flashcards
Where is almost all heritable information written?
DNA sequences (3 x10^9 nt)
Where else can written information be stored in the body?
Epigenetics
Why is genetic information stored in DNA?
When sugar is incorporated into the DNA structure (backbone) it gives it a very supported structure (stable) so it is easily extractable.
Which direction is DNA written in?
DNA sequences are written in a 5´ → 3´ direction
This is the direction in which DNA and RNA are synthesized
Which strand would usually be written/ transcribed?
Sense strand
Why is it harder to copy the other DNA strand?
Because DNA can only be written in a 5’ to 3’ direction therefore the other strand runs in an opposing direction therefore RNA primer has to be involved and Okazaki fragment to be joined after the RNA primer is removed. (Multi step process)
How accurate is human DNA replication?
Every person has 12 new mutations
Where do significant errors of the human body occur in the genome?
Exons
What percentage of the genome do exons occur?
2%
What is achondroplasia?
A type of bone growth disorder. Due to genetic mutations, the cartilage does not convert into a bone during foetal development, resulting in dwarfism
What percent of the time is a condition (Achondroplasia) due to a new mutation rather than inherited?
80%
What happens when you get to the end of the chromosome?
Telomeres - holds chromosome intact so can be copied almost up to end of chromosome
TTAGGG telomeric repeat sequence
Specialized replication machinery
Telomerase, TERT
Inactive in somatic cells
Why would someone older than you have shorter telomeres?
Telomeres shorten with somatic cell division
Finite number of cell divisions to senescence
When would someone older than you having shorter telomeres not be the case?
TERT reactivation in cancer
What is the relationship between DNA and chromesomes?
Packaging relationship (So they can fit into the nucleus of cells)
What is a nucleosome?
Carries around 200 base pairs of DNA wrapped around it with a histone core.
what is a centromere?
Middle of a chromosome holding the two chromatids together
what is a p telomere?
Two short arms
What is a q telomere?
Two long arms
What is a chromosome ideogram?
Idiogram is the diagrammatic representation of karyotype showing all the morphological feature of the chromosomes grouped on the basis of position of centromere and ordered in a series of decreasing size. Chromosome banding and painting technique are used to identify each chromosome.
what are chromosome coordinates?
Sequence that has been ordered and oriented on the chromosome. The locations of these sequences can usually be expressed in chromosome coordinates. A sequence found in an assembly that is associated with a specific chromosome but cannot be ordered or oriented on that chromosome.
What is the issue with chromosome coordinates?
There is no single correct version of the entire genome.
Genetic reports must specify the version of the reference genome being used.
What is the chromosome complement?
The chromosome complement is diploid
n = 23
2n = 46
DNA content (3×109 bp)×2 = 6×109 bp
Two copies of every gene (pat, mat)
what is gene dosage?
Gene dosage is the number of copies of a particular gene present in a genome. Gene dosage is related to the amount of gene product the cell is able to express. However, the amount of gene product produced in a cell is more commonly dependent on regulation of gene expression.
