Chap 8 GENES, CHROMOSOMES, & GENOME Flashcards
What is the difference between euchromatin and heterochromatin?
Heterochromatin is transcriptionally silent and thus packed densley and can be seen as darker patches.
Euchromatin is transcriptionally active and thus less densely packed and seen as lighter patches.
What is the length of the human genome?
3 million base pairs
How are histones arranged with DNA?
Histones generally arrange as an octamer in complex with DNA to form the nucleosome.
How do cells differentiate?
Different cells have different functions but same DNA code, they differentiate by turning on or off different sections of stored information on DNA.
What are reasons for sequencing the human genome?
To store the information gathered for further biological and medicinal study
To understand the nature of the proteins that genes code for
To identify mutations in the gene which cause genetic disorders
Molecular medicine; new approaches to
Improve Diagnosis of disease
Prevention; detect genetic predispositions to disease
Create pharmaco-genomics-customized drugs
What is karyotyping used for?
Test to examine chromosomes in sample of cells,help identify genetic problems as the cause of a disease or disorder by looking at structural changes or chromosome number.
How does the Giesma dye stain chromosomes?
A human chromosome smear stained to show the G-bands, using Giemsa dye. The dark regions - heterochromatic, late-replicating, and AT rich, the bright regions - euchromatic, early-replicating, and GC rich.
What are some theories as to why only 5% of the genome is functional?
Selfish DNA uses the rest of DNA to replicate itself.
Structural support, bind to histones.
Evolutionary Relic, once useful but now no longer useful
Explain the central dogma of life.
Classic Central Dogma in molecular biology states that a gene will always be transcribed into mRNA and mRNA will be translated to the production of a protein
Define an allele and locus
An alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome. Locus refers to the position of the allele on a chromosome.
Explain the Dosage Compensation Mechanism in Humans.
As females have 2X chromosomes but male sonly have 1, females have twice as many X linked genes which will produce twice as much protein if unregulated compared to males.Dosage compensation (that is, limiting the expression of X-linked genes in females) is achieved by inactivating either the maternal X chromosome or the paternal X chromosome early in development.This process leads to the formation of Barr bodies in female somatic cells.X chromosome inactivated by packing chromosomes tightly into a very compact state,preventing genes from being expressed.
(Barr bodies: The condensed, inactive X-chromosome found in the nuclei of somatic cells of most female mammals. )
What is the length between w base pairs in DNA and the length of one double helix twist?
Between each BP 0.34nm, in a twist there are 10 BP so 3.4nm.
