Molecular Basis of Inheritance Flashcards
(29 cards)
Name the 3 components of a nucleotide.
Deoxyribose sugar
Nitrogenous base
Phosphate group
What distinguishes deoxyribose sugar from ribose?
It contains a hydrogen only at position C2 as opposed to an OH group.
What 2 groups are the nitrogenous bases categorised into?
Purines
Pyramidines
What are the X2 purines?
Adenine
Guanine
What are the X2 pyramidines?
Cytosine
Thymine
Which base is replaced in RNA and which base does it replace?
Thymine is replaced by Uracil.
Are the purines single or double ring structures?
Double.
Are the pyramidines single or double ring structures?
Single.
A sugar + base makes a…
NucleoSIDE
DNA nucleotides have how many phosphate groups?
X3, they are nucleotide TRIphosphates.
What type of bonds do nucleotides form?
Phosphodiestser bonds.
Which part of the nucleotide is the 5-prime end?
The phosphate group.
Which part of the nucleotide is the 3-prime end?
The hydroxyl (OH) group.
What is the name given to the inorganic molecule consisting of X2 phosphates (PPi) released when nucleotides bond.
An inorganic pyrophosphate.
What is the name of the enzyme which catalyses the formation of DNA molecules from deoxyribonucleotides?
DNA polymerase.
Describe the complementary base pairings.
A - T (X2 hydrogen bonds)
C - G (X3 hydrogen bonds)
What is the orientation of the X2 DNA strands and their base pairings?
The X2 strands run ANTIPARALLEL with the bases PERPENDICULAR to the helical axis.
What is semi-conservative DNA replication?
The process whereby X2 new daughter DNA strands are produced from a single DNA helix, each retaining X1 strand of the original DNA helix due to complementary base pairing.
What are INTRONS and EXONS?
INTRONS = non-coding regions of DNA which are lost during transcription.
EXONS = coding regions of DNA.
45% of the human genome consists of transposing based repeats such as retrotransposable elements, what are these and how do they work?
Sequences of DNA are transcripted into RNA before being reversely transcribed back to a DNA sequence and inserted back into the genome at a different site.
Examples include:
LINES (Long interspersed elements)
SINES (Shirt interspersed elements)
6.6% of the human genome is heterochromatin. What is this?
Chromatin that is so tightly compact it is transcriptionally inactive.
What is the name of the gene which is responsible for x-chromosome inactivation in females?
Xist
What is it called when one X chromosome in females is transcriptively inactive in order to prevent over transcription?
Dosage compensation.
What is the name of the X inactivation centre on the X chromosome which causes mass compression of the X chromosome into heterochromtin?
XIC.
