Molecular Basis of Inheritance Flashcards
Definition of nucleoside
Sugar + base
Definition of nucleotide
Sugar + base + phosphate
Definition of introns
Non coding region of a gene
Definition of exons
Coding regions of a gene
Definition of transposon based repeats
DNA sequence that move to a randomly selected location in the sequence
Definition of satellite DNA
V large arrays of tandemly repeating non coding DNA, main structural constituent of heterochromatin
Definition of dosage compensation
Process by which the gene expression in sex genes are stopped by forming heterochromatin
Definition of matrilineal
Does not follow any autosomal/sex linked inheritance patterns, only maternal DNA is passed on
What is DNA
Genetic material
Nucleotide composition
Deoxyribose(OHH)/ribose(OHOH)
PO4 3-
Nitrogenous bases
Purine
-Adenine NH2
-Guanine NH2, C=O
Pyramidine
- Cytosine C=O NH2
- Thymine C=O CH3
- Uracil C=O
Nucleoside composition
Sugar + base = nucleoside
Adenine + deoxyribose = deoxyadenosine
Formation of phosphodiester bonds
DNA polymerase forms PDB between 3C OH and PO4 3-
Releases 2 PO4 3-
Polarity of polynucleotide chains
5 PO4 3- => 3 Deoxyribose
Structure of DNA
RH double helix
Antiparallel strands
A=T, C=-G, perpendicular to helical axis
Describe semiconservative replication
2 single template strands for base pairing
2 new strands made up of 1 old and 1 new strand
Describe the composition of coding DNA
How does this differ between eukaryotes and prokaryotes?
2000 bases code for a gene
1.1% of genome codes for protein
Eukaryotes have
- promoters, coding, non coding, termination sequences
- premRNA must have introns spliced out => mRNA
Prokaryotes have
-promoters, coding, termination sequences
What are transposon based repeats
What are the 2 consequences
What are the 2 types
Section of DNA => mRNA =reverse transcriptase=> DNA moves to random location
Often enters inactive regions = no effect
Enters functioning genes => cancer possible
LINES
SINES
What is heterochromatin
How is it used?
Compact = transcriptionally inactive
Long arrays of tandem repeats/satellite DNA
Forensics, paternity testing
What is snRNA
Small nuclear RNA
Associates with proteins = ribonucleoprotein needed to splice premRNA
What is rRNA
rRNA + protein = ribosome
Describe the structure of tRNA
Clover shaped
5’ HB within molecule anticodon AA binding site 3’
What is dosage compensation
How is it used in the X chromosome
Xist gene in X inactivation center transcribed => ncRNA
Heterochromatin forms => inherited somatically
Only 1 X expressed per cell, both => death
What is miRNA
How does it work
Types of ncRNA (regulates gene expression)
Transcribed from miRNA gene, exported into cytoplasm and processed by nuclease
Single strand base pairs with mRNA => binds and cleaves for
-translational repression
-deadenylation => unstable mRNA
What is mtDNA
How is it inherited
What are the consequences of mutations here
Circular 13 polypeptides, rRNA, tRNA
Matrilineal
Mutations affect organs with high energy reqs (muscles, nerves, LHON, Ataxia)
