Structure and Function of Genes and Genomes Flashcards
What is a gene? What is it composed of?
It is the unit of inheritance and is composed of DNA.
What is a genome?
It is a package of informational, historical, and noncoding DNA along with unknown regions.
How many haploid bps are in a human genome?
3.3x10^9
Where is most of the DNA found in a human cell? Where is the rest of it located?
Most of the DNA is found in the nucleus and the rest is coded into the mitochondria
Who invented the microscope and when? What was observed?
Karl Von Nageli reported thread like structures (chromosomes) in 1842.
What theory was proposed by whom in 1865?
Mendel proposed inheritance
What did Watson and Crick publish in what year?
They described the double-helix structure of DNA in 1953
Who came up with the x-ray technology that provided evidence of the double helix DNA?
Rosalind Franklin
How much of the nuclear genome codes for genes?
25%
How much larger than the mitochondrial genome is the nuclear genome?
5x10^6
What did Francis Crick describe in what year?
In 1957, he described that DNA is transcribed to RNA which is translated into a functioning protein
What is the difference between an intron and an exon?
Introns are non-coding DNA sequences removed during splicing, and exons are coding and protein assembling sequences
What portion of the nucleus is exons/introns?
10% exons and 90% introns
What are the three described parts of a DNA strand?
Regulatory sequences, Promoters, and Terminators
How can we visually tell a prokaryotic from a eukaryotic gene?
Eukaryotic genes have introns
What binds to what part of DNA during transcription?
The regulatory sequences bind regulatory proteins, and promotors bind RNA polymerase
What are the 4 regions of RNA?
Ribosomal binding site, start codon, codons, and the stop codon
What is a codon?
It is a three nucleotide sequence that specifies an amino acid
What are the two proponents of a regulatory sequence of a protein coding DNA strand?
The promotor and the enhancer/silencer
What direction does the sense/coding strand go?
5 to 3
What strand binds to RNA polymerase?
The antisense/template strand
What are the two parts of the promotor?
The core and the proximal/cis sequence
What is the enhancer/silencer sequence of DNA located far from the core?
The distal/trans sequence
How many polypeptide proteins are needed for optimal control of DNA transcription?
Approximately 60 per eukaryotic gene
How is the preinitiation complex assembly assembled?
It is a binding of the TATA box binding protein (TBP) to the TFIID.
What are the 4 core promotor sequence element positions?
Positions -35, -25, 1, and 30
What is splicing?
It is pre-mRNA being processed to remove introns
What are the splicing sequence elements?
The donor site is GU at the 5 end, and the acceptor site is ag at the 3 end
What is alternative splicing?
It is a different pattern of gene splicing that allow for the diversity of proteins for different functions
What portion of which DNA strand in which direction determines transcription initiation and directionality?
The promotor region of the 5 end of the coding strand
Is DNA transcription directionality relative?
Yes
What is the translation start codon?
ATG
What are the three ways DNA sequences can be shared between genes?
- Complementary genes are transcribed in opposite directions
- Overlapping genes can be transcribed in the same direction but using different frames
- Genes can be nested in larger genes(ex. NF1) within an intron in the opposite direction (ex. OGMP, EVI2A, and EVI2B)
What is the centromere of a chromosone?
It is a narrowing point coated with kinetochore proteins
How do we find the p and q chromosomal arms?
Where are telomeres found and what is found in them?
They are found at each of the two chromosomal ends and they are rich in repetitive sequences
What DNA sequence elements provide a binding site for kinetochores? hint, it is at the centromere
Alpha satellite DNA
What is the kinetochore complex composed of?
The protein complex at the interface and microtubules from the spindle
What happens to telomeres as we age?
They get shorter
