CH 13 Genomes Reading Guide Flashcards
How does genome relate to chromosome(s)?
The genome is a complete set of chromosomes. In the case of human 23 chromosomes make up our genome
Do you
have one or two copies of the human genome in each of your cells?
2 copies
Is the genome made up of RNA or DNA?
DNA
Why is it so important to fragment the genome into many random pieces?
With existing technologies there is much less error in sequencing small sections of the genome and adding the sections together
With current technology can we sequence an entire chromosome in one piece?
No. Must fragment the chromosome into smaller sections
How large can a human chromosome be?
Chromosome 1 (the largest) is approximately 250 million nucleotides long
the genome is typically
sequenced 10-50 times over in order to determine its sequence. Why might it be a good
idea to do this?
To reduce the number of errors present in the final genome sequence and to minimize the number and size of the gaps where the genome sequence is incomplete
Which
type of repeats do you think poses the greatest challenge to sequence assembly
Short, two nucleotides (example AT) in length repeats. Because AT can fold back on itself and pair with other AT’s
Would it be meaningful for you, and for society/the field
of medicine, to know your particular genome sequence?
Yes and No.
Could allow you to plan for possible health complications, but if you don’t have the resources to help yourself then you may not want to know
what parts are there to a protein coding gene?
Regulatory elements, non coding introns and protein coding exons
Do all genes code for proteins? Explain.
Exon regions code for proteins and intron regions do not
What ‘patterns’ / ‘motifs’ might be used to find a promoter?
TATA box
What ‘patterns’ / ‘motifs’ might be used to find an ORF?
Long string of codons for amino acids with no stop codon.
What does ORF stand for?
Open reading frame
Does an ORF (open reading frame) necessarily have to contain either a start or a stop
codon?
Does not contain any stop codon
Where in a gene (intron or exon) are ORFs
located?
Exons
would genes that code for functional RNA molecules have ORFs
Yes.
The exon is the part of the gene that will become the mature RNA
How can such mRNA sequences be used to confirm
the presence of ORFs, and intron exon boundaries, in annotated genes?
mRNA is simpler than the original DNA
mRNA has had the introns removed and is only left with a long string of exons with no stop codon (an ORF)
Are 5’ and 3’UTRs (untranslated regions) part of ORFs or exons, or both? Explain.
They’re part of the first and last original exon from DNA. Not part of the “new” open reading frame
If large differences in gene number does not explain the
greater complexity of the human body compared to that of the microscopic nematode
worm C. elegans, what might?
Human genes are able to do much more with the fewer numbers that we have ie. protein can have multiple functions
gene number is not a good predictor of organismal
complexity. How about genome size?
No. A protozoa has close to 10^6 base pairs while humans have 10^10 base pairs
Define polyploidy
Has more that two sets of chromosomes in the genome
what class of organisms are you very likely to find examples of polyploidy?
Plants
What might explain the large difference in genome size between organisms that
otherwise have comparable numbers of genes?
Ploidy levels: Diploid vs polyploid
Some eukaryotes contains large sections of non-coding DNA.
What is highly repetitive DNA?
noncoding DNA that consists of sequences present in more than 100,000 copies per genome
What is moderately repetitive DNA?
noncoding DNA that consists of sequences present from 100 - 10,000 copies per genome
Approximately how much of the human genome is sequence that actually specifies the
order of amino acids in a protein?
2.5%
Are protein coding genes the only genes in the genome?
No
In addition to exon sequences (specifying the order of amino acids), what other parts are
there to a gene?
Noncoding RNA, repetitive DNA, introns
Transposable elements make up how much of a gene?
Approximately 45%
What is the overall electrical charge of a DNA molecule and why?
Negative due to the phosphate back bone
What is the overall
charge of histone proteins?
Positive. From the amino acids lysine and arginine
Do mitochondria and chloroplast contain their own genetic material?
Yes
