PL5 Flashcards
what is a genome
entirety of an organisms hereditary or genomic information
are genomes always DNA
usually DNA
but some vriuses have RNA genomes
what is dsDNA (double stranded) measured in
base pairs (bp)
1000bp = 1kbp or kb (usually for genes)
1000000 = 1Mbp or Mb (for whole genomes)
is biological complexity related to DNA content in genome
NOOOOOOO
just because more DNA does not mean more complex (ex amoeba dubia has more DNA than humans)
how many animal species have been sequenced
genomes of 3278 species of animals have been sequenced
~0.2% of animals
name and describe largest sequenced genome
australian lungfish xiphophorus = 43 Gb (giga. bases - 14x human genome)
does not have many more genes than other vertebrates but has lots of transposable elements
definition of a gene
entire nucleic acid sequence that is necessary for synthesis of a functional product (polypeptide/RNA)
are all coding genes meant to be translated into a functional product
NOOOO
Sometimes genes encode RNAs that are not meant to be translated into protein but have a function of their own (genes that encode ribosomal RNA, tRNA, spliceosomes have some RNA parts that are not translated)
what can genes be considered as
transcription units
describe a transcription unit
segment of DNA that includes all the info needed for primary transcript to be made
what do exons of a gene contain
coding region or open reading frame (ORF)
describe open reading frame
contained in 3 exons
part of protein encoding gene with AUG (start) which is for initiation of translation and continues until reaches terminator codon
has info that specifies amino acid sequence of proteins
what are control regions
promoter - place where RNA polymerase gets recruited
cis regulatory factors = control regions, neighbours promoter, part of gene since they are essential for regulating expression
where are control regions found
upstream 5’ end of transcription of mRNA start
controls expression of gene
what do introns do
separate exons and are spliced out during mRNA processing (spliced out of primary transcript)
what happens after mRNA is produced, transcribed and terminated
enzymatically a series of A residues are added to 3’ end (polyadenylation)
not template driven - added enzymatically
every gene must have poly a site on 3’ end that has signal that directs enzymes that directs termination and addition of all A residues
what do proteins with similar functions often contain
similar amino acid sequences that encode functional domains
what can be found using BLAST
nucleic acid and protein sequence similarity
match against database and can find highly conserved domains during evolution (usually functional domains)
what is BLAST
computer algorithm
aligns 2 or more sequences in optimal way
does protein number or DNA content vary more among species
protein number varies much less among species than DNA content
what is difference in genome size often due to
Difference in genome size among species is mostly due to different amounts of non-coding DNA and transposable elements
in what type of species is gene density much greater
much greater in lower eukaryotes than in more complex eukaryotes
describe lower and higher eukaryotes (what they have)
lower eukaryotes have a
lot less genes and higher eukaryotes have a lot more DNA but not as many genes
what is a pseudogene
resembles a gene but has many stop codons so not productively expressed
what are alu sites
remnants of transposable elements (repeated sequences that are highly abundant in human genome)
what are orthologs
the same protein in different species
ex= alpha tubulin in humans and flies