Unit 4 (Part II) Flashcards
(41 cards)
The genomes of salamanders contain ten times more DNA than the genomes of humans because salamanders…
have more noncoding DNA than humans have.
A gene can be defined as a segment of DNA that codes for…
a functional product.
Introns in the mRNA-coding genes are the transcribed sequences…
between protein-coding sequences.
In the nucleus, introns are removed from transcripts by…
splicing
The human genome is estimated to contain about … genes.
20,000 - 25,000
Introns were discovered when mRNA for adenovirus protein expressed in mammalian cells was hybridised to single-stranded virus DNA coding for that mRNA. When the complexes were observed under the electron microscope,…
a partial hybrid with loops of DNA extending from the hybrid regions was seen.
Introns can encode…
All of the above (answer)
*Small nuclear RNAs;
microRNAs
Sequences that control RNA processing;
Introns are found…
commonly in eukaryotic genes and rarely in prokaryotic genes.
Histones genes have…
no introns
Introns constitute about what percentage of the average human gene?
90%
Synthesis of different proteins from the same gene is due to…
alternative splicing
Evidence for exon shuffling is that some genes…
are chimeras whose exon sequences are derived from other genes.
Simple-sequence repeats…
All of the above (answer)
*sediment as unique bands in equilibrium density-gradient centrifugation;
are present in tandem arrays of thousands of copies;
reassociate more rapidly than non repeated sequences;
A gene family is a…
set of related but slightly different genes present in multiple copies in one individual.
Pseudogenes are…
nonfunctional gene copies.
Most pseudogenes are thought to have originated via….
reverse transcription of an mRNA and integration of the cDNA into a new chromosomal site.
The chromosomes of eukaryotes differ from those of prokaryotes in that eukaryotic chromosomes are…
All of the above (answer)
*linear;
multiple;
complexed with histones;
both b and c
A chromosome is a complex of eight core
histones, one histone H1 molecules, and 166 bak pairs.
Most of the euchromatin in interphase nuclei is in the form of … fibres
30nm
Heterochromatin consist of …
high condensed, transcriptionally inactive chromatin.
A centromere is a…
All of the above (answer)
*region of heterochromatin;
point of attachment of sister chromatids;
region where proteins bind to form kinetochores;
Kinetochores are the …
sites of spindle fiber attachment to chromosomes.
Centromeric DNA sequences were first identified by…
selecting for sequences inserted into yeast plasmid that distributed equally among daughter cells during mitosis.
Telomeres are…
chromosome end structures required for complete replication of liner chromosomes.
