WK8 Cell Bio

winniesmith's version from 2017-01-27 10:05

Section 1

Question Answer
what does the internal structure of the nucleus doorganizes the genetic material and localizes nuclear functions.
how are chromosomes organizedindividual chromosomes occupy distinct regions/territories in mammalian cell nuclei and are organized so that transcriptional activity is correlated with gene position.
During interphase; heterochromatin remains highly condensed and is transcriptionally inactive
During interphase; euchromatinis decondensed and distributed throughout the nucleus
How are chromosomes arranged during interphaseare organized and arranged into discrete functional domains.
in interphase, how is chromatin organizedinto looped domains containing about 50-100kb.
what do chromatin domains representdiscrete functional units that independently regulate gene expression.
what does inactive heterochromatin bind tolamins and inner nuclear membrane
What does nucleolus surroundedheterochromatin
What occupies regions around the nuclear pore complex decondensed transcriptionally-active chromatin
Where can you find actively transcribed genesRegions around the nuclear pore complex and at the periphery of chromosome territories adjacent to channels between the chromosomes.
Where are newly transcribed RNAs processedin channels

Section 2

Question Answer
where does DNA replication take place(in large complexes called) replication factories.
how can you see replication factories by labeling cells with bromodeoxyuridine (an analog of thymidine) and then staining with fluorescent antibodies.
what are nuclear bodiesorganelles within the nucleus that concentrate proteins and RNAs for specific processes.
What is the structure of nuclear bodiesDynamic structures (not enclosed membranes) maintained by protein-protein and protein-RNA interactions. The nucleolus is a nuclear body.
What are nuclear specklesmRNA splicing machinery concentrated in nuclear bodies.
How can nuclear speckles be seenwith immunofluorescent staining with antibodies against snRNPs and splicing factors.
What do PML bodies dointeract with chromatin and are sites of accumulation of transcription factors, chromatinmodifying proteins, and DNA repair enzymes. A
What were PML bodies first identified as sites with a transcriptional regulatory protein involved in acute promyelocytic leukemia (PML).
What do cajal bodies contain the protein coilin and are enriched in snRNPs
What is the function of cajal bodies sites of snRNP assembly and processing
What nuclear bodies do?/function in gene silencingRNA editing and proteasomal proteolysis

Section 3

Question Answer
What is the function of the nucleolusthe site of rRNA transcription and processing, and ribosome assembly.
How many ribosomes do actively growing mammal cells have5 to 10 million ribosomes that must be synthesized each time the cell divides.
How is a 45S ribosomal precursor RNA transcribed5.8S, 18S and 28S rRNAs are transcribed as a single unit in the nucleolus by RNA polymerase 1
How does the transcription of 5S rRNA take placeoutside the nucleolus and is catalyzed by RNA polymerase 111
Describe the abundance of rRNA genes in cellscells have multiple copies of the rRNA genes. In oocytes the rRNA genes are amplified to support synthesis of ribosomes needed for early development.
How are rRNA genes amplifies in xenopus oocytes2000-fold, in thousands of nucleoli, resulting in .0^12 ribosomes per oocyte,
what are the 3 nucleoli regionsfibrillar center, dense fibrillar component, and granular component.
what do the 3 nucleoli regions representtranscription,processing and ribosome assembly.
what follows each cell divisionnucleoli become associated with the nucleolar organizing regions that contain the 5.8S, 18S and 28S rRNA genes. transcription of 45S pre-rRNA leads to fusion of small prenucleolar bodies. The initially separate nucleoli then fuse to form a single nucleolus
What does each nucleolar organizing region contain a cluster of tandemly repeated rRNA genes separated by spacer DNA. The genes and their growing RNA chains can be seen in electron micrographs.

Section 4

Question Answer
In higher eukaryotes what is the primary transcript of rRNA genes the 45S pre-rRNA. processed via a series of cleavages, which is similar in all eukaryotes. Processing
What is base modification in pre-rRNAAddition of methyl groups to bases and ribose residues, and conversion of uridine to pseudouridine.
What do nucleoli containover 300 proteins and many small nucleolar RNAs (snoRNAs) that function in pre-rRNA processing
how are snoRNPs formedsnoRNAs complexed with proteins. They assemble on pre-rRNA to form processing complexes similar to the formation of spliceosomes on pre-mRNA.
what do snoRNAs doguide RNAs to direct specific base modifications of pre-rRNA.
what do snoRNAs includeshort nucleotide sequences that are complementary to 18S or 28S rRNA and include the sites of base modification in the rRNA.
what does the formation of ribosomes requireassembly of pre-rRNA with ribosomal proteins and 5S rRNA.
in the formation of ribosomes what happens prior to cleavageRibosomal proteins are imported from the cytoplasm to the nucleolus, where they assemble with the pre-rRNA
what and where are 5S rRNAs assembledinto pre-ribosomal particles elsewhere in the nucleolus
What happens in the assembly of ribosomes after ribosomal proteins are imported into the nucleolusAdditional ribosomal proteins and the 5S rRNA are incorporated as cleavage and processing proceeds. The two nascent ribosomal subunits separate and are exported to the cytoplasm
Evidence suggest nucleoli do whathave a role in processing many types of small RNAs.
Small RNAs are transcribed outside of the nucleolus, but undergo modifications catalyzed by snoRNPs in the nucleolus.
The nucleolus is also involved in regulating cell division and in cell response to stress.