Term
| What are some of the functions of the nucleus? |
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Definition
1. Protect chromosomes from damage (free radicals in cytosol)
2. Repair chromosomes when damaged
3. Replicate chromosomes
4. Facilitate expression of gene programs through transcription
5. Synthesize ribosomes |
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Term
| The lumen of the rough ER is contiguous with which part of the nuclear membrane? |
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Definition
| the perinuclear space (space between inner and outer nuclear membranes) |
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Term
| Which portion of the nuclear membrane is anchored to the nuclear lamina? |
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Definition
| The inner nuclear membrane |
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Term
| The nuclear lamina is made of which type of cytoskeletal elements? |
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Definition
| intermediate filaments (lamin a, b, and c) |
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Term
| What structure in the nucleus is responsible for the organization of the chromosomes? |
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Definition
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Term
| The membrane of the ER is contiguous with what part of the nucleus? |
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Definition
| the outer nuclear membrane |
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Term
| What chemical process causes the breakdown of nuclear lamina? When in the cell cycle does this occur? |
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Definition
| Phosphorylation of the lamin proteins breaks down the nuclear lamina; this occurs during mitosis (prometaphase) |
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Term
| By what chemical process are intermediate filaments made? |
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Definition
| oligomerization (a process by which several different polymers eg lamin A, B, and C, are polymerized into a single polymer) |
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Term
| How does the dividing, mitotic cell ensure nuclear envelope materials end up in both daughter cells? |
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Definition
| When the nuclear lamina depolymerizes, the monomers form vescicles with the nuclear envelope which then fuse onto chromosomes. |
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Term
| Vancomycin is an antibiotic with a molecular mass of 1.4kDa. By what process can vancomycin enter the nucleus? |
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Definition
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Term
Rastoni toxin A, a poison found in jellyfish has a molecular weight of 46kDa and lacks a nuclear localization signal. The area of the cell where rastoni toxin A is most biologically relevent is:
A)Cytosol
B)Nucleus
C)Both
D)Neither |
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Definition
| A) Cytosol. A protein without a NLS that is > 44kDa cannot enter the nucleus. |
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Term
| (T/F) Certain NPCs are specialized for facilitating diffusion of specific molecules in and out of the nucleus. |
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Definition
| False. All NPCs are functionally equivalent |
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Term
| The anchor with which importin must interact on the NPC is called what? |
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Definition
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Term
| NPCs exhibit which type of symmetry? |
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Definition
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Term
| What is the diameter of the NPC? |
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Definition
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Term
| Importin binds to which region of a protein? What is chemically unique about this region? |
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Definition
| Nuclear localization signal; contains 4-8 positively charged amino acids (lysine and/or arginine) |
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Term
| Which side of the cell (cytosol or nucleus) will be composed of primarily Ran-GDP? |
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Definition
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Term
| Which side of the cell (cytosol or nucleus) will be composed primarily of Ran-GTP? |
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Definition
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Term
| RanGEF, instead of phosphorylating GDP to make GTP, does what? Where (cytosol or nucleus) is RanGEF found? |
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Definition
| RanGEF completely replaces GDP with GTP on the Ran molecule. It is located in the nucleus. |
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Term
| Which molecule dephosphorylates (or hydrolyzes) RanGTP to make RanGDP? Where (cytosol or nucleus) is this molecule located? |
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Definition
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Term
| How is the nucleolus separated from the rest of the nucleus? |
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Definition
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Term
| The nucleolus is responsible primarily for the creation of what? |
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Definition
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Term
| How many autosomes contain rDNA? How many chromosomes? |
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Definition
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Term
| Which 3 rRNA species are transcribed as a 45S precursor? |
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Definition
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Term
| Approximately how many rDNA genes can be found per organism? |
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Definition
| ~400 per diploid organism or 200 per haploid organism |
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Term
| How many simultaneous transcription units can be made per gene? |
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Definition
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Term
For each of the following rRNAs, choose the correct subunit (large or small) to which they are destined:
1) 28S
2) 18S
3) 5.8S
4) 5S |
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Definition
1. 28S (large)
2. 18S (small)
3. 5.8S (large)
4. 5S (large)* this rRNA is made somewhere separate from the other rRNAs |
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Term
| What are the two mature ribosomal subunits called? |
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Definition
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Term
| How many pairs of autosomes do humans have? How many sex chromosomes? |
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Definition
| 22 pairs of autosomes; 2 sex chromosomes |
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Term
| Chromosomes are made primarily of which two types of molecules? |
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Definition
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Term
| Approximately how large is the haploid human genome? The diploid genome? |
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Definition
| 3 x 10^9 base pairs; 6 x 10^9 base pairs |
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Term
| What is the functional importance of the centromeres? |
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Definition
| The centromere on each duplicated chromosome is the region where the kinetochore will bind; This binding allows in the segregation of the chromosomes at mitosis and meiosis |
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Term
| What structure of the chromosome prevents the shortening of the genome after every cellular division? |
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Definition
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Term
| Why are DNA molecules prone to shortening? What mechanism does the cell have for preventing this? How does it work? |
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Definition
| The the end of a lagging strand cannot be primed by RNA primer; Unless telomerase is active the end of a lagging strand cannot be copied and shortening will result. Telomerase adds a repeating sequence of GGGGTTA to the end of the lagging strand so that the end can be copied. |
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Term
An individual is born with a mutated telomerase gene. When this individual is karyotyped, what is the geneticist likely to see?
A) Smaller than normal chromosomes
B) Larger than normal chromosomes
C) Unchanged chromosomes |
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Definition
| A) Smaller than normal chromosomes |
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Term
A gene sequence is 8 x 10^4 base pairs long, of which 6 x 10^4 base pairs are introns and 2 x 10^4 base pairs are exons. Which of the following is most likely the length of the processed mRNA product:
A) 6.4 x 10^4 base pairs
B) 8 x 10^4 base pairs
C) 2.3 x 10^4 base pairs
D) 2 x 10^4 base pairs |
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Definition
| C) 2.3 x 10^4 base pairs (poly A tail and 5' cap add to the length of the molecule) |
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Term
In a neuron, the genes responsible for producing cytotoxic effects of T-cells are likely to be found in which area of the chromatin?
A)Euchromatin
B)Heterochromatin |
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Definition
| B) Heterochromatin contains genes that are not being expressed. |
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Term
Melanocytes are cells that actively produce the antigen MART-1. MART-1 is likely to be located in what type of chromatin in melanocytes?
A) Euchromatin
B) Heterochromatin |
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Definition
| A) Euchromatin - genes that are actively transcribed are located in euchromatin |
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Term
| What are the 5 kinds of major histones? |
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Definition
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Term
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Definition
| A nucleosome is an histone octamer made up of 2 copies of H2A, H2B, H3, and H4. 146 bp of DNA wrap around the octamer. Including linker DNA, the total nucleosome contains 200bp of DNA |
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Term
| What protein is important in the formation of the 30nm fiber of chromatin? |
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Definition
| a single copy of H1 histone per nucleosome coils nucleosomes into 30 nm fibers. |
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Term
| How can the 30 nm fiber be disrupted to allow transcription? |
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Definition
| Regulatory proteins can bind and disrupt the 30nm fiber. |
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Term
| Which portion of the is prone to post-translational modification? |
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Definition
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Term
| What types of modifications can be made to N-terminal tails of the histones? |
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Definition
| Lysine residues can be acetylated or methylated; acytelation affects chromatin structure and can affect accessibility to/recruiting of regulatory proteins. |
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Term
| Can acetylation patterns be preserved following cellular division? |
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Definition
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Term
| What nuclear structure is responsible for organizing euchromatin into a few, small foci and by keeping the channels to the nuclear pores clear? |
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Definition
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Term
| Which disorder arises when patients produce auto-reactive antibodies to nuclear antigens? |
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Definition
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Term
| Which severe bleeding disorder presents due to a reciprocal translocation that fuses the retinoic acid receptor to the nuclear protein PML? |
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Definition
| Acute promyelocytic leukemia |
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Term
| Which childhood disease arises due to a mutation in SMN1, an RNA processing factor? |
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Definition
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