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47 Cards in this Set
- Front
- Back
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The contents of the nucleus are enclosed by the _______.
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Nuclear Envelope
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What size solutes can easily pass through the nuclear pores?
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<40kD
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The inner surface of the nuclear envelope is lined by the _______.
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Nuclear Lamina
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The _______ is composed of lamins and supports the nuclear envelope.
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Nuclear Lamina
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The integrity of the nuclear lamina is regulated by _______ and _______.
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phosphorylation and dephosphorylation
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Nuclear pores contain the _______ that appears to fill the pore like a stopper.
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Nuclear pore complex (NPC)
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The NPC is composed of about _______ proteins called _______.
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30
nucleoporins |
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Proteins synthesized in the cytoplasm are targeted for the nucleus by _______.
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Nuclear Localization Signal (NLS)
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What is the basic residues of the NLS?
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P-K-K-K-R-K-V
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What is the first step in importing proteins from the cytoplasm to the nucleus?
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The protein with NLS binds to importin alpha/beta.
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What is the second step in importing proteins from the cytoplasm to the nucleus?
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The importin alpha/beta and protein form a complex with the cytoplasmic filament.
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What is the third step in importing proteins from the cytoplasm to the nucleus?
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The protein complex is moved through the nuclear pore.
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What is the fourth step in importing proteins from the cytoplasm to the nucleus?
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The protein complex moves into the nucleoplasm and interacts with Ran-GTP and dissociates.
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What is the fifth step in importing proteins from the cytoplasm to the nucleus?
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Importin beta is transported back to the cytoplasm, along with Ran-GTP.
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What is the role of guanine exchange factors (GEF)?
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GDP to GTP
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What is the role of GTPase activating protein (GAP)?
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GTP to GDP
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Chromosomes consist of _______ fibers, composed of DNA and associated proteins.
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chromatin
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What amino acids do histones have a large content of?
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Arginine and Lysine
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What are the five different groups of histones?
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H1
H2A H2B H3 H4 |
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Why are histones so highly conserved?
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Their positive charge is associated with the negative charges on the backbone of DNA.
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What is the %Arg and %Lys in H1? What is its UEP?
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%Arg - 1
%Lys - 29 UEP - 8 |
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What is the %Arg and %Lys in H2A? What is its UEP?
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%Arg - 9
%Lys - 11 UEP - 60 |
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What is the %Arg and %Lys in H2B? What is its UEP?
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%Arg - 6
%Lys - 16 UEP - 60 |
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What is the %Arg and %Lys in H3? What is its UEP?
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%Arg - 13
%Lys - 10 UEP - 330 |
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What is the %Arg and %Lys in H4? What is its UEP?
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%Arg - 14
%Lys - 11 UEP - 600 |
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DNA and histones are organized into repeating subunits called _______.
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nucleosomes
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The histone core complex consists of two molecules each of _______, _______, _______, and _______ forming an octamer.
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H2A
H2B H3 H4 |
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What is the preferred organizational model of chromatin structure?
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Zig-zag (solenoid is the other)
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_______ returns to a dispersed state after mitosis.
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Euchromatin
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_______ is condensed during interphase.
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Heterochromatin
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What kind of heterochromatin is found around centromeres and telomeres, remains condensed all the time (no gene expression), and consists of highly repeated sequences?
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Constituative Heterochromatin
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What kind of heterochromatin is inactivated during certain phases of an organism's life and found on one of the X chromosomes as a Barr body?
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Facultative Heterochromatin
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What are two ways that histone tail modifications influence chromatin?
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-serve as docking sites to recruit non-histone proteins
-alter the way in which histones of neighboring nucleosomes interact with one another |
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Histone _______ leads to DNA inactivation.
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methylation
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Histone _______ leads to DNA activiation.
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acetylation
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Chromatin of a _______ cell exists in its most highly condensed state.
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mitotic
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A preparation of homologous pairs ordered according to size.
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Karyotype
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The end of each chromosome is called a _______ and is distinguished by a set of repeated sequences.
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telomere
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The _______ is located at the site markedly indented on a chromosome.
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centromere
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_______ contain constituative heterochromatin.
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centromeres
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_______ DNA is the site of microtubule attachment during mitosis.
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Centromeric
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_______ inheritance depends on factors other than DNA sequences.
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epigenetic
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The _______ is a network of protein-containing fibrils.
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nuclear matrix
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_______ involve the breakage of a chromosome and resealing of the segment in a reverse order.
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inversions
A B C D -> D C B A |
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_______ are the result of the attachment of all or one piece of one chromosome to another chromosome.
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translocations
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_______ result when there is a loss of a portion of a chromosome.
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deletion
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_______ occur when a portion of a chromosome is repeated.
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duplication
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