Exam 2 Flashcards by Dasha Gubarev

Which of the following questions would not be answered by using karyotyping?

Do any chromosome contain point mutations?

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The octameric histome core is composed of four different histone proteins. Once the core octamer has been formed, DNA wraps around it to form a nucleosome core particle. Which of the following histone proteins does not form a part of the octameric core?

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The N-terminal tail of histone H3 can be extensively modified and depending on the number, location, and combination of these modification, these changes may promote the formation of heterochromatin? What is the result of heterochromatin formation?

gene silencing

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What is a chromosome?

a dna molecule with attendant proteins that acts as an independent unit during cell division

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A kinetochore is found where on a chromosome?

the centromere

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which of the following is an effect of histone acetylation?

compacts chromatin and actiavtes transcription

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Chromosomes we typically see in images are isolated from mitotic cells. These mitotic chromosomes are in the most highly condensed form. Interphase cells contain chromosomes that are less densely packed and

occupy discrete territories in the nucleus.

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methylation and acetylation are common changes made to histone H3, and the specific combination of theses changes is something referred to as the histone code. Which of the following patterns will probably lead to gene silencing?

lysine 9 methylation

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which of the following not a chemical modification commonly found on core histone n terminal tails

hydroxylation

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most eukaryotic cells only express 20-30% of the genes they possess. The formation of heterochromatin maintains the other genes in a transcriptionally silent state. Which histone modification directs the formation

H3 lysine 9 methylaiton

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how do changes in histone modifications lead to changes in chromatin structure?

they recruit other proteins to the chromatin

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the core histones are small basic proteins that have a globular domain at the c terminus and a long extended conformation t the N terminus. which of the following is not true of the n terminal tail of the histones?

it binds to dan in a sequence specific manner

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the chromosomal locus that regulates the movements of the chromosomes during mitosis and meiosis. It is defined by specific DNA sequences and the proteins that bind them.

centromere

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The centromeric subunit that bind microtubules and directs chromosome movement during mitosis

Kinetochore

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specialized structure at either end of the chromosomal DNA molecule that ensures replication of the DNA ends and protects the ends

Telomere

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keeps in place the DNA that has already wrapped around the histone

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4 histones involved in packaging

2 H3:H4

2 H2A:H2B

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transcriptionally active areas associated with relatively open chromatin

euchromatin

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transcriptionally inactive areas associated with compact (or closed) chromatin

Heterochromatin

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– proposes that posttranslational modifications of histones are read by proteins that bind to modified histones to determine whether regions of the chromosome are transcribed or remain in an inactive state

histone code

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is associated with “open” chromatin

acetylation

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associated with either open or closed chromatin

methylation

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HDAC helps wrap or unwrap

wrap

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which disease would be used for HDAC?

PML (cancers)

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HDAC inhibitors inhibit what?

the removal of acetyl groups from histone resulting in gene inactivation

Chronic Myeloid Leukemia:

translocation: t(9;22)(q32;q11) chromosomes: BCR/ABL

Acute Myeloid Leukemia

translocation: t(8;21)(q22;q22) chromsome: AML1/ETO

Non-Hodkin's Lymphoma

translocation: t(14;18)(q32;q21)

used to synthesize transcription factor for HOX gene

MLL

code for proteins

messenger rna

form the core of the ribosomes structure and catalyze protein synthesis

ribosomal rna's

regulate gene expression

micro rna

serve as adaptors between mrna and amino acids during protein synthesis

transfer rna

used in RNA splicing, gene regulation, telomere maintaince, and many other processes

other noncoding RNA's

most rRNA

rna polymerase 1

all protein coding genes, miRNA genes, plus genes for other noncoding RNA's

rna polymerase 2

tRNA genes, 5s rRNA gene, genes for many other small RNA's

RNA polymerase 3

RNA pol 2 intiation

(TAF & TBP) TFIID bind to the TATA box TFIIA and TFIIB are recruited to the complex Recruits RNA POL2 and the cofactor TFIIF (stabilizes) TFIIE and TFIIH complex.

more common Rho. forms hair pin, induces release of paused polymerase to release the mRNA

rho-indepedent termination

less common Rho. Rho hexameter binds specific c-rich sequence of RNA, rho migrates 5' to 3' to signal release of pol on contact. rho's helices activity unwinds rna/dna duplex releasing RNA

rho-dependent termination

transcription occurs where

nucleus

translation occurs where

cytoplasm, rough endoplasmic reticulum

7-methylguanosine +triphosphate linkage, add's to the 5' end

RNA capping

cleaves poly A to the end of 3'

polyadenylation

all noncoding introns are spliced out of a pre-mRNA by the

splicesome

five RNA's that are collectively called nRNA's. associated with proteins to form snRNPS

``` U1 U2 U4 U5 U6 ```

two snRNP's that attach to end of pre-mrna

U1 and U2

binding of an additional snRNP - assembles the splicesome

U4/U6 and U5

which snRNP is spliced out

Allows the production of more than one mRNA, thus, more than one protein from a single gene

alternative splicing

every three base pairs encodes an amino acid

genetic code

start codon

aug

stop codon

uaa, uag, uga

redundancy in the genetic code, some tRNA's only require base pairing of the first two codon positions and can tolerate a mismatch at the third position

wobble effect

what couples the amino acid to the specific tRNA for that AA

aminoacyl-tRNA synthetases

what is rRNA responsible for?

ribosome overall structure and ability to catalyze protein synthesis

contains 3 rRNA responsible for decoding the mRNA message and assembling peptide chains

large subunit

contains one rRNA

small subunit

accepts

a site

peptide

p side

exit or eject

e site `

escorts the charged tRNA to the A-site

eEF1A + GTP

gtp is cleaved to gap which releases

eEF1A

Series of ribosome that will simultaneously translate the same mRNA molecule

polyribosome

loss of function

albinism cancer cf haemophila disorders marble brain syndrome phenyl keton uria

gain of toxic function

alzheimers type 2 diabetes als parkinsons

infectious misfolding

mad cow kuru jaokb disease

degradation using target protein and polyubiquitin chain

protein degradation

expressed genes that are common to all cells

housekeeping genes

specialized genes give different cells unique properties

master transcription regulators