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Flashcards in Genes Deck (62)
1

Nucleotide: monomer

A sugar (deoxyribose) with a phosphate group attached to it and a base

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Deoxyribose bases

Adenine (A), Guanine (G), Cytosine (C), or Thymine (T)

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Protein: polypeptide

Long chain of 20 types of amino acids, each linked by a covalent peptide bond

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Protein: pH 7

Both the amino and carboxyl groups are ionized

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optical isomers

Proteins consist of exclusively L amino acids

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Lysine side chain

Basic NH3+ amide group

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Arginine side chain

Basic NH2+ resonance

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Histidine side chain

Basic NH+ weak pentagon

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Deoxyribose sugar

H at the 2' carbon position

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Ribose sugar

OH at the 2' carbon position

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Purine bases

Adenine and Guanine with double rings

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Pyrimidine bases

Thymine, Cytosine and Uracil with single rings

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Nucleoside

A base attached to only a sugar: adenine+ribose-->adenosine

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Adenosine triphosphate

ATP nucleotide containing adenine, ribose, and three phosphate groups

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Guanosine triphosphate

GTP nucleotide containing guanine, ribose, and three phosphate groups

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deoxyadenosine triphosphate

dATP nucelotide containing adenine, deoxyribose, and three phosphate groups

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phosphodiester bond

two covalent phosphoester bonds with phosphate attached to 5' carbon of one sugar and 3'carbon of another sugar

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Chargaff's rule

Equal amounts of A&T, G&C. A+G=T+C

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DNA directionality

Phosphate group adds on to 3' hydroxyl end

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Complete helix turn

One helix turn is 3.4 nm and contains 10 nucleotides

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Bases: hydrogen bonds

G and C -> 3 bonds. A and T -> 2 bonds

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A DNA

Right handed helix and tilted on axis

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B DNA

Predominant DNA in living cells, right handed helix

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Z DNA

Left handed helix, may affect transcription and level of chromosome compaction

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RNA helix

RNA can be single stranded or be double stranded at some points

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Structural gene

Nucleotide sequences that encode proteins

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Intergenic regions

nontranscribed regions of DNA located between adjacent genes

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DNA gyrase

In bacteria travels in front of DNA helicase and relaxes positive supercoils

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Topoisomerase I

In bacteria relaxes negative supercoils

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Quinoline + coumarin

Drugs that inhibit gyrase and bacterial topoisomerases but not eukaryotic topoisomerase

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Chromatin

DNA-protein complex found within eukaryotic chromosomes

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Centromere

Recognition site for kinetochore proteins during mitosis and meiosis

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Eukaryotic origin of replication

each chromosome contains OR every 100,00 bp

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Eukaryotic Chromosome bp

Tens of millions to hundreds of millions bp

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Telomeres

inhibit chromosomal rearrangements such as translocations

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Nucleosome

double stranded segment of DNA wrapped around octamer of histone proteins

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DNA:nucleosome

150 bp around histones + 20-100 bp linker region

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Interphase compaction

Nucleosomes+zigzag 30 nm fiber+radial loops

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Radial loops

Chromosome sequences matrix attachment regions attaching to nuclear matrix

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Euchromatin

capable of gene transcription and forms radial loop domains during interphase

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heterochromatin

compacted regions at centromere and telomere

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Facultative heterochromatin

chromatin that can occasionally interconvert between heterochromatin and euchromatin

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histone code hypothesis

Patterns involving phosphorylation of serine at first position in H2A and acetylation of 5th and 8th lysine in H4 may attract chromatin loosening proteins

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Condensin

Enters nucleus at M phase and converts euchromatin in chromatids to heterochromatin

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cohesin

promotes binding between sister chromatids after s phase through prophase along entire length

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Separase

cohesins at centromere remain attached until anaphase

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Semiconservative model

14N and 15N radioiosyptes showed DNA replication

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bacteria ori

DnaA binds to ori and recriuts DNA helicase

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DNA helicase

when this enzyme encounters double stranded regions it breaks the hydrogen bonds between the strands to generate single strands

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Single strand binding proteins

binds to single DNA strands and prevents double helix

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DNA primase

synthesizes short strands of RNA called RNA primers

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okazaki fragment

1,000-2,000 fragments in length

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DNA polymerase III fidelity

1 mistake in 100 million nucleotides

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oriC regulation

DnaA protein amount and GATC methylation sites in oirigin

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Eukaryotic origins

replication proceeds bidirectionally from many origins during S phase

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ARS elements

50 bp and necessary to initiate chromosome replication

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DNA polymerase y(gamma)

replication of mitochondria DNA

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DNA polymerase a(alpha)

associates with primase to synthesize RNA primers followed by 20 DNA bp

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DNA polymerase delta

possible greater role in lagging strand synthesis

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DNA polymerase e(epsilon)

possible greater role in leading strand synthesis

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telomerase

synthesizes additional repeats of telomeric sequences

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homologous chromosomes

homologs - the maternal and paternal chromosomes of a pair