Genetics Exam 3

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Centric fragment

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176 Terms
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Centric fragment

A piece of chromosome containing a centromere

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Acentric fragment

A chromosomal piece without a centromere

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dicentric chromosome

A chromosome with two centromeres

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Inversion

The replacement of a section of a chromosome in the opposite orientation

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deletion

the loss or absence of one or more nucleotides from a chromosome

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Translocation

a part of the translation process in which the mRNA is shifted one codon in relation to the ribosome.

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reciprocal translocation

A chromosomal configuration in which the ends of two nonhomologous are broken off and become attached to the non-homologs

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<p>deletion loop</p>
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<p>deletion loop</p>

deletion loop

See image

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pseudodominance

the phenomenon in which a recessive allele confers the phenotype when only one copy of the allele is present, as in hemizygous alleles or in deletion heterozygotes

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Deletion mapping

a technique used to find out the mutation sites within a gene

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genetic imbalance

unnatural ratio of gene expression

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Haploinsufficiency

lethal phenotype due to expression of only a single wild type allele

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pericentric inversion

A chromosomal inversion that includes the centromere within the inverted region

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paracentric inversion

A chromosomal inversion that does not include the centromere in the inverted region

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Suppression (of recombination)

The phenomenon where a mutation (suppressor) restores the wild-type phenotype to a different mutation. the suppressor mutation may be in the same gene as the original mutation (intragenic suppression) or may be in a different gene (intergenic suppression)

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variegation

Patchiness; a type of position effect that results when particular loci are contiguous with heterochromatin

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duplication

extra copies of a chromosomal region are formed

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aneuploidy

the condition of a cell or of an organism that has addition or deletions of whole chromosomes

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euploidy

the condition of a cell or organism that has one or more complete sets of chromosomes

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polyploid

anything above diploid

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tetraploid

organism with four homologous sets of chromosomes

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triploidy

organism containing three homologous sets of chromosomes

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monosomy

absence of one member of a chromosomal pair

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disomy

normal state of chromosomes in a eukaryote cell

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trisomy

chrosomal abnormality in which there is one more than the normal number of chromosomes in a cell

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nullisomic

A diploid cell missing both copies wof the same chromosome

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Down syndrome

Trisomy 21 (three chromosomes on chromosome 21)

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nondisjunction

the failure of a pair of homologous chromosomes to separate properly during meiosis

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mosaic

Individuals made up of two or more cell lines with different genotypes that originated in the same zygote

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heterochromatin

Chromatin that remains tightly coiled ( and darkly staining) throughout the cell cycle (transcriptionally inactive)

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Chromatin

The DNA-protein complex that composes the eukaryotic chromosome

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ribose

a pentose sugar important as a component of ribonucleic acid

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deoxyribose

a sugar that is a constituent of nucleic acids

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phosphate

a salt of phosphoric acid

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nitrogenous base

A molecule that contains nitrogen and has the chemical properties of a base

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pentose sugar

5 carbon sugar

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nucleotide

Basic structure of DNA and RNA that consists of a nitrogenous base, a sugar, and one or more phosphates

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nucleoside

A sugar-base compound that is a nucleotide precursor. A 5-carbon sugar with a nitrogenous base attached

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Purine

Double C and N rings, has Adenine and Guanine

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Pyrimidine

Single C and N rings, has Thymine, and Cytosine, and Uracil

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DNA base pairs

Adenine, guanine, cytosine, thymine

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RNA base pairs

Adenine, guanine, cytosine, uracil

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DNA

Deoxyribonucleic acid, heritable molecule

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RNA

Ribonucleic Acid, single helix, shorter than DNA

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dsDNA

double-stranded DNA

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ssDNA

single strand DNA

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sugar-phosphate backbone

Forms the structural framework of nucleic acids, including DNA and RNA, joins together nucleotides in a DNA sequence

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phosphodiester bond

a chemical bond of the kind joining successive sugar molecules in a polynucleotide

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Chargaff's ratios

Amount of A = T, amount of G=C

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double helix

the normal structure of DNA consisting of two helices rotating about the same axis

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antiparallele

parallel but orientated oppositely

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complementarity

the correspondence of DNA bases in the double helix so that adenine in one strand is opposite thymine in the other strand and cytosine in one strand is opposite guanine in the other. relationship explains Chargaff's rule

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histones

Arginine- and lysine- rich basic proteins making up a substantial portion of eukaryotic nucleoprotein

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nucleosome

the basic structure of eukaryotic chromatin that is composed of approximately 165 base pairs of DNA wrapped around a histone structure that consists of two molecules each of H2a, H2b, H3, and H4

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solenoid

contains six nucleosome per turn

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2nm fiber

short region of DNA double helix

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11nm fiber

1st level packaging (nucleosome) "beads- on- a- string" form of chromatin

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30nm fiber

2nd level (solenoid)

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240nm fiber

3rd level (chromosome scaffold)

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700nm fiber

4th level condensed scaffold

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1400nm fiber

metaphase chromosome

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chromosome banding

Characteristic banding pattern in chemically stained chromosomes

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euchromatin

Eukaryotic chromosomal regions that are diffuse during interphase and presumably are the regions that are actively transcribed. (transcriptionally active)

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Facultative heterochromatin

can shift between transcriptionally active and inactive states

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centromeres

constrictions in eukaryotic chromosomes on which the kinetochore lies. Also, the DNA sequence within the constriction that is responsible for binding the kinetochore

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telomere

the ends of linear eukaryotic chromosomes

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C-value

genome size

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C-value paradox

Genome size does not correlate with complexity of organism

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transposon

repetitive DNA sequences that have the capability to move (transpose) from one location to another in genome

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junk DNA

Eukaryotic DNA that lacks genes and has no known purpose

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semiconservative replication

the mode by which DNA replicates, where each strands acts as a template for a new double helix.

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theta structure

an intermediate structure formed during the replication of a circular DNA molecule

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replication fork

The point at which the two strands of DNA are separated to allow replication of each strand

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replication bubble

an unwound open region of the DNA helix from where the replication of DNA occurs

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origin of replication

a sequence of DNA at which replication is initiated on a chromosome, plasmid or virus

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DNA polymerase 1

removes RNA primers and replaces with DNA

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DNA polymerase 3

Builds leading strand and Okazaki fragments

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Primer

In DNA replication, a length of DNA or RNA, which is base paired to a single- stranded DNA template, that provides a 3' end for the addition of another nucleotide

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leading strand

Strand of DNA being replicated continuously towards the replication fork

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lagging strand

The DNA strand that is replicated discontinuously away from the replication fork

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continuous replication

uninterrupted DNA replication in the 5' to 3' direction that is moving in the same directions the replication fork

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discontinuous replication

DNA replication in short 5' to 3' segments that are moving away from the replication fork

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Okazaki Fragments

Segments of newly replicated DNA produced during discontinous DNA replication on the lagging strand a

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RNA Primase

A RNA polymerase that creates the short RNA primer for initiation of okazaki fragment synthesis during DNA replication. (places RNA primers)

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