Genetics Exam 3

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176 Terms
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Centric fragment
A piece of chromosome containing a centromere
Acentric fragment
A chromosomal piece without a centromere
dicentric chromosome
A chromosome with two centromeres
The replacement of a section of a chromosome in the opposite orientation
the loss or absence of one or more nucleotides from a chromosome
a part of the translation process in which the mRNA is shifted one codon in relation to the ribosome.
reciprocal translocation
A chromosomal configuration in which the ends of two nonhomologous are broken off and become attached to the non-homologs
knowt flashcard image
deletion loop
See image
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
Deletion mapping
a technique used to find out the mutation sites within a gene
genetic imbalance
unnatural ratio of gene expression
lethal phenotype due to expression of only a single wild type allele
pericentric inversion
A chromosomal inversion that includes the centromere within the inverted region
paracentric inversion
A chromosomal inversion that does not include the centromere in the inverted region
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)
Patchiness; a type of position effect that results when particular loci are contiguous with heterochromatin
extra copies of a chromosomal region are formed
the condition of a cell or of an organism that has addition or deletions of whole chromosomes
the condition of a cell or organism that has one or more complete sets of chromosomes
anything above diploid
organism with four homologous sets of chromosomes
organism containing three homologous sets of chromosomes
absence of one member of a chromosomal pair
normal state of chromosomes in a eukaryote cell
chrosomal abnormality in which there is one more than the normal number of chromosomes in a cell
A diploid cell missing both copies wof the same chromosome
Down syndrome
Trisomy 21 (three chromosomes on chromosome 21)
the failure of a pair of homologous chromosomes to separate properly during meiosis
Individuals made up of two or more cell lines with different genotypes that originated in the same zygote
Chromatin that remains tightly coiled ( and darkly staining) throughout the cell cycle (transcriptionally inactive)
The DNA-protein complex that composes the eukaryotic chromosome
a pentose sugar important as a component of ribonucleic acid
a sugar that is a constituent of nucleic acids
a salt of phosphoric acid
nitrogenous base
A molecule that contains nitrogen and has the chemical properties of a base
pentose sugar
5 carbon sugar
Basic structure of DNA and RNA that consists of a nitrogenous base, a sugar, and one or more phosphates
A sugar-base compound that is a nucleotide precursor. A 5-carbon sugar with a nitrogenous base attached
Double C and N rings, has Adenine and Guanine
Single C and N rings, has Thymine, and Cytosine, and Uracil
DNA base pairs
Adenine, guanine, cytosine, thymine
RNA base pairs
Adenine, guanine, cytosine, uracil
Deoxyribonucleic acid, heritable molecule
Ribonucleic Acid, single helix, shorter than DNA
double-stranded DNA
single strand DNA
sugar-phosphate backbone
Forms the structural framework of nucleic acids, including DNA and RNA, joins together nucleotides in a DNA sequence
phosphodiester bond
a chemical bond of the kind joining successive sugar molecules in a polynucleotide
Chargaff's ratios
Amount of A = T, amount of G=C
double helix
the normal structure of DNA consisting of two helices rotating about the same axis
parallel but orientated oppositely
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
Arginine- and lysine- rich basic proteins making up a substantial portion of eukaryotic nucleoprotein
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
contains six nucleosome per turn
2nm fiber
short region of DNA double helix
11nm fiber
1st level packaging (nucleosome) "beads- on- a- string" form of chromatin
30nm fiber
2nd level (solenoid)
240nm fiber
3rd level (chromosome scaffold)
700nm fiber
4th level condensed scaffold
1400nm fiber
metaphase chromosome
chromosome banding
Characteristic banding pattern in chemically stained chromosomes
Eukaryotic chromosomal regions that are diffuse during interphase and presumably are the regions that are actively transcribed. (transcriptionally active)
Facultative heterochromatin
can shift between transcriptionally active and inactive states
constrictions in eukaryotic chromosomes on which the kinetochore lies. Also, the DNA sequence within the constriction that is responsible for binding the kinetochore
the ends of linear eukaryotic chromosomes
genome size
C-value paradox
Genome size does not correlate with complexity of organism
repetitive DNA sequences that have the capability to move (transpose) from one location to another in genome
junk DNA
Eukaryotic DNA that lacks genes and has no known purpose
semiconservative replication
the mode by which DNA replicates, where each strands acts as a template for a new double helix.
theta structure
an intermediate structure formed during the replication of a circular DNA molecule
replication fork
The point at which the two strands of DNA are separated to allow replication of each strand
replication bubble
an unwound open region of the DNA helix from where the replication of DNA occurs
origin of replication
a sequence of DNA at which replication is initiated on a chromosome, plasmid or virus
DNA polymerase 1
removes RNA primers and replaces with DNA
DNA polymerase 3
Builds leading strand and Okazaki fragments
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
leading strand
Strand of DNA being replicated continuously towards the replication fork
lagging strand
The DNA strand that is replicated discontinuously away from the replication fork
continuous replication
uninterrupted DNA replication in the 5' to 3' direction that is moving in the same directions the replication fork
discontinuous replication
DNA replication in short 5' to 3' segments that are moving away from the replication fork
Okazaki Fragments
Segments of newly replicated DNA produced during discontinous DNA replication on the lagging strand a
RNA Primase
A RNA polymerase that creates the short RNA primer for initiation of okazaki fragment synthesis during DNA replication. (places RNA primers)
the DNA pol reads the newly added base before adding the next one, so a correction can be made
3’ to 5’ exonuclease activity
Removes mismatched base pairs (proofreading)
Joins Okazaki fragments into continuous daughter strand
unzips DNA
Single- strand binding (ssb) protein
maintains ssDNA
initiator proteins
(dnaA) bind to origin and separate
relaxes supercoiling
template strand
The DNA strand that serves as the DNA template for transcription, which will be complementary to the RNA sequence; also the DNA strand that is used by DNA polymerase in a DNA sequencing reaction.
exo- external nucl - nucleous/ nucleic acid ase - enzyme
gene expression
The process of producing a functional gene product
central dogma
the original postulate that information can be transferred from DNA to RNA and then to protein, barring any transfer originating from the protein
the process whereby RNA is synthesized from DNA template
the process of protein synthesis wherein the nucleotide sequence of the mRNA determines the amino acid sequence of the protein
initiation (transcription)
RNA polymerase (RNAP) binds to promoter, DNA strand unwind, RNA polymerase builds RNA
elongation (transcription)
RNAP moves downstream elongating RNA transcript from 5' to 3', DNA strand rewinds after RNAP passes
termination (transcription)
RNA transcript (mRNA) is released and polymerase detaches from DNA
messenger RNA (mRNA)
Brings info for protein production from genes to ribosome
transfer RNA (tRNA)
Brings amino acids that are used to build new proteins to ribosome
ribosomal RNA (rRNA)
RNA components of the subunits of the ribosomes
a DNA region that RNA polymerase binds to in order to initiate transcription
a section of nucleic acid sequence that marks the end of a gene or operon in genomic DNA during transcription
sigma factor
helps RNAP recognize where to start transcription
RNA polymerase
the enzyme that polymerizes the RNA by using DNA as a template
Template, Noncoding, antisense strand
Strand used to create mRNA message (complementary but not identical)
nontemplate, coding, sense strand
mirrors mRNA sequence (identical except T replaces U)
pribnow box
consensus sequence of TATAAT in prokaryotic promoters centered at the position -10
5' UTR
untranslated region, leader sequence
3' UTR
untranslated region at the end
open reading frames (ORF)
sequence of codons between the translation initiation and termination codons in a gene
start codon
codes for the start of translation (AUG)
Stop codon (nonsense codon)
codes for the stop of translation (UGA,UAA,UAG)
transcription factors
regulatory proteins that bind DNA and either stimulate or repress gene expression
A sequence of adjacent genes that are transcribed on a polycistronic mRNA and are under a common mechanism of transcriptional regulation
posttranscriptional modification
Changes made to eukaryotic mRNA after transcription is completed (ex, addition of the 5' cap, polyadenylation of 3' end, and removal of introns
5' guanine cap and 3' poly A tail
used for export, protection, and attachment to ribosome
noncoding region
coding region
exon shuffling
The proposed mixing of different exons either within a gene or between two nonallelic genes (likely rare)
alternative RNA splicing
exons are joined in different combinations, leading to different (alternative) mRNA strands.
reverse transcriptase
an enzyme that can use RNA as a template to synthesize DNA
reverse transcription
the process in cells by which an enzyme makes a copy of DNA from RNA
RNA genome
the template for synthesis of additional RNA strands
one-gene/one-protein hypothesis
the theory that each gene directly produces a single protein, which consequently affects an individual step in a metabolic pathway
one-gene/one-enzyme hypothesis
the theory that each gene directly produces a single enzyme, which consequently affects an individual step in a metabolic pathway
one-gene/many-phenotypes hypothesis
one gene may code for multiple phenotypes
amino acids (AA)
polymerized chains, have amino and carboxyl functional groups, and variable side chains (R)
Primary structure
sequence of amino acids, N-end (begins protein), C-end
secondary structure
has a-helix or B-pleated sheet
tertiary structure
3-D folding
quaternary structure
interaction between 2+ proteins
amino terminus
signal peptide
Carboxy terminus (C - terminus)
the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH).
peptide bonds
bonds found between amino acids that form a polymer forming a protein
dehydration synthesis
the formation of larger molecules from smaller reactants, accompanied by the loss of a water molecule
complexes at which translation takes place. they are made up of two subunits that are each composed of proteins and rRNAs
a linear organic polymer consisting of a large number of amino-acid residues bonded together in a chain, forming part of (or the whole of) a protein molecule
initiation (translation)
Initiator tRNA binds Methionine and the corresponding codon on mRNA and small subunit
Elongation (translation)
AA’s are added one by one to the chain, tRNA and MRNA rotation between A, P and E site
Termination (translation)
ribosome eventually reaches a stop (aka nonsense) codon in the mRNA
initiation factors (IFI, IF2, IF3)
Proteins (prokaryotic with eukaryotic analogs) required for the proper initiation of translation.