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Genetics Exam 2
N/A
150
Biology
Undergraduate 3
03/08/2012

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Term
conjugation
Definition
physical interaction between two bacterial cells (donor f+/recipient F-
Term
transduction
Definition
transference of genetic material via a virus
Term
transformation
Definition
genetic material is released into and taken in from the environment
Term
types of genetic transfer
Definition
conjugation, transduction, transformation
Term
What is a plasmid?
Definition
an extra-chromosomal DNA molecule, generally circular and double-stranded
Term
Tra genes
Definition
products necessary for transfer between touching bacteria
Term
fertility factor
Definition
necessary for conjugation, is present on plasmid
Term
sex pilus
Definition
attaches to recipient cell and draws the two bacteria together
Term
cytoplasmic bridge
Definition
forms between cells where genetic material can pass from donor cell to recipient cell
Term
sex pilus
Definition
attaches to recipient cell and draws the two bacteria together
Term
cytoplasmic bridge
Definition
forms between cells where genetic material can pass from donor cell to recipient cell
Term
nucleic acid + protein =
Definition
nucleoprotein
Term
relaxosome
Definition
protein complex which recognizes the origin of transfer in the F factor, cuts the plasmid on one strand
Term
T DNA
Definition
transfer DNA, single stranded and has the relaxase nucleoprotein at one end
Term
relaxase
Definition
nucleoprotein that is recognized by a coupling factor on the exporter
Term
exporter
Definition
protein complex on the membrane of donor cell that allows the T DNA to be transferred to the recipient cell
Term
F' factor
Definition
F factor that contains genes that were once part of the bacterial chromosome
Term
Hfr strain
Definition
high frequency of recombination; F factor that has become integrated into the bacterial chromosome
Term
gene conversion
Definition
crossing over between plasmid and chromosome
Term
bacteriophage
Definition
composed of genetic material surrounded by protein coat; can "high jack" DNA replication of the host cell
Term
lytic cycle
Definition
immediate production of viral parts until cell bursts
Term
steps of lytic cycle
Definition
attachment, entry replication, assembly release
Term
lysogenic cycle
Definition
integrated into host DNA and replicates with DNA until something triggers it into lytic cycle
Term
steps of lysogenic cycle
Definition
attachment, injection, integration, cell multiplication
Term
generalized transduction
Definition
any piece of the bacterial chromosomal DNA can be incorporated into a phage
Term
cotransduction
Definition
when a bacteriophage packages a single piece of the chromosome that carries two genes and transfer it to another bacterium
Term
natural transformation
Definition
when living bacteria take up pieces of DNA from dead bacteria in the environment
Term
competent cells
Definition
cells that are able to take up DNA because they possess genes that encode for competence factors
Term
competence factors
Definition
machinery needed to bring DNA across the cell membrane and incorporate it into the host chromosome
Term
Oswald Avery and Collin McLeod
Definition
worked with S strain and R strain of streptococcus pneumonia to determine if bacteria can change from one form to another
Term
artificial transformation
Definition
forcing of DNA into cells
Term
electroporation
Definition
uses electric currents to force DNA into cells
Term
ways to accomplish artificial transformation
Definition
electroporation, heat shock, chemically
Term
How is artificial transformation done with chemicals?
Definition
high concentration of calcium ions
Term
horizontal transfer
Definition
transfer between two different species
Term
vertical transfer
Definition
parent to daughter cells
Term
How much of the genes of E coli and Salmonella typhimurium have been acquired horizontally?
Definition
about 17%
Term
How is antibiotic resistance acquired among bacteria?
Definition
horizontally
Term
maternal effect
Definition
the genotype of mother is expressed in the phenotype of her offspring, regardless of the genotype of the father or offspring themselves
Term
What surrounds the oocytes(n)?
Definition
nurse cells (2n)
Term
Why does the maternal phenotype show up in offspring?
Definition
nurse cells produce gene products that can be transported to the oocyte and this assistance can persist after the egg has been fertilized
Term
epigenetic inheritance
Definition
a pattern in which a modification occurs to a nuclear gene or chromosome that alters gene expression, but it is not permanent over the course of many generations
Term
dosage compensation
Definition
one sex chromosome is altered with the result that males and females have similar levels of gene expression
Term
How is dosage compensation in placental mammals accomplished?
Definition
random inactivation of one X chromosome
Term
Barr body
Definition
inactivated X chromosome
Term
Xic locus
Definition
a short region on the X chromosome that plays a critical role in X inactivation
Term
Xist gene
Definition
within the Xic region and codes for a long RNA molecule that binds to one of the X chromosomes and promotes its compaction
Term
Xce region
Definition
to some degree affects which X chromosome is inactivated
Term
TsiX gene
Definition
encodes for an RNA that is complementary to the Xist RNA; binds to Xist RNA and prevents it from inactivating the X chromosome
Term
What genes are expressed on inactivated X chromosomes?
Definition
Xist (necessary for compaction) and psuedoautosomal genes
Term
Number of Barr bodies in a normal female?
Definition
one
Term
Number of Barr bodies in a normal male?
Definition
zero
Term
Number of Barr bodies in an individual with Turner Syndrome (XO)?
Definition
zero
Term
Number of Barr bodies in an individual with triple X syndrome?
Definition
two
Term
Number of Barr bodies in an individual with Klinefelter syndrome (XXY)?
Definition
one
Term
SRY gene
Definition
sex-determining region Y; gene located on the p arm just outside the pseudoautosomal region;
Term
What does SRY gene trigger?
Definition
conversion of embryo into a male
Term
Androgen Insensitivity Syndrome (AIS)
Definition
males without the ability to respond to male hormones
Term
imprinting
Definition
type of marking process with memory
Term
genomic imprinting
Definition
segment of DNA is marked and expressed throughout the life of the organism
Term
monoallelic expression
Definition
expression of either the maternal or paternal gene
Term
What X in marsupials is always inactivated in somatic cells?
Definition
paternal
Term
DMRs
Definition
differentially methylated regions
Term
How is DNA marked?
Definition
with DMRs
Term
How do DMRs silence gene expression?
Definition
they contain binding sites for one or more proteins that regulate the transcription of nearby genes
Term
mtDNA
Definition
mitochondrial DNA
Term
cpDNA
Definition
chloroplast DNA
Term
What is the size of human mtDNA?
Definition
about 17,000 bp
Term
What is the size of cpDNA?
Definition
about 100-200kbp
Term
Does extranuclear genetic material follow Mendelian inheritance?
Definition
no because mitochondria and chloroplast do not segregate into gametes in the same way as nuclear chromosomes
Term
heteroplasmy
Definition
when a cell contains variations in a type of organelle (wild type and mutant)
Term
paternal leakage
Definition
occurs in species where maternal inheritance is usually observed, the paternal parent on rare occasions may provide mitochondria via the sperm
Term
What is the ratio of paternal to maternal mitochondria?
Definition
about 1-4 paternal for every 100,000 maternal
Term
chromosome mutation
Definition
large change in chromosome structure
Term
genome mutation
Definition
change in chromosome number
Term
metacentric
Definition
centromere is in the middle of the chromosome (p=q arm)
Term
submetacentric
Definition
short p and long q arm
Term
acrocentric
Definition
very short p and really long q arm
Term
telocentric
Definition
p arm is lost, only q is present
Term
karyotype
Definition
graphic representation of the chromosomes within a cell matched up
Term
G banding
Definition
staining procedure where mild heat or enzymes partially digest chromosome proteins, then chromosomes are exposed to Giesma dye and some regions bind more heavily so chromosomes can be distinguished and abnormalities can be detected
Term
What are the two ways chromosomes can be altered?
Definition
genetic material within a single chromosome can be changed or material within one or more chromosomes can be rearranged
Term
deletion
Definition
a chromosome segment is lost
Term
duplication
Definition
a section of a chromosome is repeated
Term
inversion
Definition
a change in direction
Term
translocation
Definition
a segment attaches to a different chromosome
Term
simple translocation
Definition
piece of chromosome is attached to another
Term
reciprocal translocation
Definition
two different chromosomes exchange pieces
Term
terminal deficiency
Definition
a single break and piece without centromere is lost
Term
interstitial deficiency
Definition
central fragment is lost and two outer pieces reattach to each other
Term
Cri-du-chat syndrome
Definition
segment of p arm in a single copy of chromosome 5 is missing
Term
Prader-Willi syndrome
Definition
deletion in paternal chromosome 15
Term
Angelman syndrome
Definition
deletion in maternal chromosome 15
Term
Smith-Magenis syndrome
Definition
deletion in a specific region of chromosome 17
Term
Rubinstein-Taybi syndrome
Definition
deletion of short arm of chromosome 16
Term
What do duplications occur from?
Definition
unequal crossing-over between homologous chromosomes or unequal sister chromatid exchange
Term
What diseases are caused by duplications?
Definition
Charcot-Marie tooth disease and bar-eye phenotype in fruit flies
Term
gene family
Definition
consists of two or more genes that are similar
Term
homologous genes
Definition
two or more genes that are derived from a single ancestral gene
Term
paralogs
Definition
homologous genes within a single species
Term
orthologs
Definition
homologous genes found in multiple species
Term
inversion
Definition
segment of chromosome is flipped in opposite direction
Term
pericentric inversion
Definition
centromere lies within the inverted region
Term
paracentric inversion
Definition
centromere is found outside the inverted region
Term
inversion heterozygote
Definition
individual with one normal and one inverted chromosome
Term
inversion loop
Definition
loop formed during meiosis I to permit homologous genes to align
Term
telomeres
Definition
ends of chromosomes containing tandemly repeated sequences
Term
reactive ends
Definition
broken ends of chromosomes that lack telomeres
Term
Robertsonian translocation
Definition
centromeric region of two nonhomologous acrocentric chromosomes become fused to form a single chromosome
Term
euploid
Definition
total chromosome number that is an exact multiple of a chromosome set
Term
How many chromosomes do humans have?
Definition
46 chromosomes
Term
triploid
Definition
three sets of chromosomes (3n)
Term
polyploid
Definition
three or more sets of chromosomes
Term
aneuploid
Definition
alteration in chromosome number so that the total number is NOT an exact multiple of a set
Term
trisomic
Definition
(2n+1) diploid cell with one extra chromosome
Term
monosomic
Definition
(2n-1) diploid cell missing a chromosome
Term
nondisjuction
Definition
occurs when either homologous chromosomes or sister chromatids do not segregate properly
Term
endopolyploidy
Definition
the occurrence of polyploid tissues or cells in organisms that are otherwise diploid
Term
polytene chromosome
Definition
a bundle of chromosomes that lie together in a parallel fashion formed by repeated rounds of replication without cell division
Term
colchicine
Definition
used to increase ploidy level in plants
Term
meiotic nondisjunction
Definition
will produce haploid cells with too many or too few chromosomes
Term
autopolyploidy
Definition
having more than two sets of chromosomes from the same species
Term
allopolyploidy
Definition
an organism with sets of chromosomes from two or more different species
Term
allotetraploid
Definition
diploid for two genomes each from a different species
Term
homeologous chromosomes
Definition
evolutionarily related chromosomes from two species that can properly synapse during meiosis to create haploid gametes
Term
non-homeologous chromosomes
Definition
chromosomes from two species that cannot properly synapse
Term
cell fusion
Definition
individual cells are mixed together and made to fuse
Term
protoplast
Definition
a plant cell without a cell wall
Term
heterokaryon
Definition
a cell containing two separate nuclei
Term
hybrid cell
Definition
a cell where two separate nuclei have fused
Term
parthenogenesis
Definition
inducement of egg to begin development without fertilization
Term
anther culture
Definition
used to produce diploid plants that are homozygous for all genes
Term
molecular genetics
Definition
the study of DNA and RNA structure and function at the molecular level
Term
nucleotide
Definition
the repeating structural unit of nucleic acids that is composed of a phosphate group, a pentose sugar, and a nitrogenous base
Term
purines
Definition
adenine and guanine
Term
pyrimidines
Definition
cytosine, uracil, and thymine
Term
nucleoside
Definition
nitrogenous base attached only to a sugar
Term
phosphodiester linkage
Definition
linkage between two carbons and a phosphate group through two oxygens
Term
Linus Pauling
Definition
proposed the alpha helix
Term
Erwin Chargaff
Definition
discovered the amount of A=T and G=C
Term
Rosalind Franklin
Definition
suggested DNA was composed of two or more strands with ten bases per turn
Term
Watson, Crick, and Wilkins
Definition
discovered the double helix DNA molecule
Term
DNA helix
Definition
double stranded with ten base pairs per 360 degree around backbone
Term
hydrogen bonding
Definition
stabilizes DNA double strand
Term
Chargaff's Rule (AT/GC rule)
Definition
purines always bond with pyrimidines
Term
B DNA
Definition
right handed; 10bp per 360 degrees; H bonds between bp occur perpendicular relative to central axis
Term
A DNA
Definition
right handed; 11bp per 360 degrees; H bonds substantially tilted relative to central axis; occurs under low humidity
Term
Z DNA
Definition
left handed; 12bp per 360 degrees; zigzag appearance; H bonds substantially tilted; occurs at high ionic strength; favored by sequence that alternates between purines and pyrimidines
Term
triplex DNA
Definition
triple helix; synthetic DNA binds into major grooves of natural DNA
Term
DNA binding proteins
Definition
necessary for compaction of DNA
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