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bacterial dna
circular dna, condensed by supercoiling, arranged in a single loop, no telomeres
bacterial chromosome positively and negatively supercoiled
dna is overrotated, dna is underrotated
bacterial plasmid
small circular dna that replicates independently
bacterial conjugation
plasmids replicated and copies transferred to another bacterium
bacterial resistance factors
proteins that protect against antibiotics
bacterial fertility factors
proteins that enable them to engage in conjugation with other bacteria
eukaryotic dna
linear, condensed around histone protein, arranged in multiple chromosomes, has telomeres
eukaryotic nucleosome
dna wound around cluster of eight histone proteins
histone 1 protein
locks dna around the histones
linker dna
connects chromatosomes
chromatosomes
nucleosome and h1
scaffold proteins
hold the coils together
chromatin
combination of dna and protein, relaxes for gene expression
p arm, centromere, q arm
smaller arm, middle, longer arm
metacentric, submetacentric, acrocentric, teolocentric
centromere in middle, centromere off center, longer q arm, no p arm
centromere
has a characteristic repeated sequence, contain histone h3 and adopt chromatin configuration
kinetochore
specialized protein in centromere, spindle fiber bind to pull apart homologous chromosome
telomeres must be stabilized
shelterin binds the telomeres and keeps them from being repaired
euchromatin
less condensed, genes are active
heterochromatin
more condensed, gene inactive
human chromosome
46 chromosomes, 23 pairs, chromosome 1 large, chromosome 22 small, xx, xy
karyotype purpose
refer to individual’s chromosome status or a picture of individual’s actual chromosome
how to write karyotype
total number chromosomes, sex chromosome, any abnormalities
g banding process
cells grown in culture and additives added, cells burst open and chromosomes spread, enzymes added and dyed with giemsa, unique pattern shown
aneuploidy
not having standard number of chromosomes
nullisomy
no copies of specific ch
monosomy
1 copy of specific ch
disomy
2 copies of specific ch
trisomy
3 copies of specific ch
tetrasomy
four copies of specific ch
polyploidy
having one or more extra set of ch
haploid
having one set of ch
diploid
haivng two sets of ch
triploid
having three sets of ch
tetraploid
having four sets of ch
polyploidy triploid
when two sperm fertilize one egg
chromosome deletion
a segment of chromosome deleted
deletion causes pseuododominance
individual loses dominant allele, only recessive allele present
deletion causes haploinsufficicney
one working copy of gene cannot make enough protein
displaced duplication
not side by side
reverse duplication
inverted duplication
insertion or nonreciprocal translocation
a piece of chromosome broken out and inserted in another chromosome
reciprocal translocation
two chromosomes break and exchange pieces
balanced reciprocal translocation
no dna lost
unbalanced reciprocal translocation
dna lost
balanced reciporal translocations cause what
breaks in middle of genes, move active gene to silence gene
robertsonian translocation
fusion of two acrocentric chromosome, short arm of one is exchanged with long arm of another creates large metacentric chromosome and small fragment
Robertsonian tranloction can result in trisomies
two fully functioning chromosome with one centromere, second copy of second chromosome pulled in during division
inversion
a segment of chromosome is turned 180
pericentric inversion
breakpoints lie on either side of the centromere
paracentric
breakpoints lie within the same chromosome arm
unbalanced inversion
some dna may or may not be lost at one or both breakpoints
balanced inversion
one or both breakpoints fall inside gene sequence
probability of nondisjunction
increases with age
autopolyploidy
chromosomes from same species, result from wholesale nondisjunction of chromosomes or failure of cell to split
allopolyploidy
chromosomes from two different species
FISHing for chromosome abnormalities
probe dna, labeling with fluorescent dye, grow cells and stop mitosis, put culture on glass slide, denature chromosome and probe, incubate slide, view chromosomes
