Unit 1 Ch.8-9: Chromosomal Mutations

what are the types of extranuclear inheritance?

organelle heredity

infectious heredity

maternal effect

what is the endosymbiotic theory

mitochondria and chloroplast arose independently

endosymbiotic theory: Mitochondria

has its own DNA, absent introns, uses mtDNA for translation, mtDNA and tDNA to encode genes

consequence of cellular respiration: ROS, and why it is negative?

toxic and mutagenic, produced by cell respiration, mtDNA mutates more often

__________ and __________ can cause genetic diseases

chromosome mutations

major chromosomal changes

aneuploidy

± 1 or more chromosomes, don’t gain a complete set

polyploidy

more than 2 sets of chromosome are present

euploidy

gains additional haploid set of genome

nondisjunction, and consequences

failure of chromosomes to separate in meiosis

nondisjunction is more detrimental during the ___ meiotic division

1st

why would monosomy or aneuploidy be detrimental?

because the single copy of the chromosome could contain a mutant/ lethal allele that can’t be masked by a second copy that doesn’t exist

polyploidy vs autopolyploidy vs allopolyploidy

more than 2 multiples of haploid chromosome set are found

each set of chromosomes identical to the parent species, caused by failure of chromosomes to segregate during meiotic divisions or when 2 sperm fertilize one ovum

organism has 3+ complete sets of a chromosome

chromosomal aberrations

deletions

duplications

translocations

inversions

chromosomal aberrations: deletions

a chromosome breaks and a portion is lost

centromere portion usually maintained

what are the different types of chromosomal deletions?

terminal- at end of a chromosome

intercalary- withing interior of chromosome- condensation loop

duplications

genetic material present more than once in genome, caused by unequal crossing over during meiosis or replication errors

translocation

movement of a chromosomal segment to a new location

what are the different types of translocation?

reciprocal translocation: exchange of segments without loss of genetic information

familial down syndrome

heritable version of down syndrome, translocation of chromosome 21

familial down syndrome: probability of normal, carrier, trisomy, and individual

2/3 chance normal( 1/3 chance carrier), 1/3 chance down syndrome

inversions

chromosome segments turned 180 degrees within chromosome, no genetic loss

what are the different types of inversions?

paracentric- centromere not part of inverted segment

pericentric- centromere part of inverted segment

copy number variations

large duplications of DNA sequences in coding and non coding regions, can be positive or negative

associated with autism, cancer, and type I diabetes

gene redundancy

multiple copies of the same gene sequences, found in rRNA genes needed for ribosomes to translate RNA code into amino acids to generate proteins

gene amplification

amount of rDNA is increased without permanent changes to DNA, occurs via the nuclear organizer region of chromosome where rDNA info is encoded

fragile sites

susceptible to breakage, linked to cancer

fragile-X syndrome: folate sensitive sites on X chromosome