Chapter 17 Flashcards
Organellar inheritance
the transmission of genes on mitochondrial and chloroplast chromosomes (genes located in organelles, not nucleus)
Compare genome size/complexity, copy number per cell, mitosis, and meiosis/sexual mating between the Nuclear genome and Mitochondrial genome
Nuclear Genome
- large & complex, multiple linear chromosomes
- one to a few copies per cell
- replicate only once during mitosis (stringent partitioning)
- follows Mendelian laws during meiosis; biparental inheritance
Mitochondrial Genome
- small and simple, one circular chromosome
- tens to thousands of copies
- variable amount of replication (no stringent partitioning)
- clonal propagation, does not follow Mendelian laws; uniparental/maternal inheritance
Most organisms have a __________ circular mitochondrial DNA but ______ have one linear mitochondrial DNA or 2 or more.
single, some
T or F: similar to nuclear genomes, mitochondrial genome size is the same in all eukaryotes and directly relates to number of genes
False, in eukaryotes, mitochondrial genome size varies greatly and the size does not directly relate to number of genes.
Mutations in human mitochondrial genes can cause many diseases such as….. (Let Me Make Porn My Nigga)
LHON, MELAS, MILS, PEO, MERRF, NARP
LHON - affects the optic nerve, causing vision loss in young males
Compared to nuclear tRNA genes, there are ________ mitochondrial tRNA genes and thus, fewer ________________.
less, unique codons
Chloroplasts are _____________________________ and possess a third membrane system, the ____________________.
enclosed by a double membrane, thylakoid membranes
Describe the Chloroplast genome structure and gene content
chloroplast genomes are generally circular but some are linear, the genome size is usually 120 - 200 kilobases, encoding for 100 - 250 genes.
Endosymbiosis Theory
the theory that free-living bacteria infected ancient eukaryotic cells, then evolved along with the hosts to produce organelles
What is the evidence for the Endosymbiosis Theory?
(1) double-membrane system in mitochondria/chloroplast is similar to bacteria
(2) organelle size is similar to bacteria
(3) organellar DNA is packaged similarly to bacteria
(4) transcriptional/translational machinery is similar to bacteria
(5) protein coding genes are more similar to bacteria
T or F: due to the discovery of ancient gene transfers and recent gene transfers, it is evident that organellar genes have transferred to the nuclear genome over time
True
Describe Homoplasmy & Heteroplasmy
Homoplasmy: a cell or organism where all copies of an organellar gene are the same
Heteroplasmy: a cell or organism where not all copies of an organellar gene is the same
What are the three factors that influence mitochondrial inheritance during mitosis?
(1) Within each mitochondrion, different mitochondrial DNA molecules replicate at different speeds, meaning the replicated genomes do not segregate evenly among daughter mitochondria
(2) Within each cell, different mitochondria replicate at different speeds, meaning parental mitochondria do not segregate evenly among progeny
(3) Per base mitochondrial DNA mutation rate in animals is 10x higher than their nuclear genomes
T or F: in most eukaryotes, organellar DNA is inherited via uniparental inheritance (maternal inheritance). However, there are exceptions like Baker’s Yeast (biparental inheritance) and in gymnosperms (paternal inhertiance)
True
