Organelles

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What is the origin of mitochondria?
An anaerboic eukaryotic cell engulfed an aerobic eubacterium by endocytosis
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What is the origin of the chloroplast?
a photosynthesising eubacterium engulfed a cyanobacterium by endocytosis
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What is the role of mitochondria and chloroplasts?
To provide energy to cell by producing ATP
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How are mitochondria inherited?
By uniparental transmission, from the mother
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What is the purpose of uniparental transmission?
To avoid genomic heterogeneity in mitochondria
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Why are organelles dependent on the nucleus?
Because many genes have migrated to the nucleus, therefore they are dependent on nuclear protein synthesis for basic functions
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How big are chloroplast genomes?
80,000 - 600,000 base pairs
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What are properties of the chloroplast DNA?
It is usually circular double stranded DNA and is highly coiled. There are no histone proteins or histone-like proteins.
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What type of proteins do mitochondria produce?
respiratory proteins
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What proteins do mitochondria use that are synthesised by the nucleus?
DNA polymerase, RNA polymerase, some tRNAs, initiation factors, aminoacyl tRNA synthetases, ribosomal proteins and other respiratory proteins
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Can cells have multiple chloroplasts/mitochondria per cell?
yes, also each chloroplast can contain multiple genome copies
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What genes are present in a chloroplast?
rRNAs, tRNAs, ribosomal proteins and genes involved in photosynthesis
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How are genes ordered in a chloroplast?
in operons (gene order of many genes shared with E.coli)
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Can chloroplast genes contain introns?
yes, as it contains non-coding DNA
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Transcription and translation in a chloroplast is similar to what organism?
eubacteria - genes transcribed in groups like bacteria operons, proteins and RNAs involved in protein synthesis most similar to eubacteria, antibiotics that inhibit protein synthesis in mitochondria and eubacteria also inhibits it in chloroplasts
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What is the use of mitochondria in phylogenetics?
used for phylogenetic studies in metazoan species
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What is the use of chloroplasts in phylogenetics?
used to assess phylogenetic relationships among plant species, and DNA evolves more slowly than mitochondria and nuclear genomes
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What type of genome evolves the slowest?
Chloroplast
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How big are mitochondrial genomes?
6000 - several million base pairs
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How are most of the 900 proteins found in mitochondria produced?
they are encoded in the nucleus, translated in cytoplasmic ribosomes and then imported into the mitochondria
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How many genes do mitochondria have?
40-50
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What are the mitochondrial genes purpose?
They encode proteins for: respiration, oxidative phosphorylation, transcription, translation, RNA processing and import of proteins into the cell
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Are ribosome structures in mitochondria similar to bacteria and eukaryotes?
no
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The proteins involved in mitochondrial translation are most similar to which genome?
bacterial genes
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Do mitochondrial genomes vary between different types of organism?
yes
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What is the mitochondrial genome like in animals, fungi and plants?
plants - multiple circular DNA molecules. animals and fungi - single, coiled circular DNA molecule. some species contain mitochondria with a single linear DNA molecule
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Can mitochondria have introns?
yes, in plant and fungi mitochondria.
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What are properties of mitochondrial genes expression
full strand transcription, operon structures and single gen transcription
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What are properties of the human mitochondrial genome?
about 16000 base pairs, there are no untranslated regions, single promoter per strand, two long transcripts are cleaved. (the genome is very economical)
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What are porperties of the yeast mitochondrial genome?
78000 base pairs, high non-coding DNA content, many introns, UTRs and intergene spacers
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What are properties of plant mitochondrial genomes?
great variation in size between species, can have multiple circular genomes, high repeat DNA content
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Where are the enzymes for electron transport and oxidative phosphorylation?
embedded in the inner mitochondrial membrane
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How do the mitochondria play a role in ageing?
free radicals are produced by oxidative phosphorylation, these damage lipids, DNA and proteins, the dmaage accumulates and contributes to ageing
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Which tissues are most affected from lower mitochondrial function?
CNS, muscle, pancreatic islets, kidney and liver
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What is mitochondrial segregation?
the mitochondria divide independently from the cell cycle, thus segregate randomly among daughter cells during cell division. This therefore explains why heteroplasmic mitochondria can divide into homoplasmic organelles.
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How are embryos with healthy mitochondria generated?
egg nucleus from mother is palced into a donor egg cell, which has healthy mitochondria. Donor egg fertilised with sperm from father. Fertilised egg inserted into womb of mother by IVF. Baby is born with three biological parents
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Card 2

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What is the origin of the chloroplast?

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a photosynthesising eubacterium engulfed a cyanobacterium by endocytosis

Card 3

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What is the role of mitochondria and chloroplasts?

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Card 4

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How are mitochondria inherited?

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What is the purpose of uniparental transmission?

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