Organellar Inheritance

  1. Mitochondria
    membrane-bounded organelles found in most eukaryotic cells, that convert energy derived from glucose and other nutrient molecules into ATP
  2. Mitochondria have their own DNA, separate from the _______ ______. The mitochondrial genome encodes some, but not all, of the proteins needed for ______ _______. The remainder are encoded by the ______ ______ and imported into the organelle
    • nuclear genome
    • energy conversion 
    • nuclear genome
  3. The unwrinkled outer membrane surrounds an inner membrane (of mitochondria) bent into wrinkles called _______. The inner membrane in turn surrounds an area called the ________
    Image Upload 1
    • cristae
    • matrix
    • Image Upload 2
  4. Mitochondria produce packets of energy (ATP) in two stages: (broad strokes)
    • First, enzymes in the matrix catalyze the Krebs cycle, which metabolizes pyruvate and fatty acids to produce the high-energy electrons carriers NADH and FADH2
    • Second, a series of multisubunit enzyme complexes embedded in the inner mitochondrial membrane harness this energy in a process called oxidative phosphorylation
  5. Some of the enzyme complexes form an ______ ________ ______ that transfers the electrons from NADH and FADH2 to the ultimate electron acceptor, _______. The energy released from these steps of electron transport is used to pump protons out of the _______ into the space between the ______ and ______ membrane, creating an _______ potential across the ______ membrane
    • electron transport chain 
    • oxygen 
    • matrix
    • inner and outer membranes
    • electrical 
    • inner
  6. The protons then flow back into the _______ through an enzyme complex called _____ ________, which is embedded in the _______. ATP synthase uses the energy released by this flow of protons to ________ ADP and thus form ______
    • matrix
    • ATP synthase
    • cristae
    • phosphorylate
    • ATP
  7. A single mitochondrion usually contains several ______ of its genome within the matrix; the number of _____ can vary depending on the _______ needs of the cell, but is usually between 2 and 10
    • copies 
    • copies
    • enrgy
  8. The 16.5 kb human mitochondrial genome, which is only 1/100,000th the length of the haploid genome in a human gamete, is a ________ DNA molecule that carries ____ genes. Thirteen of these genes encode _______ subunits of the protein complexes that make up the _______ _______ apparatus. The mitochondrial genome also encodes 22 _____ genes and 2 genes for the large and small ______ found in mitochondrial ribosomes
    Image Upload 3
    • circular 
    • 37
    • polypeptide
    • oxidative phosphorylation
    • tRNA 
    • rRNAs
  9. A significant feature of the human mitochondrial genome is the _______ of its gene arrangement. Adjacent genes either _____ each other or in few cases, even slightly ______. With virtually no nucleotides between them and no _______ within them, the genes are packaged very _______
    • compactness
    • abut 
    • overlap
    • introns
    • tightly
  10. Protozoans parasites of the genera Trypanosoma and Leishmania exhibit mtDNAs that have a highly unusual ________. These _______-celled euk organisms carry a single mitochondrion known as a ________. Within this structure, the mtDNA exist as a large network of 10-25,000 ______ 0.5-2.5 kb in length interlocked with 50-100 ______ 21-31 kb long
    • organization 
    • single-celled
    • kinetoplast 
    • minicircles
    • maxicircles
    • Image Upload 4
  11. Researchers discovered the unexpected phenomenon of RNA editing in the mitchondrion  (______) of trypansomes. DNA sequencing of maxicircle DNA, minicircle DNA and cDNAs copied from ______ mRNAs revealed major surprises
    • kinetoplast
    • kinetoplast
  12. The minicircles did not encode any _____ ______ genes, while the maxicircles contained gene sequences that were clearly ______, but far from ______, to the cDNAs corresponding to the protein-coding mRNAs. These results imply that the maxicirlces are transcribed into _____ _____ that are then changed into _______ ______
    • protein-coding genes
    • related
    • idnetical
    • precursor RNAs (pre-mRNAs)
    • mature mRNAs
  13. RNA editing
    A special type of transcript processing that converts pre-mRNAs to mature mRNAs
  14. Without RNA editing, the____-_____ do not encode polypeptides. Some pre-mRNAs lack a ______ _____ suitable for translation initiation; others lack a ______ ______ for the termination of translation. _____ _____ creates both types of sites, as well as many new codons within the genes
    • pre-mRNAs 
    • first codon
    • stop codon
    • RNA editing
  15. In trypanosomes, the RNA editing machinery adds or deletes _______ to convert pre-mRNAs into _____ ______. We see _____ editing occurs in stages in which enzymes organized into a structure called an _______ use an _____ template as a guide for correcting the _____. Explain why kinetoplasts have minicircles as well as maxicircles
    • uracils 
    • mature mRNAs
    • uracil
    • editosome
    • RNA 
    • pre-mRNA
    • The maxicircles are transcribed into pre-mRNAs which are converted into mature mRNAs (via RNA editing) using guide RNAs which are transcribed from short stretches of DNA on minicircles
    • Image Upload 5
  16. Mitochondria have their own distinct translational apparatus, as suggested by the fact that mtDNAs carry their own _____ and _____ genes. Mitochondrial translation is quite unlike the cytoplasmic _______ of mRNAs _______ from nuclear genes in euks; in fact, many aspects of the mitochondrial translation system resemble details of translation in _______.
    • rRNA and tRNA genes
    • translation 
    • transcribed
    • prokaryotes
    • *For example, as in bacteria, N-formyl methionine and tRNAfMet initiate translation in mitochondria
    • Image Upload 6
  17. Moreover, drugs that inhibit bacterial translation, such as chloramphenicol and erythromycin, which have no effect on _____ cytoplasmic protein synthesis, are potent ______ of mitochondrial protein syntehsis
    • euk
    • inhibitors
  18. Many exceptions to the "universal" code involve mitochondria. For example, in human mt DNA, five triplets are used differently than they would be in the ______. No single mitochondrial ______ _____ functions in all organisms, and the mitochondria of higher plants use the ______ _____. How did the genetic code of some mitochondria diverge from the universal code?
    Image Upload 7
    • nucleus 
    • genetic code
    • universal code
    • By a series of mutations occurring some time after the organelles became established components of euk cells
  19. Chloroplasts capture _____ _____ and store it in the chemical bonds of _____ through the process of _______. Every time a bird takes flight, a person speaks, a worm turns etc, the organism's cells are using _____ that was originally captured from _____ by _______ and is then released through the functions of ________
    • solar energy
    • carbs
    • photosynthesis
    • energy
    • sunglight
    • chloroplasts
    • mitochondria
  20. Embedded in the membranes of internal structures called _______ are the light-absorbing pigment ______  and light-absorbing proteins, as well as proteins of the photosynthetic _______ _______ system
    • thylakoids
    • chlorophyll
    • electron transport system
    • Image Upload 8
  21. During the light-trapping phase of photosynthesis, energy of photons of light from the _____ boosts electrons in ________ to higher energy levels. The energized electrons are then conveyed to an _______ ______ system that uses the energy convert water to _____ and ______
    • sun
    • chlorophyll
    • electron transport
    • oxygen and protons
  22. Photosynthetic electron transport forms _______ and drives the synthesis of _____ via an _____ ______ similar to the one mitochondria. During the second, ______-building phase of photosynthesis, enzymes of the Calvin cycle use that _____ and _______ to convert atmospheric carbon dioxide into _________. The energy stored in the ______ of these nutrient molecules fuels the activities of both the plants that make them and animals that eat the plants
    • NADPH 
    • ATP 
    • ATP synthase
    • sugar-building 
    • ATP and NADPH
    • carbohydrates
    • bonds
  23. Chlroplasts occur in _____ and _____. The genomes they carry are much more _______ in size than the genomes of mitochondria. Although chloroplast DNAs (cpDNAs) range in size from 10 to 217 kb, most are between 120 and 160kb long. cpDNA contains many _____ genes than mtDNA
    • plants and algae
    • uniform
    • more
  24. Like the genes of bacteria and human mtDNA, these genes are ______ packed, with relatively few nucleotides _______ adjacent coding sequences. Like the genes of yeast (but no human) mtDNA, they contain _______. Although some are ______, many cpDNAs exist as _______ and ______ forms. Like mitochondria, chloroplasts contain more than one copy of their _______ (usually 15-2
    genome copies)
    • closely
    • between 
    • introns
    • circular
    • linear
    • branched
    • genome
    • Image Upload 9
  25. The chloroplast genome of the liverwort M. polymorpha, the first cpDNA to be sequenced completely, is depicted. The cpDNA-encoded proteins include many of the molecules that carry out photosynthetic ______ ______ and other aspects of _________, as well as RNA polymerase, translation factors, ribosomal proteins, and other molecules active in chloroplast gene ________
    Image Upload 10
    • electron transport
    • photosynthesis
    • expression
  26. The RNA polymerase of chloroplasts is similar to the multisubunit _______ _____ ______. Drugs that inhibit bacterial _______, such as chloramphenicol and streptomycin, inhibit _______ in chloroplasts, as they do in mitochondria
    • bacterial RNA polymerase
    • translation 
    • translation
  27. Its hard to get mutants into organelle genes so they came up with the gene gun. How does it work?
    • You make some sequence that is the gene you want to modify in mitochondria (with a few mutations/differences)
    • They coat it with a pellet and shoot that toward the cells where the pellet hits a screen, stopping the pellet but propelling the DNA toward the cell at high speeds (some of DNA might make it into the mitochondria)
    • Not a huge success rate but it’s the best method available
  28. Endosymbiont Theory (3-story)
    Image Upload 11
  29. Variegated plants typically have branches that are variegated with some parts ______ and some ______, and also branches that are either solid ______ or ______. Carl Correns performed all nine possible pairwise crosses between male (pollen) and female (ova) gametes from flowers growing in each type of branch: _______, _____ or ______. The progeny phenotypes always resembled that of the source of the ______ gamete because the color of the plant cells is controlled by _______ _____ _____
    • green 
    • white
    • green or white
    • variegated, green or white
    • female
    • maternally inherited cpDNA 
    • Image Upload 12
    • Image Upload 13
  30. The reason for the variegated phenotype is that variegated four-o'clocks have ____ kinds of chloroplasts (name them). The mutant cpDNAs have a defective allele of a gene required for synthesis of the green pigment ______; cells without _______ are white. A cell or organism with more than one genotype of an organellar genome is said to be _________
    • two kinds: wild-type and mutant
    • chlorophyll
    • chlorophyll
    • heteroplasmic
    • Image Upload 14
  31. Why is the variegated plant considered as a whole to be heteroplasmic?
    The plant also has homosplasmic cells (define).
    • because it came from a heteroplasmic egg, one that contained both wild-type and mutant chloroplasts. 
    • Homoplasmic cell: cell with with only one type of cpDNA. *For example, the solid white areas of the plant are homoplasmic for mutant chloroplasts
    • Image Upload 15
  32. When a cell undergoes mitosis, a ______ half (approx.) of the chloroplasts end up in each daughter cell. It is easy to see that after several cell divisions in which _____ and _____ ____ chloroplasts are, ______ distributed _________ in the two daugher cells, a _________ daughter cell containing only one type of cpDNA could arise from an originally ________ cell by random _______ _________
    • random 
    • mutant and wild-type
    • random
    • unequally
    • homoplasmic
    • heteroplasmic 
    • cytoplasmic segregation
  33. Once a cell becomes _______, it cannot become ________ again (except by new mutation), and so all of its descendants from that point are ___________. Chance ________ ________ of chloroplasts explains at least in part how a plant that is heteroplasmic for wild-type and mutant chloroplasts could have a mixture of heteroplasmic, homosplasmic wild-type and homoplasmic mutant cells
    • homoplasmic
    • heteroplasmic
    • homoplasmic
    • cytoplasmic segregation
  34. Variegated plants usually have a variegated main shoot with ______ of green and white tissue, and also branches that are _____ green or ______ white. In the variegated regions, the green patches contain mainly ________ cells. During mitosis, cells _______ for mutant chloroplasts can arise and they establish the white patches and also white branches. Cells _______ for wild-type chloroplasts also arise and establish the solid green branches 
    Image Upload 16
    • patches 
    • solid 
    • solid
    • heteroplasmic 
    • homoplasmic
    • homoplasmic
  35. In four-o'clocks, heteroplasmic cells are green (why?)
    Define threshold effect
    • because the amount of chlorophyll, even in a small number of wild-type chloroplasts, is still sufficient for green color
    • Threshold effect: a phenomenon in which a particular fraction of wild-type organelles is sufficient for the normal phenotype
  36. The precise fraction of wild-type organelles needed to avoid a mutant phenotype will depend on the particular ______ and ______
    gene and mutation
  37. Explain why female gametes from flowers on white branches are homoplasmic for mutant chloroplasts.
    Flowers from green branches give rise to eggs homoplasmic for wild-type chloroplasts and therefore _____ _____ (non-variegating) progeny. Finally, flowers from variegated branches can have any one of the ______ _____ types. The plant depicted came from heteroplasmic egg of a flower from a variegated branch. 
    Image Upload 17
    • they always give rise to solid white plants (which ultimately die because they cannot photosynthesize)
    • solid green
    • three egg types
    • Image Upload 18
  38. Each chloroplast or mitochondrion may have several copies of its ______, so individual organelle can itself be either ________ or ________ for wild-type versus mutant DNAs
    • genome
    • heteroplasmic or homoplasmic
  39. Two kinds of events can lead to cytoplasmic segregation of the genome within an originally heteroplasmic organelle. (Name them)
    pg 504 upper left
  40. Whether or not an individual organelle will function normally (wild-type) or not (mutant) is potentially subject to ______ effects. Therefore, just like the cells they inhabit, the phenotype of an individual organelle (whether it is functionally wild-type or mutant) is affected by its relative fractions of ____ _____ and _______ _______ copies
    • threshold effects
    • wild-type and mutant genome copies
  41. how did researchers analyze the inheritance pattern of mtDNA in yeast?
    Image Upload 19
    pg 505 top left
  42. The experiment also shows that organelles from the parental cells of different mating types segregated during the ______ _______ of vegetative growth. Immediately after mating, the diploids would contain _____ ____ of mitochondria, and the diploid cells would all be phenotypically ____ because hat allele is dominant
    • mitotic divisions
    • both kinds
    • Cr
  43. But after several rounds of division, some cells contained only _____ mitochondria and were thus phenotypically _____. Clearly the Cs and Cr mtDNAs underwent _______ cytoplasmic segregation
    • Cs
    • Cs
    • random cytoplasmic segregation
  44. One aspect of S. cerevisiae biology makes this process of cytoplasmic segregation of mtDNAs so rapid that is often achieved only a ____ rounds of _____.
    • few 
    • mitosis
  45. This yeast divides mitotically through a process of budding that creates a ____ bud from a ______ mother cell. Because of this inequality in _____, only a few mtDNA molecules are transferred into the newly formed bud, making it _____ likely that the bud will contain mostly or only one type of mtDNA
    • small 
    • larger
    • size 
    • more
  46. Leber's heredity optic neuropathy, or LHON, is a disease in which flaws in the ________ ______ ________ ______ lead to _____ ______ degeneration and ________. Family pedigrees shown that LHON passes only from _______ to offspring. LHON is caused by ________ mutations in any one of three mitochondrial genes (ND1, ND4, or ND6) each of which encodes a different subunit of the enzyme NADH dehydrogenase, the first enzyme in the ______ ______ pathway
    Image Upload 20
    • mitochondrial electron transport chain 
    • optic nerve 
    • blindness
    • mother 
    • hypomorphic mutations
    • electron transport pathway
  47. Diminished ______ flow down the respiratory transport chain reduces the mitochondrion's production of _____, causing a gradual ______ in cell function and ultimately cell ______.
    • electron 
    • ATP
    • decline
  48. Why is it that in most people affected by LHON the optic nerves cells are homoplasmic for the disease mutation (all the mitochondria are mutant); what does this usually mean for taht person?
    because the disease-causing alleles are weak mutants 

    usually this means that the person as a whole is homoplasmic for mutant mitochondria
  49. For this reason, LHON often (not always) shows the _______ possible inheritance pattern for a mitochondrial disease; all the mtDNAs in the ova of every affected female are ______, so all of their progeny (male and female) are ________ for mutant mitochondria
    • simplest
    • mutant
    • homoplasmic
  50. People with a rare inherited condition nown as myoclonic epilepsy and ragged red fibeer disease (MERRF) have a range of
Card Set
Organellar Inheritance
Ch 14