question

3' poly-A tail

answer

Protects the 3' end of nuclear mRNA from degradation, adding stability. The consensus is AAUAAA, found in 10% of plants, with few base changes including more genes. The plant model includes a far upstream element, near upstream element, and PAS. In the chloroplast and mitochondria it marks transcripts for degradation.

question

5' capping

answer

7-methylguanosine (7MG) is added to protect mRNA from degradation at the 5' end. Absent in mitochondria and chloroplast transcripts.

question

Acrocentric

answer

A chromosome with the centromere near the telomeres.

question

Active domain

answer

Loops of DNA which protrude out from the central scaffold, and may be expressed. An 11 nm nucleosome fibre.

question

Adh

answer

A gene in corn and sorghum, but not rice. Has synteny over a short span of chromosomal regions. Some rearrangements have occurred, and the spacing of the gene varies. Retrotransposons have inserted in the region, more so in corn than in sorghum. Over time retrotransposons insert into retrotransposons, increasing distance between gene fragments.

question

Angiosperm

answer

Over 6,000 species. Genome size ranges from 63 million bp to 84,150 million bp, with the average 5,800 million bp. The median size for 47 important crops is 777 million bp. Chromosome number varies from 2 to 600.

question

Annuals

answer

Have a smaller genome than perennials. Do not require genes for wood production or dormancy. Tend to have a shorter life cycle. Many crops are annuals.

question

Arabidopsis

answer

A model plant. Its genome is 125 million bp, relatively small for plants. Has 14% repeated DNA. Has hundreds of copies of a 10 kb rDNA fragment. Has 7 bp repeats for 2 - 5 kb of length at its telomeres. Each chromosome has approximately 500 kb tandem 180 repeat units in its centromeres, as well as retroelements, transposons, microsatellites, and other repeated DNA. Transposons comprise 14% of the genome. Total transposon numbers are in the tens of thousands, with a hundred to a few copies each of class I and II elements. Around 60% of the genome is large segmental duplications, suggesting polyploid origin. There were tens of millions of years of evolution after duplication, and gene orders are changed. A. thaliana (x = 5) and A. lyrata (x = 8) have high levels of synteny; chromosomal fusions and translocation explain differing genome organizations and chromosome numbers. A. thaliana chromosome 1 appears to be a fusion of A. lyrata chromosome 1 and 2, and chromosome 2 appears to be a fusion of chromosomes 3 and 4. Comparing Col and Ler ecotypes, there were 8,500 indels, comprising 6% of the genome, 26.4% of which were transposons, and 67% were due to irregularities in crossing over and recombination. Out of 80 accessions, a tenth of the reference genome was not present in one or more genotypes. The genome was sequenced in 2000. Mitochondria genome is 366 kb, with 57 genes: 22 tRNA (6 are imported), 3 rRNA, 7 ribosomal proteins, 4 ORFs, and 21 proteins for electron transport. The nucleus encodes three phage-like RNA polymerases, one targeted to chloroplasts, one to mitochondria, and one to both.

question

ATP synthase

answer

Subunits encoded by the mitochondria include ATP6 and ATP9.

question

Atrazine

answer

An herbicide. Resistance is encoded in the chloroplast.

question

Autonomous element

answer

A transposon which has inverted repeats, and codes for transposase that is necessary for its movement.

question

B1

answer

This allele in corn normally conditions pigments in leaves, husks, and tassels, but not in kernels. Insertion of a retrotransposon produces B-Peru, which has pigmented kernels. Another transposon produces B-Bolivia.

question

Bacteriophage T3 and T7-like

answer

A type of RNA polymerase found in chloroplasts. Has a YATA consensus, where Y = C or T.

question

Barbara McClintock

answer

The first scientist to recognize the possibility of transposable elements. Proposed that genes could "jump" from one position to another based on observations of corn kernel phenotypes. Won the Nobel Prize for this work. Observed that when a translocon jumped out of the C locus, it caused purple spots in a white kernel. The earlier the jump in the development of the kernel, the bigger the spot.

question

Basic chromosome number (x)

answer

The chromosomes that contain one copy of DNA, that constitutes a species.

question

Beet

answer

Its genome is 750 million bp.

question

Bladderwort

answer

Genome is 77 million bp. Has 3% repeated DNA.

question

Blood orange

answer

A darkly red pigmented orange. Derived from retrotransposon insertion. Ruby allele produces red pigment only after transposon insertion, producing Torocco allele with red pigment and cold responsiveness. Recombination with the retrotransposon produce Maro allele with increased pigment expression. Independent insertion events can produce Jingxian allele which also produces red colour.

question

Brassica oleraceae

answer

There are two types of alloplasmic cytoplasmic male-sterile systems, based on either Raphanus sativus cytoplasm (cms-Ogura) or B. nigra cytoplasm (cms-nigra).

question

Brassica rapa

answer

x = 10
There have been many duplication events, rearrangements, and loss of chromosomes.

question

Brassicaceae

answer

Has sporophytic self-incompatibility. Includes canola and broccoli. SRK is the female determinant, a receptor, and SPII/SCR is the male determinant, its ligand, a protein that is deposited on the exine of pollen grains. Only recognizes ligands from the same haplotype. When binding occurs, the receptor phosphorylates, preventing the pollen from germinating on the stigma surface.

question

Broad bean

answer

Vicia faba
Has 4,750 copies of an rDNA sequence.

question

CAAT box

answer

AGGA
Regulates the level of transcription.

question

Cacao

answer

Transposable elements are 24% of the genome.

question

Caenorhabditis elegans

answer

A model system nematode. Genome is 100 million bp, with 13,100 genes.

question

Centromere

answer

A class of repeated DNA. Sequence and copy number varies between species. Transfer of centromeres between species results in improper attachment of chromosomes to the spindle, and failure to segregate properly. About 2 million bp long, and about 5,000 is 180 bp repeats at the centromere core.

question

Chimpanzee

answer

Have 95% of genes in common with humans.

question

Chloroplast (cp)

answer

Contain machinery for photosynthesis, and participate in biosynthesis of amino acids, nucleotides, lipids, and starch. There are multiple chloroplasts per cell, and multiple copies of the genome per chloroplast. There are 100 copies per chloroplast in young leaves, and 20 - 30 in older leaves. Each leaf cell can contain 500 - 10,000 copies of the genome. Originated from a photosynthetic prokaryote that invaded a eukaryotic cell. The original prokaryote had 3 million bp with over 3,000 genes. Eventually sequences transferred to the nucleus and proteins are imported into the chloroplast through TIC and TOC. There is some cpDNA found in the nucleus, with proper regulatory sequences for nuclear gene expression: eukaryotic promoter, transit peptides, and poly-A addition sites. This is beneficial because favourable mutations can be more easily fixed in the diploid nucleus genome. There is a high level of nuclear cytoplasmic regulation required to maintain appropriate levels of proteins synthesized. There are over 3,000 proteins in the chloroplast. There are two types of RNA polymerase: E. coli type and bacteriophage T3 and T7-like. Has prokaryotic-like ribosomes. Nuclear genes can control chloroplast phenotype and development. Has maternal inheritance.

question

Chloroplast genome

answer

Circular with linear concatomers. Chloroplasts have 120 - 160 thousand bp, with 120 - 140 genes, encoding 100 proteins as well as tRNA and rRNA. Increase gene expression by increased copy number of replicated genome. Most messages are polycistronic. Encodes all its own tRNAs, and 23S, 5S, 4.5S, and 15S rRNAs for its ribosomes. There is some conservation of gene order among higher plants, with gene order highly conserved within species. There is a large inverted repeat in angiosperms, 6 - 76 kb. Changes in genome size are accounted for by changes in size of the repeated region. Genes can contain introns, and can be trans-spliced. Gene transcription can be initiated from multiple sites. Transcripts have no 5' cap, just a phosphorus, and a loop structure at the 3' end defined by inverted repeats for stability. Poly-A tails tag transcripts for degradation. There is RNA editing at about 35 sites.

question

Chromatin

answer

DNA associated with proteins. May be compacted densely to form 30 nm solenoid, in which transcription cannot occur. Includes heterochromatin and euchromatin.

question

Chromosome

answer

Numbered from largest to smallest in most cases. A cell squash is made in metaphase, and chromosomes are photographed and measured in multiple cells; there can be error when making the squash. Centromeric position and arm length may be metacentric, submetacentric, acrocentric, or telocentric. Chromosomes of similar size may be distinguished by G-banding or FISH. If you unravelled all the chromosomes and stacked them, it would be 1.4 m tall!

question

Cms-nigra

answer

Male steril Brassica oleraceae based on B. nigra cytoplasm. Exhibit chlorosis at low temperatures and lower yield and vigour.

question

Cms-Ogura

answer

Male sterile Brassica oleraceae based on Raphanus sativus cytoplasm. Small anthers with no pollen grains. Do not have chlorosis at low temperatures, and can have good seed set.

question

Common vetch

answer

Vicia sativa
Has 1,875 copies of an rDNA sequence.

question

Core genome

answer

Genome which is present in all samples of a species.

question

Corn

answer

x = 10
2n = 2x = 20
Maize
Its genome is 2.3 billion bp. Has over 1,000 families of transposons, collectively 1.3 billion individual transposon copies over 1.7 billion bp. Nearly 85% of the genome is represented by transposons. Two LTR retrotransposon families, each with 400 - 500 thousand copies represent 70% of the genome; there are 1.1 million retrotransposon copies, with 1.5 billion bp, 425 retrotransposons carry genes. 72% of gene fragments are associated with a helitron. Has 32,000 genes. Shares 20,408 genes with sorghum, 20,489 with rice, and 18,434 with Arabidopsis. Among different lines of inbred lines of corn, there are significant differences in genome organization: 50% of the genome is not shared. Specific insertion events with mostly transposons and retrotransposons have occurred recently. Several helitron gene fragments are inserted. Only genes in the core genome have synteny with rice. Out of six inbred lines, there were 30 genes present in the reference genome and absent in others, and nearly 600 genes present in others and absent in the reference genome. There was an alloploidy event in its evolution, but so much change has since occurred that it now acts like a diploid; duplications of many genes were lost. There are genes within genes, due to retrotransposons. The master circle of mitochondria is 570 kb. Two cytoplasmic genomes, N and T, 570 and 540 kb respectively, have 500 kb in common, and can recombine, rearranging gene order. The cytoplasmic sterility system produces a toxic protein, T-URF13, which causes pollen abortion, and can be inhibited by products of two nuclear restorer genes, Rf1 and Rf2.

question

Cosegregation

answer

When phenotype aligns with genotype, and are inherited together.

question

Crossover irregularity

answer

Occurs when there is a problem with alignment of chromosomes, causing an indel where in one copy of the DNA the gene is doubled, and in the other it is deleted.

question

Cytoplasmic genome

answer

Chloroplast and mitochondria genomes. It was thought to be circular based on mapping data, but new evidence suggests genomes may be linear concatomers, plus circular genomes.

question

Cytoplasmic male sterility (CMS)

answer

A maternally inherited, mitochondrial trait. Often from novel open reading frames that arise as the result of recombination of genes coding proteins involved in the electron transport chain. Genes are often chimeric, containing sequences of known genes such as rrn26, atp8, cox1, and cox2, many of which are necessary for electron transport. Only associated with pollen because respiration demands are high during microspore development.

question

Dicots and monocots

answer

Diverged approximately 180 million years ago. The most recent common ancestor had 7 chromosomes. Very little relation is conserved; 137 groups of 400 - 500 genes.

question

Diploid (2n)

answer

2n = 2x
Includes corn.

question

Direct repeat

answer

ABCDABCD
With repair and crossover, you get two smaller sub-circles.

question

DNA

answer

Coils twice around a complex of histone proteins, h2a, h2b, h3, and h4. It is attached to a central protein scaffold, forming loops 5 - 200 kb, with attachment occurring at MARs. This scaffold can be coiled further at metaphase. Loops can be active or inactive domains, changing allowing for genes to be expressed at appropriate times.

question

E. coli type

answer

A type of RNA polymerase found in chloroplasts. Have a -35 consensus TGACA and a -10 conensus TATTCT.

question

Endosymbiont theory

answer

Chloroplasts and mitochondria evolved from prokaryotes that were internalized by protoeukaryotic cells. Plant plastids are similar to cyanobacteria like Synechococcus. Mitochondrial rRNA sequences are most similar to proteobacteria that include several genera of internal parasites including Rhizobium and Rickettsia.

question

Enhancer elements

answer

Sequences important for specificity in gene expression. Can be a considerable distance from promoter, and act in an orientation-independent manner. Can work from anywhere, including introns and the 3' end. Binds to proteins for transcription.

question

Euchromatin

answer

Chromatin which is uncoiled during interphase, and condenses during mitosis, reaching maximum density at metaphase.

question

Exon

answer

Coding regions which are disrupted by introns.

question

Far upstream element (FUE)

answer

A sequence that is U ; A ;; G rich. Involved in 3' poly A tail addition in plants.

question

Fluorescent in situ hybridization (FISH)

answer

A method of distinguishing chromosomes. Differently coloured fluorescent-labelled molecular probes hybridize to specific chromosomal sequences and visualise where hybridization takes place under a microscope. Enables measurement of chromosomes.

question

Four-o'clock

answer

Mirabilis jalapa
A variegated plant with green and white patches. Only the maternal phenotype is responsible for determining phenotypes of progeny. White chloroplasts lack chlorophyll.

question

G banding

answer

A method of distinguishing chromosomes. Constitutive heterochromatin stains differently from other chromatin, and can be visualized under a microscope. Produces a particular pattern of banding on each chromosome.

question

Gene family

answer

There are 13 - 16 thousand gene families in plants. Have similar functions and catalytic domains. If protein sequences are similar 60% or more, they are in the same gene family. 9,053 of gene families are found in all plants; 60 - 70% of genes.

question

Grape

answer

The gene for pigment found in Cabernet grapes can have a retrotransposon inserted, producing the allele found in Chardonnay. Recombination around the retrotransposon results in partial expression in Ruby Okuyama grapes. Transposable elements are 41% of the genome.

question

Helitron DNA transposon

answer

There are autonomous and non-autonomous types. Replicate by rolling circle mechanism. Nicking occurs at the helitron element and target site, and a single strand of helitron is ligated to the donor site. Cleavage and ligation forms a loop. Replication at the donor site displaces the helitron. Displacement at the donor terminates, and the single-strand helitron is ligated to the target. The second strand is synthesized at the target. The site of termination for strand transfer can extend beyond the helitron sequence, and fragments of genes can be transferred along with the helitron, and can be taken along again and again. Helitrons often contain gene fragments of several genes in tandem.

question

Heterochromatin

answer

Chromatin which is condensed or tightly folded. Shows maximum condensation during interphase.

question

Heteromorphic self-incompatibility

answer

Different alleles produce different flower morphologies. Stamens may be longer than pistils for one allele, and pistils longer than stamens for another allele.

question

Heteroplasmy

answer

A mixture of different organelle genotypes in one cell. Can result in organelle dysfunction. A possible explanation for uniparental inheritance of organelles.

question

Hexaploid (6n)

answer

2n = 6x
n = 3x

question

Homologous genes

answer

Genes that have 60% similarity at the protein level. Based on gene homology, rice, grape, poplar, and Arabidopsis have 8,000 genes in common.

question

Human

answer

Mitochondrial genome is 15 kb, with 15 genes for electron transport, and 22 tRNAs.

question

Hypersensitive response

answer

Cells near an infection in a plant will die to stop the spread of a pathogen. A form of programmed cell death.

question

Idiogram

answer

A diagrammatic sketch or interpretive drawing of the karyogram.

question

Inactive domain

answer

Loops of DNA which stay close to the central scaffold, and may not be expressed. A 30 nm fibre formed by supercoiling of the 11 nm fibre.

question

Indel

answer

Insertion/deletion
You can't tell if the difference is caused by an insertion or deletion event. Comparing Col and Ler ecotypes of Arabidopsis, 67% of indels are caused by crossover irregularities.

question

Intron

answer

Non-coding regions which are spliced out of the transcript.

question

Inverted repeat

answer

ABCDDCBA
With repair and crossover, you get repeats switched around.

question

Karyogram

answer

The arrangement of chromosomes in descending order, longest to shortest, based on physical measurement of the chromosomes from a photomicrograph.

question

Karyotype

answer

The exact haploid chromosome set of an organism.

question

Linear concatomer

answer

A linear piece of DNA which has the same genes as a circular cytoplasmic genome. Usually shrot in length.

question

Lycopersicon type

answer

Tomato type
A mechanism for maternal inheritance of chloroplasts. Chloroplasts are excluded from the generative cell during pollen development.

question

Male sterility

answer

Could be misinterpreted as a false negative during SI studies. Includes cytoplasmic male sterility. It is important for plant breeding.

question

Master circl

answer

A circular DNA that contains all the sequences of the mitochondria genome, and can be constructed from restriction mapping data. Can recombine to give rise to a variety of subgenomic circular fragments. Sub-circles may be present at different copy numbers in different tissues or organs, replicating independently of each other. Meristematic regions and reproductive organs have high copy numbers, but organization into a master circle rather than sub-circles is questionable. Recombination among sub-circles and amplification of specific products can lead to major changes in mitochondrial genome.

question

Maternal inheritance

answer

Chloroplast genomes are most often transmitted by the maternal parent, except in alfalfa. There are three mechanisms: Lycopersicon, Solanum, and Triticum types. Explanations for the evolution of uniparental inheritance of organelles includes heteroplasmy, avoidance of selfish organelle genomes (maladaptive or incompatibility with the nucleus), and high mutational load in male gametes from high oxidative damage.

question

Matrix attachment region (MAR)

answer

Areas where DNA attaches to a central protein scaffold, forming active and inactive domains in the DNA.

question

Matrix processing peptidase (MPP)

answer

Removes the transit peptide from proteins imported into the mitochondria matrix.

question

Medicago

answer

Transposable elements are 30% of the genome.

question

Metacentric

answer

A chromosome with the centromere in the centre.

question

Microsatellite

answer

Tandem repeats that are moderately repeetitive, 2 - 6 bp long, with 10 - 100 copies.

question

Minimal plant genome

answer

Around 60 million bp, 40 million of which are 30,000 genes, and the rest is centromeres, telomeres, rRNA, regulatory regions, and introns.

question

Minisatellite

answer

Tandem repeats that are moderately repetitive, 10 bp - 30 kb, with hundreds of copies.

question

Mitochondria (mt)

answer

The site of energy metabolism and synthesis of ATP. There are major complexes for electron flow to generate ATP using ATP synthase. Originated from a eubacterial endosymbiont. Number of mitochondria varies among tissue and organ, 400 - 600 per cell. Mitochondria in differentiated cells may contain a subset of the mitochondrial genome or no DNA at all. Proteins are imported into the mitochondria through TOM and TIM. Proteins imported to the matrix have a signal sequence at the N terminus that is cleaved. Have T7 and T3-like bacteriophage RNA polymerase. Have prokaryotic-like ribosomes.

question

Mitochondria genome

answer

Circular with linear concatomers. The genome encodes 20 - 30 proteins, rRNA, and some tRNAs. 98% of the 1,000 mitochondrial proteins are imported, with genes transported to the nucleus. Mitochondria genome encodes components of the electron transport chain. Plant mitochondria genome size varies from 200 - 2,500 kb. There are direct and inverted repeats in the master circle that give rise to a multipartite genome, and subgenomic molecules. Gene order is variable even within a species. Contains some chloropalst sequences, with no transfer or degradation of mitochondria DNA. There is RNA editing at 400 - 500 sites. There are consensus promoters, CRTA in monocots, and CRTAAGAGA in dicots. Some genes have multiple transcription start sites. mRNA is not capped, and 3' stability is from a double loop structure. Poly A tails target transcripts for degradation.

question

Mycoplasma genitalium

answer

A bacteria without a cell wall. Genome is 0.58 million bp, wtih 482 genes.

question

Near upstream element (NUE)

answer

A sequence that is AAUAAA in 10% of plants. Involved in 3' poly A tail addition in plants.

question

Non-autonomous element

answer

A transposon which has inverted repeats but no functional transposase. It can move only in the presence of autonomous elements with functional transposase in the genome. Has inverted repeats, but the transposase is mutated.

question

Norway spruce

answer

The genome is 19.6 billion bp.

question

Nuclear restorer (Rf)

answer

A nuclear gene that affects CMS to eliminate it, suggesting nuclear-cytoplasmic interactions. May affect mitochondria or gene transcription, processing of RNA or protein, elimination of submolar genome, or altering metabolism.

question

Nucleosome

answer

140 bp of DNA, plus protein. A spacer of 60 bp occurs between nucleosomes. The nucleosome and spacers form 11 nm fibres in which transcription can occur.

question

Pangenome

answer

Complete gene contents for a species. Includes core genome, plus all unique genes found in individual genotypes. In early years of genome sequencing, it was assumed that all genotypes would have the same genome. High-throughput sequencing shows that multiple genotypes within species have unique sequences and differ in gene content. The number of genes varies with species; in soybeans 80% of the pangenome is found in all plants.

question

Papaveraceae

answer

Has self-recognition gametophytic self-incompatibility. Includes poppies. The male determinant is a receptor expressed by the pollen tube. The female determinant is the ligand of the receptor. When ligand binds to receptor, it opens Ca²⁺ channels in the pollen tube, causing programmed cell death.

question

Papaya

answer

Transposable elements are 52% of the genome.

question

Parthenocarpy

answer

Fruit forms without fertilization. Can be misinterpreted as a false positive during SI studies.

question

Pear

answer

Pyrus communis
Self- and cross-incompatibility determination is unclear. Have gametophytic self-incompatibility. Most cultivars are completely self-incompatible, thus inter-planted pollinators are required. Narrowing of the genetic base for new commercial cultivars has lead to increased cases of cross-incompatibility, specifically use of 'Willams' and 'Coscia' varieties as parents. Every plant of one variety is genetically identical, propagated with grafting. For the 'Tosca' variety, it was necessary to look at pollen grain swelling in the pistil to genotype its S locus.

question

Perennial

answer

Have larger genomes than annuals. Cell cycle time, and time required to replicate the genome is a factor in this.

question

Petunias

answer

In the Solanaceae family. The female determinant can deactivate various other haplotypes, depending on its own haplotype. S₇ and S₉ alleles can deactivate RNAse in S₅, S₉, S₁₁, S₁₇, and S₁₉.

question

Pigeonpea

answer

Transposable elements are 52% of the genome.

question

Pine

answer

Its genome is 23 billion bp.

question

Plants

answer

Gene numbers vary from 25 - 45 thousand, varying only by 30% whereas genome size varies much more. There are 13 - 16 thousand gene families related by descent with similar functions, but may be expressed differently or invovled in different pathways or physiological functions.

question

Poly A addition site (PAS)

answer

A sequence 40 nucleotides away from the NUE. U > A > C rich in plants, A > U > C rich in algae. Involved in 3' poly A tail addition in plants.

question

Polycistronic

answer

Having more than one protein encoded in the same transcript. Subsequently processed.

question

Potato

answer

Transposable elements are 62% of the genome.

question

Promoter

answer

A 5' upstream region preceding the transcribed sequence at the transcription start site. Contains signal elements important for gene expression including enhancer elements.

question

Protoplast fusion

answer

A process where cell walls are digested, leaving only spherical protoplasts. The solution must have a specific osmotic potential to maintain the protoplasts. The cells are used to mix cytoplasms, and the cell wall is regenerated and whole plants are produced. Has been used to create intergeneric and interspecific somatic hybrids, and to manipulate cytoplasmic traits. Enabled the combination of cms with atrazine resistance, replacement of Raphanus sativus chloroplasts in Ogura lines, transfer of Polima cms to broccoli, and production of cold-tolerant cms cauliflower.

question

Retrotransposons

answer

Class I elements
A type of transposable element. Includes long terminal releat (LTR)-retrotransposons and non-LTR retrotransposons. Encodes reverse transcriptase, which converts RNA into DNA. An RNA copy is made from DNA incorporated into the chromosome. RNA is made into cDNA which incorporates into the genome. There is net increase in retrotransposon number, amplifying amount of DNA.

question

Rf1

answer

A nuclear restorer gene of corn. Reduces accumulation of urf13 transcripts.

question

Rf2

answer

A nuclear restorer gene of corn. Encodes aldehyde dehydrogenase, which detoxifies aldehydes. Has no effect on the abundance of urf13 transcripts, but may remove a toxic compound produced by the URF13 protein.

question

Ribosomal DNA (rDNA)

answer

A class of repeated DNA. Tandem repeat units, 7.5 - 185 kb, depending on species. Interact with ribosomal proteins to form the ribosome.

question

Rice

answer

Transposable elements are 25% of the genome.

question

RNA editing

answer

In mitochondria, there are 400 - 500 sites that are edited, and around 35 in chloroplasts. A predicted protein sequence can differ from observed amino acids. The mRNA is produced from a DNA template, but some cytosines are turned into uracils. The difference between cytosin and uracil is in one side group. The mechanism is most likely a chemical reaction: deamination or transamination, where the nucleotide is modified rather than excised and substituted.

question

RNA polymerase II

answer

Attaches at the start site; generalized transcription factors help it bind to DNA.

question

Rosaceae

answer

Self-incompatibility is controlled by a homomorphic, gametophytic, monofactorial multiallelic system.

question

Saccharomyces cerevisiae

answer

A yeast. Genome is 12.5 million bp, with 6,000 genes.

question

Satellite

answer

Tandem repeats one to several thousand bp in length. Very highly repetitive, up to thousands of copies.

question

Sedimentation coefficient (S)

answer

A measure of the size and density of a ribosome. Used to distinguish different ribosomes. Example: 70S.

question

Self-incompatibility

answer

It was evolevd separately by different families, using different mechanisms.

question

Self-pollination

answer

Self-pollinating plants have smaller genomes than cross-pollinating plants.

question

Solanaceae

answer

Has non-self-recognition gametophytic self-incompatibility. The female determinant is an RNAse which can kill the pollen grain. The male determinant is a cluster of genes which deactivate the RNAse except those which have the same haplotype. Includes petunias.

question

Solanum type

answer

Potato type
A mechanism for maternal inheritance of chloroplasts. Chloroplasts disappear or degrade in generative cells. The most common mechanism.

question

Sorghum

answer

Transposable elements are 63% of the genome.

question

Sorting out

answer

Causes maternal inheritance of variegation phenotype in four-o'clock plants. Egg cells contain many chloroplasts, and pollen cells contain none. If the maternal branch is variegated, three types of zygotes can result: all green chloroplasts, all white chloroplasts, or a mixture. The zygote produced may be green or white or variegated, based on random chance and sorting out of chloroplasts.

question

Southern blotting

answer

Used before introduction of PCR. Determines if a DNA sequences is present. A DNA probe is labelled and hybridized to the DNA, which is then separated out on agarose gel.

question

Soybean

answer

x = 20
Transposable elements are 59% of the genome. Since the divergence of dicots and monocots, the line for soybeans has had one triplication event and two duplication events, but chromosome loss leads to the 20 chromosomes of soybean. Out of seven accessions, 80% of the pangenome was present in all genotypes.

question

Spruce

answer

Its genome is 160 larger than that of Arabidopsis.

question

Start sequence

answer

AUG
Codes for methionine.

question

Stop codon

answer

UAA, UAG, or UGA.

question

Strawberry

answer

2n = 8x = 56
A polyploid. Transposable elements are 22% of the genome.

question

Stromal processing peptidase (SPP)

answer

Removes a piece of the transit peptide of imported proteins in the stroma of chloroplasts.

question

Submetacentric

answer

A chromosome with the centromere near the centre.

question

Synteny

answer

Genetic loci in different organisms located on a chromosomal region of common evolutionary ancestry. The collinearity of genes in different organisms. Arabidopsis and rice have 137 syntenic groups at 75 locations, each consisting of a few genes. Indicates collinearity of sequences, but not absolute identity along the chromosome. The distance between collinear genes varies among species, resulting from varying amounts of repeated DNA in the species.

question

Tandem repeat

answer

A class of repeated DNA. Includes satellites, minisatellites, and microsatellites.

question

TATA box

answer

Present in all expressed genes, involved in orientation of RNA polymerase II. Rich in A and T, causing the DNA to be easier to unravel. It is some distance from the start site.

question

Telocentric

answer

A chromosome with the centromeres at the telomeres.

question

Telomere

answer

A class of repeated DNA. 6 - 7 bp repeats. Expendable DNA which is degraded every time the cell replicates. PRoduced by telomerase, which is only active in reproductive cells of animals and meristem cells of plants. This is so that cells are not immortal, which can lead to cancer. When telomerase was discovered it was thought it would be a "fountain of youth" since telomere shortening is a sign of aging.

question

Tetraploid (4n)

answer

2n = 4x

question

Thylakoid processing peptidase (TPP)

answer

Removes a piece of the transit peptide of imported proteins in the thylakoid lumen of chloroplasts.

question

Trans-splicing

answer

Independently transcribed exons are spliced together to form a transcript.

question

Transcript termination

answer

Primary transcript ends at a point that is not well defined.

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Translocator inner chloroplast (TIC)

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A complex in the inner membrane of the chloroplast through which proteins involved into the chloroplast must pass.

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Translocator inner membrane (TIM)

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A complex in the inner membrane of the mitochondria, through which proteins imported into the mitochodnria must pass.

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Translocator outer chloroplast (TOC)

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A complex in the outer membrane of the chloroplast through which proteins imported into the chloroplast must pass.

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Translocator outer membrane (TOM)

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A complex in the outer membrane of mitochondria, through which proteins imported into the mitochondria must pass.

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Transposon

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Class II element
A type of transposable element. DNA is transposed in the genome; it moves without replication, and inserts into another locus in the genome. Includes autonomous and non-autonomous elements. Movement of transposons can eliminate or activate gene expression.

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Transposable element

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Mobile genetic element
A class of repeated DNA. Includes retrotransposons and transposons.

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Triploid (3n)

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2n = 3x
Sterile.

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Triticum type

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Wheat type
A mechanism for maternal inheritance of chloroplasts. Chloroplasts are excluded from the egg during fertilizatioin: "stripping off".

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Untranslated region (UTR)

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5' and 3' terminal regions of the transcript which contain sequences that are not translated into protein. Flank the first and last exon.

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Variable genome

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Dispensable genome
Genome which is present in only some samples of a species.

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Watermelon

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The mitochondrial genome is 2,500 kb.

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Wheat

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2n = 6x = 42
Has 96,000 genes. An allohexaploid with genes from three species. Has three separate sets of genes, represented three times.

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Zein

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A storage protein found in seeds.

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