CHAPTER 1 - P1 Flashcards
(96 cards)
1
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The attempt to understand biological phenomena in molecular terms
A
Molecular Biology
2
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The study of gene structure and function at the molecular level.
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Molecular Biology
3
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Early work on genes which is not considered as molecular biology or molecular genetics because early geneticists didn’t know the molecular nature of genes hence it is called ________
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transmission genetics.
4
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Deals with the transmission of traits from parental organisms to their offspring.
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transmission genetics.
5
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1944 - chemical composition of _____ was known.
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genes
6
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1865 - Gregor Mendel published his findings on the _____________
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inheritance of seven different traits in the garden pea.
7
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inheritance is ________ — each parent contributes particles, or genetic units, to the offspring which is called the _____
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particulate ; genes
8
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appearance or set of observable characteristics of an organism.
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Phenotype
9
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(MENDEL’S LAWS OF INHERITANCE) gene in different forms.
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Alleles
10
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In inheritance of seven different traits in the garden pea, allele for _________ was dominant when he mated a green- seeded pea with a yellow-seeded pea.
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yellow seeds
11
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In inheritance of seven different traits in the garden pea, All of the progeny in the F1 or first filial generation had _____ and when the F1 yellow peas were allowed to self-fertilizie, some _______ peas reappeared.
A
yellow seeds ; green-seeded
12
Q
ratio of yellow to green seeds in the second filial generation (F2) was very close to ____
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3:1
13
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Filial = filius, ___ and filia, ______
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son ; daughter
14
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_____ = first filial generation containing sons and daughters of the original parents.
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F1
15
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_____ = second filial generation containing the offspring of the F1 individuals.
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F2
16
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Mendel concluded that the allele for green seeds must have been ________, even though it didn’t affect seed color of those peas.
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preserved in the F1 generation
17
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According to mendel, the parents were ______ — each parent plant carried 2 copies of the gene. In this concept, ______ have two copies of the same allele (either 2 alleles for yellow seeds or 2 allleles for green seed) while _____ have one copy of each allele.
A
diploid ; homozygotes ; heterozygotes
18
Q
In the study of mendel, the two parents in the first mating were _____; the resulting F1 peas were all _______. Further, Mendel reasoned that sex cells contain only one copy of the gene; that is, they are ____. Homozygotes can therefore produce sex cells, or gametes, that have only one allele, but heterozygotes can produce gametes having either allele
A
homozygotes ; heterozygotes ; haploid.
19
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Mendel’s work was unrecognized or ignored until 1900 when the three botansists had arrived at similar conclusions idependently and rediscovered it.
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THE CHROMOSOME THEORY OF INHERITANCE
20
Q
Mendel had predicted that gametes would contain only one allele of each gene instead of two. If chromosomes carry the genes, their numbers should also be ____ by half in the gametes.
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reduced
21
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______ therefore appeared to be the discrete physical entities that carry the genes.
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Chromosomes
22
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__________ the notion that chormosomes carry genes.
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“Chromosome Theory of Inheritance”
23
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Remained skeptical of the chromosome theory idea.
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Thomas Hunt Morgan
24
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Thomas Hunt Morgan, in 1910, he provided the first definitive evidence for the __________
A
chromosome theory
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Thomas Hunt Morgan, worked with the ____ (___________) which is a convenient organism that is small in size, have short generation time and large number of offspring.
fruit fly ; Drosophila melanogaster
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THM...
He mated red-eyed flies (dominant) with white- eyed flies (recessive), most, but not all, of the F1 progeny were _______.
He then mated the red-eyed males of the F1 generation with their red-eyed sisters and they produced about ________
red-eyed ; one-quarter white-eyed males with no white-eyed females.
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The eye color phenotyope was said to be ______ as sex and eye color in the study are transmitted together because the genes governing these characteristics are located on the same chromosome which is the _______
sex- linked ; X chromosome
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Every gene has its place, or _____, on a chromosome. The figure depicts a hypothetical chromosome and the positions of its 3 genes called the ________.
locus ; A, B and C
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Diploid organisms such as human beings normally have _____ of all chromosomes (except ______) which means that they have 2 copies of most genes and the copies can be the same alleles (_______) or different alleles (________)
two copies ; sex chromosomes ; homozygous ; heterozygous
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shows a diploid pair of chromosomes with different alleles at one locus (Aa) and the same alleles at the other two loci (BB and cc) where the genotype or allelic constitution of the organisms with respect to the three genes is AaBBcc.
Because this organism has two different alleles (A and a) in its two chromosomes at the A locus, it is ______ at that locus (Greek: hetero, meaning different).
Since it has the same, dominant B allele in both chromosomes at the B locus, it is _______ at that locus (Greek: homo, meaning same).
And because it has the same, recessive c allele in both chromosomes at the C locus, it is __________ there.
Since the A allele is dominant over the a allele, the phenotype of this organism would be the dominant phenotype at the A and B loci and the recessive phenotype at the C locus.
heterozygous ; homozygous dominant ; homozygous recessive
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Another Morgan’s genetic concept.
Wild Type Vs. Mutant
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a phenotype that is most common or at least the generally accepted standard, phenotype of an organism also called standard type. In the case of Drosophila, red eys and full- size wings are _______
Wild-Type
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the least common type that are a result of mutation. In the case of drosophila, it is white eyes and miniature wings. ______ are usually recessive but not always.
Mutant ; mutant alleles
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Genes on separate chromosomes behave _______ in genetic experiments while genes on the same chromosome (eg. miniature wing and white eye) behave as if they are ______
independently ; linked
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Genes on the same chromosome usually don’t show perfect _____such as in the study of morgan, although white and miniature are both on the X chromosome, they remain linked in offspring only _____ of the time
genetic linkage ; 65.5%
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Other offspring have a new combination of allleles not seen in the parents are called _______
recombinants.
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The recombinants are produced in ______ between the chromosomes that carry the same genes or alleles of the same genes or what is called _______.
crossing over ; homologous chromosomes
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In the case of the drosophila, during formation of eggs in the female, an X chromosome bearing the white and miniature alleles experienced ______ with a chromosome bearing the red eye and normal wing alleles.
crossing over
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Since the crossing-over event occurred between these two genes, it brought together the white and normal wing alleles on one chromosome and the red (normal eye) and miniature alleles on the other. Because it produced a new combination of alleles, we call this process ________
recombination
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Morgan assumed that genes are arranged in a _______ on chromosomes, like beads on a string. With this, together with his awareness of recombination, he proposed that the _______ two genes are on a chromosome, the more likely they are to recombine.
linear fashion ; farther apart
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(PHYSICAL EVIDENCE FOR RECOMBINATION)
______ and _____ provided a direct physical demonstration of recombination in 1931 by examining ______ microscopically where they could detect recombinations between two easily identifiable features of a particular chromosome (a knob at one end and a long extension at the other) so when physical recombination occur, they could also genetically detect recombination.
Barbara McClintock and Harriet Creighton ; maize chromosomes ;
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(physical ev...)
They established a direct relationship between a region of a ______ and a ______.
chromosome ; gene
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Recombination could be detected both ______ and ______ in animals as well as plants
physically and genetically
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What genes are made of or how they work.
MOLECULAR GENETICS
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1869, Friedrich Miescher discovered ______ which is a mixture of compound in the cell nucleus.
nuclein
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_________ the major component
deoxyribunucleic acid (DNA)
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______ - related compound of DNA.
ribonucleic acid (RNA)
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____ and _____ are both long polymers — chains of small compounds called ______.
DNA and RNA ; nucleotide
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Composition of nucleotides are _____, _____ and _____ in which this chain is formed by linking the sugars to one another through their _______
sugar, phosphate group, and a base ; phosphate groups
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(THE COMPOSITION OF GENES)
Geneticists agreed that chromosome must be composed of a polymer of some kind which _____, _____ and _____ was the choices.
DNA, RNA and protein
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_____ was the other major component of Miescher ’s nuclein; its chain is composed of links called ______. The amino acids in protein are joined by ______, so a single protein chain is called a ______.
Protein ; amino acids ; peptide bonds ; polypeptide
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_____ and _____ in 1944 states that DNA is the right choice.
Oswald Avery and his colleagues
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They build on an experiment performed by Frederick Griffith in which he transferred a genetic trait from one strain of bacteria to another. In this case, the trait was ______ which has the ability to cause a lethal infection and it could be transferred simply by mixing dead vriulent cells with a live avirulent (nonlethal) cells.
virulence
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The substance that caused the transformation from avirulence to virulence in the recipient cells was the _______, because the recipient cells passed this trait on to their progeny.
gene for virulence
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Avery and his coworkers did this by applying a number of _____ and ______ to the transforming agent, showing that it had the characteristics of DNA, not of RNA or protein.
chemical and biochemical tests
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________ noticed that the human disease alcaptonuria seemed to behave as a Mendelian recessive trait.
1902, Archibald Garrod
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Garrod believes that the disease was caused by a ______ or _____
defective, or mutant gene.
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The main symptom of ______ was the accumulation of a black pigment in the patient’s urine which he believed derived from the abnormal buildup of an intermediate compound in a biochemical pathway.
alcaptonuria
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Biochemists had shown that all living things carry out countless chemical reactions and that these reactions are accelerated, or catalyzed, by proteins called _____ where many of the reactions take place in _____ so that one chemical product becomes starting material or _____ for the next reaction and that such sequences of reactions are called _____ and the products or substrates within a pathway are called _______.
enzymes ; sequence ; substrate ; pathways ; intermediates
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Garrod postulated that an intermediate accumulated to ________ in alcaptonuria because the enzyme that would normally convert the said intermediate to the next was _____.
abnormally high levels ; defective
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Putting this idea together with the finding that alcaptonuria behaved genetically as a Mendelian recessive trait, Garrod suggested that a defective gene gives rise to a defective enzyme. To put it another way: _____________
“A gene is responsible for the production of an enzyme”
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____ and ____ proved the relationship between genes and enzymes by using the mold _______ as their experimental system which has an enormous advantage over the human being as the subject of genetic experiments.
George Beadle and E.L Tatum ; Neurospora
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They found many instances where they could create neurospora mutants and then pin the defect down to a single step in a biochemical pathway, and therefore to a single enzyme. They did it by adding the ______ that would normally be made by the defective enzyme and showed that it restored normal growth so by circumventing the ______, they discovered where it was.
With that, therefore, a ________
intermediate ; blockade ; defective gene gives defective or absent enzyme.
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A gene seemed to be responsible for making one enzyme thus where the one-gene/one- enzyme hypothesis began but the hypothesis is said to be not quite right for three reasons:
1. An enzyme can be composed of more than one _____, whereas a gene has the information for making only _______.
2. Many genes contain the information for making ______ that are not enzymes.
3. The end products of some genes are not polypeptides, but _______
polypeptide chain ; one polypeptide chain ; polypeptides ; RNAss
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So, the modern restatement for the hypothesis would be: "______________"
Most genes contain the information for making one polypeptide.
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ACTIVITIES OF GENES
Genes do more than one thing.
First, they are ________.
Second, they _____________.
Third, they ______________.
replicated faithfully ; direct the production of RNAs and proteins ; accumulate mutations and so allow evolution
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(HOW GENES ARE REPLICATED)
Watson and Crick proposed that DNA is a ________ - two DNA strands wound around each other. More important, the bases of each strand are on the inside of the helix, and a base on one strand pairs with one on the other in a very specific way.
double heliX
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(HOW GENES ARE REPLICATED)
DNA has four bases: _______, _______, _______, _______ and two strands are complementary A/T, G/C. The ________ is what allows DNA to be replicated faithfully.
Adenine (A), Guanine (G), Cytosine (C), and Thymine (T) ; complementarity
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(HOW GENES ARE REPLICATED)
The two strands come apart, and enzymes build new partners for them using the old strands as templates and following the Watson-Crick base- pairing rules which is called __________ because one strand of the parental double helix is conserved in each of the daughter double helices
semiconservative replication
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__________ proved that DNA replication in bacteria follows semiconservative pathway.
1958, Matthew Meselson and Franklin Stahl
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(HOW GENES DIRECT THE PRODUCTION OF POLYPEPTIDE)
The process by which a cell makes a gene product which is an RNA or a polypeptide.
GENE EXPRESSION
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2 steps required to make a polypeptide from the instructions in a DNA gene: _____ and _______
transcription and translation
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In the __________ step, RNA polymerase makes a copy of one of the DNA strands which is not DNA but its close cousin RNA.
transcription step
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In the _________, the RNA (mRNA) carries the genetic instructions to the cell’s protein factories called _______ which reads the genetic code in the mRNA and put together a protein according to its instructions.
translation step ; ribosomes
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Ribosomes already contain molecules of RNA called ___________
ribosomal RNA (rRNA)
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______ thought that ______ carried the message from the gene.
Francis Crick ; rRNA
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According to the theory, each ______ would be capable of making only one kind of ____ which is the one encoded in its _____.
ribosome ; protein ; rRNA
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_______ and _____ had another idea that the ribosomes are ____________ that can make an unlimited number of different proteins.
Francois Jacob and Sydney Brenner ; nonspecific translation machines
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_______ and ______ cracked the code in the early 1960s where they found that 3 bases constitute a code word, called a _______ that stands for one amino acid.
Marshall Nirenberg and Gobind Khorana ; codon
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The ribosomes scan a messenger RNA 3 bases at a time and bring in the corresponding amino acids to link to the growing polypeptide chain. When they reach a stop signal, they release the __________
completed polypeptide.
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(HOW GENES ACCUMULATE MUTATIONS)
Genes change in a _______ and the simplest is a change of one base to another such as certain codon in a gene is GAG (for the amino acid called glutamate), a change to GTG converts it to a codon for another amino acid, valine so the protein that results from this mutated gene will have valine instead of glutamate.
number of ways
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One change out of hundreds of amino acids but it can have ______
profound effects.
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In fact, this specific change has occurred in the gene for one of the human blood proteins and is responsible for the genetic disorder we call ________
sickle cell disease.
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Genes can suffer more profound changes, such as ________ or ______ of large pieces of DNA. Segments of DNA can even move from one locus to another. The more drastic the change, the more likely that the gene or genes involved will be __________
deletions or insertions ; totally inactivated
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Since the 1970s, geneticists have learned to isolate genes, place them in new organisms, and reproduce them by a set of techniques collectively known as _______
gene cloning
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________ can also be transplanted to plants and animals, including humans.
Cloned genes
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(THE THREE DOMAINS OF LIFE)
Early 20th century, scientists divided all life into 2 kingdoms: _______ and ______ where bacteria were considered plants hence why refered as ________.
animal and plant ; intestinal flora
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Middle of the century, the classification system was abandoned in favor of the 5 kingdom system which includes ______, _______ and ______ in addition to ______ and _____
bacteria, fungi, and protists ; plants and animals.
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late 1970s, ______ performed sequencing studies on the rRNA genes of many different organisms and reached a conclusion: A class of organisms that had been classified as bacteria have rRNA genes that are more similar to those of ______ than they are to those of classical bacteria like E. coli and he named these organisms _______ to distinguish them from true bacteria or eubacteria.
Carl Woese ; eukaryotes ; archaebacteria
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_______ are not really bacteria despite the superficial resemblance. Since they represent a distinct domain of life, Woese changed their name to ______
Archaebacteria ; archaea.
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The three domains of life that are now recognized are _____, ______ and _______
bacteria, eukaryota, and archaea.
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Like bacteria, they are prokaryotes or organisms without nuclei but their molecular biology is actually more like that of eukaryotes than that of bacteria.
ARCHAEA
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They live in most inhospitable regions of the earth.
ARCHAEA
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(ARCHAEA)
______ or _____ that live in seamingly unbearably hot zones at temperatures above 100°C near geothermal vents or in hot sprint such as Yellowstone National Park.
Thermophiles or heat-lovers
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(ARCHAEA)
_____ or ______ where they can tolerate very high salt concentration that would dessicate and kill other forms of life.
Halophiles or halogen-lovers
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(ARCHAEA)
______ or ______ that inhabit environments such as a cow’s stomach, which explains why cows are such a good source of ______.
Methanogens or methane-producers ; methane
