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47 Cards in this Set

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Describe Chromosome duplication and distribution during cell division. (see figure 12.4) Draw the diagram.
1. Before duplication each chromosome has a single DNA molecule.
2. Once duplicated a chromosome consists of two sister chromatids connected at the centromere. Each chromated contains a copy of the DNA molecule
3. Mechanical processes separate the sister chrmatids into two chromosomes and distribute them to two daughter cells.
Familiarize yourself with Mitotic Division-see pages 222-223
Includes Interphase, prophase, prometaphse, metaphase, anaphase, telophase and cytokinesis
What are the four steps of bacterial cell division (binary fission)? See figure 12.11
1. Chromosomes replication begins. Soon thereafter, one copy of the origin moves rapidly toward the other end of the cell.
2. Replications continues. One copy of the origin is now at each end of the cell.
3. Replcation finishes. The plasma membrane grows inward and new cell wall is deposited.
4. Two daughter cells result
How many chromatids are in a duplicated chromosome?
2- if you start with one chromosome when it is duplicated it doubles its self, creating two sister chromatids
Describe the process of cytokinesis and how it differs in animal and plant cells
1. The division of the cytoplasm to form two separate daughter cells immediately after mitosis.
2. In animal cells cytokinesis involves the formation of a cleavage furrow, which pinches the cell in two, while in plant cells cytokinesis involves the cell plate formation.
What phase of the cell cycle are most of your body cells in?
an non-dividing stage called G0
What are nonsister chromatids? Draw and example of homologous chromosomes, sister chromatids and nonsiter chromatids. See figure 13.4
any two chromatids in a pair of homolgous chromosomes that are not sister chromatids.
Describe the human life cycle. See figure 13.5
Multicellular Diploid adults, through meiosis haploid gametes are formed (Women-ovary and Ovum, Men- testis and sperm), then these two gametes are fused through fertilization into a diploid zygote, which goes through mitosis and development. and back to multicellular diploid adults.
Describe how meiosis reduces chromosome number. See figure 13.7
Starting with a homologous pair of chromosomes in diploid parent cell, these chromosomes replicate into homologous pair of replicated chromosomes which is a diploid cell with replicated chromoosmes. This goes through Meiosis I where the homologous chromosomes separate into haploid cells with replicated chromosomes. Then Meiosis II happens and the sister chromatids separate into four haploid cells with unreplicated chromosomes.
Review the Meiotic division of an animal cell
See pages 244-245
How do Mitosis and Meiosis differ in DNA replication, number of division, synapsis of homologous chromosomes, number of daughter cells and genetic composition, and the role in the animal body.
See figure 13.9
In the absence of mutation, asexually reproducing organisms produce offspring that are genetically identical to each other and to their parents. Explain.
Such organisms reproduce by mitosis, which generates offspring whose genomes are virtually exact copies of the parent's genome.
In organisms that reproduce sexually, how similar are the offspring to their parents? Explain.
Offspring resemble their parents but are not genetically identical to them or their siblings because sexual reproduction generates different combinations of genetic information
How does the alternation of meiosis and fertilization in the life cycles of sexually reproducing organisms maintain the normal chromosome for each species.
In meiosis, the chromosome count is reduced from diploid to haploid, the union of two haploid gametes in fertilization restores the diploid chromosome count.
What process (meiosis or mitosis) is more directly involved in the production of gametes in animals? In plants and most fungi?
Meiosis is involved in the production of gametes in animals. Mitosis is involved in the production of gametes in plants and most fungi.
Using the concept of chromosome sets, explain briefly how mitosis conserves chromosome number, whereas meiosis reduces the number of chromosomes by half.
In mitosis, a single replication of the chromosomes is followed by one division of the cell so the number of chromosome sets in daughter cells is the same as in the parent cells. In meiosis, a single replication of the chromosomes is followed by two cell divisions that reduce the number of chromosome sets from two (diploid) to one (haploid)
What are Darwin's two main ideas?
That evolution explains life's unity and diversity and that natural selection is a cause of adaptive evolution
What are the five observations Darwin made of the teory of natural selection?
1. For any species, population sizes would increase exponentially if all individuals that are born reproduced successfully.
2. Nonetheless, populations tend to remain stable in size, except for the seasonal fluctuations.
3. Resources are limited.
4. Members of a populations vary extensively in their characteristics, no two individuals are exactly alike.
5. Much of this variation is heritable.
What are the three inferences based off of the five observations darwin made on natural selection?
1. Production of more individual s than the environment can support leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving each generation.
2. Survival depends in part on inherited traits. Individuals whose inherited traits give them a high probability of surviving and reproducing in a given environment have higher fitness and are likely to leave more offspring than less fit individuals.
3. This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over generations.
What three points summarize Natural Selection?
1. It is the differential success in reproduction among individuals that vary in their heritable traits. These reproductive differences emerge as each individual interacts with its environments.
2. Over time, natural selection can increase the adaptation of organisms to their environment.
3. If an environment changes over time, or if individuals of a particular species move to a new environment, natural selections may result in adaptation to these new conditions, sometimes giving rise to new species in the process.
What is the smallest unit that can evolve?
a population
What type of traits can natural selection amplify or diminish?
Only heritable traits.
Describe how the following concepts relate to Darwin's theory of evolution by natural selection, overreprocudtion of populations, limited resources, and heritable variation.
Species have the potential to produce more offspring than survive (overreprocudtion), leading to a struggle for resources, which are limited. Populations exhibit a range of heritable variations, some of which confer advantages to their bearers that make them more likely to leave more offspring than less well-suited individuals. Over time this natural selection can result in a greater proportion of favorable traits in a population (evolutionary adaptation)
What are the four stages in the origin of life on earth?
1. abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nucleotides.
2. Joing of these small molecules (monomers) into polymers
3. The packaging of these molecules into "probionts"
4. the origin of self-replicating molecules that eventually made inheritance possible
How is life defined?
LIfe is defined partly by two properties: accurate replication and metabolism.
What was the "RNA world"?
the molecular biology of today may have been preceded by an "RNA world" in which small RNA molecules that carried genetic information were able to replicate and to store information about the protobionts that carried them.
What are different types of Radiometric dating?
Carbon dating or Measuring the radioactive isotope potassium-40 (Potassium dating?)
What are the different eons?
Phanerozoic (broken up into Cenozoic, Mesozoic and Paleozoic), Proterozoic and Archaean.
How did eukaryotic cells evolve from the simpler prokaryotic conditions?
A process called endosymbiosis probably led to mitochondria and plastids (general term for chloroplast). Endosymbiont refers to such a cell that lives within another cell, which is called the host cell.
How long did prokaryotes inhabit Earth before eukaryotes evolved?
1.3 billion years
What do fossilized stromatolites suggest about the evolution of prokaryotes?
That prokaryotes must have existed at least 3.5 billion years ago, when the oldest fossilized stromatolites were formed.
The first appearance of free oxygen in the atmosphere must have triggered a massive wave of extinctions among the prokaryotes of the time, why?
Many of the organisms of that period could not live in the anaerobic habitats, the free oxygen attacked their chemical bonds and inhibited enzymes and damaged the cells.
What evidence supports the hypothesis that mitochondria proceeded plastics in the evolution of eukaryotic cells?
All eukaryotes have mitochondria or genetic remnants of these organelles, but not all eukaryotes have plastids (general term for chloroplast)
How is a eukaryotic cell like a chimera?
The chimera of Greek mythology contained parts from different animals. Similarly a eukaryotic cell contains parts from various prokaryotes,: mitochondria from one type of bacteria, plastids from another type and a nuclear genome from parts of the genomes of these endosymbionts and at least one other cell.
HOw does the division of function differ for single-celled and multicellular organisms?
A single-celled organism must carry out all the functions required to stay alive, Most multicellular organisms have many types of specialized cells, and life function are divided among specific cell types.
Which kingdoms in Whittaker's five-kingdom system include organisms now in the domain Eukarya?
Protista, Plantae, Fungi, and Animalia
Why is the kingdom Monera no longer considered a valid taxon?
Monera included both bacteria and archaea, but archaea are more closely related to eukaryotes than to bacteria.
What are the two domains for prokaryotes?
Bacteria and Archaea
Identify and explain at least two examples of adaptations that enable prokaryotes to survive in environments too harsh for other organisms
Adaptations include the capsule (shields prokaryotes from host's immune system), plasmids (confer "contingency" functions such as antibiotic resistance.) and the formation of endospores (enable cells to survive harsh conditions and to revive when the environment becomes favorable.
Contrast the cellular and genomic organization or prokaryotes and eukaryotes
Prokaryotic cells generally lack the internal compartmentalization of eukaryotic cells. Prokaryotic genomes have much less DNA than eukaryotic genomes, and most of this DNA is contained in a single ring-shaped chromosome located in the nucleoid region rather than within a true membrane-bounded nucleus. In addition many prokaryotes also have plasmids, small ring-shaped DNA molecules containing a few genes.
Explain how rapid reproduction allows prokaryotes to adapt to changing environments
Rapid reproduction enables a favorable mutation to spread quickly through a prokaryotic population by natural selection.
A bacterium requires only the amino acid methionine as an organic nutrient and lives in lightness caves. What mode of nutrition does it employ? Explain?
Chemoheterotrophy, the bacterium must rely on chemical sources of energy, since it is not exposed to light, and it must be a Heterotroph if it requires an organic source of carbon rather than Co2
What are the sources of carbon and nitrogen for the cyanobacterium Anabaena?
Anabaena is a photoautotroph that obtains its carbon from CO2. As a nitrogen-fixing prokaryote Anabaena obtains it nitrogen from N2
Explain how molecular systematics has greatly increased our understanding of prokaryotic phylogeny
Before molecular systematics, taxonomists classified prokaryotes according to phenotypic characters that did not clarify evolutionary relationships. Molecular comparisons indicate key divergences in prokaryotic lineages.
What characteristics enable some species of archaea to live in extreme environments.
Their ability to use hydrogen, sulfur and other chemicals as energy sources, and to survive without oxygen.
Although individual prokaryotes may be tiny, they are giants in their collective impact on Earth and its life, explain.
they decompose wastes, recycle chemicals, and provide nutrients to other organisms.
Contrast exotoxins and endotoxins
Exotoxins- are proteins secreted by prokaryotes
Endotoxins- are lipopolysaccharides released from the outer membrane of gram-negative bacteria that have died.