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31 Cards in this Set
- Front
- Back
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What is a Population?
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group of individuals of one species living n a given geographic area
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What is a Genotype?
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actual genetic makeup, or sum total of all alleles carried by an individual
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What is a Phenotype?
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Actual physical expression of genes for a given individual
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What is Natural Selection?
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acts on phenotypes at the individual level withen a population. Is also the differential rates of survival and reproduction. Made possible through heritable variation among indivduals within a population and the tendency for the population to produce more individuals than evironment can support. process of natural selection changes genotype frequencies within a population
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What is Directional selection?
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shifts the frequency of phenotypes in one direction. THis also is most common during periods of environmental change or when a population migrates to a new environment.
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What is Stabilizing Selection?
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Acts against the extreme phenotypes within a population and favors the more common variant.
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What is Disruptive Selection?
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occurs when environmental conditions are varied in a way that favors individuals of both extreme phenotypes over the intermediate phenotypes
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What is Fitness?
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is defined as the difference in reproductive success between individuals or an organism's ability to propagate its genes.
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What is Evolution?
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Changes in genetic composition of a population over time. Darwin termed this "Decent with modification." Evolution occurs very, very slowly in most cases. Natural selection is the mechanism that drives evolution.
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What is Mutation?
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Ultimate source of all genetic variation. However, most mutations are either neutral or delterious(Bad) and reduce the fitness of the organism. Occasionally a mutation occurs that is beneficial and increases the fitness of the individual.
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What is Adaptation?
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The change in structur of function over time of an organism or any of its parts that result from natural selection and by which the organism becomes better suited to survive and reproduce in its environment
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What are the 3 major components of the theory of evolution?
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Principle of variation, Principle of heredity, and Principle of selection.
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What is the Principle of variation?
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Among individuals within any population, there is variation in morphology, physiology, and behavior.
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What is Principle of heredity?
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Alleles are passed on from parents to offspring. In diploid organisms one allele for each gene is obtained from each parent. In haploid organisms, such as bacteria that reproduce through binary fussion, the offspring only has one parent and thus only inherits one gene. A good way to remember this is that offspring resemble their parent more than they resemble unrelated individuals.
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What is the Principle of Selection?
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Some individuals are more successful at surviving and reproducing than other forms in a given environment. Individuals that are well suited to their environment will have higher survival and reproduction.
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What is DNA (deoxyribonucleic acid)
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The molecule that encodes genetic information. DNA is a double-stranded molecule held together by weak bonds between base pairs of nucleotides. The four nucleotides in DNA contain the bases: adenine (A) guanine (G) cytosine(C) and thymine(T) In nature, base pairs form only between A and T and between G and C; thus the base sequence of each single strand can be deduced from that of its partner.
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What is a GENE?
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The fundeamental physical and functional unit of heredity. A gene is an ordered sequence of nucleotides located in a particular chromosome that encodes a specific functional product. (protein or RNA molecule)
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What is a Chromosome?
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The self-replicating genetic structure of cells containing the cellular DNA that vears in its nucleotide sequence the linear aray of genes. Eukaryotic genomes consist ofa number of chromosomes whose DNA is associated with different kinds of proteins.
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What is a Chromatid?
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One of the daughter strands of a chromosome that has recently been copied (during mitosis or meiosis), and which is still connected to the other daughter strand. Upon separation from each other, the chromatids become chromosomes.
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What is a Chromatin?
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Mass of genetic material composed of DNA and proteins that condense to form chromosomes in eukaryotic cell dividion. Chromatin is located in the cell's nucleus.
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What is Centromere?
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A specialized chromosome region to which spindle fibers attach during cell division.
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What is Centrosome?
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A small region of cytoplasm adjacent to the nucleus that contains the centroles and serves to organize microtubles.
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What is a Centriole?
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A short cylindrical organelle, found in pairs arranged at right angles to each other at the centre of the microtublule organizing centre(MTOC)or centrosome, found in eukaryotes(except in higher plants). The centrosome organizes formation of a spindle during mitosis or meiosis
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What is Spindle Fibers?
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Microtubular structures that extend from the centrioles and attach to the centromere of a chromosome during mitosis and meiosis.
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What is the Metaphase Plate?
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An imaginary plane perpendicular to the spindle fibers of a dividing cell, along which chromosomes align during mitiosis and meiosis
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What are Holologous chromosomes?
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A pair of chromosomes containing sequences for the same genes, each deprived from one parent
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What is a Tetrad?
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A four-part structure that forms during the prophase of meiosis and consists of two homologous chromosomes, each of two sister chromatids
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What is a Dyad?
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One pair of homologous chromosomes resulting from the division of a tetrad during meiosis
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What is a Haploid?
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A single set of chromosomes (half the full set of genetic material), present in the egg and sperm cells of animals and in the eg and pollen cells of plants. Human beings have 23 chromosomes in their reproductive cells.
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What is Diploid?
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A full set of genetic material, consisting of paired chromosomes one chromosome from each parental set. Most animal cells except the gametes have a diploid set of chromosomes. The diploid human genome has 46 chromosomes.
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What is a Gamete?
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Mature male or female reproductive cell(sperm or ovum)with a haploid set of chromosomes(23 for humans)
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