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Ch. 11 bio
zzch. 11
| Word | Definition |
|---|---|
| genetics | the scientific study of heredity |
| fertilization | the process where male and female reproductive cells join. Produces ONE new cell. |
| true-breeding | if the plants were allowed to self pollinate they would produce offspring identical to themselves |
| trait | specific characteristic |
| hybrid | offspring with crosses between parents with different traits |
| genes | chemical factors that determine traits |
| alleles | different forms of a gene |
| segregation | separation |
| gametes | sex cells |
| probability | likely hood that a particular event will occur |
| Punnette Square | a diagram that can determine the gene combinations that may result from a genetic cross |
| homozygous | organisms that have two identical alleles for a particular trait |
| heterozygous | organisms that have two different alleles for the same trait |
| phenotype | physical characteristics |
| genotype | genetic makeup |
| independent assortment | genes for different traits can segregate independently during the formation of gametes |
| incomplete dominance | when an allele is not completely dominant over another |
| codominance | both alleles contribute to the phenotype |
| multiple alleles | when genes have more than two alleles |
| polygenic traits | traits controlled by two or more genes |
| homologous | each of the four chromosomes that came from the male parent has a corresponding chromosome form the female parent |
| diploid | two sets |
| haploid | one set |
| meiosis | process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell |
| tetrad | a structure that forms when a chromosome pairs with its corresponding homologous chromosome |
| crossing over | the exchange of alleles between homologous chromosomes and produces new combinations of alleles |
| gene map | map that shows the reletive locations of each known gene on one of the drosophila chromosomes |
| how many pea plant traits did mendal study? | 7 |
| After Mendals' first experiment what was his next wuestion | had the recessive alleles disappear or were they still present in the F1 plants |
| what % of the recessive traits re-appeared | 25% |
| independent assortment accounts for | the many genetic variations observed in plants, animals, and other organisms |
| Mendel's Principle 1: | The inheritance of biological characteristics is determined by individual units known as genes. Genes are passed from parents to their off spring |
| Mendel's Principle 2: | In cases in which two or more forms (alleles) of the gene for a single trait exists some forms of the gene may be dominant and others may be recessive. |
| Mendel's Principle 3: | In most sexually reproducing organisms each adult has tow copies of each genes -one from each parent. These genes are separated from each other when gametes are formed. |
| Mendel's Principle 4: | the alleles for different genes usually separate independently of one another |
| Exeptions to Mendel's Principles | some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or genes |
| Where are genes? | They are located on chromosomes in the nucleus |
| Mendel's Principles of genetics require at least these two things: | 1. Each organism must inherit a single copy from each of its parents. 2. When an organism produces its own gametes those two sets of genes must be separated from each other so that each gamete contains only one set of genes. |
| by the end of meiosis 2 | the diploid cell that entered meiosis has become four haploid cells |
| meiosis 1:::Prophase 1 | 1. Chromosomes become visible. 2. crossing over occurs. 3. nucleolus disappears. 4. The meiotic spindle forms. 5. Nuclear envelope disappears. |
| meiosis 1:::Metaphase 1 | Pairs of chromosomes become arranged on the metaphase plate and are attached to the now fully formed meiotic spindle |
| meiosis 1:::Anaphase 1 | The two chromosomes in each tetrad separate and migrate to opposite poles. A key difference between mitosis and meiosis is that sister chromatids remain joined after metaphase in meiosis where as in mitosis they separate. |
| meiosis 1:::Telophase 1 | The homologous chromosome pairs reach the poles of the cells, nuclear envelopes form around them, and cytokinesis follows to produce two cells. |
| What happens at the end of telophase 1? | There is a haploid set of chromosomes at each pole, with each chromosome still having two chromatids |
| meiosis 2:::Metaphase 2 | one of two identical sister parts of a duplicated chromosome |
| meiosis 2:::Prophase 2 | Nuclear envelopes dissolve and spindle fibers form. Everything else is the same as in prophase in mitosis. |
| meiosis 2:::Anaphase 2 | The paired chromatids separate and move to opposite ends of the cell |
| In male animals the haploid gametes produced by meiosis are called: | Sperm |
| In female animals the gamete is called: | Egg |
| Mitosis produces: | two genetically identical diploid cells |
| Meiosis Produces: | four genetically different haploid cells |