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| transmission of traits from one generation to the next, also known as inheritance |
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| non-identical copies of offspring |
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| scientific study of heredity and hereditary variation |
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| hereditary units of coded information |
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| all cells of the body excluding sex cells |
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| a gene's specific location along the length of a chromosome |
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| a single individual is the sole parent and passes copies of all its genes to its offspring without fusion of gametes |
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| group of genetically identical individuals, products of asexual reproduction |
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| two parents give rise to offspring that have a unique combination of genes from the two parents; produces genetic variation |
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| the generation-to-generation sequence of stages in the reproductive history of an organism, from conception to the production of its own offspring |
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| images of an ordered display of chromosomes arranged in pairs, starting form the longest chromosomes |
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| two chromosomes composing a pair that have the same length, centromere position, and staining pattern |
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| chromosomes that determine an individual's sex (X and Y chromosomes) |
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| chromosomes that have to relationship to determining an individual's sex |
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| any cell with two chromosome sets (2n); somatic cells |
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| any cell with a single set of chromosomes (n); gametes |
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| union of gametes, resulting in the fusion of their nuclei |
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| a fertilized egg that is diploid; bears genes representing maternal and paternal family lines |
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| gamete formation in sexually reproducing organisms; only occurs in germ cells in animals and produces haploid cells |
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| paired homologs become physically connected to each other, occurs in meiosis I (prophase I) |
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Definition
| genetic rearrangement between sister chromatids involving the exchange of corresponding segments of DNA molecules (prophase I); homologous chromosomes in prophase I exchange corresponding segments of maternal and paternal chromatids (portions of two nonsister chromatids trade places each time a crossover occurs) |
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| X-shaped regions that exist at point where cross over has occured |
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| Three events unique to meiosis |
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Definition
1. Synapsis and crossing over - duplicated homologs pair up and the formation of the synaptonemal complex between them holds them in synapsis
2. Homologous pairs at the metaphase plate - chromosomes in homologous pairs line up at the metaphase plate instead of individual chromosomes
3. Separation of homologs - At anaphase I of meioisis, duplicated chromosomes of each homologous pair move toward opposite poles, but the sister chromatids of each duplicated chromosome remain attached (in anaphase of mitosis, sister chromatids separate) |
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Definition
| each homologous pair may orient the maternal or paternal homolog closer to either pole; this random orientation gives each homolog an equal chance of going into either cell |
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| individual chromosomes that carry genes derived from two different parents that are not exclusively from one parent or the other because of crossing over |
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| random nature of fertilization adds to genetic variation; male gametes and female gametes can produce any of about 70 trillion diploid combinations, and with variation brought in by crossing over the number is astronomical |
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| chromosome theory of inheritance |
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Definition
| Mendelian genes have specific loci (positions) along chromosomes, and it is the chromosomes that undergo segregation and independent assortment |
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Definition
The two alleles for each gene separate during gamete formation
1. alleles separate at anaphase I, yielding two types of daughter cells
2. each gamete gets one chromosome with either allele
3. fertilization recombines alleles at random |
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Term
| Law of Independent Assortment |
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Definition
alleles of genes on nonhomologous chromosomes assort independently during gamete formation
1. Alleles at both loci segregate in anaphase I, yielding four types of daughter cells, depending on the chromosome arrangement at metaphase I
2. Each gamete gets a long and a short chromosome in one of four allele combinations |
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Definition
| phenotype for a character most commonly observed in natural populations (red eyes) |
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| traits that are alternative to the wild type, named so because they are due to alleles assumed to have originated as changes, or mutations, in the wild-type allele (white eyes) |
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| gene located on either sex chromosome |
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| those located on Y chromosome are passed along from fathers to sons nearly intact |
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| human X chromosome contains nearly 1,100 of these genes |
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| genes located near each other on the same chromosome that tend to be inherited together in genetic crosses |
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| production of offspring with combinations of traits that differ from those found in either parent |
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| a phenotype that matches the parental (P) generation phenotypes |
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| also called recombinants, two nonparental phenotypes found in offspring |
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| an ordered list of the genetic loci along a particular chromosome |
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| a genetic map based on recombination frequencies |
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| distances between genes, one map unit equivalent to a 1% recombination frequency (can have a max of 50%, or else they're considered basically on another gene they're so unrelated) |
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Definition
| mishap in meiotic spindle distributing chromosomes; in these cases, one gamete receives two chromosome of the same type and another receives no copy; other chromosomes usually distributed normally |
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Definition
| abnormal number of a particular chromosome |
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| fertilization with a gamete that has received no copy of a chromosome leads a zygote to be monosomic for that chromosome |
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Definition
| fertilization with a gamete that has a chromosome in triplicate leads a zygote to be trisomic for that chromosome |
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| some organisms having more than two complete chromosome sets in all somatic cells; triploidy (3n) and tetraploidy (4n) falls under this |
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Definition
| occurs when a chromosomal fragment is lost; the affected chromosome is now missing certain genes (if the centromere is deleted, the entire chromosome will be lost) |
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Definition
| a deleted fragment becoming attached as an extra segment to a sister chromatid; repeats a segment |
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Definition
| a chromosomal fragment reverses the order of a segment in a chromosome; reattaches to the original chromosome but in reverse orientation |
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Definition
| a fragment joins a nonhomologous chromosome; reciprocal tramslocation involves two segments from nonhomologous chromosomes trading places |
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| result of an extra chromosome 21; also called trisomy 31 |
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| a process by which a DNA molecule is copied and how cells repair their damaged DNA |
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| a change in genotype and phenotype due to the assimilation of external DNA by a cell; seen in mixing dead pathogenic bacteria with live cells which caused live cells to become pathogenic |
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Definition
| also called "phages" for short; a virus that infects bacteria |
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Definition
| DNA (sometimes RNA) enclosed in a protective coat, which is often just protein; to reproduce they must infect living cells and take over the cell's metabolic machinery |
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Definition
| two strand structure in DNA |
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Definition
| the subunits that make up sugar phosphate backbones run in opposite directions |
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Definition
| when a double helix replicates, each of the two daughter molecules will have one old strand and one new strand (the parental molecule is partially conserved) |
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Definition
| replication of a DNA molecule begins at particular sites called origins of replication which are short stretches of DNA having a specific sequence of nucleotides; this opens up a replication "bubble." |
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Definition
| at the end of a replication bubble is this Y-shaped region where parental strands of DNA are being unwound |
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Definition
| enzymes that untwist the double helix at the replication forks, separating the two parental strands and making them available as template strands |
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| Single-strand binding proteins |
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Definition
| bind to the unpaired DNA strands and keep them from re-pairing |
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Definition
| since untwisting proteins causes tighter twist and strain ahead of replication fork, this enzyme helps relieve this strain by breaking, swiveling and rejoining DNA strands |
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Definition
| initial RNA nucleotide chain that is produced during DNA synthesis |
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Definition
| synthesizes primer, starting a complementary RNA chain from a single RNA nucleotide; adds RNA nucleotides one at a time, using the parental DNA strand as a template |
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Definition
| enzymes that catalyze the synthesis of new DNA by adding nucleotides to a preexisting chain |
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Definition
| elongates continuously towards 3' end |
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Definition
| synthesized discontinuously in a series of fragments, going in 3' direction towards 5' end |
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| segments of a lagging strand |
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Definition
| joins sugar-phosphate backbones of Okazaki fragments into a continuous DNA strand |
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Definition
| other enzymes remove and replaced incorrectly paired nucleotides that have resulted from replication errors; defects in these enzymes lead to cancer-causing errors to accumulate quickly in DNA |
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Definition
| DNA-cutting enzyme that cuts out segments of DNA strands that contain damage, which allow a DNA polymerase and DNA ligase to fill the gap |
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Term
| Nucleotide excision repair |
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Definition
| DNA repair system; repairs enzymes in our skin cells to prevent covalent linking of thymine bases (thymine dimers) which cause the DNA to buckle and increase skin cancer chances |
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Term
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Definition
| located at the end of DNA and do not contain genes; instead it is multiple repetitions of nucleotide sequence (in humans it is TTAGGG); acts as a buffer and postpones erosion of genes located near the ends of DNA molecules |
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Definition
| catalyzes the lengthening of telomeres in eukaryotic germ cells; it is not active in most human somatic cells, but its activity in germ cells results in telomeres of maximum length in the zygote |
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| the process by which DNA directs the synthesis of proteins; includes two stages, transcription and translation |
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Definition
| synthesis of RNA using information on DNA; rewriting DNA into an RNA format (the general term for the synthesis of any kind of RNA on a DNA template) |
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Term
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Definition
| serves as a template for assembling a complementary sequence of RNA nucleotides; carries a genetic message from the DNA to the protein-synthesizing machinery of the cell. |
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Definition
| the synthesis of a polypeptide using the information in mRNA |
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Term
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Definition
| sites of translation that facilitate the orderly linking of amino acids into polypeptide chains |
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Definition
| initial RNA transcript from any gene that is not translated into a protein |
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Term
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Definition
| genetic instructions for a polypeptide chain are written in DNA as a series of nonoverlapping, three-nucleotide words |
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Definition
| only one of two DNA strands is transcribed and this one provides the pattern, or template, for the sequence of nucleotides in an RNA transcript; for any given gene, the same strand is used as a template every time the gene is transcribed |
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Term
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Definition
| mRNA nucleotide triplets, customarily written in a 5'->3' direction |
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Definition
| reading the symbols in the correct groupings, which codes for the correct peptides |
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Term
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Definition
| pries two strands of DNA apart and joins together RNA nucleotides complementary to the DNA template strand, thus elongating the RNA polynucleotide |
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Definition
| the DNA sequence where RNA polymerase attaches and initiates transcription |
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Definition
| DNA sequence that signals the end of transcription |
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| stretch of DNA that is transcribed into an RNA molecule |
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Definition
| contained within the promoter of a gene that states where the RNA synthesis actually begins |
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Definition
| a collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription |
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| Transcription initiation complex |
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Definition
| bound to complex of transcription factors and RNA polymerase II |
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Definition
| both ends of the primary transcript are altered in the eukaryotic nucleus before the genetic messages are dispatched to the cytoplasm; in most cases certain interior sections of the RNA molecule are cut out and the remaining parts are spliced together |
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Definition
| modified form of guanine nucleotide added onto the 5' end after transcription of the first 20-40 nucleotides |
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Definition
| 50-250 adenine nucleotides added to the 3' end |
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Definition
| removal of large portions of the RNA molecule that is initially synthesized, then splicing the remaining segments together |
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Definition
| noncoding segments of nucleic acid that lie between coding regions, intervening sequences |
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Definition
| regions of nucleic acid that are eventually expressed, usually by being translated into amino acid sequences |
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Definition
| several small nuclear ribonucleoproteins (snRNPs) joined together along with additional proteins; interacts with certain sites along an intron, releasing the intron, which is rapidly degraded, and joining together exons that flank the intron |
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Definition
| RNA molecules that function as enzymes |
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Definition
| many genes are known to give rise to two or more different polypeptides, depending on which segments are treated as exons during RNA processing |
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Definition
| discrete structural and functional regions in the modular architecture of proteins |
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