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Patho
Genetic process and alterations
| Question | Answer |
|---|---|
| The Cell cycle 2 phases Interphase Mitosis | Interphase: Normal cellular fxing Mitosis: reproductive phase where 2 exact daughter cells produced |
| Interphase | 2 gap phases and synthesis phase synthesis phase: where DNA is duplicated |
| Chromatin | uncoiled strands of DNA found in interphase |
| prep for mitosis starts with synthesis of DNA | replicated in synthesis phase then coiled around histones to form chromosomes. DNA is seen as chromosomes in Mitosis and meiosis |
| Centromere | joins two chromatids in center. Landmark to id one chromosome from another. location can chagne. Chromatids: two duplicate strands of DNA to form chromosome. One will move to each daughter cell. |
| 4 phases of mitosis | prophase, metaphase, anaphase, telophase |
| Mitosis | cellular division. By first phase, all organelles and dna have been duplicated |
| prophase | nuclear env disappears, spindle fibers form and attach at chromosomes at centromeres |
| metaphase | chromosomes align at equatorial plate by centromeres. Easiest to id by microscope in this phase |
| anaphase | centromeres split to make separate chromatids and spindle fibers pull them to opp poles of ea cell |
| telophase | new nuclear membranes form around ea set of 46 chromatids now known as chromosomes. They uncoil to form chromotin and cytokinesis occurs producing 2 daughter cells ea with diploid number of 46 chromatin strands |
| Meiosis Haploid number | process done only in reproductive organs Haploid: produces gametes resulting in half of number of chromosomes 23 from mother, 23 from father |
| two cellular divisions | Meiosis I: reduction to haploid number Meiosis II: divide like mitosis |
| phases of meiosis I phases of Meiosis II | I: pro, meta, ana, telo II: meta, ana, telo |
| Meiosis I, reduction phase | sister chromosomes align (mom 1 with dad 1), crossing over happens, centromeres don't split just the pairs of chromosomes |
| What is crossing over | exchange of genetic material in sister chromosomes (mom1 and dad1) |
| By end of Meiosis I | two daughter cells produced with ea 23 chromosomes |
| Beginning of Meiosis II, mototic division | mitotic division results of 4 gametes ea w/ 23 chromosomes |
| gene | seq of DNA in chromosome that codes for specific protein or specific piece of genetic info |
| locus | position along chromosome that spec. gene is located |
| allele | diff forms of genes on same gene locus, eye or hair color |
| codon (triplet codon) | seq. of three nucleic acid bases that code for spec amino acid. 20 diff aa |
| karyotype | ordered display of chromosomes |
| DNA | genetic code 4 necleic acids: adenine, thymine, cytosine, guanine replication by enzyme DNA polymerase |
| Altered genetic process | mutations aneuploidy altered chromosomal structure |
| mutation | probelms wtih genes not chromosomes, a segment of DNA that codes for a protein. Alteration in DNA seq and occurs during DNA replication in S phase before cell division. mutated DNA can be passed onto daughter cells or offspring in gametes |
| types of mutation: base pair or frameshift | base pair: replacement of single base pair by diff base pair frameshift mutation: 1 or more base pairs inserted or deleted from DNA seq |
| Aneuploidy euploid | cells with multiples of normal number of chromosomes haploid: 23 normal gamete diploid: 46 normal somatic cell |
| polyploidy | abn cells contain multiples of euploid number (3x: triploid fetus: 69 or 4x: tetraplid fetus: 92) Cannot survive |
| aneuploid | Can survive, do not contain euploid no. |
| polysomy trisomy monosomy | p: extra copies of chromosomes t: 1 extra copy of chrom m: only 1 copy of chrom, usually not survive EXCEPT with female inf. w/ monosomy of X chrom |
| Cause of aneuploidy | nondisjuntion: failure of separation of chromosomes during cellular reprod. In meitotic div = gametes w/ abn no. of chrom(aneuploidy). Duplication is more survivable than deletion of genetic mat. |
| Mosaic Aneuploidy | special case where duplication or deletion of genetic matierial is not present in all cells May be result of nondisjx during mitotic div after fertilization |
| example of autosomal aneuploidy | trisomy 21 (Down's syndrome), incr with maternal age 13 or 18 tend to die |
| features of trisomy 21` | low nasal bridge, low set ears, simian creases, epicanthal folds, protruding tongue, mental retardation, cardiac defects |
| Ex of Aneuploidy of sex chromosomes | Turner Syndrome: 45 chromosomes with monosomy of X (monosomy) Klinefelter syndrome: extra X chrom, 47 XXY |
| Types of altered structure | deletions, duplications, inversions, translocations Can happen in crossing over phase, not always. Silent passed to children and loss of genetic material usually ends in death |
| Ex of chromosomal deletion | Cri du chat syndrome: deletion of short arm of chrom 5 high pitched cry, low birth wt, microcephaly, cardiac defects, severe mental retardation |
| Patterns that genetic inheritance and how alterations are transferred to offspring | not all inherited from parents Homozygous: 2 alleles from mom/dad r identical(ex: both genes code for blue eyes, AA) Heterozygous: 2 alleles not identical (Aa). One is dominant A, other recessive a. Can express dominant and carry recessive |
| genotype phenotype | g: actual genetic code in DNA p: appearance or fx of individual. Can be influenced by env, not all predetermined by genetic structure |
| Ex of environmental influence of phenotype | phenylketonuria (PKU): inborn error of metabolism, lacks ability to metabolize phenylalanine. On long arm of chrom 12. Both recessive genes severe, but reduced with dietary restriction, so phenotypic expression is influenced |
| 4 main patterns of genetic inheritance | autosomal dominant autosomal recessive x-linked dominant x-linked recessive |
| autosomal dominant transmission Dd affected x Dd affected Dd Affected x dd normal | Affected: DD, Dd, Dd Normal: dd Affected: Dd, Dd Normal: dd, dd |
| Common autosomal dominant disorders | marfan syndrome, connective tissue weakness, fibrilin, risk for aorta tear neurofibromatosis Huntington's disease, Chorea, progressive dementia |
| Autosomal recessive transmission Dd x Dd | homo DD normal, hetero Dd carrier, Dd hetero carrier, dd homo affected |
| Ex. autosomal recessive inheritance | cystic fibrosis Most common mutation: Delta 508 from deletion of triplet code for phenylalinine phenylketoniuria Tay-sachs disease: fat cells sickle cell: hemoglobin molecules |
| Ex. X-linked dominant inheritance | hypophasphatemic rickets: defective protein in kidney, decr phosphate |
| X-Linked Recessive transmission XHXh x XHY XHXH x XhY XHXh x XhY | more common affected: XhY, carrierXHXh, norm XHXH, XHY aff: none, carrier XHXh, XHXh, norm XHY aff: XhXh, XhY, carrier XHXh, norm XHY |
| Ex. X-linked Recessive inheritance | Duchenne Muscular Dystrophy absent protein dystrophin which maintains structural integrity so get muscle wasting |
| Other X-linked Recessive disorders | Hemophilia A Glucose-6-Phosphate Dehydrogenase deficiency (G6PD) Agammaglobulinemia color blindness |
| What is threshold of liability | no of defective alleles need to be present for disorder to be phenotypically expressed, may differ with gender |
| What is the human genome project | Determines location of many genes that code for disorders. It maps specific genes to spec disorders. Gene therapy is experimental, not very successful. |
Created by:
palmerag
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