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Concept Dis. Ch 3
Chromosomes, Genes & Cell Division
| Question | Answer |
|---|---|
| activities of cells controlled by | chromosomes present in nucleus |
| chromosomes exist in pairs in all | somatic cells |
| genome is ___ for every cell within an individual | identical |
| ___ chromosome in females will differ randomly from cell to cell | inactive X |
| types of cells that do not divide | nerve, skeletal, & cardiac |
| spermatogenesis is ___ | continuous |
| spermatogenesis produces more ___ cells from each precursor | useful |
| recessive gene can only be expressed through | a heterozygous pairing |
| HLA haplotypes combine in such a way that ___ are possible for any combination of 2 parents | 4 separate pairings |
| diseases caused by a failure of mitochondrial DNA are | usually transmitted from the mother |
| Gene therapy typically uses a virus to | introduce desirable genetic material into the patient |
| practice of inserting genetic material into bacterium/yeast to synthesize desired pharmaceutical products is called | recombinant DNA technology, genetic engineering &/or gene splicing |
| somatic cells are | cells other than those giving rise to eggs/sperm |
| one member of each paired chromosome is derived from | the male and female parent, respectively |
| homologous chromosomes | matched pair of chromosomes, derived from each parent |
| in humans the normal chromosome component is | 22 pairs of autosomes |
| autosomes | chromosome other than a sex chromosome |
| sex chromosomes | X & Y chromosomes that determine genetic sex |
| genes | units of inheritance & segments of DNA chain determining some property of the cell |
| genes are arranged along the chromosome like | "beads on a string" |
| sum total of all the genes contained in a cell's chromosomes, & is same for all cells, is | its genome |
| genes sometimes code for | specific enzymes/other proteins need for cell function |
| genes are also known to code so that they | can act as regulators controlling activities of neighboring genes |
| gene product | protein/enzyme specified (coded) by a gene |
| only a small % of total DNA in genome consists of | genes |
| it is not yet known the functions of DNA remaining, which are | interspaced between genes |
| exons | part of chromosome DNA chain coded for specific protein/enzyme |
| intron | non coding part of chromosomal DNA chain |
| when makes gene product both exons & introns are | transcribed |
| removed from cytoplasm, when making gene product, before RNA leaves nucleus | introns |
| only coding sequences that specify ___ to be constructed delivered to ribosomes by mRNA | protein |
| genes expressed in given cell determine | both its structure & function |
| Human Genome Project | international collaboration of scientists who mapped nucleotide sequence of entire human genome |
| genomics | study of gene structure |
| attempts to correlate structure of genes with effects of genes on individual | genomics |
| gene expression | process, or regulation of process, by which effects of a gene are manifested |
| single nucleotide polymorphism (SNP) | genetic polymorphism between 2 genomes that based on deletion/insertion/exchange of single nucleotide |
| SNPs are pronounced as | "snips" |
| may effect how genes function | single nucleotide variation |
| sex cells of normal female contain | two X chromosomes |
| sex cells of normal male contain | 1X and 1Y chromosome |
| female sex cells function as though they contain | genetic material equivalent to 1 X chromosome |
| genetic activity of both X chromosomes, in a female, is only essential | during first wk of embryonic development |
| inactivated X chromosome appears as a small mass of chromatin attached to | nuclear membrane of somatic cells |
| Barr body | inactivate X chromosome applied to nuclear membrane in female |
| also called sex chromatin body | Barr body |
| Lyon hypothesis | X-chromosomes in excess of 1 inactivated on random basis at an early stage of embryonic life, leading to mosaicism for X linked genes in female, since paternal X chromosome inactivated in some cells & maternal 1 in remainder |
| mosaicism | presence in an individual of two or more cell lines that are karyotypically or genotypically distinct and are derived from a single zygote |
| combination of staining & ultraviolet light makes it possible to determine | X & Y chromosomes composition of intact cells |
| during process of staining, cells of normal male posses | florescent spot but lack sex chromatin body |
| during process of staining, cells of normal female posses | sex chromatin body but lack florescent spot |
| cell division in which chromosomes duplicated in daughter cells are identical to those in parent cell | mitosis |
| characteristic cell division found in all cells of human body except | in gametes |
| meiosis | special type cell division occurring in gametes in which # chromosomes reduced by 1/2 in ovum & sperm |
| gametogenesis | development of mature eggs & sperm from precursor cells |
| daughter cell | cell resulting from division of single cell (called parent cell) |
| mitosis is characteristic of all___ however not all mature cells are able to divide | somatic cells |
| divide as needed to replace lost/damaged cells, or to heal an injury | liver & connective tissues cells |
| rate of cell division is controlled closely to match body's need and | excess cells are not normally produced |
| growth factors | soluble growth promoting substance produced by cells attached to receptors on cell membrane of other cells |
| activates receptors & initiates events leading to growth/division of target cells | growth factors |
| depending on biochemical signals sent to "machinery" inside cell it will either | grow & divide or growth is inhibited |
| cells are programmed to undergo ____ number of cell division and then they die | a limited |
| chromatids | one of two newly formed chromosomes held together by centromere |
| the process by which chromatids separate | mitosis |
| each chromosome duplicates itself before cell division, so in a somatic cell just before cell division | there are actually 96 chromosomes |
| when chromosomes shorten during cell division, term chromatid is applied to | still-joined chromosomes |
| as soon as chromatids separate they are | called chromosomes again |
| during prophase each chromosome | thickens & shortens |
| centrioles migrate to opposite poles of cell forming mitotic spindle during | prophase |
| mitotic spindle consists of | small fibers radiating in all directions from centrioles |
| some of the ____ attach to chromatids during prophase | mitotic spindle fibers |
| the nuclear membrane breaks down towards | the end of prophase |
| during metaphase the chromosomes | line up in the middle of the cell |
| during metaphase, chromatids are partially separated but still remained joined | at the centromere |
| centromere | structure that joins each pair of chromatids formed by chromosome duplication |
| site where spindle fibers are attached during metaphase | centromere |
| chromatids constituting each chromosome separate & are pulled to opposite poles of cell by spindle fibers during | anaphase |
| nuclear membranes of 2 daughter cells reform & cytoplasm divides forming 2 daughter cells during | telophase |
| synapse | paring of homologous chromosomes in meiosis |
| crossover | interchanging of genetic material between homologous chromosomes during synapse & meiosis |
| pairing of homologous chromosomes & interchange of genetic material during prophase is the characteristic feature of | meiosis |
| in female, 2 X chromosomes synapse in same way | as autosomes |
| in male, X & Y chromosomes synapse | end to end & do not exchange segments |
| each daughter cell created during meiosis contains only one member of | each homologous pair of chromosomes & chromosomes are not exact duplicates of parent |
| during 2nd meiotic division | 2 chromatids composing each chromosome separate, 2 daughters formed each containing 1/2 of normal # of chromosomes |
| 1st meiotic division daughter cells receive | 23 chromosomes |
| 2nd meiotic division daughter cells receive | 23 chromosomes because 2nd division is similar to mitotic division |
| gonads | testes & ovaries |
| contain precursor cells/germ cells capable of developing into | mature sperm/ova |
| mature germ cells are called | gametes |
| gametogenesis | process by which gametes are formed |
| spermatogenesis | process by which sperm form |
| oogenesis | process by which ova form |
| spermatogonia | precursor cells in testicular tubules |
| singular term for spermatogonia | spermatogonium |
| each spermatogonium contains | 46 chromosomes |
| spermatogonia divide by mitosis to form | spermatocytes |
| spermatocytes contain ___ chromosomes | 46 |
| primary spermatocytes divide by | meiosis |
| spermatids | germ cells in late stage of sperm development just before complete maturation to form mature sperm |
| after 1st meiotic division two 2ndary spermatocytes divide by 2nd meiotic div. forming | 2 spermatids containing 23 chromosomes |
| entire process of spermatogenesis takes | about 2 months |
| sperm are produced | continually |
| precursor cells of ova are called | oogonia |
| singular term for oogonia is | oogonium |
| each oogonia contains 46 chromosomes & continually divide in fetal ovaries before birth into | oocytes containing 46 chromosomes |
| oocytes become surrounded by | granulosa cells |
| granulosa cells | cells lining ovarian follicle |
| primary oocytes in follicles begin prophase of 1st meiotic division during fetal life but do not | follow the division through to completion |
| large number of primary follicles are formed, but many | degenerate during infancy & early childhood |
| cyclic ovulation begins under influence of | pituitary gonadotrophic hormones, follicle-stimulating hormone & luteinizing hormone |
| when oocyte is discharged it completes | its first meiotic division, giving rise to 2 daughter cells-unequal in size |
| after oocyte completes 1st meiotic division one daughter cell | receives 1/2 of chromosomes & almost all of cytoplasm |
| daughter cell receiving 1/2 of chromosomes & almost all of cytoplasm is called | secondary oocyte |
| daughter cell receiving 1/2 of chromosomes & almost none of cytoplasm is called | first polar body |
| first polar body is | discarded |
| 2ndary oocyte begin 2nd meiotic division leading to | formation of mature ovum & 2nd polar body - each containing 23 chromosomes |
| unless ovum is fertilized | meiotic division is not completed |
| each precursor cell, in spermatogenesis, produces | four spermatozoa |
| each precursor cell, in oogenesis, produces | one ovum |
| oocytes are not produced continually; all oocytes present in ovaries were | formed before birth |
| oocytes remain in a prolonged | prophase of meiotic division from fetal life until ovulated |
| presence of abnormalities in chromosome number/structure can be detected by | culturing cells in suitable medium |
| in order to study chromosomes, lymphocytes can be induced to | undergo mitotic division |
| chemicals are added to lymphocytes to stop the mitotic division once the chromosomes have become separate & distinct, which causes | accumulation of cells arrested in mitosis in the culture medium |
| normal dividing cell arrested in mitosis contains | 46 chromosomes, each consisting of chromatids joined at their centromeres |
| size, location of centromere, arms of chromosome, & pattern of light/dark bands along chromosomes are | classifications of chromosomes |
| karyotype | arrangement of chromosomes from single cell arrangement in pairs in descending order according to size of chromosomes & position of centromeres |
| locus | position of gene on chromosome |
| one of several related genes that may occupy same locus on a homologous chromosome | alleles |
| alleles are always found on the same ___ of the gene | locus |
| if both alleles are the same an individual is | homozygous |
| if both alleles are different an individual is | heterozygous |
| expression of the gene | manifestation of a heritable trait in individual carrying gene(s) that determine it |
| a recessive gene expresses a trait only when present in | the homozygous state |
| gene that expresses a trait in either the heterozygous/homozygous state | dominant gene |
| sex-linked gene | present on X chromosome |
| term applied to genes located on X chromosome in male | hemizygous |
| when both alleles of a pair are expressed the alleles are called | codominant |
| gene imprinting | modification of gene during spermatogenesis or oogenesis |
| gene imprinting does not change the structure of the gene only | the way the gene is expressed in offspring |
| mitochondria have small amounts if DNA that contain | some of genes required for synthesis of energy-generating mitochondrial proteins |
| in mitochondria genes determine | various enzymes & other proteins that produce ATP-generating machinery |
| mutations to mitochondrial DNA may take place during | duplication/replication |
| transmission of abnormal mitochondrial DNA is almost always | from the mother, because ovum contains large number of mitochondria |
| antigens present on cells are determined by | cluster of genes on chromosome 6 |
| major histocompatibility complex MHC | group of genes on chromosome 6 that determine antigens on surface of cells |
| MHC, in humans these cell surface proteins/antigens were 1st identified on | peripheral blood leukocytes |
| designations HLA complex & HLA antigen and MHC complex & MHC antigen are | used interchangeably |
| self-antigens, which set us apart from one another | HLA complex & HLA antigen and MHC complex & MHC antigen |
| antigenicity of HLA complex/antigens depends on | whether one's own proteins or HLA proteins of another person |
| self-antigens are unique for person possessing them & are recognized by immune system as | being a part of that person, or not foreign |
| non-self antigens | foreign proteins |
| non-self antigens in another person for whom they are antigenic cause | an immune response |
| cells containing MHC proteins different from transplant recipients caused | rejection of transplanted organ unless immune system is suppressed |
| there are 1200 different allelic genes that can occupy gene loci with | HLA system |
| each allele, in a locus, is designated | specific letter to identify locus and number to indicate allele |
| haplotype | set of HLA genes on one chromosome that is transmitted in a set |
| each person has two haplotypes, each consisting of | four HLA genes |
| two haplotypes together determine a total of | eight HLA proteins on the cell |
| during HLA typing of organ donors, one attempts to match | major antigens of donor as closely as possible, so graft has better chance to survive |
| MHC Class I proteins are determined by | HLA-A, HLA-B & HLA-C genes |
| present on all nucleated cells & blood platelets | MHC Class I proteins |
| platelets | cytoplasmic fragments of large nucleated bone marrow cells |
| because cells lack nuclei, MHC Class I proteins are not found on | surface of red blood cells |
| MHC Class II proteins are determined by | HLA-D genes |
| only found on macrophages (and related cells having same functions) & some types of lymphocytes | MHC Class II proteins |
| child will only have ___ haplotype in common with each parent | one |
| from each parent, a children will inherit | one of two possible haplotypes |
| due to way chromosomes inherited from parent to chil, a child can have | any of four possible combinations of haplotypes |
| presence of this HLA gene indicates a predisposition to an arthritis of spine & sacroiliac joints | HLA-B27 |
| certain HLA-D types have been associated with | type 1 diabetes & Rheumatoid Arthritis |
| reason for association of specific disease with certain HLA type in related to | association of HLA gene complex to genes controlling immune system response |
| those with certain HLA types appear to have genes less capable of | regulating immune responses when subjected to antigenic stimulation |
| autoimmune diseases | disease associated with formation of cell-mediated/humoral immunity against one's own cells/tissue components |
| recombinant DNA technology | methods for combining gene from one organism, such as specifying insulin synthesis, with gene's from another organism, such as bacterium |
| genetic engineering | genes being manipulated; same as recombinant DNA technology |
| gene splicing | piece of genetic material being cut open & another piece of genetic material being spliced into it |
| plasmid | small, circular DNA molecule separate from main bacterial chromosome |
| circular plasmids are opened, during recombinant DNA technology, by means of | enzyme that "cuts" plasmid DNA so desired gene can be inserted btwn cuts end of plasmid |
| DNA tech has been source of insight into molecular basis of genetic diseases by | increasing understanding of normal gene structure & function |
| possible to identify mutation of gene in fetal cell DNA obtained from | amniotic fluid |
| gene therapy | normal gene inserted into defective cell, inserted gene compensates for missing/dysfunctional gene |
| successful application of gene therapy requires | identify/select correct gene to insert, choose proper cell to receive gene, effective means of inserting gene into cell, ensure inserted gene able function long enough for desired effects |
| the agent used to introduce gene into selected cell, in gene therapy, is called | vector |
| vector in gene therapy is usually | a virus, coupling to lipid or other material taken into cell by endocytosis |
| gene therapy targets | somatic cells |
| lymphocytic leukemia was a side effect of gene therapy because | gene inserted into lymphocyte-producing stem cell which disrupted function of other cells regulating growth & function |
| alternate forms of the same gene are called | alleles |
| being characteristic of germ cells, chromosomes reduced by half, & entails two separate divisions vs.being characteristic of somatic cells, no loss of chromosomes, & only one division | major differences between meiosis vs. mitosis |
Created by:
lfrancois
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