Biology Chapter 10

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Flashcards on Biology Chapter 10, created by E A on 13/11/2013.
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Flashcards by E A, updated more than 1 year ago
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Created by E A almost 11 years ago
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Question Answer
Gregor Mendel Provided foundation for modern genetics
Gregor Mendel details Austrian Monk Mid 1800's Edible pea plants
Gregor Mendel first geneticist to choose right organism/design performed experiments/analyzed data correctly
Self-fertilization fertilized by sperm from same organism fusion of gametes from w/ in
Example Self-fertilization Pea Plants
Cross-fertilization sperm from different organism fusion of gametes from 2 indv
Cross-fertilization example mating two plants by hand breeders remove stamen dust sticky end of carpel
Stamen male produces pollen
Carpel female produces eggs
Parental generation (P) 2 individual plants being crossed
First-generation (F1) offspring of the parental generation
Second-generation (F2) Offspring of the F1 generation
Homozygous (particular characteristic) Pea Plants always produce the same physical forms purple flowers=purple flowers True-breeding
True-breeding Plants homozygous for a characteristic
Dominant determines the phenotype of heterozygotes completely masks recessive ie: AA or Aa
Recessive expressed fully ONLY in homozygotes ie: aa
Law of segregation 2 alleles of a gene separate from one another at meiosis
Genotype the actual combination of alleles carried by an organism
Phenotype observable/measurable feature of the organism Traits: physical appearance, behavior, blood type
Punnett square method named after R.C. Punnett 1900 geneticist
Punnett square method You must be able to determine: Homozygous vs. heterozygous Dominant vs. recessive allele Gametes Genotypes/Phenotypes genotypic ratio/phenotypic ratio
Mendel Hypothesized Genes on different chromosomes are inherited independently Law of independent assortmen
Law of independent Assortment 2 or more genes are inherited independently of each other Alleles of one gene may be distributed to gametes independently of alleles for other genes
alleles of one gene may be distributed to gametes independently of alleles for other genes metaphase 1 paired homologous chromosomes line up randomly then separate independently during anaphase 1
Genes on the same chromosome tend to be inherited together Linked
Recombination can create new combinations of linked allels
Sex determined sex chromosomes XX female XY male
Sex-linked genes found Only on X or Y chromosome
Y chromosome carries 78 genes
X chromosome carries 1000 genes only a few have a role in reproduction
X genes have no counterpart on Y to make up for this One X of female is condensed
X chromosome genes color vision blood clotting some structural proteins in muscles
Females of 2 X chromosomes can be homoxygous or heterozygous Dominate vs recessive
males only one X Chromosome full express all alleles on their X (color blindness, hemophilia, muscular dystrophy occur)
Y chromosomes contain SRY gene
Mendelian Rules of Inheritance does not apply to all traits because traits are influenced by: Incomplete dominance co-dominance polygenic inheritance Pleiotropy Environment
Incomplete Dominance Phenotype of heterozygotes is intermediate between the phenotypes of the homozygotes Red + White = Pink Straight hair + Curly hair = Wavy hair
Co-Dominance Single gene may have multiple alleles ie: blood type
Polygenic Inheritance Interaction between 2 or more genes contributes to a single phenotype ie: height, weight, eye color, skin color, wheat color
Pleiotropy A single gene has several phenotypic effects
Pleiotropy example SRY gene (sex-determining Region of the Y chromosome) found 1990
SRY gene Codes for a protein that activates other genes, which then code for other proteins that switch on male development in an embryo
Environment External surroundings influence gene expression
Environment examples Intelligence (environmental and genetic) Temperature (fur) UV exposure (eye color in babies)
Temperature (fur) enzymes that produce pigments become inactive at certain temperatures heat 93 degrees cold 32 degrees
Siamese cats genotype dark fur all over body enzyme that produces dark pigment inactive above 93F 34F
Siamese babies born white after birth: ears/nose/paws/tail cool and darken
Investigating human genetic disorders Family pedigrees: diagrams that show genetic relationships among a set of related individuals
Human genetic disorders are caused by recessive alleles albinism: defect in melanin production sickle cell anemia: (low blood oxygen) defective allele for hemoglobin synthesis
Genetic Disorders Caused by dominate allels Cleft chin marfan syndrome huntingtons disease
Genetic disorders Sex linked Color blindness hemophilia muscular dystrophy
Chromosome number affect humans 1) Abnormal number of sex chromosomes 2)Abnormal number of autosomes
Abnormal number of sex chromosomes Non-disjunction of sex chromosomes during meiosis ie: Turner syndrome Trisomy X Klinefelter Syndrome Jacob Syndrome
Turner Syndrome females only one X (XO) no menstration no mature eggs cannout bear children 1/3000
Trisomy X females XXX 1/1000
Klinefelter Syndrome Males XXY low sperm show mixed secondary sex characteristics 1/1000
Jacob Syndrome Males XYY high levels of testosterone severe acne tall (over 6 ft) 1/1000
Abnormal number of autosomes 22 pairs most embryos with 3 copies of autosome spontaneously abort -exeption tristomy 21 -trisomy 18 Trisomy 13
Trisomy 21 Down syndrome 1/900 90% due to egg 10% due to sperm
Trisomy 18 edward syndrome 50% survive 2 weeks
Trisomy 13 Patau Syndrome 90% die in the first month
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