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17.1

GENOTYPE = GENETIC MAKEUP FO ORGANISM (ALL ALLELES)

PHENOTYPE = OBSERVABLE CHARACTERISTIC DUE TO INTERCTION BETWEEN GENOTYPE AND THE ENVIRONMENT

GENE = SEQUENCE OF NUCLEOTIDE BASES CODING FOR THE PRIMARY SEQUENCE OF A PARTICULAR POLYPEPTIDE. POSITION OF GENE ON DNA STRAND IS THE LOCUS

ALLELE = DIFFERENT VERSION OF A GENE 

DIPLIOD = HOMOLOGOUS PAIRS OF CHROMOSOMES, EACH CELL HAS TWO ALLELES FOR THE SAME GENE

HOMOZYGOUS = TWO ALLELES ARE THE SAME, TWO DOMINANT OR RECESSIVE

HETEROZYGOUS = TWO ALLELES ARE DIFFERENT, EXPRESSED ALLELE IS DOMINANT, THE OTHER IS RECESSIVE

CODOMINANT = TWO ALLELES CONTRIBUTE TOWARDS PHENOTYPE 

MULTIPLE ALLELES = MORE THAN TWO ALLELES FOR A, (ABO BLOOD GROUPS)

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17.2

MONOHYBRID INHERITANCE = INHERITANCE OF A SINGLE GENE

PURE-BREEDING = BREEDING PLANTS WITH THE SAME CHARACTERISTIC WITH EACHOTHER, THEY ARE HOMOZYGOUS

LAW OF SEGREGATION = IN DIPLOID ORGANISMS CHARACTERISTICS ARE DETERMINED BY ALLELES THAT OCCUR IN PAIRS. ONLY ONE OF EACH PAIR CAN BE PRESENT IN A SINGLE GAMETE

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17.3

RATIO = MEASURE OF RELATIVE SIZE OF TWO CLASSES EXPRESSED AS PROPORTION. LARGER SAMPLE MORE ACCURATE RATIO. RATIOS NOT EXACT DUE TO RANDOM FERTILISATION, SOME ALLELES MAY NOT BE DISTRIBYTED EQUALLY

BACK CROSS = WORK OUT THE GENOTYPE OF AN ORGANISM

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17.4

DIHYBRID INHERITANCE = TWO DIFFERENT CHARACTERISTICS DETERMINED BY DIFFERENT GENES LOCATED ON DIFFERENT CHROMOSOMES ARE INHERITED

MENDEL = CROSSED TWO PURE BRED TYPES OF PLANT (ROUND R AND YELLOW Y, AND WRINKLED r AND GREEN y) FOUND RATIO OF 9:3:3:1 (RY:Ry:rY:ry). FOUR DIFFERENT GAMETES PRODUCED AS GENES FOR SHAPE AND COLOUR ARE ON DIFFERENT CHORMOSOMES

LAW OF INDEPENDANT ASSORTMENT = EACH MEMBER OF A PAIR OF ALLELES MAY COMBINE RANDOMLY WITH EITHER OF ANOTHER PAIR

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17.5

CODOMINANCE = BOTH ALLELES ARE DOMINANT AND BOTH EXPRESSED IN THE PHENOTYPE. E.G. SNAPDRAGON RED CROSSED WITH WHITE MAKES PINK

MULTIPLE ALLELES = MORE THAN TWO ALLELES BUT ONLY TWO MAY BE PRESENT ON A CHROMOSOME. E.G. HUMAN ABO BLOOD GROUPS A AND B DOMINANT TO O

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17.6

GAMETES = FEMALES HAVE **, MALES HAVE XY

SEX-LINKAGE = ANY GENE OF A SEX CHOMOSOME IS SEX LINKED. E.G. HAEMOPHILLIA CAUSED BY RECESSIVE ALLELE CODING FOR FAULTY PROTEIN, NO EQUIVALENT ALLELE ON Y CHROMOSOME SO ONLY ONE IS NEEDED FOR A MALE TO BE AFFECTED

PEDIGREE CHART = TRACE INHERITANCE OF SEX-LINKED CHARACTERISTICS

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17.7

AUTOSOME = ANY CHROMOSOME THAT IS NOT A SEX CHROMOSOME

AUTOSOMAL LINKAGE = TWO OR MORE GENES ARE CARRIED ON THE SAME AUTOSOME ARE LINKED. LINKED GENES DO NOT SEGREGATE

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17.8

EPISTASIS = THE ALLELE OF ONE GENE AFFECTS OR MASKS THE EXPRESSION OF ANOTHER GENE IN THE PHENOTYPE. E.G MICE COATS, EXPRESSION OF ALLELES FOR PRODUCING AND NOT PRODUCING MELANIN GIVES AGOUTI COAT COLOUR

OTHER FORMS = GENES ACT IN SEQUENCE BY DETERMINING THE ENZYMES IN A BIOLOGICAL PATHWAY

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17.9

CHI SQUARED TEST = USED TO TEST DIFFERENCE BETWEEN OBSERVED AND EXPECTED DATA IN BEHAVIOUR OR GENETIC EXPERIMENTS

NULL HYPOTHESIS = THERE WILL BE NO SIGNIFICANT DIFFERENCE BETWEEN THE OBSERVED (STATE) AND EXPECTED (STATE) DISTRIBUTIONS, AN DIFFERENCE IS DUE TO CHANCE

1 = DECIDE ON CUT OFF POINT (p=0.05) 

2 = CALCULATE X2 USING SUM OF (O-E)2 / E

3 = CALCULATE DEGREES OF FREEDOM (NO. CATEGORIES - 1)

4 = COMPARE CALCULATED X2 TO X2 IN TABLE FOR THE DEGREES OF FREEDOM

5 = IF CALCUATED X2 IS LARGER THAN CRITICAL VALUE REJECT NULL HYPOTHESIS, DIFFERENCE IS STATISTICALLY SIGNIFICANT, LESS THAN 0.05 PROBABILITY THE DIFFERENCE BETWEEN O AND E IS DUE TO CHANCE

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