genetics

• gene - a sequence of bases on a DNA molecule that codes for a protein which results in a characteristic
• allele - an alternative version of a gene that is found at the same position on a chromosome
• genotype - genetic constitution of an organism
• phenotype -  expression of this genetic constitution and its interaction with the environment
• dominant - alleles whose characteristics appear in the phenotype
• recessive - allele where it only appears on the phenotype if two copies are present
• co-dominant - alleles that are both expressed in the phenotype
• locus - the fixed position of a gene on a chromosome
• homozygote - an organism that carries two copies of the same allele
• heterozygus - an organism that carries two different alleles
• carrier - a person carrying an allele which is not expressed on the phenotype but can be passed onto the offspring
• diploid organism - the alleles at a specific locus may be either homozygous or heterozygous.
• diploid - two sets of chromosomes and so we also have two alleles for each gene
• gamete - contain only one allele for each gene
• genetic diagrams - can be used to predict the genotypes and phenotypes of offspring
• monohybrid inheritance - inheritance of a characteristic controlled by a single gene. show the likelihood of different alleles of that gene being inherited
• dihybrid crosses - how two different genes are inherited at the same time
• add the labels

  A) dihybrid

  B) 3

  C) 9

  D) 3

  E) 1

  F) heterozygous

  G) heterozygous

  H) heterozygous

  I) 2

  
• autosome - any chromosome that is not a sex chromosome
• autosomal genes - genes that are found on autosomes (non-sex chromosomes)
• genes on the same autosome are linked because they will stay together during independent segregation of chromosomes in meiosis I and their alleles will be passed onto their offspring together. the only way this wont happen is if crossing over takes place and splits them up
• the closer the genes on autosome the more closely they are linked this is because crossing over is less likely to split them up
• if two genes are autosomally linked you will not get the phenothypic ratio you would expect
• episatis - when one gene affects the expression of the other gene by blocking it
• the chi-squared test - is a statistical test used to see if the results of an experiment support the expected results
• the chi-squared test can tell us if we can reject the null hypothesis
• null hypothesis - there is no significant difference between the expected data and observed data
• if the null hypothesis is rejected then it means that there is a significant difference between the expected and observed data so accept the alternative hypothesis
• chi-squared can be used to com-pare the goodness of fit of observed phenotypic ratios with the expected ratios
• labels

  A) E

  B) o

  C) 2

  D) observed

  E) expected

  F) degrees of freedom

  G) classes - 1

  H) 0.05

  I) there is

  J) rejected

  K) rejected

  L) observed and expected