8. Origins of genetic variation

• What is a gene?

  A sequence of DNA nuclotide bases that encodes for the amino acid sequence of polypeptides
• What is an allele?

  One or two or more different forms of a gene
• What is a genotype?

  genetic constitution of an organism
• How many copies of a chromosome does a diploid have?

  2
• In what process is a gamete produced in a diploid cell?

  Meiosis
• What is a phenotype?

  Is the observable or measurable characteristic of an organism
• What is a homozygous genotype?

  Both copies of a gene are the same allele
• What is a homozygous genotype of a diploid called?

  Homozygote
• What is a heterozygous genotype?

  Two copies of the same gene are different alleles
• What allele has its effects shown in the phenotype when present?

  Dominant allele
• What allele has its effects masked?

  Recessive
• What does codominant mean?

  Are equally dominant, both allele can be seen in the phenotype of a heterozygote
• What is a gene called with two alleles?

  Multiple allele
• What is a sex-linked gene?

  Is one that is present on only of the sex chromosome
• Is haemophilia an inherited condition?

  Yes
• What does haemophilia effect?

  The time it take for blood to clot
• How does haemophilia affect the blood clotting time?

  Increase or decrease the time it takes
• What are two ways that you can show how inheritance haemophilia is passed on?

  A genetic cross or a pedigree diagram
• What does a genetic cross look like?

  
• What does a pedigree diagram look like?

  
• What is an autosome?

  Any chromosome other than a sex chromosome
• How many sex chromosome does a fruit fly have, Drosophila melanogaster

  1 pair
• How many autosome chromosome does a fruit fly have

  3 pairs
• What two genes are located in the autosome chromosome, in a fruit fly?

  Body colour and wing length
• What can be expected if independent assortment and random fertilization occurs?

  Equally numbers of each potential fertilization
• What do non-interacting gene do?

  When they control 2 unrelated phenotypic features
• What is an unlinked gene?

  When the loci are located on different chromosomes
• What do the two non-interacting unliked genes control in pea plants?

  Flower colour and stem height
• What is categoric data?

  When only certain values can exist
• What does the O represent in the equation?

  Observed value

  
• What does the E represent in the equation?

  Expected value

  
• What is a gene pool?

  All the alleles of all the gene present in a particular population at a given time
• What happens to the beneficial and disadvantaged alleles when natural selection occurs?

  Beneficial alleles increase and disadvantage alleles decrease
• What is genetic drift?

  Is the changes in allele frequency that occurs by chance in small population
• When does a population bottleneck occur?

  When a population is drastically reduced in size
• During a population getting bottlenecked, what happens to the allele?

  Fewer of the alleles of each gene are represented among the survivors of the population crash
• What does the hardy-Weinberg equation allow?

  — Use observation of phenotypes frequencies to calculate the associated allele frequency is a population

  — Monitor whether allele frequencies are changing in a population
• What is the hardy-Weinberg equation?

  p^2 + 2pq + q^2 = 1
• What does allele frequency measure?

  How common alleles of a gene are in a population
• If the gene has two alleles, say A and a, what would represent p in the hardy-Weinberg equation?

  A