6.2 Patterns of inheritance part 2

• Continuous variation is when induviduals in a population vary within range = no distinct categories
• discontinuous variation is when there are two or more categories = no intermediates
• Induviduals of the same species have the same genes just different alleles
• meiosis makes gametes with unique assortment of alleles through crossing over and independent assortment of chromosomes = increase genetic variation in offspring
• what is characteristics displayed by an organism called?


  phenotype
• inherited chracteristics usually influenced by many genes (continuous variation) = polygenic
• inherited chracteristics usually influenced by one gene (discontinuous variation) = monogenic
• what type of variation is usually influenced by multiple genes?


  continuous variation
• what type of variation is usually influenced by one gene?


  discontinuous variation
• What are some examples of the environment that can impact variation?


  Climate food lifestyle
• most phenotypic variation is due to the combination of genotype + environmental factors
• What is it called when alleles are both expressed in the phenotype = neither are recessive?


  Codominant
• what is organism carries two copies of the same allele called?


  Homozygote
• what is an organism that carries two different alleles?


  Heterozygote
• What are gametes?


  sex cells
• Monogenic inheritance is the inheritance of chracteristics controlled by a single gene
• diybrid inheritance is the inheritance of two characteristics which are controlled by different genes
• What are females chromosomes?


  XX
• what are males chromsomes?


  XY
• A characteristic is sex linked when the allele that codes for it is on a sex chromosome eg X + Y
• males only have one X chromosome = one allele for sex linked genes
• What is an autosome?


  a non sex chromosome
• Autosomal genes are located on the autosome
• genes on the same autosome are linked as they say together during independent assortment of chromosomes. The only reason they will split is if crossing over occurs
• the closer two genes are on an autosome the more linked —> as they are less likely to be split up
• Two autosomally-linked alleles are inherited together
• what is the term for when allele of one gene masks the expression of the alleles of other genes?


  epistatis
• in chi squared test if your $X^2$ value is larger or equal to critical value it means your results are significant + null hypothesis can be rejected
• Complete range of alleles present in a population is called what?


  gene pool
• How often alleles occur in a population is called what?


  allele frequency
• What are three examples of selection pressure?


  predation disease competition
• what is the term for an allele that increases their chance of survival?


  advantageous characteristic
• when an environment isn’t changing much, alleles for characteristics in the middle of the range are more likely to survive = stabilising selection —> reduces range of possible phenotypes
• when there are changes in the environment, induviduals with alleles for characteristics of extreme type = more likely to survive = directional selection
• what is the term for when chance dictates which alleles are passed on?


  genetic drift
• genetic drift is when chance dictates which alleles are passed on
• Evolution by genetic drift usually has greater effect in a smaller population where chance has greater influence
• A genetic bottle neck is an event that causes a big reduction in population size = reduction in gene pool
• what is the term for when an event causes a big reduction in population size = reduction in gene pool?


  Bottleneck effect
• Founder effect is when a small group of individuals leave a population and start a new population = small number of different alleles in a initial gene pool.