REVIEW SHEET MODERN GENETICS ANSWERS
1. Multiples alleles- 3 or more forms of a gene for a particular trait.
Blood type is a trait controlled by a gene with multiple alleles.
2 Traits controlled by multiple genes include skin color and height.
3. At least 4 genes affect a person’s height as well as environmental
factors.
4. XX- female
XY- Male
5. Recessive allele carried on X chromosome. More common in males
because a male only has one X chromosome so if they get one allele
they have the disease, females however need to have 2 recessive in order
to get the disorder.
6. A pedigree is a chart that tracks which members of a family have a
particular trait. They can be used to see how likely it is that offspring
will inherit a certain trait.
7. Child’s blood could be type B or O.
IB or iO parents could have IB/IB, IB/iO, or iO/iO.
8. Genetic disorders can be caused by recessive alleles, codominant
alleles, recessive allele on X chromosome, a mutation or a change in the
structure or number of chromosomes.
9. Cystic Fibrosis- recessive allele on one chromosome caused by a
mutation. Produces unusually thick mucus in the lungs and intestines.
Hemophilia- recessive allele on the X chromosome. Blood clots very
slowly or not at all due to not producing a protein necessary for normal
blood clotting.
Down Syndrome- caused by an extra copy of chromosome 21.
(Chromosomes did not separate during meiosis). Causes mental
retardation.
Sickle-Cell disease- allele for abnormal cells is codominant with normal
cell allele. Effect is abnormal shaped red blood cells that don’t carry as
much oxygen and can clog blood vessels.
10. A Karyotype is a picture of all of the chromosomes in a cell.
11. A carrier is a person who has one recessive allele for a trait (hybrid)
but does not have the trait.
12. The DNA sequence that produces insulin can be inserted into
bacterial cell so the bacteria and its offspring produces insulin. (diagram
pg 126 in textbook)
13. Cloning involves using a body cell inserted into an egg cell with its
nucleus removed to produce an organism with the same genes as the
organism it was produced from.
14. The Human Genome project identified the DNA sequence of every
gene in the human genome. This knowledge may allow scientists to use
genetic engineering techniques to cure genetic disorders or other health
problems.
15. Inbreeding is selective breeding involving crossing 2 organisms with
similar characteristics to produce offspring with desired characteristics.
Hybridization is selective breeding where 2 organisms with different
genetic characteristics are bred to combine the best characteristics of
both.
16. Species-A group of organisms that can mate and produce fertile
offspring.
17. Variations- differences in traits between members of a species.
18. Evolution- The change in a species over time.
19. Adaptation- Any trait that helps an organism survive and reproduce.
20. Natural selection- The process where organisms that are best adapted
survive and reproduce. The offspring of these organisms are more likely
to have the same traits as their parents causing the beneficial traits to
become more common in the species.