Competency Goal # 3
The learner will develop an
understanding of the continuity of
life and the changes of organisms
over time.
Part 4
1. Why should close relatives not mate?
 Most human disorders are inherited as
rare recessive alleles. Mating with close
relatives increases the chances that a
recessive disorder will be inherited.
2. If a trait is sex-linked, where is the gene
located?
 On the 23rd chromosome; most on X
3. Name sex-linked traits in humans.
 Red-green color blindness
 Hemophilia
4. Show a Punnett square of a carrier
female and normal male.
5. What is a pedigree?
 A graphic representation
of genetic inheritance
6. Who determines the sex of a child?
 It is the male gamete that determines the
sex of the offspring.
7. What is meant by a polygenic trait?
 A trait that is controlled by two or more
genes.
 Skin color, and height are examples
8. What important contribution did Charles
Drew make?
 Improved storage for blood
storage and increasing the
blood blank
9. What is a karyotype?
 Chart of chromosome pictures enlarged and
arranged in pairs
10. What can you tell by looking at the
chromosomes in a karyotype?
 Valuable in identifying unusual chromosome
numbers in cells
11. Explain how amniocentesis can be used to
screen for genetic disorders.
 A small amount of amniotic fluid, which
contains fetal tissues, is extracted and the fetal
DNA is examined
12. How can gel electrophoresis be useful:
 Law enforcement: Matching DNA samples
from crime scenes; fingerprinting
 Medicine: Research in
developing cures for
diseases
13. How can human insulin be produced using
DNA technology?
 The human gene for insulin is inserted into a
bacterial plasmid by genetic engineering
techniques. Recombinant bacteria produce
large quantities of insulin.
14. What is a transgenic organism?
 A plant or animals that contain functional
recombinant DNA from an organism of a
different genus
 Example: high protein corn, better tasting, last
longer, resistance to pest and disease,
increased vitamins
15. What is cloning?
The process of making a genetically
identical copy
16. What are the advantages and
disadvantages of cloning?
Advantage: Rancher and dairy farmers
could clone particularly productive, healthy
animals to increase yield;
medical research
Disadvantage: Ethical issues