science

Genetic disorder: a disease or disorder that is inherited genetically (it is caused by mutation)

Describe a genetic disorder caused by a mutation in a single gene. hemophilia, it reduces activity of a
protein needed for blood clotting.

What causes Down syndrome? when someone has 47 chromosomes instead of 46 in each cell, there is
an extra 21st chromosome

What is nondisjunction? is the failure of replicated chromosomes to separate during meiosis

What is gene therapy? inserting normal genes into cells with mutant genes in order to correct genetic
disorders

Explain why genetic disorders caused by abnormal numbers of chromosomes most often involve the X
chromosome. males only have one x chromosome, they have only one allele for any X linked trait so a
recessive allele is always expressed in males.

Darwin’s theory of evolution evolution occurs.. 2evolution occurs by natural selection.

Darwin’s theory of evolution by natural selection states that living things with beneficial traits produce
more offspring than others do. This produces changes in the traits of living things over time.

Artificial selection: He was also aware that humans could breed plants and animals to

have useful traits. By selecting which animals were allowed to reproduce, they could change an
organism’s traits.
Fitness to refer to an organism’s relative ability to survive and produce fertile offspring.
Natural selection: Nature selects the variations that are most useful. Therefore, he called this type of
selection natural selection.
Scientists who find and study fossils are called paleontologists. (evidence of evolution)
Comparative anatomy is the study of the similarities and differences in the structures of different
species.

Homologous structures are structures that are similar in related organisms because they were inherited
from a common ancestor. These structures may or may not have the same function in the descendants.
(evidence of evolution)
Analogous structures are structures that are similar in unrelated organisms. The structures are similar
because they evolved to do the same job, not because they were inherited from a common ancestor.
(evidence of evolution)
Comparative embryology is the study of the similarities and differences in the embryos of different
species. Similarities in embryos are evidence of common ancestry.
Vestigial structures: Evolution has reduced their size because the structures are no longer used.
Scientists compare the anatomy, embryos, and DNA of living things to understand how they evolved.
Similar DNA sequences are the strongest evidence for evolution from a common ancestor. (cladogram)
Biogeography is the study of how and why plants and animals live where they do.
Adaptive radiation: This is the process by which a single species evolves into many

new species to fill available niches.
Island Biogeography is the study of the species composition and species richness on islands.
Paleontologists are the scientists most closely related to fossil evidence for evolution
The appendix and tailbone are examples of vestigial structures in humans.

The fact that there are species belonging to the camel family living in South America, Asia and North
Africa is evidence of evolution according to: Biogeography

Orcas are mammals while sharks are fish. Even though their common ancestor lived around 470 million
years ago, they both have a very similar structure that help them swim effectively. (Flippers for Orcas,
and fins for Sharks) This is an example of: Analogous Structures
The Theory of Evolution

Vestigial structures are structures that evolution has reduced in size because it is no longer used. one
example is your appendix

Define biotechnology. A form of technology that uses living organisms, usually genes, to modify
products, to make or modify plants and animals, or to develop other microorganisms for specific
purposes.

What is recombinant DNA? acquire DNA from any organism, recombine it with DNA of a carrier and
insert it into the cell of another organism

Identify the steps of gene cloning. 1. In isolation, an enzyme (called a restriction enzyme) is used to
break DNA at a specific base sequence. This is done to isolate a gene. 2. During ligation, the enzyme DNA
ligase combines the isolated gene with plasmid DNA from bacteria. (A plasmid is circular DNA that is not
part of a chromosome and can replicate independently.) Ligation is illustrated in the Figure below. The
DNA that results is called recombinant DNA. 3. In transformation, the recombinant DNA is inserted into
a living cell, usually a bacterial cell. Changing an organism in this way is also called genetic engineering.
4. Selection involves growing transformed bacteria to make sure they have the recombinant DNA. This is
a necessary step because transformation is not always successful. Only bacteria that contain the
recombinant DNA are selected for further use.

What is the purpose of the polymerase chain reaction? makes many copies of a gene or other DNA
segment. This might be done in order to make large quantities of a gene for genetic testing.

Describe the three steps of PCR. 1. Denaturing involves heating DNA to break the bonds holding
together the two DNA strands. This yields two single strands of DNA. 2. Annealing involves cooling the
single strands of DNA and mixing them with short DNA segments called primers. Primers have base
sequences that are complementary to segments of the single DNA strands. As a result, bonds form
between the DNA strands and primers. 3. Extension occurs when an enzyme (Taq polymerase or Taq
DNA polymerase) adds nucleotides to the primers. This produces new DNA molecules, each
incorporating one of the original DNA strands.