Transcript MCAS BIOLOGY REVIEW GENETICS AND EVOLUTION

Ms. Mezzetti
Lynn English High School
Describe the basic structure (double helix,
sugar/phosphate backbone, linked by complementary
nucleotide pairs) of DNA, and describe its function in
genetic inheritance. What is DNA:
http://www.statedclearly.com/what-is-dna/
DNA is a long polymer
made up of many
smaller units called
nucleotides
A nucleotide consists of
a phosphate group, 5
carbon sugar and
nitrogenous base
DNA contains 4
nitrogenous bases
DNA stores the genetic code which carries the
instructions for making proteins and inheritance
3.2 Describe the basic process of DNA replication and
how it relates to the transmission and conservation of the
genetic code.
Transcription takes
place in the nucleus;
transcribes message
from DNA
Translation takes place
at the ribosome in the
cytoplasm; translates
mRNA to tRNA to amino
acid
Explain how mutations in the
DNA sequence of a gene may
or may not result in
phenotypic change in an
organism.
Explain how mutations in gametes may result in
phenotypic changes in offspring.
Distinguish among observed inheritance patterns caused by
several types of genetic traits (dominant, recessive, codominant,
sex-linked, polygenic, incomplete dominance, multiple alleles).
DOMINANT/RECESSIVE
CODOMINANT
INCOMPLETE
Traits that are
controlled by more
than one gene. In
humans height,
weight and skin
color are polygenic.
Blood type is an
example of
multiple alleles:
ABO
codominance:
AB blood
Usually passed on by the mother who is a
carrier; usually affects males
• Cross 2 homozygous
dominant or 2 recessive
and the offspring will be
the same as the parents.
• Cross 2 heterozygous
parents and the
probability is a 3-1 ratio
for the dominant trait to
be expressed. The
probability for genotype is
a 1:2:1 ratio