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Role of DNA: The DNA makes up genes
must be capable of storing, copying, and
transmitting the genetic info of a cell
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Copying info: Before a cells divides, it
must make a complete copy of every
one of its genes, similar to the way that
a book is copied
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Transmit info: When a cell divides, each
daughter cell must receive a complete
copy of the genetic info
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DNA has 4 kinds of nitrogenous
bases: Adenine (A), Guanine (G),
Cytosine (C), and thymine (T)
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Nucleic acids are made
up of nucleotides, linked together to
form long chains
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Same goes for Cytosine and
Guanine
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Two strands twist
around each other like a spiral staircase
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Transcription: During Transcription,
segments of DNA serve as templates to
produce complementary RNA molecules
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This
arrangement enables the nitrogenous
bases on both strands to come into
contact at the center of the molecule
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Hydrogen Bonding: Watson and Crick’s
model showed that hydrogen bonds
could form between certain nitrogenous
bases, providing just enough force to
hold the two DNA strands together
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Base Pairing: A=T , C=G

Translation: The sequence of nucleotide
bases in mRNA molecule is a set of
instructions that gives the order in which
amino acids should be joined to produce
a polypeptide
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Beings when
ribosome attaches to an mRNA molecule
to cytoplasm
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Ribosome reads each
codon it directs tRNA to bring specified
amino acid in the ribosome
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One at a
time the ribosome attaches each amino
acid the growing chain
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3

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Insertions and Deletions: Are point
mutations in which one base is inserted
or removed from the DNA sequence
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Eukaryotic- Replication may begin at
dozens or even hundreds of places on
the DNA molecule, proceeding in both
directions until each chromosomes in
completely copied
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The role of Enzymes: DNA replication is
carried out by a series of enzymes
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They are named for the reactions they
catalyze
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2
The role of RNA: RNA, like DNA, is a
nucleic acid that consists of a long chain
of nucleotides
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Functions of RNA: RNA is in a way like a
disposable copy of a segment of DNA, a
working copy of a single gene
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They generally occur during
replication
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Duplication produces an
extra copy of all or part of a
chromosome
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Mutagens: Some mutations arise from
mutagens, chemical or physical agents in
the environment
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Beneficial effects: Plant and animal
breeders use good mutations
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Harmful Effects: Can change protein
structure which disrupt normal
biological activities
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Autosomal Chromosomes: The
remaining 44 human chromosomes are
known as autosomal chromosomes, or
autosomes
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Human
genome consists of 46 chromosomes,
including 44 autosomes and 2 sex
chromosomes (gametes)
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X-Chromosome Inactivation: In female
cells most of the genes in one of the X
chromosomes are randomly switched
off, forming a dense region in the
nucleus known as a Barr body
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The
defective polypeptide makes
hemoglobin less soluble, causing
hemoglobin molecules to stick together
when the blood oxygen level decreases
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Cystic Fibrosis: Most common with
people of European ancestry
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Codon is CAG
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Chromosomal Disorder: The most
common error in meiosis occurs when
homologous chromosomes ail to
separate
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It
can result in gametes with abnormal
number of chromosomes
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3
Separating DNA: Scientists use a
technique known as gel
electrophoresis to separate and
analyze thee differently sized
fragments
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Cutting DNA: Nucleic acids are
chemically different from other
macromolecules such as proteins
and carbohydrates

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