Biology Unit 2 focuses on key concepts in molecular biology, including nucleic acids, DNA structure, and the processes of DNA replication and cell division. This unit is essential for students in Biology 152, providing a foundation for understanding genetic information and cellular mechanisms. Topics covered include the roles of DNA and RNA, the significance of nucleotides, and the intricacies of the cell cycle. Ideal for college students preparing for exams in molecular biology and genetics.

Key Points

  • Explains the structure and function of nucleic acids, including DNA and RNA.
  • Covers the processes of DNA replication and the cell cycle in detail.
  • Discusses the significance of nucleotides and their role in genetic information.
  • Includes diagrams and models to illustrate complex biological processes.
jasmine
17 pages
Mitosis
jasmine
17 pages
Mitosis
144
/ 17
biology
unit
nucleic
acids
and
an
a
worl
chapter
a
Deoxyribonucleic
acid
(DNA)
:
stores
genetic
info
and
is
replicated
using
proteins
4
.
I
-
What
is
a
nucleic
acid
?
G
polymers
made
up
of
monomers
called
nucleotides
components
of
a
nucleotide
·
32
phosphate
sugar
nitrogenous
covalent
base
bond
how
do
nucleotides
polymerize
to
form
nucleic
acids
?
·
sugar
:
central
component
both
RNASDNA
have
an
↳
via
condensation
reactions
between
the
hydroxyl
on
the
↳
base
is
attached
at
the
1
carbon
3
-
OHe3'
carbon
BUT
·
ribose
:
- Ohe2'
carbon
sugar
of
1
nucleotide
and
phosphate
group
of
another
.
↳
phosphate
group
at
the
5'
carbon
·
deoxyribose
:
-Hez'carbon
forms
a
new
covalent
bond
,
molecule
of
H2O
is
released
-
>
monomers
of
DNA
:
deoxyribonucleotides
bridge
formed
by
the
phosphate
group
is
called
a
-
>
monomers
of
RNA
:
ribonucleotides
n
a
phosphodiester
linkage/bond
.
·
nitrogenous
bases
differ
in
1
of
their
bases
S
linkage
connets
the
31
↳
purines
:
double
rings
formed
from
9
atoms
·
As
carbon
of
1
nucleotide
*
adenine
(A)
&guanine
(G)
I
3
the
5'
carbon
of
another
↳
pyramidine
:
single
ring
formed
from
6
atoms
RNA
DNA
H
*
when
linkages
join
ribonucleotides
*
cytosine
(c)
,
uracil(u)
,
thymine
(T)
together
,
polymer
produced
is
PNA
*
when
linkages
join
deoxyribonucleotides
together
,
polymer
produced
is
DNA
DNA
and
RNA
strands
are
directional
nucleic
acids
have
a
sugar-phosphate
backbone
·
sugar-phosphate
backbone
of
a
nucleic
acid
is
directional
.
in
a
strand
,
one
end
has
a
unlinked
5'phosphate
other
end
has
unlinked
3'
hydroxyl
G
groups
are
not
bonded
to
another
nucleotide
order
of
diff
.
nucleotides
form
the
primary
structure
of
the
nucleic
acid
↳
EX
.
DNA
consisting
of
6
nucleotides
:
ATTAGC
sequences
of
bases
in
strands
are
always
written
in
the
5'-3'
direction
nucleotides
are
added
only
at
the
3'
end
of
a
growing
nucleic
acid
molecule
polymerization
requires
an
energy
source
joing
of
nucleotides
into
nucleic
acids
dramatically
decrease
entropy
,
thus
not
spontaneous
.
-
>
input
of
energy
needed
to
tip
the
energy
of
balance
in
favor
of
polymerization
.
nucleic
acid
polymerization
can
take
place
in
cells
be
potential
energy
of
monomers
is
1st
raised
by
reactions
that
add
2
more
phosphate
groups
to
the
5'
phosphates
,
creating
nucleoside
triphosphates
.
aka
"activated
nucleotides"
I
-
Ex
.
of
activated
ribonucleotide
,
adenosine
triphosphate/ATP
⑫
G
Used
for
DNA
synthesis
:
deoxy
adenosine
triphosphate
(dATP)
addition
of
phosphat
eial
ribose
energy
of
monomer
4
.
2
+
DNA
structure
d
function
primary
structure
of
DNA
is
similar
to
primary
structure
of
proteins
.
DNA-sugar-phosphate
backbone
,
created
by
phosphodiester
linkages
,
&
sequence
of
any
4
bases
what
is
DNA's
secondary
structure
?
↳
announced
in
1953
by
Watson
Crick
Watson
and
crick's
model
was
a
hypothesis
based
on
a
series
of
other
labs
.
①
WSC
knew
the
molecule
had
a
sugar-phosphate
backbone
②
Erwin
Chargolff
had
2
rules
on
bases
in
DNA
↳
D
#
of
purines
in
DNA
=
#
of
pyramidines
in
DNA
↳
②
DNA
has
=
#
of
T&A
,
and
=
#of
CSG
③
Rosalind
Franklind
Maurice
Wilkins
calculated
the
distance
between
groups
of
atoms
in
the
molecule
↳
technique
:
X-ray
crystallography
:
determines
3-d
structure
for
large
molecules
↳
pattern
of
X-ray
showed
molecule
was
a
repeating
structure
Shelical/spiral
in
nature
/ 17
End of Document
144

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FAQs

What are the main components of nucleic acids?
Nucleic acids, such as DNA and RNA, are polymers made up of monomers called nucleotides. Each nucleotide consists of three components: a phosphate group, a sugar molecule, and a nitrogenous base. The arrangement of these components allows nucleotides to link together, forming long chains that serve as the genetic blueprint for organisms. Understanding these components is crucial for studying molecular biology and genetics.

How does DNA replication occur?
DNA replication is a vital process that occurs during the S phase of the cell cycle. It begins at specific locations called origins of replication, where the double helix unwinds and separates into two strands. DNA polymerase then synthesizes new strands by adding nucleotides complementary to the template strands, ensuring that each daughter cell receives an identical copy of the DNA. This process is essential for cell division and the maintenance of genetic continuity.

What is the significance of the cell cycle?
The cell cycle is a series of phases that cells go through to grow and divide. It includes interphase, where the cell prepares for division, and the M phase, where mitosis occurs. Understanding the cell cycle is crucial for comprehending how cells replicate and how errors in this process can lead to diseases such as cancer. Each phase is tightly regulated to ensure proper cell function and genetic stability.

What are the differences between DNA and RNA?
DNA and RNA serve different roles in the cell. DNA, or deoxyribonucleic acid, is the hereditary material that stores genetic information, while RNA, or ribonucleic acid, plays a crucial role in protein synthesis. Structurally, DNA is double-stranded and contains the sugar deoxyribose, whereas RNA is usually single-stranded and contains ribose. Additionally, RNA includes uracil in place of thymine, which is found in DNA.

What role do nucleotides play in genetics?
Nucleotides are the building blocks of nucleic acids and play a critical role in genetics. Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base, and the sequence of these nucleotides encodes genetic information. Changes or mutations in the nucleotide sequence can lead to variations in traits and can influence an organism's development and function. Understanding nucleotides is essential for studying heredity and genetic disorders.

How do mutations affect DNA?
Mutations are changes in the nucleotide sequence of DNA that can occur during replication or as a result of environmental factors. These alterations can have various effects, ranging from benign to harmful, depending on their location and nature. Some mutations may lead to genetic disorders or increase the risk of diseases like cancer, while others can provide beneficial adaptations. Studying mutations helps scientists understand evolutionary processes and the mechanisms of disease.

What is the function of DNA polymerase in replication?
DNA polymerase is an essential enzyme that catalyzes the synthesis of new DNA strands during replication. It adds nucleotides to the growing chain in a 5' to 3' direction, ensuring that the new strand is complementary to the template strand. This enzyme also has proofreading capabilities, allowing it to correct errors that occur during DNA synthesis, which is crucial for maintaining genetic fidelity. Understanding the role of DNA polymerase is fundamental in molecular biology.