Topic 1 Biological Molecules Nucleic Acids Student 2010501 S

BIOLOGY

TENTH EDITION

Global Edition

Campbell • Reece • Urry • Cain • Wasserman • Minorsky • Jackson

5
Biological Macromolecules and Lipids

Topic 1 Biological Molecules (Part 4)

Lecture Presentation by
Nicole Tunbridge and
Kathleen Fitzpatrick

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Learning Outcome

a) Describe structure and composition of nucleic acids,
DNA and RNA.
b) Discuss the importance of base pairing and hydrogen bonding. ©©
2015
Pearson
Education
Ltd
2011
Pearson
Education,

Inc.

Concept 5.5: Nucleic acids store, transmit, and help express hereditary information
a) The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a ________________.
b) Genes consist of ___________, a nucleic acid made of monomers called ________________.

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The Roles of Nucleic Acids

a) There are two types of nucleic acids
a)_________________________ (DNA)
b)_________________________ (RNA)

b) DNA provides directions for its own _____________.

c) DNA directs synthesis of ____________________ and, through mRNA, controls __________ synthesis.
d) This process is called ________________________.

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Figure 5.23-3

DNA

1 Synthesis of mRNA mRNA

NUCLEUS
CYTOPLASM
mRNA
2 Movement of mRNA into cytoplasm Ribosome

3 Synthesis of protein

Polypeptide
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Amino acids a) Each gene along a DNA molecule directs synthesis of a messenger RNA (mRNA)

b) The mRNA molecule interacts with the cell’s proteinsynthesizing machinery to direct production of a polypeptide c) The flow of genetic information can be summarized as ________ → _________ → ______________

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The Components of Nucleic Acids

a) Nucleic acids are polymers called _______________.
b) Each polynucleotide is made of monomers called
_________________________.
c) Each nucleotide consists of a __________________, a _________________ sugar, and one or more
__________________ groups.
d) The portion of a nucleotide without the phosphate group is called a ____________________.

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a) Nucleoside = nitrogenous base + sugar
b) There are two families of nitrogenous bases
a)_________________________ (cytosine, thymine, and uracil) have a single six-membered ring
b)________________________ (adenine and guanine) have a six-membered ring fused to a five-membered ring c) In DNA, the sugar is _________________; in RNA, the sugar is ___________________.
d) Nucleotide = nucleoside + phosphate group

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Sugar-phosphate backbone
(on blue background)
Why is the sugar called pentose?
5′ end

Figure 5.24a

What’s the diff between nucleoside & nucleotide?

5′C
3′C

Nucleoside
Nitrogenous
base
5′C

1′C
5′C
3′C

Phosphate group Sugar
(pentose)

(b) Nucleotide

3′ end
(a) Polynucleotide, or nucleic acid
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3′C

At which sugar C no. is:
i.
phosphate attached? ii. A base attached?

Figure 5.24b

NITROGENOUS BASES
Pyrimidines

Cytosine
(C)

Thymine
(T, in DNA)
Purines

Uracil
(U, in RNA)

1. What are the elements present in ALL these bases? 2. What bases are found in a. RNA?

b. DNA?
Adenine (A)

Guanine (G)

(c) Nucleoside components
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Figure 5.24c

Structural Similarity & Difference between
Sugars in DNA & RNA
SUGARS

Deoxyribose
(in DNA)

Ribose (in RNA)

(c) Nucleoside components

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Nucleotide Polymers
a) Nucleotides are linked together to build a polynucleotide.
b) Adjacent nucleotides are joined by a
_____________________ linkage, which consists of a phosphate group that links the sugars of two nucleotides
(________ group on ___ carbon of one nucleotide and
_____________ on ___ carbon on the next).

c) These links create a __________________ of sugarphosphate units with nitrogenous bases as appendages.
d) The sequence of bases along a DNA or mRNA polymer is
_______________ for each gene.

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The Structures of DNA and RNA Molecules
a) DNA molecules have two polynucleotides spiraling around an imaginary axis, forming a
______________________.
b) The backbones run in opposite ___ → ___ directions from each other, an arrangement referred to as
_________________.
c) One DNA molecule includes
___________ genes.

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a) Only certain bases in DNA pair up and form hydrogen bonds: adenine (A) always with thymine (T), and guanine (G) always with cytosine (C) adenine (A)

thymine (T)

guanine (G)

cytosine (C)

b) This is called _______________________________.
c) This feature of DNA structure makes it possible to generate two identical copies of each DNA molecule in a cell preparing to divide
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a) RNA, in contrast to DNA, is single stranded. b) Complementary pairing can also occur within an RNA molecule allows it to take on particular ______ shape.
c) tRNA shape result from base pairing between nucleotides where complementary stretches of molecule run antiparallel to each other.

d) While DNA always exists as a
__________________, RNA molecules are more ___________ in form. © 2015 Pearson Education Ltd

Figure 5.UN03

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Figure 5.UN04

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Figure 5.UN05

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Figure 5.UN06

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