The document describes the processes of DNA replication, transcription, translation, and cell division. It includes: - DNA replication involves unwinding the DNA double helix and using each strand as a template to build new complementary strands. This results in two identical copies of the DNA molecule. - Transcription is the process where the DNA sequence of a gene is transcribed into mRNA by RNA polymerase. The mRNA strand then leaves the nucleus and attaches to a ribosome for protein synthesis. - Translation occurs when the mRNA binds to a ribosome in the cytoplasm. Transfer RNA molecules matching the mRNA codons bring amino acids to the ribosome to form a polypeptide chain according to the mRNA sequence.

1. Human
Anatomy
& Physiology
SEVENTH EDITION
Elaine N. Marieb
Katja Hoehn
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
PowerPoint® Lecture Slides
prepared by Vince Austin,
Bluegrass Technical
and Community College
C H A P T E R 3Cells: The
P A R T D
Living Units

2. DNA Replication
 DNA helices begin unwinding from the
nucleosomes
 Helicase untwists the double helix and exposes
complementary strands
 The site of replication is the replication bubble
 Each nucleotide strand serves as a template for
building a new complementary strand
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3. DNA Replication
 The replisome uses RNA primers to begin DNA
synthesis
 DNA polymerase III continues from the primer
and covalently adds complementary nucleotides to
the template
PPLLAAYY DNA Replication
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4. DNA Replication
 Since DNA polymerase only works in one
direction:
 A continuous leading strand is synthesized
 A discontinuous lagging strand is synthesized
 DNA ligase splices together the short segments of
the discontinuous strand
 Two new telomeres are also synthesized
 This process is called semiconservative replication
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5. DNA Replication
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Figure 3.31

6. Cell Division
 Essential for body growth and tissue repair
 Mitosis – nuclear division
 Cytokinesis – division of the cytoplasm
PPLLAAYY Mitosis
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7. Mitosis
 The phases of mitosis are:
 Prophase
 Metaphase
 Anaphase
 Telophase
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8. Cytokinesis
 Cleavage furrow formed in late anaphase by
contractile ring
 Cytoplasm is pinched into two parts after mitosis
ends
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9. Early and Late Prophase
 Asters are seen as chromatin condenses into
chromosomes
 Nucleoli disappear
 Centriole pairs separate and the mitotic spindle is
formed
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10. Early Prophase
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Figure 3.32.2

11. Late Prophase
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Figure 3.32.3

12. Metaphase
 Chromosomes cluster at the middle of the cell with
their centromeres aligned at the exact center, or
equator, of the cell
 This arrangement of chromosomes along a plane
midway between the poles is called the metaphase
plate
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13. Metaphase
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Figure 3.32.4

14. Anaphase
 Centromeres of the chromosomes split
 Motor proteins in kinetochores pull chromosomes
toward poles
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15. Anaphase
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Figure 3.32.5

16. Telophase and Cytokinesis
 New sets of chromosomes extend into chromatin
 New nuclear membrane is formed from the rough
ER
 Nucleoli reappear
 Generally cytokinesis completes cell division
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17. Telophase and Cytokinesis
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Figure 3.32.6

18. Control of Cell Division
 Surface-to-volume ratio of cells
 Chemical signals such as growth factors and
hormones
 Contact inhibition
 Cyclins and cyclin-dependent kinases (Cdks)
complexes
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19. Protein Synthesis
 DNA serves as master blueprint for protein
synthesis
 Genes are segments of DNA carrying instructions
for a polypeptide chain
 Triplets of nucleotide bases form the genetic
library
 Each triplet specifies coding for an amino acid
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20. From DNA to Protein
Transcription
RNA Processing
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Figure 3.33
Nuclear
envelope
DNA
Pre-mRNA
mRNA
Ribosome
Polypeptide
Translation

21. From DNA to Protein
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Figure 3.33
DNA

22. From DNA to Protein
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Figure 3.33
Transcription DNA

23. From DNA to Protein
Transcription
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Figure 3.33
DNA
Pre-mRNA
RNA Processing
mRNA

24. From DNA to Protein
Transcription
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Figure 3.33
DNA
Pre-mRNA
RNA Processing
mRNA
Nuclear
envelope

25. From DNA to Protein
Transcription
RNA Processing
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Figure 3.33
Nuclear
envelope
DNA
Pre-mRNA
mRNA
Ribosome
Polypeptide
Translation

26. Roles of the Three Types of RNA
 Messenger RNA (mRNA) – carries the genetic
information from DNA in the nucleus to the
ribosomes in the cytoplasm
 Transfer RNAs (tRNAs) – bound to amino acids
base pair with the codons of mRNA at the
ribosome to begin the process of protein synthesis
 Ribosomal RNA (rRNA) – a structural component
of ribosomes
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27. Transcription
 Transfer of information from the sense strand of
DNA to RNA
 Transcription factor
 Loosens histones from DNA in the area to be
transcribed
 Binds to promoter, a DNA sequence specifying the
start site of RNA synthesis
 Mediates the binding of RNA polymerase to
promoter
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28. Transcription: RNA Polymerase
 An enzyme that oversees the synthesis of RNA
 Unwinds the DNA template
 Adds complementary ribonucleoside triphosphates
on the DNA template
 Joins these RNA nucleotides together
 Encodes a termination signal to stop transcription
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29. Coding
strand
Template
strand
Promoter
Termination signal
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA
nucleotides
RNA polymerase
bound to promoter
mRNA synthesis begins
RNA polymerase moves down DNA;
mRNA elongates
RNA
nucleotides
mRNA synthesis is terminated
RNA
polymerase
mRNA
DNA
(a) mRNA transcript
RNA polymerase
Unwinding
of DNA
RNA
nucleotides
Coding strand
Rewinding of DNA
Template strand
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.34

30. Coding
strand
Template
strand
Promoter
Termination signal
Transcription unit
(a)
RNA polymerase
Unwinding
of DNA
RNA
nucleotides
Coding strand
Rewinding of DNA
Template strand
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.34

31. Coding
strand
Template
strand
Promoter
Termination signal
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA polymerase
bound to promoter
(a)
RNA polymerase
Unwinding
of DNA
RNA
nucleotides
Coding strand
Rewinding of DNA
Template strand
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.34

32. Coding
strand
Template
strand
Promoter
Termination signal
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA
nucleotides
RNA polymerase
bound to promoter
mRNA synthesis begins
(a)
RNA polymerase
Unwinding
of DNA
RNA
nucleotides
Coding strand
Rewinding of DNA
Template strand
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.34

33. Coding
strand
Template
strand
Promoter
Termination signal
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA
nucleotides
RNA polymerase
bound to promoter
mRNA synthesis begins
mRNA
(a)
RNA polymerase
Unwinding
of DNA
RNA
nucleotides
Coding strand
Rewinding of DNA
Template strand
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.34

34. Coding
strand
Template
strand
Promoter
Termination signal
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA
nucleotides
RNA polymerase
bound to promoter
mRNA synthesis begins
RNA polymerase moves down DNA;
mRNA elongates
RNA
nucleotides
mRNA
(a)
RNA polymerase
Unwinding
of DNA
RNA
nucleotides
Coding strand
Rewinding of DNA
Template strand
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.34

35. Coding
strand
Template
strand
Promoter
Termination signal
Transcription unit
In a process mediated by a transcription
factor, RNA polymerase binds to
promoter and unwinds 16–18 base
pairs of the DNA template strand
RNA
polymerase
Unwound DNA
RNA
nucleotides
RNA polymerase
bound to promoter
mRNA synthesis begins
RNA polymerase moves down DNA;
mRNA elongates
RNA
nucleotides
mRNA synthesis is terminated
RNA
polymerase
mRNA
DNA
(a) mRNA transcript
RNA polymerase
Unwinding
of DNA
RNA
nucleotides
Coding strand
Rewinding of DNA
Template strand
mRNA
RNA-DNA
hybrid region
(b)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.34

36. Initiation of Translation
 A leader sequence on mRNA attaches to the small
subunit of the ribosome
 Methionine-charged initiator tRNA binds to the
small subunit
 The large ribosomal unit now binds to this
complex forming a functional ribosome
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37. RNA polymerase
Template strand
of DNA
Released mRNA
Nuclear membrane
Nuclear pore
After mRNA processing, mRNA
leaves nucleus and attaches to
ribosome, and translation begins.
Amino acids
tRNA
Aminoacyl-tRNA
synthetase
Direction of
ribosome advance
tRNA “head”
bearing
anticodon
Small ribosomal
subunit
1
Codon 15 Codon 16 Codon 17
Large
ribosomal
subunit
mRNA
Portion of mRNA
already translated
Nucleus
4 3
Once its amino acid is
released, tRNA is
ratcheted to the E site
and then released to
reenter the cytoplasmic
pool, ready to be
recharged with a new
amino acid.
Incoming aminoacyl-tRNA
hydrogen bonds
via its anticodon to
complementary mRNA
sequence (codon) at
the A site on the
ribosome.
As the ribosome
moves along the
mRNA, a new amino
acid is added to the
growing protein chain
and the tRNA in the A
site is translocated
to the P site.
Energized by ATP,
the correct amino
acid is attached to
each species of tRNA
by aminoacyl-tRNA
synthetase enzyme.
2
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.36

38. RNA polymerase
Template strand
of DNA
Released mRNA
Nuclear membrane
Nuclear pore
mRNA
Nucleus
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.36

39. RNA polymerase
Template strand
of DNA
Released mRNA
Nuclear membrane
Nuclear pore
After mRNA processing, mRNA
leaves nucleus and attaches to
ribosome, and translation begins.
Small ribosomal
subunit
Direction of
ribosome advance
1
Codon 15 Codon 16 Codon 17
Large
ribosomal
subunit
mRNA
Portion of mRNA
already translated
Nucleus
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.36

40. RNA polymerase
Template strand
of DNA
Released mRNA
Nuclear membrane
Nuclear pore
After mRNA processing, mRNA
leaves nucleus and attaches to
ribosome, and translation begins.
Amino acids
tRNA
Aminoacyl-tRNA
synthetase
Small ribosomal
subunit
Direction of
ribosome advance
1
Codon 15 Codon 16 Codon 17
Large
ribosomal
subunit
mRNA
Portion of mRNA
already translated
Nucleus
Energized by ATP,
the correct amino
acid is attached to
each species of tRNA
by aminoacyl-tRNA
synthetase enzyme.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.36

41. RNA polymerase
Template strand
of DNA
Released mRNA
Nuclear membrane
Nuclear pore
After mRNA processing, mRNA
leaves nucleus and attaches to
ribosome, and translation begins.
Amino acids
tRNA
Aminoacyl-tRNA
synthetase
Direction of
ribosome advance
tRNA “head”
bearing
anticodon
Small ribosomal
subunit
1
Codon 15 Codon 16 Codon 17
Large
ribosomal
subunit
mRNA
Portion of mRNA
already translated
Nucleus
Incoming aminoacyl-tRNA
hydrogen bonds
via its anticodon to
complementary mRNA
sequence (codon) at
the A site on the
ribosome.
Energized by ATP,
the correct amino
acid is attached to
each species of tRNA
by aminoacyl-tRNA
synthetase enzyme.
2
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.36

42. RNA polymerase
Template strand
of DNA
Released mRNA
Nuclear membrane
Nuclear pore
After mRNA processing, mRNA
leaves nucleus and attaches to
ribosome, and translation begins.
Amino acids
tRNA
Aminoacyl-tRNA
synthetase
Direction of
ribosome advance
tRNA “head”
bearing
anticodon
Small ribosomal
subunit
1
Codon 15 Codon 16 Codon 17
Large
ribosomal
subunit
mRNA
Portion of mRNA
already translated
Nucleus
Incoming aminoacyl-tRNA
hydrogen bonds
via its anticodon to
complementary mRNA
sequence (codon) at
the A site on the
ribosome.
As the ribosome
moves along the
mRNA, a new amino
acid is added to the
growing protein chain
and the tRNA in the A
site is translocated
to the P site.
Energized by ATP,
the correct amino
acid is attached to
each species of tRNA
by aminoacyl-tRNA
synthetase enzyme.
2
3
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.36

43. RNA polymerase
Template strand
of DNA
Released mRNA
Nuclear membrane
Nuclear pore
After mRNA processing, mRNA
leaves nucleus and attaches to
ribosome, and translation begins.
Amino acids
tRNA
Aminoacyl-tRNA
synthetase
Direction of
ribosome advance
tRNA “head”
bearing
anticodon
Small ribosomal
subunit
1
Codon 15 Codon 16 Codon 17
Large
ribosomal
subunit
mRNA
Portion of mRNA
already translated
Nucleus
4 3
Once its amino acid is
released, tRNA is
ratcheted to the E site
and then released to
reenter the cytoplasmic
pool, ready to be
recharged with a new
amino acid.
Incoming aminoacyl-tRNA
hydrogen bonds
via its anticodon to
complementary mRNA
sequence (codon) at
the A site on the
ribosome.
As the ribosome
moves along the
mRNA, a new amino
acid is added to the
growing protein chain
and the tRNA in the A
site is translocated
to the P site.
Energized by ATP,
the correct amino
acid is attached to
each species of tRNA
by aminoacyl-tRNA
synthetase enzyme.
2
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.36

44. Genetic Code
 RNA codons code
for amino acids
according to a
genetic code
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Figure 3.35

45. Information Transfer from DNA to RNA
 DNA triplets are transcribed into mRNA codons
by RNA polymerase
 Codons base pair with tRNA anticodons at the
ribosomes
 Amino acids are peptide bonded at the ribosomes
to form polypeptide chains
 Start and stop codons are used in initiating and
ending translation
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46. Information Transfer from DNA to RNA
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Figure 3.38

47. Other Roles of RNA
 Antisense RNA – prevents protein-coding RNA
from being translated
 MicroRNA – small RNAs that interfere with
mRNAs made by certain exons
 Riboswitches – mRNAs that act as switches
regulating protein synthesis in response to
environmental conditions
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48. Cytosolic Protein Degradation
 Nonfunctional organelle proteins are degraded by
lysosomes
 Ubiquitin attaches to soluble proteins and they are
degraded in proteasomes
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49. Extracellular Materials
 Body fluids and cellular secretions
 Extracellular matrix
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50. Developmental Aspects of Cells
 All cells of the body contain the same DNA but
develop into all the specialized cells of the body
 Cells in various parts of the embryo are exposed to
different chemical signals that channel them into
specific developmental pathways
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51. Developmental Aspects of Cells
 Genes of specific cells are turned on or off (i.e., by
methylation of their DNA)
 Cell specialization is determined by the kind of
proteins that are made in that cell
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52. Developmental Aspects of Cells
 Development of specific and distinctive features in
cells is called cell differentiation
 Cell aging
 Wear and tear theory attributes aging to little
chemical insults and formation of free radicals that
have cumulative effects throughout life
 Genetic theory attributes aging to cessation of
mitosis that is programmed into our genes
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings