1. Chapter 3: Biology of the cell
Lecture 6
Chapter 3: Biology of the cell

2. Studying Cells Cell Theory: Four Basic Concepts
Basic building blocks of all animals and plants
Smallest functional units of life
Products of cell division
Basic homeostatic units
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

3. The Diversity of Cells in the Human Body
Studying Cells
The Diversity of Cells in the Human Body
Figure 3-1

4. Studying Cells Cytology Study of structure and function of cells
Cytology depends on seeing cells
Light microscopy (LM)
Electron Microscopy (EM)
Scanning EM (SEM)
Transmission EM (TEM)
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

5. Studying Cells Overview of Cell Anatomy Extracellular fluid
Also called interstitial fluid
Cell Membrane
Lipid barrier between outside and inside
Cytoplasm (intracellular fluid)
Around nucleus
Cytosol + organelles
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

6. Studying Cells
Anatomy of a Representative Cell
Figure 3-2

7. The Cell Membrane Functions of Membrane Proteins Receptors Channels
Carriers
Enzymes
Anchors
Identifiers
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

8. The Cell Membrane
Table 3-2

9. The Cytoplasm Organelles: The Cytoskeleton
Cytoplasmic strength and form
Main components
Microfilaments (actin)
Intermediate filaments (varies)
Microtubules (tubulin)
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

10. The Cytoplasm Nonmembranous Organelles
Centrioles—Direct chromosomes in mitosis
Microvilli—Surface projections increase external area
Cilia—Move fluids across cell surface
Flagella—Moves cell through fluid
Ribosome—Makes new proteins
Proteasome—Digests damaged proteins
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

11. The Cytoplasm Membranous Organelles
Endoplasmic reticulum—Network of intracellular membranes for molecular synthesis
Rough ER (RER)
Contains ribosomes
Supports protein synthesis
Smooth ER (SER)
Lacks ribosomes
Synthesizes proteins, carbohydrates
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

12. The Cytoplasm
Key Note
Cells respond directly to their environment and help maintain homeostasis at the cellular level. They can also change their internal structure and physiological functions over time.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

13. The Cytoplasm
Key Note
Mitochondria provide most of the energy needed to keep your cells (and you) alive. They consume oxygen and organic substrates, and they generate carbon dioxide and ATP.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

14. The Nucleus
The Nucleus
Figure 3-16

15. The Nucleus
Chromosome Structure
Figure 3-17

16. The Nucleus The Genetic Code Triplet code A Gene
Comprises three nitrogenous bases
Specifies a particular amino acid
A Gene
Heredity carried by genes
Sequence of triplets that codes for a specific protein
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

17. The Nucleus Protein Synthesis
Transcription—the production of RNA from a single strand of DNA
Occurs in nucleus
Produces messenger RNA (mRNA)
Triplets specify codons on mRNA
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

18. Figure 3-18 3 of 5 DNA RNA polymerase Promoter Triplet 1 1 1 Gene
Complementary
triplets
Triplet 2 2 2 3
Triplet 3 3 4
KEY
Triplet 4 4
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
Figure 3-18
3 of 5
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

19. Figure 3-18 4 of 5 DNA RNA polymerase Promoter Triplet 1 1 1 Gene
Codon 1
Gene
Complementary
triplets
Triplet 2 2 2 3
RNA
nucleotide
Triplet 3 3 4
KEY
Triplet 4 4
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
Figure 3-18
4 of 5
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

20. Transcription and Translation
NUCLEUS
The mRNA strand binds to the small ribosomal subunit and is joined at the start codon by the first tRNA, which carries the amino acid methionine. Binding occurs between comple-mentary base pairs of the codon and anticodon.
The small and large ribosomal subunits interlock around the mRNA strand.
mRNA
Amino acid
Small
ribosomal
subunit
tRNA
KEY
KEY
Anticodon
Adenine
Guanine
tRNA binding sites
Cytosine
Uracil (RNA)
Large
ribosomal
subunit
Thymine
Start codon
mRNA strand
A second tRNA arrives at the adjacent binding site of the ribosome. The anticodon of the second tRNA binds to the next mRNA codon.
The first amino acid is detached from its tRNA and is joined to the second amino acid by a peptide bond. The ribosome moves one codon farther along the mRNA strand; the first tRNA detaches as another tRNA arrives.
The chain elongates until the stop codon is reached; the components then separate.
Small ribosomal
subunit
Peptide bond
Completed
polypeptide
Stop
codon
Large
ribosomal
subunit
PLAY
Transcription and Translation
Figure 3-19
6 of 6
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21. The Nucleus
Key Note
Genes are the functional units of DNA that contain the instructions for making one or more proteins. The creation of specific proteins involves multiple enzymes and three types of RNA.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

22. The Cell Life Cycle The Cell Life Cycle Highly Variable
Interphase duration
Mitotic frequency
Figure 3-20

23. The Cell Life Cycle
DNA Replication
Figure 3-21

24. Nucleus Spindle fibers Mitosis begins Chromosome with two
Interphase
Early prophase
Late prophase
Nucleus
Spindle
fibers
Mitosis
begins
Chromosome
with two
sister chromatids
Centrioles
(two pairs)
Centromeres
Metaphase
Anaphase
Telophase
Separation
Daughter
chromosomes
Cytokinesis
Metaphase
plate
Cleavage
furrow
Daughter
cells
Figure 3-22
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25. The Cell Life Cycle Key Note
Mitosis is the separation of duplicated chromosomes into two identical sets and nuclei in the process of somatic cell division.
PLAY
Interphase, Mitosis, and Cytokinesis
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

26. The Cell Life Cycle Cell Division and Cancer Abnormal cell growth
Tumors (also called, neoplasm)
Benign
Encapsulated
Malignant
Invasion
Metastasis
Cancer—Disease that results from a malignant tumor
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

27. The Cell Life Cycle Key Note
Cancer results from mutations that disrupt the control mechanism that regulates cell growth and division. Cancers most often begin where cells are dividing rapidly, because the more chromosomes are copied, the greater the chances of error.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

28. Cell Diversity and Differentiation
Somatic Cells
All have same genes
Some genes inactivate during development
Cells thus become functionally specialized
Specialized cells form distinct tissues
Tissue cells become differentiated
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings