Upload
angelica-smith
View
216
Download
1
Tags:
Embed Size (px)
Citation preview
Cell Division and Gene ExpressionCell Division and Gene Expression
• The Need for Cell Reproduction
- The Nature of Chromosomes
- The Cell Cycle
- Mitosis and Cytokinesis
- Cancer Cells: Abnormal Cell Cycle
• The Expression of Genes as Proteins: DNA gene --> RNA --> Protein
- Transcription by RNA Polymerase
- The Three Types of RNA
- Translation by Ribosome
What Cell Reproduction Accomplishes
• Reproduction
– The birth of new organisms.
– Occurs much more often at the cellular level
Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
• Cell division plays a role in
– The replacement of lost or damaged cells.
– Cell reproduction and growth.
Passing On Genes from Cell to Cell
• Before a parent cell divides, it duplicates its chromosomes.
• The two resulting “daughter” cells are genetically identical, each getting a duplicate set of chromosomes
Cell Division and Gene Expression Cell Division and Gene Expression
• The Need for Cell Reproduction
- Copying Chromosomes
- The Cell Cycle
- Mitosis and Cytokinesis
- Cancer Cells: Abnormal Cell Cycle
• The Expression of Genes as Proteins: DNA gene --> RNA --> Protein
- Transcription by RNA Polymerase
- The Three Types of RNA
- Translation by Ribosome
Types of Reproduction
• Asexual reproduction
– Single cells reproduce by mitosis
– Two daughter cells produced from one parent cell
• Daughter cells are genetically identical to each other
• Daughter cells are genetically identical to the parent cell
• Sexual reproduction
– Single or multi-celled organisms reproduce by meiosis
– Four daughter cells called gametes (eggs and sperm) produced from one parent cell
• Gametes are genetically different from each other and parent cell
• Gametes must unite with other gametes of opposite type to produce viable organism
– Use for growth and repair as well as producing new individuals
– Finding a mate is unnecessary
– Relatively “cheap” energetically
– Used solely for making more individual single or multicellular organisms
– A mate or a second organ for producing other gametes is required
– Relatively “expensive” energetically; lower efficiency in producing offspring
Both Daughter Cells in Mitosis Must Get Chromosomes
12
chromosomes
12
chromosomes
12
chromosomes
?
12 + 12
chromosomes
Duplication (Replication)
DNA Replication (Duplication) Occurs in S Phase of the Cell Cycle
Figure 3.32
AdenineThymineCytosineGuanine Old (template) strand
Two new strands (leading and lagging)synthesized in opposite directions
DNA polymerase
DNA polymerase
Laggingstrand
Leading strand
Free nucleotides
Old strand acts as atemplate for synthesisof new strandChromosome
Helicase unwindsthe double helix andexposes the bases
Old DNA
Replicationfork
DNA Replication is Performed by DNA Polymerase
Cell Division and Gene Expression Cell Division and Gene Expression
• The Need for Cell Reproduction
- The Nature of Chromosomes
- The Cell Cycle
- Mitosis and Cytokinesis
- Cancer Cells: Abnormal Cell Cycle
• The Expression of Genes as Proteins: DNA gene --> RNA --> Protein
- Transcription by RNA Polymerase
- The Three Types of RNA
- Translation by Ribosome
The Cell Cycle
G1
Growth
SGrowth and DNA
synthesis G2
Growth and finalpreparations for
divisionM
G2 checkpoint
G1 checkpoint(restriction point)
>95% of the cells in your body are not progressing through the cell cycle and will never divide
Chromosomes Must Be Condensed or Packaged Before Cell Division
DNA Packing
Cell Division and Gene Expression Cell Division and Gene Expression
• The Need for Cell Reproduction
- The Nature of Chromosomes
- The Cell Cycle
- Mitosis and Cytokinesis
- Cancer Cells: Abnormal Cell Cycle
• The Expression of Genes as Proteins: DNA gene --> RNA --> Protein
- Transcription by RNA Polymerase
- The Three Types of RNA
- Translation by Ribosome
Mitosis Overview
Prophase Metaphase Anaphase Telophase/
Cytokinesis
Mitosis (All Phases)
Animal Mitosis
Sea Urchin (time lapse)
Figure 8.8.1
G2 of Interphase:
• Chromosomes indistinct
• Centrosomes replicate
Mitosis Overview
To M Phase:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase and Cytokinesis
Late Interphase
Figure 8.8.2
1. Chromosomes condense, become visible2. Nuclear membrane dissolves3. Centrioles move to opposite poles, grow fibers
1. Chromosomes line up in a column 90o to spindle
Prophase Prometaphase Metaphase
1. Sister chromatids separate and move towards opposite poles
2. Two nuclear membranes reform
3. Cell divides in half (cytokinesis)
1. Chromosomes unwind (decondense)
Anaphase Telophase
• Cytokinesis
– Typically occurs during telophase.
– Involves contracting microfilaments
Cytokinesis
Cell Splitting in Telophase: Cytokinesis
Mitosis Overview
Prophase Metaphase Anaphase Telophase/
Cytokinesis
Mitosis (All Phases)
Animal Mitosis
Sea Urchin (time lapse)
Cell Division and Gene Expression Cell Division and Gene Expression
• The Need for Cell Reproduction
- The Nature of Chromosomes
- The Cell Cycle
- Mitosis and Cytokinesis
- Cancer Cells: Abnormal Cell Cycle
• The Expression of Genes as Proteins: DNA gene --> RNA --> Protein
- Transcription by RNA Polymerase
- The Three Types of RNA
- Translation by Ribosome
Cancer Cells: Growing Out of Control
• Normal plant and animal cells have a cell cycle control system.
• Cancer is a disease of the cell cycle.
• Cancer cells do not respond normally to the cell cycle control system.
• Cancer cells can form tumors,
– Abnormally growing masses of body cells.
• If a tumor is malignant and metastasizes it can spread to other parts of the body.
Figure 8.10
Breast Cancer
Cell Division and Gene Expression Cell Division and Gene Expression
• The Need for Cell Reproduction
- The Nature of Chromosomes
- The Cell Cycle
- Mitosis and Cytokinesis
- Cancer Cells: Abnormal Cell Cycle
• The Expression of Genes as Proteins: DNA gene --> RNA --> Protein
- Transcription by RNA Polymerase
- The Three Types of RNA
- Translation by Ribosome
Central Dogma of Biology: How Shape and Form Are Dictated By DNA Genes
A segment of DNA (gene)
carries specific coded
instructions for the making
of a single proteins.
Genotype:The genes carried in a cell for a particular trait
Phenotype: The physical expression of genes for a particular trait
Figure 3.34
Nuclearpores
mRNA
Pre-mRNARNA Processing
Transcription
Translation
DNA
Nuclearenvelope
Ribosome
Polypeptide