Chapter 8 DNA Replication, Binary Fission, and Mitosis World s tallest man Frederic J. Brown/AFP/Getty Images Copyright McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
What are the 2 forms of reproduction? 1) Asexual 2) Sexual Human family: Corbis RF; Amoeba reproducing by binary fission: Carolina Biological Supply Company/Phototake; Mother cat and kittens: Jane Burton/Dorling Kindersley/Getty Images
Two Types of Cell Division Interact in the Sexual Life Cycle Sex cells combine at fertilization.
DNA Replication Precedes Cell Division Semi conservative: ½ old & ½ new Section 8.2 Figure 8.6
The image at right shows a cell s DNA before replication. Which of the following best represents the position of the newly created (red) DNA strands after replication is complete? A. B. Flower: Doug Sherman/Geofile/RF
Binary fission Binary Fission
Why is binary fission an asexual process? A. It occurs only in prokaryotes. B. It does not require DNA replication. C. It produces two identical cells. D. The chromosome is circular. Flower: Doug Sherman/Geofile/RF
Cell Cycle Interphase Mitotic phase (karyokinesis) Prophase Prometaphase Metaphase Anaphase Telophase Cytokinesis
The Cell Cycle What are cells doing when they are not dividing? What phase are the majority of your cells in? What s occurring during G1, S & G2 phases of Interphase? Section 8.5 Figure 8.10
Replicated Chromosomes Condense Before Eukaryotic Cell Division Divide by mitosis Interphase (chromatin, DNA replication) Prophase chromosomes condensed for mitosis Section 8.4 Cell division: Clouds Hill Imaging Ltd./Corbis Figure 8.8
Replicated Chromosomes Condense Before Eukaryotic Cell Division Naked DNA wraps nucleosomes, groups of histone proteins. Section 8.4 Figure 8.9
Replicated Chromosomes Condense Before Eukaryotic Cell Division Chromatin Section 8.4 Figure 8.9
Replicated Chromosomes Condense Before Eukaryotic Cell Division Condensing into a replicated chromosome Section 8.4 Figure 8.9
Interphase G 1 S DNA replication or DNA synthesis G 2
Chromosomes Divide During Mitosis Mitosis is divided into several steps, summarized here and shown in more detail on the following slides. Section 8.5 Figure 8.22
Chromosomes Divide During Mitosis Section 8.5 Animal cells Ed Reschke/Peter Arnold/Getty Images; Plant cells Ed Reschke Figure 8.11
Chromosomes Divide During Mitosis Section 8.5 Animal cells: Ed Reschke/Peter Arnold/Getty Images; Plant cells: Ed Reschke Figure 8.11
Prophase/Prometaphase Early Prophase Longest of mitotic phases Centrioles move to poles Nuclear envelop disappears Nucleolus disappears Late Prophase
Figure 12.5-3 If you could 1 see chromosomes in interphase 2 Chromosomes Centromere Chromosome arm Chromosomal DNA molecules Chromosome duplication (including DNA replication) and condensation Sister chromatids 3 Separation of sister chromatids into two chromosomes
Figure 12.4 Replicated chromosome Centromere Sister chromatids Sister chromatids Centromere 0.5 m
Chromosomes Divide During Mitosis This figure summarizes the changes that occur to one chromosome during a cell cycle. Section 8.5 Figure 8.21
Metaphase Duplicated chromosomes line up Metaphase plate
Anaphase Sister chromatids separate Chromosomes
Telophase & Cytokinesis Nuclear envelop reforms Nucleolus reappears Cell pinches in two Animal cells: Cleavage furrow Plant cells: Cell plate
Cytoplasm Splits in Cytokinesis In an animal cell, the first sign of cytokinesis is the cleavage furrow. Section 8.5 Cleavage furrow: Dr. David M. Phillips/Visuals Unlimited Figure 8.12
Concept Check The diagram represents the cell cycle through time of a eukaryotic organism. During which of the phases of the cell cycle will you copy or replicate your DNA? a) G 1 phase b) S phase c) G 2 phase d) M phase e) Cytokinesis 2012 Pearson Education, Inc.
Concept Check The diagram represents the cell cycle through time of a eukaryotic organism. During which of the phases of the cell cycle will sister chromatids separate? a) G 1 phase b) S phase c) G 2 phase d) M phase e) Cytokinesis 2012 Pearson Education, Inc.
Telophase Animal & Plant
Animal Mitosis
Plant Mitosis
Somatic Cell Nuclear Transfer: Cloning an Adult The nucleus is removed from an unfertilized egg taken from a female. A body cell from the adult animal to be cloned is inserted into the egg. Electrical current is applied to fuse the cells. The nucleus of the animal to be cloned is now the nucleus of the egg. The egg is implanted into a surrogate mother. The surrogate mother gives birth to a clone. Figure 17.16
The Cell Cycle Creates New Cells Complete cell cycle takes 18 24 hours Mitosis and cytokinesis < 1 hr Many cells enter a nondividing state, G 0, either temporarily or permanently Liver cells will divide when stimulated Neurons, osteocytes enter G 0 after adolescence
Asexual Cell Division 1. Growth 2. Repair/replace 3. Regenerate body parts All somatic (body) cells Nerve & muscle Exception: Certain nerve cells
Asexual Cell Division 1. Growth 2. Repair/replace 3. Regenerate body parts 4. Reproduction Budding Fragmentation All somatic (body) cells Nerve & muscle Exception: Certain nerve cells
Factors that influence cell division 1. Growth factors 2. Density dependent inhibition (contact)
Factors that influence cell division 3. Restriction points G 2 checkpoint M checkpoint Figure 17.13 M G 2 G 1 S G 1 checkpoint 4. Cell size
Factors that influence cell division 5. Regulatory proteins cyclical changes
Cancer Arises When Cells Divide Out of Control Chemical checkpoints regulate the cell cycle. Section 8.6 Figure 8.13
Cancer Arises When Cells Divide Out of Control But what if the body loses control of cell division? Section 8.6
Mitosis & Cancer Cancer cells Divide uncontrollably No normal regulation Stimulates angiogenesis Benign tumor Malignant tumor Metastasis Figure 12.20 Tumor Lymph vessel Blood vessel Glandular tissue Cancer cell Metastatic tumor 1 A tumor grows from a single cancer cell. 2 Cancer cells invade neighboring tissue. 3 Cancer cells spread through lymph and blood vessels to other parts of the body. 4 Cancer cells may survive and establish a new tumor in another part
Benign vs malignant tumors capsule benign tumor cancer in situ
How Cancer Develops Mutated or damaged genes Proto-oncogenes Normal regulatory genes Oncogenes Mutated or damaged proto-oncogenes Mutator genes Involved in DNA repair during replication May be mutated themselves and not function Tumor suppressor genes Regulatory genes repress cell growth, division, differentiation, and adhesion May be turned off, damaged, or mutated in cancers
Cancer Arises When Cells Divide Out of Control A tumor is an abnormal mass of tissue. The cells of a tumor divide out of control. Tumors are either benign or malignant. Section 8.6 Figure 8.14
Cancer Arises When Cells Divide Genes and the environment both can increase cancer risk. Out of Control Section 8.6 Figure 8.18
Cancer Arises When Cells Divide Out of Control A tumor may arise from overactive proto-oncogenes or from underactive tumor suppressor genes. No cancer Section 8.6 Figure 8.16
Tumor Suppressors
Tumor Suppressors p53 gene p21 gene BRCA1 BRCA2
Telomeres Repetitive DNA Tips of chromosomes Shorten during division Limit # of divisions
Telomerase Immortalizing enzyme Replaces telomeres Allows for more cell division
Self exams Fig. 20B
Self exams finger pads
Self exams Fig. 20C
8.6 Mastering Concepts What keeps cells from dividing when they are not supposed to? World s tallest man Frederic J. Brown/AFP/Getty Images
Cancer Development
Cancer Development Genetically altered epithelial cell Hyperplasia Cell divides more rapidly than normal Dysplasia Cells change form In situ cancer Cells stay in one place Malignant tumor (cancer) Cancer cells invade normal tissue and enter blood and lymph Metastases form at distant sites Metastases Blood vessel Normal underlying connective or muscle tissue Invasion Figure 18.2
Page 450 Copyright McGraw-Hill Education. Permission required for reproduction or display. malignant tumor
Colon Cancer
Advances in Diagnosis: Early Detection Tumor imaging X-rays Example: mammogram Positron emission tomography (PET) Magnetic resonance imaging (MRI) Genetic testing Identify mutated genes Privacy and treatment issues Enzyme tests for cancer markers Screening large numbers of people
Tumor-Busting Viruses Virotherapy uses scientifically-engineered viruses to target cancer cells.
Tumor-Busting Viruses Tying topics together - Comprehension How do viruses selectively attach to target cells? a) target cells display unique cell-surface receptors b) target cells secrete unique identification proteins c) viruses attach to specific materials engulfed by cells d) viruses are not selective about target cells
Apoptosis Is Programmed Cell Death Apoptosis has two functions: Eliminates excess cells, carving out structures Weeds out aging or defective cells Section 8.7 Syndactyly: Imaginechina/Corbis Figure 8.19