Chapter 9 Cellular Basis of Inheritance 9 1

Chapter 9: Cellular Basis of Inheritance

9. 1 All Cells Come From Cells

Why do cells reproduce? n n n 1. Replace dead and worn-out cells 2. Add new cells=growth 3. Reproduction of new organisms (to continue species)

Intro to Cell Reproduction

2 Types of Cell Reproduction n n Sexual Asexual

Asexual Reproduction

Asexual Reproduction n n Used in unicellular organisms Offspring identical to parents Ex: Paramecium Some multicellular organisms can reproduce asexually!

Sexual Reproduction

Sexual Reproduction n n 2 parents involved Genetic material comes from each Occurs with a special form of cell reproduction New cells are NOT identical to parent cells

Vocab in 9. 1 n n Asexual Reproduction Sexual Reproduction

Concept 9. 2 The Cell Cycle Multiplies Cells

Chromosomes & Cell Division n n n Genetic info is carried on chromosomes Chromatin is long and thin, not visible Chromosomes are short, thick & visible BEFORE cell division each chromosome is copied 2 copies=sister chromatids Centromere= holds copies together

Cell Cycle

Cell Cycle n n Length depends on cell type Some cells don’t divide… Begins with “birth” of cell 2 Phases n n Interphase Mitotic Phase

Interphase

Interphase n n 90% of cell cycle time Performs daily functions Prepares for cell division Broken into 3 parts: n n n G 1= Gap 1; growth and replication S= Synthesis; DNA duplicates G 2= Gap 2; final preparations

Mitotic Phase

Mitotic Phase n n When cell is actual dividing 2 Phases n n Mitosis=division of the nucleus Cytokinesis= division of everything outside nucleus Produces 2 identical cells Very accurate!

9. 2 Vocab n n Chromatin Chromosome Centromere Sister chromatids n n Interphase Mitosis cytokinesis Cell cycle

Concept 9. 3 Cells Divide During Mitotic Phase

Remember… n n n DNA has already copied Mitosis is a continual process Broken into 4 Stages

Mitosis-Preview

Prophase

Prophase n n Chromatin becomes chromosomes=visible Nucleolus disappears Nuclear membrane disappears Spindle fibers form

Metaphase

Metaphase n n Chromatids attach to spindle fibers Chromatics move to line up in center

Anaphase n n n Sister chromatids separate from each other Each chromatid is now a chromosome Chromosomes move to poles

Telophase n n Chromosomes reach poles Reverse of Prophase n n Spindle disappears 2 nuclear membranes form Chromosomes uncoil to chromatin Nucleolus reappear

Cytokinesis n n Division of cytoplasm and contents Usually occurs along with telophase

Cytokinesis in Plant vs. Animal n 1 st sign is indentation in cell membrane n Plant n n Can’t pinch so… New cell wall (cell plate) forms from center out

9. 3 Vocab n n n Spindle Centrosomes Centrioles Prophase metaphase n n Anaphase Telophase Cytokinesis Cell plate

Cell Cycle & Mitosis Review

Concept 9. 4 Cancer cells grow and divide out of control…

Cancer…

Tumors and Cancer n Tumor= large mass of cells n Benign tumor= consists of normal cells Surgery is an option n Location may cause health problems n n Malignant tumor= consists of cancer cells Cancer= cells who’ve lost control of cell cycle n Can lead to death n Replace normal cells as they grow n n Metastasis=cells break off and relocate

Cancer Treatment n n Surgery= remove cancerous cells Radiation= high energy radiation interrupts cell division Chemotherapy= uses drugs to stop cell cycle Last 2 have undesirable side effects

Vocab 9. 4 n n Benign tumor Malignant tumor Cancer Metastasis