Ch 10 Cell Growth and Division 10.1 Cell Growth, Division, and Reproduction

Limits to Cell Size The larger a cell becomes, the more demands the cell places on its DNA. The larger a cell grows the less efficient in moving nutrients and waste materials across its cell membrane.

DNA Information is used to build the molecules needed for cell growth The bigger the cell- the more the information is needed.

Exchanging Materials Nutrients and wastes pass through cell membrane The greater surface area the more materials that can pass Key is surface area to volume.

Cell Division The splitting of a larger cell into two “daughter” cells Cell makes a second copy of its DNA Reduces cell volume so it increases surface area to volume ratio.

Asexual Reproduction Involves a single parent Produces genetically identical offspring Simple, efficient, and effective to produce many offspring Binary fission and budding.

Good and Bad of Asexual Reproduction Simple Don’t need to find a mate Quick No genetic variability.

Sexual Reproduction Offspring are produced by the fusion of two sex cells one from each of two parents Offspring are genetically different Most animals and plants, and many single-celled organisms.

Good and Bad of Sexual Reproduction Increased variability Generally need two individuals More complex Greater investment.

Ch 10 Cell Growth and Division 10.2 The Process of Cell Division

Chromosomes Carries and passes on genetic information from one generation to another Each cell must copy its genetic information before cell division begins Each daughter cell gets its own copy Different organisms have different number of chromosomes.

Prokaryotic Chromosomes Most prokaryotes contain a single, circular chromosome Located in the cytoplasm (no nucleus).

Eukaryotic Chromosomes Located in the nucleus Made up of chromatin DNA and histone proteins.

Eukaryotic Chromosomes Chromatin is DNA and histone proteins.

Eukaryotic Chromosomes DNA coils around histones to make nuclesome.

Eukaryotic Chromosomes Nucleosomes coil and form supercoils that form chromosomes.

The Prokaryotic Cell Cycle Regular pattern of growth, DNA replication, and cell division Binary fission Asexual reproduction Two genetically identical cells are produced.

The Eukaryotic Cell Cycle G1, S, G2, and M Interphase is G1, S, and G2.

G1 Phase: Cell Growth Cells increase in size and synthesize new proteins and organelles.

S Phase: DNA Replication New DNA is synthesized (chromosomes are replicated).

G2 Phase: Preparing for Cell Division Organelles and molecules are produced.

M Phase: Cell Division Mitosis Cytokinesis Division of the cell nucleus Cytokinesis Division of the cytoplasm.

Cell Structures Involved in Mitosis Chromatid Each strand of a duplicated chromosome Centromere Area where each pair of chromatids is joined Centrioles Tiny structures in cytoplasm of animal cells that help organize the spindle Spindle Fanlike microtubule structure that helps separate the chromatids.

Mitosis Prophase Metaphase Anaphase Telophase.

Prophase Chromosome condense and become visible.

Prophase Chromosome condense and become visible Centrioles move to opposite sides.

Prophase Chromosome condense and become visible Centrioles move to opposite sides The spindle forms.

Prophase Chromosome condense and become visible Centrioles move to opposite sides The spindle forms Nucleolus disappears and nuclear envelope breaks down.

Metaphase Chromosomes line up across the center of the cell.

Metaphase Chromosomes line up across the center of the cell Spindle fibers connect the centromere.

Anaphase The chromatids separate Chromosomes are pulled to opposite ends.

Telophase Chromosomes arrive at poles Nuclear envelope reforms Spindle breaks apart.

Animal Cytokinesis Cell membrane is drawn in until the cytoplasm is pinched into two equal parts containing its own nucleus and organelles.

Plant Cytokinesis Cell plate forms between the divided nuclei Forms into a cell membranes Cell wall created between the membranes.

Ch 10 Cell Growth and Development 10.3 Regulating the Cell Cycle

Controls on Cell Division Controlled by regulatory proteins both inside and outside the cell Can be turned on and off Cells are stimulated to divide rapidly with a broken bone and slow when healing nears completion.

Cyclins Proteins that regulate the timing of the cell cycle.

Regulatory Proteins Internal regulators External regulators Respond to events inside a cell Allow the cell cycle to proceed only once certain processes have occurred External regulators Respond to events outside the cell Direct cells to speed up or slow down the cell cycle.

Regulatory Proteins Growth factors External regulators that stimulate the growth and division of cells Embryonic development and wound healing.

Apoptosis Programmed cell death Plays a role in development in shaping structures- fingers.

Cancer Uncontrolled cell growth Absorbs nutrients needed by other cells, blocks nerve connections, and prevents organs from functioning.

Tumor Mass of cells from uncontrolled growth Benign tumor Noncancerous, does not spread Malignant tumor Cancerous, invades and destroys surrounding tissue Metastasis Spread of cancer cells.

Causes of Cancer Defects in genes that regulate cell growth and division p53 gene defect is common, doesn’t respond to growth signals Normally many defects or mutations are needed Sources of gene defects Smoking tobacco, radiation exposure, defective genes, and viral infection.

Cancer Treatments Tumors can be removed by surgery Tumors treated with targeted radiation Chemotherapy Use of compounds that kill or slow the growth of cancer cells.

The Rise and Fall of Cyclins Scientists measured cyclin levels in clam eggs as the cells went through the cell cycle. The data is shown on the following slide. Cyclins are continually produced and destroyed. Cyclin production signals cells to enter mitosis and their destruction signal cells to enter interphase.

Ch 10 Cell Growth and Division 10.4 Cell Differentiation

All organisms start life as just one cell Embryo Early stage of development most multicellular organisms pass through Cells become more differentiated and specialized.

Differentiation Process of cells becoming specialized.

Cell’s role can be determined at a specific point in development.

Differentiation in Mammals Controlled by a number of interacting factors in the embryo Chemical signals Regulatory factors Interaction between cells Adult cells generally can no longer differentiate.

Stem Cells Unspecialized cells from which differentiated cells develop Totipotent Can form all the tissues of the body Only the fertilized egg and first few divisions

Embryonic Stem Cells Pluripotent Blastocyst Capable of developing into many, but not all, cell types Located in inner mass of cells of blastocyst Blastocyst Early embryo stage with a hollow ball of cells with a cluster of cells inside

Adult Stem Cells Multipotent Can produce many types of differentiated cells Typically produce only the types of cells that are unique to that tissue where they are located.

Potential Benefits Research may lead to new ways to repair the cellular damage that results from heart attack, stroke, and spinal cord injuries.

Ethical Issues Most techniques for harvesting, or gathering, embryonic stem cells cause destruction of the embryo Government funding vs. private funding.

Cellular Differentiation of C. elangans The adult microscopic worm C. elangans contains 959 cells. Copy the data table and then answer the following questions.

Calculate Calculate the percentage of the total cell number reprented by each tissue or organ listed including ‘other’. Infer Why does C. elanans make an ideal model for studying cellular differentiation Infer Why would it be more difficult to map the differentiation patterns in a different organisms like a mammal