Chapter 3- From a Cell to an Organism Life Science 7th grade

BELL WORK CH3 L.1 Cell cycle: a cycle of growth, development and division that most cells in an organism go through. Interphase: the period during the cell cycle of a cell’s growth and development. Sister Chromatid:two identical chromosomes that make up a duplicated chromosome. Centromere: a structure that holds sister chromatids together. Mitosis: a process during which the nucleus and its contents divide. Cytokinesis: a process during which the cytoplasm and its contents divide. Daughter cell: the two new cells that result from mitosis and cytokinesis.

Lesson 1: The Cell Cycle and Cell Division What are the phases of the cell cycle? Why is the result of the cell cycle important?

Cell Cycle Cycle of growth, development and division Grow, develop, replace old/damaged cells, produce new cells

Launch lab p.85 (10min) Each person gets half a cell drawing Finish the drawing Add in missing organelles/structures Compare your drawing to your partner’s drawing Why were they different? How did your cell compare to original?

Phases of the Cell Cycle Two phases Interphase Period of cell’s growth and development Mitotic phase Period of cell division Divided in two phases Division of nucleus Division of cytoplasm End result= two identical cells In eukaryotes, usually takes 24 hours to complete cell cycle

Interphase Most of cell’s life in this phase Rapid growth and replication (copying) of organelles Copying DNA Called chromatin Preparing for cell division

Phases of Interphase G1 (longer than other stages) S (synthesis) G2 Period of rapid growth Some cells are stuck in this phase and don’t divide again S (synthesis) Copies DNA (uses energy) DNA coils to form chromosomes Identical chromosomes= sister chromatids Sister chromatids held together by centromere G2 Final period of growth Stores energy to use during mitotic phases Mature nerve cells stuck in G1

Organelle Replication Cell makes copy of organelles before division Each cell gets one copy Copied during all stages of Interphase Mitochondria and Chloroplasts have their own DNA They do their own division

The Mitotic Phase Follows Interphase Two stages Mitosis Nucleus and its contents divide After division, sister chromatids separate and now the individual chromatids are called chromosomes Cytokinesis Cytoplasm and contents divide Organelles divided between daughter cells End result: two identical daughter cells

Prophase Copied chromatin (looks like spaghetti) coils together tightly to form chromosomes Nucleolus disappears Nuclear membrane breaks down Spindle fibers form in cytoplasm

Metaphase Duplicated chromosomes line up in the center of the cell Called metaphase plate Shortest phase in mitosis

Anaphase Sister chromatids separated from each other Spindle fibers pull them apart Now chromatids are identical single stranded chromosomes Cells begin to elongate Ends when identical chromosomes are at opposite ends of the cell

Telophase Spindle fibers disappear Chromosomes uncoil Nuclear membrane forms around chromosomes at opposite ends of the cell End up with two nuclei Reverse of prophase

Results of cell division Two new daughter cells Identical to each other and to parent cell (parent cell doesn’t exist anymore) Reproduction (All clones of each other) Paramecium reproduce this way Growth Fertilized egg into human Replacement Replaces old/worn/damaged cells Skin always rubbing off, need new skin Repair Bone breaks Mature nerve cells stop in G1 phase- never replicate= can’t be repaired ONE STEP UP: CAN YOU THINK OF ANY CELLS THAT DON’T REPLICATE THIS WAY?

Cytokinesis Divides the cell Animal cell: Plant cell: Cell membrane contracts around the middle of the cell Looks like it’s pinching Furrow= crease where membrane contracts Plant cell: Cell wall forms in the middle of the cell Vesicles join together in the middle of the elongated cell to form the cell plate Cell plate grows outward to the cell wall until separates into two cells VIDEO MITOSIS MICROSCOPE SLIDES? HISTOLOGICAL SECTION? 7-12

HOMEWORK Vocabulary words on flash cards Outline Lesson 1 Memorize for quiz Outline Lesson 1 Page 94 (Lesson 1 review) Questions 1-10

BELL WORK CH3 L.2 Cell differentiation: the process by which cells become different types of cells Stem cell: an unspecialized cell that is able to develop into many different cell types Tissue: a group of similar types of cells that work together to carry out specific tasks Organ: a group of different tissues working together to perform a particular job Organ system: a group of organs that work together and perform a specific task

Lesson 2: Levels of Organization How do unicellular and multicellular organisms differ? How does cell differentiation lead to the organization within a multicellular organism?

Life’s Organization Atoms < Molecules < Cell Animals made up of trillions of different cells Cells specialized for function Some organisms are unicellular Atoms combine to form molecules which combine to form cells

Unicellular organisms Only one cell Everything they need for survival is done in only one cell Respond to environment Get food Get rid of waste Reproduce Prokaryote Some live in groups called colonies Some live in extreme environments Eukaryote Algae Fungus WHAT IS A PROKARYOTE? EUKARYOTE?

Multicellular organism Made up of many eukaryotic cells working together Each one has a specific job ONE STEP UP: DO DIFFERENT CELL TYPES WITHIN THE SAME ORGANISM HAVE DIFFERENT DNA IN THE NUCLEUS?

Cell Differentiation All cells in a multicellular organism come from one cell= fertilized egg First cells made can become anything This is the process by which cells become different types of cells Nearly all the cells have identical sets of chromosomes How can have different cell types? Use different parts of the DNA VIDEO

Stem Cells Animal stem cells Plant cells Some cells are unspecialized and they can develop into many different cells Fewer in adults than in embryos Important for repair and replacement Found in bone marrow (can make blood cells) and skeletal muscle (can make muscle cells) Plant cells Unspecialized cells grouped in areas called meristems In tips of roots and stems ONE STEP UP: WHY DO YOU THINK THE MERISTMS ARE LOCATED WHERE THEY ARE?

Tissues Groups of similar types of cells that work together to carry out specific tasks Humans (and most animals) have four kinds: Muscle, nervous tissue, connective tissue and epidermal tissue Plants have three kinds: Dermal tissue, vascular tissue, ground tissue

Human tissues Muscle : Connective tissue: Nervous tissue: Causes movement Connective tissue: Provide structure, support and connections Nervous tissue: Carries messages to/from the brain Epithelial tissue: Forms protective outer layer of skin and lining of major organs and body cavities

Plant tissues Dermal tissue: Vascular tissue: Ground tissue: Protection and reduces water loss Vascular tissue: Transports water and nutrients Ground tissue: Provides storage and support. This is where photosynthesis takes place

Organs Groups of different tissues working together to perform a particular job Example: stomach (has all four kinds of tissues) Example: leaves (has all three kinds of tissues) Dermal covers outer surface of leaf Ground tissue tightly packed on top half of leaf Vascular tissue moves water and food throughout leaf and rest of plant

Organ Systems Groups of different organs that work together to complete a series of tasks Example: human digestive system Stomach, small intestine, large intestine, liver Plants have two major organ systems Shoot system Leaves, stems and flowers Food and water transported throughout the plant by this Root system Anchors the plant and takes in water and nutrients

Organisms Multicellular organisms usually have many organ systems Each organ system depends on the others to function

HOMEWORK Vocabulary words on flash cards Outline Lesson 2 Memorize for quiz Outline Lesson 2 Page 105 (Lesson 2 review) Questions 1-8 Quiz Lesson 1 & 2

Lab: Cell Differentiation Page 106-107 Record findings in science notebook

HOMEWORK Study Guide for Ch3 Extra Credit (Must complete all of it) Vocabulary words Outlines Review questions Extra Credit (Must complete all of it) (+5 points on the Exam) Page 109 Study Guide Page 110-111 Chapter 3 Review Page 112-113 Standardized Test Practice