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

2. 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.

3. 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?

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

5. 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?

6. 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

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

8. 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

9. 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

10. 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

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

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

13. 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

14. 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

15. 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?

16. 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

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

18. 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

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

20. 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

21. 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?

22. 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?

23. 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

24. 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?

25. 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

26. 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

27. 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

28. 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

29. 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

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

31. 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

32. Lab: Cell Differentiation
Page
Record findings in science notebook

33. 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 Chapter 3 Review
Page Standardized Test Practice