TOPIC 2: CELLSCells may have different shape.

List the properties of living things

Is a river living organism? Why?

Is a TV living organism? Why?

Is a mushroom living thing? Why?

Metabolism ResponseGrowth

Characteristics of life

Reproduction Nutrition

Excretion

Types of microscopeLight microscope can magnify objects about 1000 times.

Electron microscope (EM): focuses beam of electrons through specimen or onto its surface.

a.Scanning EM: it is used to study of detailed structure of the surface of the cell.b.Transmission EM: is used to study details of internal structure of the cell.

• Scanning electron microscope 580X

• Light microscope • 230X

Different techniques in microscope

Different techniques in microscope

• Transmission electron micrograph 9,375X

• Differential interference contrast micrograph 380X

Organization of LifeArrange the following words from largest

structure to smallest structure:

Atom Protein Plant Cell Molecule Virus

Mitochondria Bacteria Nucleus Long Nerve CellChicken Egg Grain of rice

Cell size and scales

http://learn.genetics.utah.edu/content/begin/cells/scale/

THE CELL THEORY

1. All living things are composed of cells2. The cell is the smallest unit of life3. All cells come from pre-existing cells

HOW CAN WE GROUP CELLS ACCORDING TO THEIR TYPE?

PROKARYOTIC CELLSEUKARYOTIC CELLS

PROKARYOTIC CELL (DEFINITION)- No true nucleus- No membrane-bound organelles- Ex. Bacteria

EUKARYOTIC CELL (DEFINITION)- True nucelus- Membrane bound organelles- Ex. Animal cell, plant cell

• Bacterial colony at the tip of a needle.

CELL MEMBRANE

Parts of PROKARYOTIC CELLS1. Cell membrane

2. Cytoplasm

3. Nucleoid (genetic material)

4. Cell wall

5. Ribosomes

Parts of PROKARYOTIC CELLS6. Capsule

7. Pili

8. Flagella

9. Plasmid

What does the term “bacterial growth” mean?

What are the conditions for bacterial growth?

Is there any bacterium in your body?

Are all bacteria harmfull?

Classification of Bacteria• According to shape

                                    

                                                      

Eukaryotic cellsWhat are these cells?

Is it an animal cell or plant cell? Why? What are the parts that you can identify?

EUKARYOTIC CELLS

1. Cell membrane2. Cytoplasm3. Nucleus4. Ribosomes5. Rough endoplasmic reticulum6. Smooth endoplasmic reticulum7. Golgi apparatus8. Mitochondria

What are the diffreneces between the cell in slide 4 and this cell?

EUKARYOTIC CELLS

Plants Animals9. Cell wall 9. Lysosome10. Chloroplast 10. Centrioles11. Vacuoles 11. Vacuoles12. Cytoskeleton 12. Cytoskeleton

13. Cilia14. Flagella

What does the eukaryotic cell cytoplasm contain? Explain.

• Organelle name:Nucleus• Structure:• Function:

• Label the parts of the nucleus.

Structure: Nucleus is made of double membranes with pores. It contains genetic material (chromatin)

What is the function of the nucleus? to cotrol all cellular activities. E.g: protein synthesis

• Why are there pores on the nuclear membrane? To allow molecules to enter and exit the nucleus. These molecules carry messages to the organelles.

• Define chromatin. It is eukaryotic genetic material which consists of DNA and protein.

• Organelle name: rough endoplasmic reticulum

(rER) and smooth endoplasmic reticulum (sER)

• Structure: It has flattened membranous structure which has ribosome on the membrane.

• Function of rER: produce proteins and transport them to Golgi body.

• Structure-function relation: folded membranes have more surface area, more protein syntheis takes place.

sER

• It produces lipid and transport these proteins to the Golgi body.

• It has role in the synthesis of cell membrane. Why?

• It stores Ca2+ in the muscle cell

Golgi body

• Organelle name: Lysosome• Structure: Membrane bound vesicle.• Function: a. To digest old organelles, harmful chemicals, bacteriab. Autolysis during development of embryo

• Organelle name:• Vacuole• Structure: Mebrane bound

vesicleFunction: a. To store food or

wasteb. To pump out

excess water from fresh water protist cells.

• Organelle name:Mitochondria• Structure: Membrane bound

organelle. It has double membranes, inner membrane has folded structure

• Function: To supply energy

(ATP) to the cell by breaking down of sugar.

• Why is the inner membrane folded?

• Organelle name: Chloroplast• Structure: It has double membranes, It contains chlorophyll(green pigments)• Function: to produce sugar by photosynthesis.• What is photosynthesis? Name the three things which are

used in photosynthesis.

• Name a similarity between nucleus, mitochondrion and chloroplast.

• Do all cells of a plant have chloroplast? Justify your answer.

• Name of the cell part: cell wall

• Structure: cellulose

• Function: to protect cell against water pressure in the plant cell.

• Organelle name: Ribosome• Structure: Has two subunits, made of rRNA and proteins.

• Function: to produce protein• What else do we need to produce protein?

SKELETON OF THE CELL

• Name of the cell part: cytoskeloton

• Structure: protein fiber

• Function: a. to give shape to

animal cells.b. To transport

organelles in the cell.

Muscle fibers for movement

• Organelle name: centrosome

• Structure: protein fibers

• Function: have role in cell division.• They are found only in animal cells.

• Name of the cell part: flagella

• Structure: protein fiber

• Function: movement

HOW CAN WE GROUP ORGANISMS IN TERMS OF CELL NUMBER?

1- Unicellular organisms (one celled organism) Ex. Bacteria and protisits

2- Multicellular organisms (many celled organism) Ex. Plants, animals, fungi

The endosymbiont theory explains the origin of mitochondria and chloroplasts.

• Eukaryotic cells evolved when prokaryotes established residence within other, larger prokaryotes.

• This theory is supported by present-day mitochondria and chloroplasts that

– have structural and molecular similarities to prokaryotic cells and

– replicate and use their own DNA, separate from the nuclear DNA of the cell.

EVOLUTION CONNECTION: Secondary endosymbiosis is the key to much of protist

diversity

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Evolution of eukaryotic cell

Stem cell

It is an unspecialized cell that can produce an identical daughter cell and a more specialized cell that undergoes differentiation.

Stem cells can be used for therapeutic purpuses.

Therapeutic cloning can produce stem cells with great medical potential

When grown in laboratory culture, stem cells can• divide indefinitely and• give rise to many types of differentiated cells.

Adult stem cells can give rise to many, but not all, types of cells.

Embryonic stem cells are considered more promising than adult stem cells for medical applications.

The ultimate aim of therapeutic cloning is to supply cells for the repair of damaged or diseased organs.

© 2012 Pearson Education, Inc.

Embryo /fetus has stem cells (ES). Umblical cord has stem cells. Adult tissues have stem cells . Development of adult

stem cells is limited.

Example: Stem cell from the bone tissue may develop into heart muscle cell, heart muscle and nerve tissue.

© 2012 Pearson Education, Inc.

Figure 11.15

Blood cells

Nerve cells

Heart muscle cells

Different types ofdifferentiated cells

Different cultureconditions

Culturedembryonicstem cells

Adult stemcells in bone

marrow

Cell size surface area volume ratio

• When surface area volume ratio is small, that means surface area of the cell is not enough and cell will divide.

Emergent properties

Group of cells can perform more complex function than a single cell. This property is called emergent property.