Parts of the CellUNIT THREE, LESSON 3.5BY MARGIELENE D. JUDAN

LESSON OUTLINEIntroductionParts of the CellAnimal Cell vs. Plant Cell

Cells are discovered by Robert Hooke after looking at a think slice of cork from an oak tree.

Cells resemble the shape of rectangular rooms.

TRIVIA!An organism as big as a whale has the same cell size as that of an organism as small as an ant. The size of cells is relatively the same in all forms of life.

All cells perform specific functions to sustain life.

Ex. a red blood cell transports oxygen and nutrients to the body

These functions are not performed by the cell alone. Each cell have organelles that perform more specific functions.

All cells are composed of 3 major parts: 1. External

coverings and locomotive organs

2. Cytoplasm3. Nucleus

External Coverings and Locomotive Organs

Cell Wall• Touch and thick

layer composed of cellulose

• Protects and gives support to cell

• Only present in plants and prokaryotes

Plasma membrane• Composed of

phospholipid bilayer• Selectively

permeable• Separates cells

from other cells

The phospholipid bilayerComposed of two layers of phospholipidLike a sandwich (see figure)The head is hydrophilic (loves water) while the tail is hydrophobic (afraid of water). The reason for this structure is that the outside and inside of the cell are composed of water.

The phospholipid bilayerIt is also embedded with proteins and carbohydrates sandwiched between the layers.

The phospholipid bilayerIt acts as a semipermeable membrane (only permits certain kinds of molecules, mainly simple molecules like water and glucose)It doesn’t permit large and complex molecules like starch, however, it can enter the cell via the protein channels with the use of energy.

Flagella and Cilia• Appendages

attached to the plasma membrane; for movement

Flagella and Cilia• The cilia has

absorption properties that help the roots get water and lungs to filter the incoming air.

Cytoplasm and the Organelles

CytoplasmThe cytoplasm is the semisolid, semiliquid, gel-like substance that hold the internal structures of the cell. It also serves as a medium of transport.It holds all the organelles (meaning “little organs”) of the cell.

OrganellesOrganelles are little organs that perform specific functions inside the cell.The endomembrane system refers to the group of organelles that produce and transport substances on the cytoplasm through the use of vesicles.

Mito-chondria“Powerhouse of the Cell”• Sausage-

shaped, also composed of phospholipid bilayer

• Its inner structure is called the matrix, cause its like a maze.

Mito-chondria“Powerhouse of the Cell”

• It produces energy in the form of ATP (adenosine triphosphate) molecules.

Mito-chondria“Powerhouse of the Cell”

• Very small, dot-like structure• Function mainly to

make proteins (it receives instructions via RNA or mRNA produced in the nucleus).

Ribosomes“Protein Factories of the Cell”

• Have two types:1. Free ribosomes

(just floating free in the cytoplasm)

2. Attached ribosomes (mostly in the RER)

Ribosomes“Protein Factories of the Cell”

• Smallest organelle but makes one of the most important molecule for life, proteins.

Ribosomes“Protein Factories of the Cell”

Protein strand in the making

ribosome

• Manufactures various organic compounds• Also serves as a

transport membrane across the cell

Endo-plasmic reticulum“Manufacturer of the Cell”

• Have two types: smooth ER and rough ER.

Endo-plasmic reticulum“Manufacturer of the Cell”

• Called rough because of ribosomes attached.

• Together w/ ribosomes, they produce secretory proteins that are to be transported out of the cell.

Rough Endo-plasmic Reticulum (RER)

• Tube-like structure next to RER

• Has no ribosomes• Functions in

synthesis of lipids, phospholipids, and steroids. (they are all fats)

Smooth Endo-plasmic Reticulum (SER)

• Appears like stack of pancakes• Functions in

transport of molecules made by the ER via transport vesicles.

Golgi Body“Packaging of the Cell”

• Like a packaging office, they modify, sort, pack, and finally ship the molecules outside or inside the cell.

Golgi Body“Packaging of the Cell”

Receiving side

Shipping side

• Transport vesicles are circular containers from the Golgi Body that is used for shipping. It freely moves in and out the cell.

Golgi Body“Packaging of the Cell”

Vesicles

• Small, spherical-shaped

• It produces hydrolytic enzymes called lysozyme that digests and destroys molecules and organelles that are not needed anymore by the cell.

Lysosomes“Waste Disposal of the Cell”

• It protects the cell by destroying foreign substances.

• The molecules to be destroyed are carried by the vesicles.

• Amazingly, it can also destroy the whole cell itself.

Lysosomes“Waste Disposal of the Cell”

• Have oxidative enzymes which breaks down long chains of fatty acids and lipids (fats)• Has a lipid (fat)

bilayer membrane

Peroxi-somes“Waste Disposal of the Cell”

• Rod-like structure• Aids in cell division• During cell division,

they produce fibers to pull the chromosomes to opposite poles of the cell.

Centrioles

The Centrioles in Cell DivisionCentrioles produce spindle fibers that pull away the chromosomes at the end of each pole.It is necessary to pull the chromosomes at both poles because they contain the DNA. Without DNA, life wouldn’t exist. Chromosomes, which contain DNA,

was pulled away by spindle fibers

• Composed of microtubule units

Centrioles

• Provide structural support like bones• Composed of

actin filaments and microtubules

Cyto-skeleton“Framework of the Cell”

• The vacuole functions primarily in the storage of water and dissolved substances

• The vesicles are smaller versions of vesicles, mainly for transport

Vacuole and Vesicles“Water Tank of the Cell”

• Vacuoles are larger in plant cells than in animal cells.

• In plant cells, there is usually a single, central vacuole. In animal cells, there are many small vacuoles scattered in the cytoplasm.

Vacuole and Vesicles“Water Tank of the Cell”

Small vacuole Large vacuole

• Capsule-shaped organelle• Contains

chlorophyll molecules which is the location of photosynthesis

Chloroplasts“Food Manufacturer of the Cell”

• Present only in plant cell and animal autotrophs like planktons.

Chloroplasts“Food Manufacturer of the Cell”

• Dark, spherical-shaped structure

• Stores the genetic code DNA

• Covered by bilipid membrane (like that of plasma membrane) called nuclear envelope

Nucleus“Brain of the Cell”

• Contains a denser, darker sphere in the center called nucleolus.

• The nucleolus contains the RNA that contains the code to make proteins in the ribosomes.

Nucleus“Brain of the Cell”

The next slides are pictures of a real cells. See if you could distinguish the organelles.

Chloroplasts are abundant in plant leaves

PLANT VS. ANIMAL CELLS

Centrioles

Assignment: Answer letter B, p. 120

Group activity tomorrow: Each group will bring a cartolina (any color) and any art materials. You will choose whether to draw the structure of a plant or an animal cell. Then, label the parts. (choose one) You may search the internet for better diagrams of the cell.

Quiz on the first meeting, next week: Pointers: Parts of the Cell Focus your study on Table 2.3, pp. 110-111.

Sources:Science Links 7