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Intro to Cells

Key Concept: Cells are the basic unit of life.

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Introduction to CellsCells are the basic units of organismsCells can only be observed under microscope

Basic types of cells:

Animal Cell Plant Cell Bacterial Cell

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Cell Theory

The cell theory grew out of the work of many scientists and improvements in the microscope.

3 principles of the Cell Theory:

1. The cell is the basic unit of life.

2. All living things are made of cells.

3. All cells are made from other living cells.

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Scientists who contributed to cell theory

• Hooke: first to identify cells & name them

• Leeuwenhoek: developed better lenses for microscope

• Schleiden: said that plants were made of cells

• Schwann: said that animals were made of cells

• Virchow: said that all cells come from other living cells (all cells reproduce)

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All Cells:

• Microscopic

• Enclosed by a membrane

• Filled with cytoplasm

• Have DNA

Bacterium(colored SEM; magnification 8800x)

cell membrane

cytoplasm

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There are 2 types of cells:

1. Prokaryotic Cells

2.Eukaryotic Cells

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� Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organelles (“Pro = no”)

�Eukaryotes include most other cells & have a nucleus and membrane-bound organelles (“Euk has a nuk”)

Cells May be Prokaryotic or Eukaryotic

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Prokaryotes (bacteria)•No nucleus or organelles

•Has a Cell membrane & cell wall

• Contain ribosomes (no membrane) to make proteins in their cytoplasm

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Two Main Types of Eukaryotic Cells

Plant Cell Animal Cell10

Number of CellsOrganisms may be:• Unicellular –composed of one cell (prok & euk)• Multicellular-composed of many cells that are organized (euk only)

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Eukaryotic Cell

Contain 3 basic cell structures:

• Cell Membrane

• Nucleus

• Cytoplasm with organelles

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Basic Structure of a Cell

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• Outer covering of cell

• Made of protein and phospholipids

• Selectively permeable---

Cell membrane

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Controls the normal activities of the cell

Bound by a nuclear membrane (function?)

Contains chromosomes

Nucleus

Each cell has fixed number of chromosomes that carry genes that give the cell its characteristics

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Nucleolus

Inside the nucleus; makes ribosomes16

Jelly-like substance enclosed by cell membrane

Provides a medium for chemical reactions to take place

Cytoplasm

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Organelles

Very small size

Can only be observed under a microscope

Have specific functions

Found throughout cytoplasm

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Organelles Found in ALL Eukaryotic Cells

Examples of Organelles include:

Endoplasmic reticulum, Ribosomes, Nucleolus, Golgi Bodies, Lysosomes, Mitochondria, Vacuoles, Chloroplasts,

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Endoplasmic Reticulum: internal membrane system (“highway”)

Smooth ER lacks ribosomes & makes lipids & carbohydrates

Rough ER has ribosomes on its surface which make proteins to EXPORT

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Ribosomes• Make proteins to be used inside the

cell, while others leave the cell• Some are attached to the Rough ER

while others float freely in the cytoplasm

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Golgi Bodies

Process, Sort, & Deliver proteins

(Modifies/Packages/Transports) 22

Lysosome

digests & gets rid of wastes or foreign materials like bacteria/viruses; recycles

worn-out cell parts

*not found in plant cells*

VESICLES• Small sacs that transport

materials from place to place

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*Rod shape*Site of Cellular respiration*has its own DNA

Mitochondrion( mitochondria )

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*Burn sugars to produce energy (ATP)*Active cells like muscles have more mitochondria

Mitochondria

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Vacuoles• Used to store

food and water• There are

many, small vacuoles in animals cells only; only one large one in plant cells

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Cytoskeleton• Framework/structure of cell• Movement of parts of cell• 2 parts:

– Microtubules—thick tubes; make up centrioles

– Microfilaments—thin tubes; make up cilia & flagella

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Special Cell Structures

• Cilia—short, hair-like projections; used for movement (locomotion)

• Flagella—long, whip-like projection; moves organism/cell in one direction

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Organelles found in PLANT cells

only

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• Contain the green pigment chlorophyll

• Converts light energy into chemical energy (glucose)

• Process called photosynthesis

Chloroplast

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• Have a large central vacuole

• Stores sugars, proteins, minerals, wastes, & pigments

Vacuole

Plant Cell

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• Protects

• Gives shape to cell

• Made of cellulose

– Strong and rigid– Found in plant, fungi, and bacteria

• Freely permeable

Cell wall

Plant Cell

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Organelles found in ANIMAL cells

only

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mitochondrion

nucleus

glycogen

granule

cell

membrane

cytoplasm Animal cell

No cell wall or chloroplastStores glycogen in the cytoplasm for food energy

vacuole

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Animal Cell Organelles

• Help cell divide• Near the nucleus• Paired structures

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Different kinds of plant cells

Onion Epidermal Cells

Root Hair Cell

root hair

Guard Cells

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Different kinds of animal cells

white blood cell

red blood cell

cheek cellssperm

nerve cell

muscle cell

Amoeba

Paramecium 38

Similarities between plant cells and animal cells

Both have a cell membrane surrounding the cytoplasm

Both eukaryotic

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Differences between plant cells and animal cells

Animal cells Plant cells

Relatively smaller in size

Irregular shape

No cell wall

Relatively larger in size

Regular shape

Cell wall present

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Animal cells Plant cells

Vacuole small or absent

Glycogen as food storage

Centrioles present

Large central vacuole

Starch as food storage

Centrioles absent

Differences between Plant Cells and Animal Cells

Cell Song Video

https://www.youtube.com/watch/?v=rABKB5aS

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Animal Cell DiagramLETTER NAME OF ORGANELLE

A CELL MEMBRANE

B CYTOPLASM

C NUCLEUS

D NUCLEOLUS

G RIBOSOMES

H MITOCHONDRIA

I NUCLEAR ENVELOPE OR MEMBRANE

J1 ROUGH ENDOPLASMIC RETICULUM

J2 SMOOTH ENDOPLASMIC RETICULUM

K GOLGI APPARATUS

L LYSOSOME

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Plant Cell DiagramLETTER NAME OF ORGANELLE

A CELL WALL

C CYTOPLASM

E RIBOSOME

F1 ROUGH ENDOPLASMIC RETICULUM

F2 SMOOTH ENDOPLASMIC RETICULUM

G MITOCHONDRIA

H CHLOROPLAST

M GOLGI APPARATUS

N NUCLEUS

J CENTRAL VACUOLE

B CELL MEMBRANE