Basic Cell Structure

IntroductionCells help living creatures with activities of life

such as movement, growth, and reproduction

Cell Theory

(Developed after Robert Hooke invented the microscope in 1665)

All living things are made of cells.

Cells are the basic units of structure and function for all living things.

All cells come from cells that already exist.

Microscopes

•Microscopes are instruments to see things that may not be visible to the human eye

•A microscope’s magnification if found by multiplying the powers of the eyepiece and the objective lens

Eyepiece

Objective Lenses

Cell Types

Bacteria

-Once-celled organisms; larger organisms are made of many cells, sometimes TRILLIONS of cells!

Cell Types

Plant Cell

Cell Types

Animal Cell

Plant cell

Cell membrane

•Flexible structure that lies immediately against the cell wall•Made of protein and lipid•Controls everything that goes into and comes out of the cell; selectively permeable

Plant cell

– Made of cellulose – Gives shape to cell– Strong and rigid– Resists entry of

excess water – Support and

protection for cell

Cell wall

Plant cell

Cytoplasm

• Jelly-like substance enclosed by cell membrane• Provide s a medium for chemical reactions to take place

Cell Organelles

•Specialized structures in a cell that are responsible for the various jobs that take place within the cell

•Include, for example, nucleus, mitochondria, endoplasmic reticulum, golgi apparatus, ribosomes, vacuoles, nucleolus, chloroplasts, etc.

Plant cell

Chloroplasts

Contain the green pigment chlorophyll

To trap light energy to make food by photosynthesis

Contain starch grains (products of photosynthesis)

Plant cell

Mitochondrion

•Cellular respiration takes place here – uses oxygen to convert food energy into a form the cell can use •Release energy, carbon dioxide, and waterPOWERHOUSE of the cellActive cells (sperm, liver cells) have more mitochondria

Plant cell

Non-living granules

Starch granulesOil dropletsCrystals of insoluble wastes

Plant cell

Nucleus

Controls the normal activities of the cellBound by a nuclear membraneContains hereditary material called chromosomes

Chromosomes carry genes

Plant cell

Vacuole

Contains cell sapa solution of chemicals (sugars, proteins, mineral salts, wastes, pigments)Stores water, food and wastes

Different kinds of plant cells

Animal cell

No cell wall

No chloroplasts

No large central vacuole

Animal cell

• Endoplasmic Reticulum (ER): Transports materials from place to place in the cell

•Golgi Apparatus:Packages materials before sending them out to other places in the cell

Animal cell• Ribosomes:Some are attached to the ER make proteins

• Nucleolus:Makes RNA/ribosomes

• Lysosomes:Contain digestive enzymes

Different kinds of animal cells

Differences between plant cells and animal cells

Animal cells Plant cells

Relatively smaller

Irregular in size

No cell wall

Vacuole small or absent

Glycogen granules as food store

Nucleus at the centre

Relatively larger

Regular in size

Cell wall present

Large central vacuole

Starch granules as food store

Nucleus near cell wall

Cells Cells in many-celled organisms are specialized in

shape and size for their function– Human specialized cells include fat cells, bone cells,

nerve cells, and muscle cells Fat cells can store so much fat that the nucleus is pressed

against the cell membrane A hard calcium and phosphorus material surrounds bone

cells Nerve cells have many long branches to send and receive

messages Muscle cells have fibers that can contract and relax

– Plant cells in leaves, stems, and roots are specialized to move food and water

Tissue

Cells are grouped together and work as a whole to perform special functions

A group of similar cells to perform a particular job– Animals: epithelial tissue, muscular tissue– Plants: vascular tissue, mesophyll

Organ

Different tissues group together to carry out specialized functions– Heart: consists of muscles, nervous tissue

and blood vessels– Leaf: consists of epidermis, mesophyll and

vascular tissue

Organ System

Several organs and tissues work together to carry out a particular set of functions in a coordinated way– Human: digestive, respiratory, excretory,

circulatory and reproductive systems– Plant: root and shoot systems