CELLS: STRUCTURE & FUNCTION

Biology ATAR Unit 2

Text: Chapter 7

Pages 160-163; 175-177

Organelles Cell membrane Cell wall Chloroplast Endoplasmic reticulum Golgi body (apparatus) Lysosome Mitochondria Nucleus Plastid Ribosome Vacuole

Keywords Making connections

Every cell in an organism is connected in some way to every other cell.

Cells make up tissues, tissues make up organs and organs work together as systems.

Cells are the basic unit of life. They are extremely complex machines with many interdependent parts.

Understanding how a cell works is the first step to understanding how organisms function.

LEARNING OUTCOMES

Describe and explain the function of the different organelles

Relate the structure of organelles to their function

Describe and understand the difference between plant and animal cells

CELL THEORY

Cells are the smallest living units of organisms

All cells come from pre-existing cells.

Each organism is made of one or more cells.

CELL STRUCTURE

Cells are made up of the following parts:

Cell membrane the skin Cytosol the fluid Organelles the machines Cytoskeleton the bones

Cytoplasm = cytosol + organelles

CELL STRUCTUREOrganelles are the internal structure of cells.

Cells from all sorts of organisms have at least some, if not all, of these structures.

Cell membrane Endoplasmic reticulum Golgi bodies (apparatus) Mitochondria Nucleus Ribosomes

ANIMAL CELLS Centrioles Lysosomes

PLANT CELLS Cell wall Chloroplasts Vacuoles

CELL MEMBRANE Structure Is a bilayer of

phospholipids molecules enclosing the cytoplasm in all cells

Function It controls the movement

of substances into and out of the cell

It contains receptor proteins that allow it to communicate with other cells

ENDOPLASMIC RETICULUMStructure A network of intracellular

membranes that links with the plasma membrane and other membranous organelles.

Endoplasmic reticulum may be rough (associated with ribosomes) or smooth (lacking ribosomes).

Function It is involved with the

production, processing, transport and storage of materials within the cell.

GOLGI BODIES (GOLGI APPARATUS)

Structure A stack of flat membrane sacs linked to the

endoplasmic reticulum.

Function The golgi bodies package proteins into membrane-

bound vesicles before they are secreted from the cell.

ANIMAL CELLS:LYSOSOMES

Structure Membrane-bound

vesicles containing powerful enzymes

Function The enzymes break

down debris and foreign material

NUCLEUS

Structure The nucleus is a large organelle that is surrounded

by a porous membrane. The nucleus contains genetic material (DNA)

Function The nucleus controls all cellular activity

MITOCHONDRIA

Structure Mitochondria are

composed of many folded layers of membrane

Function The mitochondria are

involved in energy production

RIBOSOMESStructure Tiny organelles located

in the cytosol, sometimes associated with endoplasmic reticulum.

Function They are sites of

production of proteins.

ANIMAL CELLS:CENTRIOLES

Structure A pair of small cylindrical

structures composed of microtubules.

Function They are involved in the

separation of chromosomes during cell division in animal cells and protists. They are not found in plant cells.

PLANT CELLS:CELL WALL

Structure The cell wall is found in plant

cells It is made of cellulose and

surrounds the cell membrane Lignin is present in the cell

wall of the xylem of woody plants to give them further support

Function provides support prevents expansion of the cell allows water and dissolved

substances to pass freely through it

PLANT CELLS:CHLOROPLASTS

Structure Found mostly in plant

leaf cells Contains chlorophyll – a

green pigment that absorbs light energy

Functionphotosynthesis

PLANT CELLS:VACUOLE Structure

A vacuole is found in most plant cells

They may contain food, enzymes and waste products

Function Vacuoles are filled

with fluid and provide physical support

SUMMARY: CELL STRUCTURES

Structure Function

Cell membrane

•Border patrol: controls movement of substances in and out of the cell•Enables chemical communication between cells

Centrioles •Separate chromosomes during cell division (protista and animalia only)

Endoplasmic reticulum

•Processing and transport centre•Rough (+ribosomes) or smooth (-ribosomes)

Golgi bodies •Packaging & export centre – vesicles

Lysosomes •Recycling & waste disposal centre (animalia only)

Mitochondria •Power supply centre

SUMMARY: CELL STRUCTURESStructure Function

Nucleus •DNA – blueprint for building specifications

Ribosomes •Assembly line – manufacture of proteins

Vacuoles •Storage centre – food or enzymes•Support – fluid (plantae)

Contractile vacuole

•Osmoregulation (maintaining fluid balance)•Protists and unicellular algae

PLANT CELLS ALSO CONTAIN:

Cell wall •Structure and support

Chloroplasts •Food manufacturing centre - photosynthesis

Plastids Class of organelles which include:•Chloroplasts•Amyloplasts (starch storage)•Chromoplasts (pigmentation organelles)

CONTRACTILE VACUOLE