Cell Organelles Use this powerpoint to complete the

post enrolment homework.

Nucleus

Function • Nucleus- Carries the DNA

code for amino acid sequences (which forms proteins)

• Nuclear envelope-Separates the genetic material from the cytoplasm

• Nuclear pore- Allows transport of mRNA

• Nucleolus- Synthesis of ribosomes

Ribosomes

Structure • Consists of 2 subunits

made from ribosomal RNA (rRNA) and protein – Large subunit – Small subunit

• Can be free or attached to rough endoplasmic reticulum (RER)

Function Protein synthesis

Rough Endoplasmic reticulum Structure • Forms a system of flattened

sacs (cisternae) which are continuous with the nuclear membrane and may link to the Golgi apparatus

• RER has ribosomes attached Function • Transports proteins which are

synthesised by the ribosomes attached.

Fact Cells which secrete large

amounts of enzymes have a larger amount of

RER

Smooth Endoplasmic reticulum Structure • Forms a system of

flattened sacs (cisternae) which are continuous with the nuclear membrane and may link to the Golgi apparatus

• Has NO ribosomes attached

Function • The synthesis and

transport of lipids

Golgi Body/ apparatus Structure • Is a similar structure to ER

however is more compact. • Surrounded by vesicles. Functions • Vesicles transport proteins to the

Golgi body to be modified and packaged

• The modified proteins are then packaged into vesicles to be transport around the cell or out of the cell (exocytosis)

Other functions • Transporting and storing lipids • Forming lysosomes

Mitochondria Structure • Rod shaped and 1-10μm diameter • Has a double membrane, the inner and

outer membranes • The membranes are separated by a narrow

fluid filled inter membrane space. • The inner membrane is folded to form

structures called cristae • The interior of the mitochondrion is called

the matrix and contains enzymes • Contains DNA and ribosomes Function • The site of aerobic respiration to release

energy in the form of ATP • The cristae increase the surface area on

which part of the respiratory process takes place

Fact Cells with high metabolic

activity contain many mitochondria

Vacuoles (vesicles) Animals

Structure • Small membrane bound

organelle Function • Act as a contractile vacuole to

maintain osmotic pressure.

Plants Structure • Large membrane bound organelle surrounded by a tonoplast Function • Storage of ions and organic

molecules e.g. proteins and maintaining osmotic pressure

Centrioles

Structure • Consists of two hollow cylinders positioned at right angles to one another Function • Are used in spindle formation (microtubles) in cell division.

Fact Found in all animal cells

and most protoctists BUT are NOT found in the cells of higher plants

Lysosomes Structure • 1.0 um in diameter • Small vacuoles formed when small

portions of the Golgi body are pinched off.

Function • They contain and isolate digestive

enzymes • They can release these enzymes

and destroy organelles • Digestion of material which has

been taken into the cell • e.g white blood cells engulf

bacteria by phagocytosis and the lysosomes are used in the digestion of the bacterium.

Chloroplast Structure •2-10um in diameter and 1 um thick •Have a double membrane •The interior is made up of a fluid called stroma, ribosomes, lipids , circular DNA and starch granules. •In addition there are thylakoids- flattened sacs, these form stacks which are called granum. Each granum consists of between 2-100 thylakoids. Between the grana the thylaskoids form lamellae Function •Site of photosynthesis •The thylakoids contain photosynthetic pigments such as chlorophyll

Cellulose Cell Wall

Structure • Made of cellulose

microfibrils in a polysaccharide matrix

Function • To provide strength and

support • Freely permeable to

water

Plasmodesmata Structure • A narrow thread of

cytoplasm that passes through the cell walls of adjacent plant cells

Function • Exchange of large organic

materials via cytoplasmic streaming

• Allows communication between adjacent cells