Cell Organelles Use this powerpoint to complete the post enrolment ...
Transcript of Cell Organelles Use this powerpoint to complete the post enrolment ...
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