2.4 eukaryotic cell structure

what is a eukaryote?

an organism whose DNA is found in a nucleus

what are organelles?

a sub-cellular part or component of a cell

what is the cytoplasm made of?

cytosol which is water, salts, an organic molecules

what is a prokaryotic cell?

single celled organism with a simple structure.

It has a single internal area called the cytoplasm

what’s a eukaryotic cell?

more complex internal structure which contains a membrane bound nucleus and cytoplasm.

It contains many membrane bound organelles

what make up multicellular organisms?

eukaryotic cells

what is the cytoskeleton made of?

• microtubule

• intermediate fibres

• micro filaments

what is the function of the cytoplasm?

the site of many cellular reactions

why is the cytoplasm divided in eukaryotes?

to provide specific environments for the different cellular reactions.

what is the cytoplasm divided into?

many different membrane bound organelles.

what does the nucleus contain?

genetic information as DNA molecules

what does DNA control?

the synthesis of all proteins needed by the cell. Many of these proteins are the enzymes necessary for metabolism

what is the necleolus

an area within the nucleus

what is the nucleolus responsible for?

producing ribosomes

what is the nucleolus made up off

proteins and RNA

what does RNA produce?

ribosomal RNA (rRNA) which combines with proteins to form ribosomes

why is the mitochondria considered an essential organelle to to eukaryotic cells?

it is the site of the final stage of cellular respiration where the energy is released by the production of ATP

what does the number of mitochondria in a cell reflect?

the amount of energy the cell uses. Very active cells have lots of mitochondria

how many membranes does the mitochondria have?

2, double membraned

what is the inside of the mitochondria called?

the matrix

why is the inner membrane of the mitochondria folded?

increase surface area

what are vesicles?

membrane bound sacs

what roles do vesicles have?

usually storage and transport.

what are lysosomes?

special types of vesicles

what do lysosomes contain?

hydrolytic enzymes

what is the hydrolytic enzyme in lysosomes used for?

breaking down waste materials in the cell such as old organelles

how do lysosomes play a part in the immune system?

they are responsible for breaking down pathogens ingested by phagocytic cells

what’s flagella like?

whip like

what’s cilia like?

hair like

what are flagellum used for?

• enable cell motility

• sometimes as sensory organelles to detect chemical change in environment

where is stationary cilia usually found?

surface or sensory cells as as in the nose

where can mobile cilia be found?

lining the trachea

how does mobile cilia work?

beats in a rhythmic manner which creates a current causing fluids or objects to be moved across the surface

where is the cytoskeleton found?

throughout the cytoplasm of all eukaryotic cells

what is the cytoskeleton?

a network of fibres needed to shape and create stability in the cell

what can the cytoskeleton control?

cell movement and the movement of organelles within cells

what are organelles held by?

by the cytoskeleton

what are microfilaments

contractile fibres that are made from protein actin

what are micro filaments responsible for?

cell movement

what are micro tubules

globular tubulin proteins that form tubes that determin s the shape of the cell

what are spindle fibres involved in cell division made from?

microtubules

what do microtubules act as?

act as tracks for the movement of organelles, especially vesicles around the cell

what’s the function of intermediate fibres?

they give mechanical strengths to cells to maintain their integrity

where are centrioles not found?

flowering plants and most fungi

what is centrioles part of?

the cytoskeleton

what are centrioles made of?

microtubules

what are two associated centrioles called?

centrosomes

what is centrosomes involved in?

assembly and organisations of the spindle fibres needed during cell divisions

which components are involved in protein synthesis?

• endoplasmic reticulum

• ribosomes

• golgi apparatus

what is the endoplasmic reticulum

a network of membranes enclosing flattened sacs called cisternae.

what is the endoplasmic reticulum connected too?

the nuclear envelope

what is the smooth endoplasmic reticulum responsible for?

lipids and carbohydrates synthesis and storage

what is the rough endoplasmic reticulum responsible for?

responsible for synthesis and transport of protein

what does the rough endoplasmic reticulum have attached to it?

ribosomes found on its surface

what are ribosomes constructed of?

RNA molecules

what is the ribosomes needed for?

site of protein synthesis (build up of protein)

do ribosomes contain membrane?

no, they do not contain a membrane

structure of golgi apparatus?

compact structure made of cisternae that does not contain ribosomes

what is the role of the golgi apparatus?

modifying proteins and packing them into vesicles

when is a vesicle considered a secretory vesicle?

if the proteins leave the cell

when is a vesicles considered a lysosomes?

if it stays inside the cell

the steps for protein production

1. proteins is synthesised on ribosomes bound on the ER

2. they pass into its cisternae and are packed into transport vesicles

3. the vesicles contain the protein and they move toward the golgi apparatus via the transport function of the cytoskeleton

4. the vesicles fuse with the cis face of the golgi apparatus and the protein enters. The protein are modified before they leave the golgi apparatus via the trans face

5. if the vesicles leave the cell, it moves and fuses with the cell surface membrane and releases its content by exocytosis

is the cell membrane an organelle?

no. it’s not an organelle but a mean for compartmentalisation