ultrastructure of eukaryotic cells and prokaryotic cells Flashcards
what is a eukaryotic cell
a cell with a true nucleus and membrane bound organelles
what is a prokaryotic cell
a cell that has no nucleus enclosing DNA and no membrane bound organelles
what are membrane bound organelle
organelles surrounded by their own membrane separating them from the cells contents
what type of microscope can we use to see features of a eukaryotic cell
electron microscope
what is a cytoskeleton
a network of protein structures within the cytoplasm
what does the cytoskeleton consist of
microfilaments, intermediate filaments, tubulin and cytoskeletal motor proteins
what are microfilaments
rod-like subunits of the protein actin. they are polymers of actin and are 7nm in diameter
what is the diameter of intermediate filaments
10nm
what is tubulin
straight, cylindrical microtubules made of protein subunits. they are 20nm in diameter
what are cytoskeletal motor proteins
myosin, kinesin, dyneins which are molecular motors. theyre also enzymes that catalyse the hydrolysis break down of ATP for energy.
what is the function of protein microfilaments
keep the cells shape stable, provide support and mechanical strength and allow cell movement
what is the function of microtubules
provide support and mechanical strength, keep the shape stable and also aid movement of substances through the cytoplasm of the cell
how do microtubles aid movement of substances across the cell through the cytoplasm
makes the track that motor proteins dynein and kinesin walk and drag organelles from one side of the cell to another. form spindle fibres that move chromosomes. make up centrioles, cilia and undilipodia
what is the nuclear envelope
a double membrane that surrounds the nucleus
what does the nucleolus contain
RNA it doesn’t have a membrane around it
what is chromatin
chromatin is a genetic material wound around histone proteins, containing DNA. when the cell isnt dividing chromatin spreads out in the cell but during cell division chromatin coils and condenses into chromosomes
what is the function of nuclear envelope
to separate nucleus contents from the rest of the cell
why do the outer and inner membrane fuse together in some reasons
to allow dissolved substances to diffuse through such as ribosomes
what is the function of nuclear pores
to allow larger substances such as mRNA to leave the nucleus. it also allows substances such as steroid hormones from the cytoplasm to enter the nucleus
whats the function of nucleolus
where ribosomes are made
functions of the nucleus
control centre of the cell
stores the organisms genome
transmits genetic information
provides the intsructions for protein synthesis
what is a rough endoplasmic reticulum (RER)
a system of membranes that contain fluid filled cavities that are consistent with the nuclear membrane. it is coated with ribosomes.
what is the function of the RER
intracellular transporting system. the cisternae create channels that transport substances across the cell. it also provides a large surface area for ribosomes to assemble amino acids into proteins. when these proteins are assembled they are transported via the cisternae to the golgi apparatus.
what is a smooth endoplasmic reticulum
a system of membranes containg fluid filled cavities called cisternae that are continuous to the nuclear membrane. it has no ribosomes on its surface.
what is the function of a smooth endoplasmic reticulum
contain enzymes that catalyses lipid metabolism such as: synthesis of cholesterol, synthesis of lipids/phospholipds,
synthesis of steroid hormones
what is the golgi apparatus
consists of a stack of membrane-bound flattened sacks
what is the function of golgi apparatus
modify, process and package proteins and lipids into vesicles
what is the vacuole
surrounded by a membrane called the tonoplast and contains fluid
what is the function of vacuoles
maintains cell stability as when they are turgid it pushes against the cell wall keeping it up
what are lysosomes
small bags formed by the golgi apparatus. each one has a single membrane. contain powerful digestive enzymes
what is the function of lysosomes
keep the powerful digestive enzymes away from the rest of the cell. lysosomes can engulf old cell organelles and foreign matter and digest them.
what are cilia and undulipodia
these are protrusions from the cell and surrounded by the cell surface membrane. they both contain microtubules and are formed from centrioles
what are the functions of cilia and undulipodia
cilia found in epithelial to move mucus. nearly all cells in body have one cilia it helps the cell detect its immediate environment.
what is the function of ribosomes in protein synthesis
translate instructions of mRNA and assemble the amino acids
describe protein synthesis
the gene that holds the genetic code for a protein such as insulin is transcribed into a length of RNA called mRNA. many copies of this mRNA are formed and they pass out of the nucleus via nuclear pores to the rough endoplasmic reticulum (REM). at the ribosome the instructions are translated and protein molecules are assembled. the protein molecules then pass through the RER’s cisternae and along the hollow sacs. once in the vesicles the proteins are pinched off and pass via the microtubules and motor proteins to the golgi apparatus. the vesicles fuse with the golgi apparatus where the protein molecules are packaged, processed and modified for release. the protein molecules then leave the golgi apparatus via vesicles and travel to the plasma membrane. the vesicle fuses with the plasma membrane and the protein molecule passes outside of the cell.
what are the similarities between eukaryotic cells and prokaryotic cells
they both have cytoplasm, they both have a plasma mebrane, they both have ribosomes for assembling proteins, they both have RNA and DNA
how are prokaryotic cells different to eukaryotic cells
they are much smaller, they don’t have cellulose cell walls but peptidoglycan walls. less developed cytoskeleton with no centrioles, no membrane bound organelles, free floating DNA (nucleoids) with no nucleus. some also have waxy capsuoles, plasmids, pili and flagella
how do prokaryotic cells divide
binary fission
what are bacteria cell walls made of
peptoglycan
what is the process of cell division in yeast called
budding
