cell structure Flashcards
Define the term eukaryotic and prokaryotic cell.
eukaryotic - DNA is contained in a nucleus, contains membrane-bound organelles.
e.g. animal and plant cells.
prokaryotic - small, circular DNA molecule free in the cytoplasm, no membrane bound organelles.
e.g. bacteria.
outline the relationship between cells, tissues, organs and organ systems.
specialised cells - tissues that perform a specific function - organs made of several tissue types - organ systems.
describe the structure of the nucleus.
surrounded by the nuclear envelope, semi-permeable double membrane.
nuclear pores allow substances to enter/exit.
dense nucleolus. (site of rRNA production and makes ribosomes).
describe the function of the nucleus.
contains DNA coiled around chromatin into chromosomes.
site of mRNA production and transcription, and semi-conservative replication.
describe the structure of the mitochondrion.
surrounded by double membrane.
inner membrane forms cristae (site of electron transport chain)
fluid centre = mitochondrial matrix.
loop of mitochondrial DNA.
describe the function of a mitochondrion.
site of aerobic respiration.
site of ATP production.
DNA to code for enzymes needed for respiration.
describe the structure of a chloroplast.
plastid with a double membrane.
contains thylakoids (flattened discs stack to form grana - contain photosystems with chlorophyll)
fluid filled stroma contain enzymes for photosynthesis.
found in plants.
state the function of chloroplasts.
site of photosynthesis to convert solar energy to chemical energy.
describe the structure of the Golgi apparatus.
folded membranes - cisternae.
stack of membrane-bound flattened sacs.
secretory vesicles pinch off of cisternae.
describe the function of the Golgi apparatus.
modifies and packages proteins for transport.
e.g. adding carbohydrates to proteins to form glycoproteins.
synthesises glycoproteins.
once modified, vesicles pinch off modified molecule so it can be transported.
describe the structure of a lysosome.
bags of digestive enzymes.
can contain 50 different enzymes.
describe the function of a lysosome.
hydrolyse phagocytic cells.
completely break down dead cells - autolysis.
exocytosis of digestive enzymes to outside of cell to destroy material.
describe the structure of a ribsome.
small, made up of two sub-units - protein and rRNA.
free in cytoplasm or attached to rough ER.
two different sizes - 80s (eukaryotic) and 70s (prokaryotic, mitochondria and chloroplasts)
describe the function of ribsomes.
site of protein synthesis via translation.
large subunit - joins amino acids.
small subunit - contains mRNA binding site.
describe the structure of the rough endoplasmic reticulum.
folded membranes - cisternae.
many ribosomes attached.
describe the function of the rough endoplasmic reticulum.
protein synthesis.
describe the structure of the smooth endoplasmic reticulum.
folded membranes - cisternae.
no ribosomes.
describe the function of the smooth endoplasmic reticulum.
lipid synthesis.
stores lipids and carbohydrates.
describe the structure of the cell wall.
in plants and fungi cells.
plants:
made of microfibrils of the cellulose polymer.
fungi:
made of chitin, nitrogen-containing polysaccharide.
state the functions of the cell wall.
structural strength to the cell.
physical barrier against pathogens.
describe the structure of the vacuole in plants.
surrounded by single membrane - tonoplast.
filled with cell sap - mineral ions, water, enzymes, soluble pigments.
describe the function of the vacuole in plants.
makes cells turgid - controls turgor pressure.
temporary store of sugars and amino acids.
explain some common cell adaptations.
folded membrane or microvilli - increase surface area e.g. for diffusion.
many mitochondria - large amounts of ATP for active transport.
walls one cell thick - reduce distance of diffusion pathway.
state the structure of plasmids in prokaryotes.
small loops of DNA which only carry a few genes.
