eukaryotic cells Flashcards
what is a eukaryotic cell?
a cell which contains a nucleus and other membrane bound organelles
- makes up multicellular organisms
describe the structure of the nucleus
- nuclear pores allow movement of molecules eg. mRNA
- double membrane forms nuclear envelope
describe the function of the nucleus
- contains genetic info (DNA) which directs protein synthesis
- DNA associates with histone proteins forming chromatin - prevents DNA getting tangled
- controls metabolic processes
describe the nucleolus
- within nucleus
- produces ribosomes
- made of proteins and RNA
describe the structure of mitochondria
- double membrane
- inner membrane folded to form cristae
- fluid interior = matrix
- contains mitochondrial DNA
describe the function of mitochondria
- site of aerobic respiration
- ATP production
describe the structure and function of vesicles
- membranous sacs for storage and transport made of phospholipid bilayer
- contains fluid
describe the structure and function of lysosomes
- specialised vesicles
- contains hydrolytic enzymes
- breaks down waste and pathogens
- important in immune system
state the 3 parts of the cytoskeleton
- microfilaments
- microtubules
- intermediate fibres
describe the structure and function of the cytoskeleton (micofilaments)
- contractile fibres
- formed from actin protein
- movement and contraction during cytokinesis
describe the structure and function of the cytoskeleton (microtubules)
- globular tublin proteins
- polymerise to form tubes
- acts like scaffold structure
- holds shape and allows movement
- composes spindle fibres
describe the structure and function of the cytoskeleton (intermediate fibres)
- mechanical strength
- maintains integrity
summarise the function of the cytoskeleton
- mechanical strength
- allows movement of organelles
- holds shape
- important in composition of spindle fibres and cytokinesis
describe the structure of the endoplasmic reticulum
- network of membranes
- flattened sacs called cisternae
- connected to nucleus
describe the function of the smooth endoplasmic reticulum
lipid and carbohydrate synthesis and storage
describe the function of rough endoplasmic reticulum
- protein synthesis and transport
- ribosomes are bound to the surface
describe the structure and function of the golgi apparatus
- stack of membrane bound cisternae
- modifies and packages proteins into vesicles - eg. changing protein structure or attaching diff. molecules
outline the structure of ribosomes
- free floating or attached to RER
- not surrounded by a membrane
- constructed of RNA made in nucleolus
describe the function of ribosomes
site of protein synthesis
outline the function of vacuoles
- large vesicles
- surrounded by thin membrane
- filled with fluid + molecules it takes in
outline the functions of vacuoles
- membrane-bound (selectively permeable membrane around a permanent vacuole in a plant cell - tonoplast), carry substances
- permanent vacuoles (in plants) - contain cell sap
- temp. food vacuoles - formed from plasma membrane, engulf food and lysosome fuses with it to give it enzymes to digest the food
outline the structure of chloroplasts
- surrounded by an envelope
- within the envelope - internal network of membranes which form flattened sacs - thylakoids
- stacked thylakoids - granum (contain chlorophyll pigments) which are joined together by lamellae
- internal liquid - stroma
- have their own ribosomes (70s) and DNA to produce their own proteins.
outline the function of chloroplasts
the site of photosynthesis
outline the structure of plasma membrane
phospholipid bilayer with various proteins and cholesterol
outline the function of plasma membrane
controls the entry and exit of substances into and out of the cell
outline the structure of cell wall
made of fibrils of cellulose embedded in a matrix of other molecules
outline the function of cell wall
- protects from pathogens
- gives cell its shape
- high tensile strength allows plant cells to become turgid + press against cell wall, making it rigid - supports both cell and the plant
- freely permeable - gaps so important molecules can get thru
- plasmodesmata - connections of cytoplasm through cell walls - allow transport of substances between adjacent cells
outline the structure of centrioles
- component of cytoskeleton
- composed of microtubules (9 sets of 3 microtubules)
outline the function of centrioles
- play a role in positioning of cilia/flagella
- two associated centrioles form a centrosome - involved in assembly and organisation of spindle fibers during cell div
state 4 examples of eukaryotic cells
- erythrocyte
- leukocyte
- oocyte
- hepatocyte
state 2 examples of prokaryotic cells
- e. coli
- streptococcus bacterium
