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 called nuclear envelope
describe the function of the nucleus
- contains genetic info (DNA) which directs protein synthesis
- DNA associates with histone proteins to form chromatin which prevents the 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
- respiration occurs
- energy is stored in bonds of organic molecules
- cristae has an increased surface area for respiration
- contains enzymes
- produces ATP
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 (microfilaments)
- 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 smooth endoplasmic reticulum
lipid and carbohydrate synthesis and storage
describe the function of the rough endoplasmic reticulum
protein synthesis and transport
describe the structure and function of ribosomes
- free in cytoplasm or attached to RER
- not membrane bound
- exits nucleus via pores
- constructed of rRNA and proteins
- site of protein synthesis
describe the structure and function of golgi apparatus
- network of membranes
- compact
- formed from cisternae
- modifies proteins
- packages proteins into vesicles
describe the structure and function of centrioles
- part of cytoskeleton
- composed of microtubules
- 2 centrioles form centrosome in organising spindle fibres
describe the structure and function of flagella
- whip like structure
- enables cell movement
- detects chemical change in cell’s environment
describe the structure and function of cilia
- hair like structure
- stationary = present on cell surface in sensory organs
- mobile = creates a current to move fluid/objects adjacent to cell
- each cilium contains 9 +/- 2 microtubules where parallel pairs slide over each other to create a beating motion
describe the structure and function of the cell surface membrane
- composed of lipids and proteins
- regulates movement of substances in and out
- receptor molecules allow it to respond to chemicals
describe how a cell moves
- depends on actin filament activity
- filament lengths change when subunits are added
- subunits change shape before being added to the minus end of the filament
- subunit concentration in cytoplasm determine whether they are added to the filament
describe the structure and function of a cellulose cell wall
- surrounds cell surface membrane
- keeps cell rigid
- freely permeable
- protects against pathogens
describe the structure and function of the permeable vacuole
- membrane lined sacs
- selectively permeable membrane (tonoplast)
- contains cell sap
describe the structure of chloroplasts
- double membrane
- stroma fluid enclosed
- thylakoids = internal membrane
- granum = stacked thylakoids
- granum contains chlorophyll pigment
- granum joined by lamellae
- starch produced in photosynthesis present as grains
describe the function of chloroplasts
- site of photosynthesis
- contains DNA and ribosomes so can make proteins
what is the function of nuclear pores?
allows transport of mRNA and nucleotides
why do liver cells have many mitochondria?
to provide sufficient energy to support the metabolic functions so large amount of ATP required
why might images of chloroplasts appear different?
if they are cut at different angles
