eukaryotic cells Flashcards
what is a eukaryotic cell?
- contain a nucleus and other membrane bound organelles
- makes up multicellular organisms
describe the structure of the nucleus
- nuclear pores allow movement of molecule e.g. mRNA
- double membrane called nuclear envelope
- contains chromatin
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
- responsible for producing ribosomes
- composed 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 mitochondira
- site of aerobic respiration
- inner membrane coated in enzymes
- energy stored in bonds of organic molecules
- produces ATP
describe the structure and function of vesicles
- membranous sacs
- single membrane with fluid inside
- transport materials inside the cell
describe the structure and function of lysosomes
- specialised vesicles
- contain hydrolytic enzymes
- break down waste materials
- role in immune system
describe the structure of the cytoskeleton
- network of fibres
- consists of microfilaments, microtubules, intermediate fibres
describe the function of the cytoskeleton
- mechanical strength
- maintain shape and stability
- many organelles bound to cytoskeleton
- microfilaments = cell movement
- microtubules = scaffold-like structure
- intermediate fibres = mechanical strength
describe the structure and function of centrioles
- component of cytoskeleton
- composed of microtubules
- 2 centrioles form centrosome in organising spindle fibres
- animal cells only
describe the structure and function of flagella
- protruding extensions
- enables cell mobility
- detect chemical changes in cell’s environment
describe the structure and function of cilia
- hair like
- stationary = present on cell surface in sensory organelles
- mobile = create a current to move fluid or objects adjacent to cell
- 9+2 microtubules, parallel slide over each other causing beating motion
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 rough endoplasmic reticulum
- ribosomes bound to surface
- synthesis and transport of proteins
- secretory cells have more RER
describe the structure and function of ribosomes
- free floating or attached to rough ER
- not membrane bound
- exits nucleus via pores
- constructed of RNA and proteins
- site of protein synthesis
describe the structure of golgi apparatus
- compact
- folded membranes making cisternae
- secretory vesicles pinch off from cisternae
describe the function of golgi apparatus
- modifies proteins
- packages proteins into vesicles
- form lysosomes
- transport, modify and store lipids
describe the structure and function of cell surface membrane
- composed of lipids and proteins
- regulates movement of substances in and out
- receptor molecules allow it to respond to chemicals
describe the structure and function of cellulose cell wall
- freely permeable
- gives it shape
- keep cell rigid
- defence mechanism
- surrounds cell surface membrane
cell wall pores
- plasmodesmata
- connect two cells by cytoplasm
- enable exchange and transport of substances
describe the structure of chloroplasts
- double membrane
- stroma fluid enclosed
- internal membrane = thylakoids
- several thylakoids = granum
- granum joined by lamellae
- granum contain chlorophyll
describe the function of chloroplasts
- site of photosynthesis
- contain DNA and ribosomes so can make proteins
- found in green parts
organelles involved in protein synthesis
- endoplasmic reticulum
- ribosomes
- golgi apparatus
why do liver cells have so many mitochondria?
to provide sufficient energy to support the metabolic functions so large amount of ATP required
what is the function of nuclear pores?
allows transport of mRNA and nucleotides
