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
