CELLS Flashcards
Eukaryotic cells
Make up multicellular rganisms
More complicated structure to prokaryotic
Membrane bound nucleus and cytoplasms
Nucleus( eukaryotes)
Double membrane( nucelar envelope)
Pores in envelope - enable substances to enter
DNA in form of chromatin( DNA wound around histone proteins)
NUCELAR ENVELOPE- protects from damage
DNA- directs protein synthesis
GENETIC material
Nucleolus
Within the nucelus, doesn’t have a membrane, made of RNA and protein
Makes ribosomes
Mitachondria
DOUBLE membrane
Inner membrane HIGHLY folded( cristae and fluid interior matrix)
Contain Loop of DNA
ROD shaped
Site of ATP production
Membrane forming cristae contains enzymes used in respiration
Cell surface membrane
Phospholipid bilayer
Barrier, selectively permeable
Site of cell- cell recognision and recieving cell signals
GOLGI
WIFI
Vesciles on ends of cisternae
Proteins are modified and packaged into vesciles
Pinched off, leave cell or stored
SMOOTH endoplasmic reticulum
System of membranes ( contain fluid filed cavities- cisternae), connected to outer nuclear membrane
ENzymes that catalyse reactions involved with lipid adm carbohydrate synthesis
Storage and transport
ROUGH er
Coated with ribosomes
SYnethsis and transport of proteins- transported to golgi
LYSOSOMES
Specialised vesicles surrounded by single membrane
Hydrolytic enzymes(digestive)
Membranes keep hydrolytic enzyme seperate
Engulf old cell roganelles, waste material and return digested components of cell for resuse
Role in apoptisis
Break down pathogens injested by phagocytic cells
VESicles
Membranous sacks surrounded by a single membrane and fluid inside
Transport materials inside cells and have storage roles
RIBOSOMES
Made of rRNA
Made in nucleus as 2 seperate subunits
Some free in cytoplasm, some on ER, mitochondria, chloroplasts
PROTEIN SYNTHESIS
CYTOSOL
Aqueous proportion of cytoplasm
reactions take place here
Messanger molecules diffuse through
The cytoskeleton
Network of fibres Organelles held in place Controls cell movement and contraction Controls organelle movement Stabilises cell shape Transport within cells Mechanical strength
Microfilaments
Contractile fibres made up of strands of protein actin
responsible for cell movement and contraction during Cytokinesis ( cytoplasm– 2 daughter cells)
Pinched shape- contraction and cytoplasmic streaming
Move against each other e.g. mvoe some organelles
Microtubules
Long, globular tubulin proteins polymerise to form tubes that are used to form a scaffold-like structure that determines cell shape
Microtubues lengthen and shorten by adding or subtracting tubulin
Microtubule shortening moves chromosomes
Interactions between micro tubules drive movement of cells
Microtubule motors
Proteins found on mirotubules
Use ATP
Move chromosomes in mitosis
Intermediate fibres
Give mechanical strength to cells to maintain integrity
Centrioles
Present in most eukaryotes with exception of flowering plant and most fungi
Made of microtubules(9 triplets for each pair of centrioles)
2 centrioles=centrosome, involved in spindle fibre assembly and organisation
Oeganisms with flagella and cilia, centrioles position structures
CELLULOSE CELL WALL
Many cellulose molecules joined together to form fibres, in many different directions, embedded in a matrix
Maintains plant cell shape+support through resisting tugor pressure
Permeable
Plasmodesmata allow direct exhange between plant cells
Defense against pathogens
Vacuole? what is it?
Sac containing cell sap
Important in the maintenance of turgor so teh contents of the cell push against the cell wall and maintain a rigid framework
Membrane is called tonoplast
Functions of teh vacuole
Selectively permeable
Only plant cells have a large permeable vacuole
Maintain cell stability- when full, cytoplasm is pushed against cell wall= turgid
When cells are turgid- helps to support
Chloroplasts
Double membrane
Inner membrane highly folded to provide large SA for reactions
Contain loops of DNA and starch grains
Fluid enclosed in the chloroplast = stoma
Internal network of membranes which form flattered sacks called thylakoids
Several stacked together= granum
Grana joined by membranes called lamellae
SITE OF PHOTOSYNTHESIS
What are prokaryotes
Single celled organisms
Simple structure of just a single undivided internal area called cytoplasm
Unicellular
DNA in prokaryotic cells
One molecule( 1 chromosome) SUpercoiled so its compact Genes on chromosomes are often grouped inot operons, meaning the number of genes are switched on and off at same time Structure same as eukaryotes extra loops of dna called plasmids
Ribosomes in prokaryotic cells
Smaller than prokarytic
Size determined by rate at which they settle in solution
70s
Cell wall of prokaryotes
Peptidogylcan/murein
Amino acids and sugars
Size of ribsoomes in eukaryotes
80S
How do the organelles work together for protein synthesis?
Proteins synthesised on ribsoomes on the ER
Pass into its cisternae and packaged into transport vesciles
Vesicles moved to golgi by cytoskeleton
Vesicles fuse with cis face of golgi and proteins enter
Modified and leave in vesicles form trans face
Leave cell or form lysosomes
FLagellum
Whip like structure Enable cells to move Thinner than cilia Attached to cell membrane of a bacterium by basal body adn rotated by a molecular motor and causes it to rotate giving the filament whip movement Used aw sensory organelles in some cells
Cilia
Mobile(rhythmic creating a current) or stationary(surface of amnu cells and role in sensory organs)
SHort (less than 10um)
Centrioles
Eukaryotes
What is the structure of a cilia /flagellum
9+2 arrangement
2 central microtubules and 9 pairs of microtubiles
parallel micro tubules slide over each other
Size of prokaryote and eukaryote cell
2um
20um
Function of cytoskeleton - inside cell
Chromosomes movment
RNA movement
