Cell Structure Flashcards
What is a eukaryotic cell?
any cell with a membrane bound nucleus
What is the structure and the function of the nucleus?
structure = contained within a double membrane (nuclear envelope) that allows molecules in and out
function = contains coded genetic information in the form of DNA molecules (which is linear and tightly wound around hist one proteins to form chromosomes), controls metabolic activities of the cell.
What is the structure and function of the nucleolus?
structure = composed of RNA and ribosomes
function = responsible for producing ribosomes (by making RNA)
What is the structure and function of ribosomes?
structure = spherical 20nm, free floating or attached to the exterior of the RER
function = sight of protein synthesis (contains the hydrolytic enzyme lysosome)
What is the structure and function of the Rough Endoplasmic Reticulum? (RER)
structure = network of membranes enclosing flattened sac (known as cisternae), folds of membranes that are connected to the outer membrane of the nucleus
function = ribosomes bound to the surface and is responsible for transport and synthesis of proteins
What is the structure and function of the Smooth Endoplasmic Reticulum? (SER)
structure = network of membranes enclosing flattened sac (known as cisternae), folds of membranes that are connected to the outer membrane of the nucleus
function = responsible for lipid and carbohydrate synthesis and storage (makes packages in vesicles)
What is the structure and function of the mitochondrion?
structure = has a double membrane, the inner membrane is highly folded form of structure called cisternae fluid interior (matrix), contains enzymes used for aerobic respiration
function = site of final stage of cellular respiration, where energy is stored in the bonds of complex organic molecules. It is made available for the cell to use by production of ATP (adenosine tri - phosphate)
What is the structure and function of a centrosome?
structure = composed of microtubules (two associated centrioles form the centrosome)
function = the centrosome is involved in the assembly and organisation of the spindle fibres during cell division
What is the structure and function of a vesicle?
structure = single membrane with fluid inside
function = transport material inside the cell
What is the structure and function of a lysosome?
structure = a specialised form of vesicle that contains hydrolytic enzymes
function = breaks down waste material in cells + breaks down pathogens
What is the structure and function of the plasma membrane?
structure = consists of a layer of lipid bilayer that is partially permeable
function = regulates the transport of material entering and exiting the cell
What is the structure and function of the golgi apparatus?
structure = compact structure of cisternae, does NOT contain ribosomes
function = modifies proteins and ‘packages’ them into vesicles. These may be secretary vesicles (if protein is designed to leave the cell) or lysosome (if it stays INSIDE the cell)
What is the structure and function of the cytoskeleton?
structure = consists of…
1. microfilament for cell movement and contraction (during cytokynesis)
2. microtubules - like scaffolding that determines the shape, and acts like a tracer for movement of organelles
3. intermediate fibres - provides mechanical strength to cells and helps maintain integrity
function = necessary for shape and stability of the cell
What is a prokaryotic cell?
Single celled organisms with a simple structure and NO nucleus
What is the structure and function of flagella?
structure = (whip like) used to move the cell, act as a tail
function = enable cell mobility, can be used as a sensory organelle detecting chemical changes in cell’s environment
What is the structure and function of cilia?
structure = (hair like) there are two types stationary and mobile
function = 1. stationary -> usually involved in sensing e.g. the nose
2. mobile -> used to move items e.g. mucus
-> they have two central microtubules and a wheel of microtubes in a pair arrangement (known as 9 + 2 arrangement)
What is the structure and function of chloroplasts?
structure = they have a double membrane structure with fluid inside (called stroma), they have an internal network of membranes (flattened sacs called thylakoids) several stacked to make granum. Pl = grana also contain chlorophyll pigments where photosynthesis takes place
function = where photosynthesis takes place, in a plant cell
What is the structure and function of a cell wall?
structure = made up of cellulose (complex carbohydrate) made through b- glucose. It is freely permeable to allow substances to pass in/out
function = supports both the individual cell and the plant as a whole, protects the contents of the cell from invading pathogens
What is the structure and function of a vacuole?
structure = membrane lined sacs in the cytoplasm containing cell sap, the membrane (tonoplast) is selectively permeable
function = important in the maintenance of turgor so that inside the cell wall (push against it) and keep the cell turgid
What is the prokaryotic cell structure?
- no nucleus = free floating DNA - sometimes plasmid
- different type of ribosomes e.g. smaller 70s ribosomes
- capsule goes around the outside - defence against the host cell
- cell wall made up of peptidoglycan (also known as murein)
- Pilli = increase surface area, some have flagella
What is the average size of prokaryotic cells?
0.1 - 10micro meters
Structure of chloroplast. What are chloroplasts?
Disc - shaped structure, about 1 micro meter wide, 7 micro meters long.
They consist of stacks of thylakoids called grana, where photosynthesis takes place
Structure of chloroplasts. What is tonoplast?
membrane which separates the vacuole from the surrounding cytoplasm, helps maintain turgor pressure
Structure of chloroplasts. What is a vacuole?
Filled with water and solutes (cell sap) which will push against the cell wall when full
Structure of chloroplasts. What is Amyloplast?
A type of colourless plastid called a leucoplast that produces and stores starch with internal membrane compartments
what do plant cells have that animal cells don’t?
cell wall, permanent vacuole, chloroplasts and peroxisomes
what do animal cells have that plant cells don’t?
temporary vacuoles, lysosomes and centrisomes
how is a protein produced and exported?
- a single strand copy of gene is made of rna = mrna
- the mrna leaves the nucleus via a nuclear pore
- travels to a ribosome on the rough endoplasmic reticulum
- the ribosome reads the code on the mrna to build the protein out of amino acids
- protein travels through the cisternae until it reaches the end of the rer
- protein is “pinched off” in a vesicle to travel to the golgi apparatus
- vesicle fuses to the golgi apparatus where is is modified and packaged into another vesicle
this vesicle containing the protein travels to the cell surface membrane - vesicle fuses to the cell surface membrane and is released by exocytosis
where are microtubules located?
forming a network around around the inside of the cell
where are microfilaments located?
concentrated around the outside of the cell
What is the differences in the nuclei of prokaryotic and eukaryotic cells?
Pro = no nucleus
Euk = have a nucleus
What is the difference between prokaryotic and eukaryotic cells’ DNA, and the organisation of the DNA?
Prokaryotic = circular DNA and proteins fold and condensed DNA
Eukaryotic = linear, associated with a protein called histones
What is the difference between cell walls in prokaryotic and eukaryotic cells?
Prokaryotic = peptidoglycan
Eukaryotic = chitin in fungi
= cellulose in plants
= not present in animals
What is the difference in the size of ribosomes in prokaryotic and eukaryotic cells?
prokaryotic = smaller, 70s
eukaryotic = larger, 80s
