Cell Structure

Question 1

What is a eukaryotic cell?

Answer 1

any cell with a membrane bound nucleus

Question 2

What is the structure and the function of the nucleus?

Answer 2

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.

Question 3

What is the structure and function of the nucleolus?

Answer 3

structure = composed of RNA and ribosomes

function = responsible for producing ribosomes (by making RNA)

Question 4

What is the structure and function of ribosomes?

Answer 4

structure = spherical 20nm, free floating or attached to the exterior of the RER

function = sight of protein synthesis (contains the hydrolytic enzyme lysosome)

Question 5

What is the structure and function of the Rough Endoplasmic Reticulum? (RER)

Answer 5

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

Question 6

What is the structure and function of the Smooth Endoplasmic Reticulum? (SER)

Answer 6

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)

Question 7

What is the structure and function of the mitochondrion?

Answer 7

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)

Question 8

What is the structure and function of a centrosome?

Answer 8

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

Question 9

What is the structure and function of a vesicle?

Answer 9

structure = single membrane with fluid inside

function = transport material inside the cell

Question 10

What is the structure and function of a lysosome?

Answer 10

structure = a specialised form of vesicle that contains hydrolytic enzymes

function = breaks down waste material in cells + breaks down pathogens

Question 11

What is the structure and function of the plasma membrane?

Answer 11

structure = consists of a layer of lipid bilayer that is partially permeable

function = regulates the transport of material entering and exiting the cell

Question 12

What is the structure and function of the golgi apparatus?

Answer 12

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)

Question 13

What is the structure and function of the cytoskeleton?

Answer 13

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

Question 14

What is a prokaryotic cell?

Answer 14

Single celled organisms with a simple structure and NO nucleus

Question 15

What is the structure and function of flagella?

Answer 15

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

Question 16

What is the structure and function of cilia?

Answer 16

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)

Question 17

What is the structure and function of chloroplasts?

Answer 17

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

Question 18

What is the structure and function of a cell wall?

Answer 18

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

Question 19

What is the structure and function of a vacuole?

Answer 19

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

Question 20

What is the prokaryotic cell structure?

Answer 20

1. no nucleus = free floating DNA - sometimes plasmid
2. different type of ribosomes e.g. smaller 70s ribosomes
3. capsule goes around the outside - defence against the host cell
4. cell wall made up of peptidoglycan (also known as murein)
5. Pilli = increase surface area, some have flagella

Question 21

What is the average size of prokaryotic cells?

Answer 21

0.1 - 10micro meters

Question 22

Structure of chloroplast. What are chloroplasts?

Answer 22

Disc - shaped structure, about 1 micro meter wide, 7 micro meters long.
They consist of stacks of thylakoids called grana, where photosynthesis takes place

Question 23

Structure of chloroplasts. What is tonoplast?

Answer 23

membrane which separates the vacuole from the surrounding cytoplasm, helps maintain turgor pressure

Question 24

Structure of chloroplasts. What is a vacuole?

Answer 24

Filled with water and solutes (cell sap) which will push against the cell wall when full

Question 25

Structure of chloroplasts. What is Amyloplast?

Answer 25

A type of colourless plastid called a leucoplast that produces and stores starch with internal membrane compartments

Question 26

what do plant cells have that animal cells don’t?

Answer 26

cell wall, permanent vacuole, chloroplasts and peroxisomes

Question 27

what do animal cells have that plant cells don’t?

Answer 27

temporary vacuoles, lysosomes and centrisomes

Question 28

how is a protein produced and exported?

Answer 28

• 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

Question 29

where are microtubules located?

Answer 29

forming a network around around the inside of the cell

Question 30

where are microfilaments located?

Answer 30

concentrated around the outside of the cell