organelles

Question 1

what is an organelle

Answer 1

they are to a cell what organs are to a complex organism,they have a defined function

Question 2

what does compartmentalisation mean

Answer 2

separating organelles using cell membrane

Question 3

what is the purpose of compartmentalisation in a cell

Answer 3

to have the correct condition for each organelle e.g.pH levels

Question 4

how does an electron microscope work

Answer 4

uses a beam of electrons to create an image of the specimen

Question 5

advantages of electron microscopes

Answer 5

greater resolving power and higher magnification

Question 6

disadvantages of electron microscopes

Answer 6

needs a specially designed room and training to operate them - expensive -

Question 7

describe the structure and function of the nucleus

Answer 7

bounded by two membranes which together make the nuclear envelopehas pores to allow mRNA to pass throughgranular material in the nucleus is nucleoplasm. it contains chromatin made of coils of DNAthe nucleolus is within the nucleus

Question 8

describe the structure and function of the nucleolus

Answer 8

spherical bodysites of formation of rRNA a constituent of ribosomesdarker heterochromatin - made from densely packed DNAlighter euchromatin - less dense, DNA acts as a template for RNA synthesis

Question 9

describe the structure and function of rough endoplasmic reticulum

Answer 9

is an elaborate system of parallel double membrane forming interconnected flattened sacs called cisternaehas ribosomes on the outer surface which is what gives it a rough look. present in large amounts in cells that make proteinsribosomes transport the proteins made

Question 10

describe the structure and function of the ribosomes

Answer 10

made up of two subunits - a small and a large onethey are the ‘protein builders’ of the cellfound floating in the cytoplasm or attached to rERinvolved in protein synthesis

Question 11

describe the structure and function of the golgi body

Answer 11

stack of flattened double membrane sacs called cisternaesurrounded by spherical membranes called vesicles involved ni the modification of proteinspackage proteins into vesiclesbuilds lysosomes

Question 12

describe the structure and function of lysosome

Answer 12

spherical vesicle containing enzymes made by the golgi body pinching off a small specific vesicleinvolved in digesting material that enters the cell

Question 13

describe the function and structure of the centriole

Answer 13

help the cell in mitosis and meiosis groups of threads attached called mitotic spindle made of microtubules go to poles of nucleus when cell is dividing

Question 14

describe the structure and functions of cilia and flagella

Answer 14

cilia — 9 pairs of microtubules around edge and 2 in centrehair like organelles that line surfaces of cells and beat in rhythmic wavesflagella — ‘organ’ of movement need liquid environment to move

Question 15

describe the structure and function of cell membrane

Answer 15

proteins and phospholipids make up the membranemembrane is made up of 3 ‘bands’ which can be seen as a lighter band sandwiched between two dark onescontrol movement in and out

Question 16

describe the structure and function of mitochondrion

Answer 16

has an inner and outer membrane inner membrane layers fold over to form cristae and improve surface area matrix pattern of inner membrane containing ribosomes and circular DNAcellular respiration - keep the cell full of energy muscle cells have lots of mitochondria

Question 17

describe the structure and function of chloroplasts

Answer 17

outer and inner membrane containing starch/sugars, stroma and thykaloid stacks or granaproduce food for the cell chlorophyll is on the surface of each thykaloid stack to capture light thykaloid stacks are held together by storm lamellae which keep the stacks a safe distance away and increases efficiencystroma - where carbon is fixed and sugars are synthesisedchlorophyll - common structure called porphyrin ring

Question 18

what does magnification mean

Answer 18

the degree to which the size of an image is larger than the image itself

Question 19

what does resolution mean

Answer 19

the degree to which it is possible to distinguish between two objects that are very close together

Question 20

how can you work out the actual size of a specimen

Answer 20

magnified size/ magnification x actual size

Question 21

how can you convert between a)cm to mm b) mm to micrometres c) micrometres to nanometres

Answer 21

a) x10b) x 1000c) x 1000

Question 22

describe the process of protein trafficking

Answer 22

protein synthesised of ribosome of ERprotein enters the cisternae of the RERprotein is folded into a 3d shapevesicles containing protein pinch of the ERvesicles travel to golgi body vesicles fuse with golgi bodyprotein is modified vesicles pinch off golgi body vesicles move to cell membrane and fusecontents of vesicle is released

Question 23

what is exocytosis

Answer 23

vesicles move to cell membrane and use with it to become part of the membrane, contents leave vesicle

Question 24

what is an organelle

Answer 24

they are to a cell what organs are to a complex organism,they have a defined function