Cell structure - Organelles

Question 1

describe the structure of the nucleus

Answer 1

nucleoplasm contains chromatin (DNA + protein)
nuclear envelope
nuclear pores
nucleolus
outer membrane is continuous with rough ER

Question 2

describe the function of the nucleoplasm

Answer 2

contains DNA that codes for proteins
during cell division chromatin condenses into chromosomes

Question 3

describe the function of the nuclear envelope

Answer 3

double membrane that encloses DNA and keeps it separate from reactions in the cytoplasm

Question 4

describe the function of the nuclear pores

Answer 4

allow entry of molecules for DNA replication
exit of mRNA for protein synthesis

Question 5

describe the function of the nucleolus

Answer 5

manufactures ribosomes

Question 6

why is the outer membrane being continuous with the rough ER useful

Answer 6

allows easy transport of substances

Question 7

describe the structure of the endoplasmic reticulum

Answer 7

cisternae: membrane bound sacs
rough ER: covered with ribosomes
smooth ER: lacks ribosomes

Question 8

describe the function of the cisternae in ER

Answer 8

allow transport within the cell

Question 9

describe the function of the rough ER

Answer 9

synthesise and transport proteins

Question 10

describe the function of the smooth ER

Answer 10

synthesis and transport lipids and steroids

Question 11

describe the structure of the ribosomes

Answer 11

2 subunits made of rRNA and protein

Question 12

where are ribosomes synthesised and how do they leave

Answer 12

synthesised in nucleolus and then pass through the nuclear pores to the cytoplasm or rough ER

Question 13

what are the two types of ribosomes

Answer 13

22nm/80S(eukaryotic cells)
18nm/70S (prokaryotic cells, chloroplasts, mitochondria)

Question 14

describe the function of ribosomes

Answer 14

protein synthesis
binds to and moves along the mRNA and translates it

Question 15

describe the structure of the Golgi apparatus

Answer 15

a stack of flattened membrane bound cavities called cisternae
secretory vesicles

Question 16

describe the function of cisternae in Golgi apparatus

Answer 16

modifies proteins (e.g adds carbohydrates)
packages proteins into secretory vesicles or lysosomes

Question 17

describe the function of the secretory vesicles

Answer 17

produced by Golgi apparatus, will fuse with the cell surface membrane to release hormones or enzymes from the cell (exocytosis)

Question 18

describe the structure of the lysosomes

Answer 18

vesicles which contain hydrolytic enzymes

Question 19

describe the function of the lysosomes

Answer 19

isolate potentially harmful enzymes from the cell
break down material ingested by phagocytes
break down old organelles
break down cells when they die

Question 20

describe the structure of the mitochondria

Answer 20

double membrane
inner membrane folded to form cristae
matrix contains: small ribosomes (18nm/70S), circular DNA, enzymes

Question 21

where are large numbers of mitochondria found

Answer 21

cells requiring lots of energy e.g muscle and liver

Question 22

describe the function of the double membrane in mitochondria

Answer 22

isolates reactions in aerobic respiration (ATP production)

Question 23

describe the function of the inner membrane folded to form cristae

Answer 23

increases surface area for enzymes to be attached

Question 24

describe the function of the small ribosomes in the matrix

Answer 24

protein synthesis

Question 25

describe the function of the circular DNA in the matrix

Answer 25

codes for proteins

Question 26

describe the function of the enzymes in the matrix

Answer 26

for aerobic respiration

Question 27

describe the structure of the chloroplasts

Answer 27

double membrane membrane-bound sacs called thylakoids stacked into grana stroma containing: enzymes, starch grains, small ribosomes, DNA, lipid droplets

Question 28

describe the function of the double membrane in the chloroplast

Answer 28

isolates photosynthesis reactions

Question 29

describe the function of the thylakoids stacked into grana

Answer 29

increases surface area for chlorophyll molecules to be attached

Question 30

describe the function of the enzymes in the stroma

Answer 30

for photosynthetic reactions

Question 31

describe the function of the starch grains in the stroma

Answer 31

carbohydrate store

Question 32

describe the function of the small ribosomes in the stroma

Answer 32

proteins synthesis

Question 33

describe the function of the DNA in the stroma

Answer 33

codes for proteins

Question 34

describe the function of the lipid droplets in the stroma

Answer 34

for membranes

Question 35

give examples of cells containing chloroplasts

Answer 35

palisade, spongy cell, guard cell

Question 36

describe the structure of centrioles

Answer 36

2 centrioles found in all animal cells at right angles to each other, adjacent to the nucleus composed of 9 sets of 3 microtubules

Question 37

where are the centrioles found

Answer 37

algae, animal cells, fungi but NOT plants

Question 38

describe the function of centrioles

Answer 38

form the spindle fibres during nuclear division to control the separation of chromatids and chromosomes

Question 39

which organelle is not membrane bound

Answer 39

ribosome

Question 40

describe the structure of the cytoskeleton

Answer 40

composed of microtubules (fine hollow tubes), microfilaments (small solid protein strands), intermediate filaments (more stable protein strands) (mechanical strength)

Question 41

describe the function of the cytoskeleton

Answer 41

- support cell organelles position - enable movement of organelles e.g vesicles and proteins, RNA (uses ATP) - strengthen cell and maintains shape - allows cell movement e.g phagocytes - allows cell to change shape

Question 42

what are other structures containing microtubules

Answer 42

spindle fibres - separate chromosomes cilia and flagella - movement

Question 43

describe the structure of the cilia and flagella

Answer 43

composed of two central microtubules surrounded by 9 pairs many short threadlike projections = cilia long whip-like projection = flagellum (prokaryotes), undulipodium (eukaryotes e.g sperm)

Question 44

describe the function of microtubules in cilia and flagella

Answer 44

sliding of microtubules brings about movement. this uses ATP

Question 45

describe the function of the cilia

Answer 45

cilia in bronchi and trachea waft mucus towards throat cilia in oviduct waft the ovum towards the uterus

Question 46

describe the function of the flagella and undulipodium

Answer 46

mainly used for movement

Question 47

describe the structure of the vacuole

Answer 47

cell sap contained within the tonoplast (vacuolar membrane)

Question 48

describe the function of the vacuole

Answer 48

maintains turgor for support storage e.g dissolved sugars, mineral ions, pigments, enzymes, amino acids, waste substances (such as tannins)

Question 49

describe the structure of the cell wall

Answer 49

made of cellulose secreted by the living cell rigid and permeable can be modified by lignin can contain pores which are penetrated by plasmodesmata middle lamella (contains pectin)

Question 50

describe the vacuole in plants compared to animals

Answer 50

common, large and permanent in plant cells absent or small and temporary in animal cells

Question 51

describe the function of the cell wall

Answer 51

support and protection allows cells to become turgid which aids in support prevents osmotic bursting of the cell

Question 52

describe the function of the pores in the cell wall

Answer 52

links neighbouring cells

Question 53

describe the function of the middle lamella

Answer 53

cements neighbouring cells together

Question 54

how does the cytoskeleton move organelles around the cell

Answer 54

using microtubules