3.2.1.1 - structure of eukaryotic cells

Question 1

what happens in complex multicellular organisms?

Answer 1

Eukaryotic cells become specialised for specific functions. The specialised cells are organised into tissues, the tissues into organs and the organs into systems.

Question 2

cell-surface membrane - structure?

Answer 2

• found in all cells
• phospholipid bilayer with molecules embedded within and attahced on the outside (proteins, carbohydrates, cholesterol)

Question 3

cell-surface membrane - function?

Answer 3

controls the entrance and exit of molecules from cells

Question 4

nucleus - function?

Answer 4

• site of DNA replication and transcription to make mRNA
• contains the genetic code for each cell
• site of ribosome formation

Question 5

structure of nucleus - nucleoplasm?

Answer 5

granular, jelly-like material which contains nucleotides and enzymes needed for DNA/RNA synthesis

Question 6

structure of nucleus - nuclear envelope?

Answer 6

double membrane surrounding it made of two phospholipid bilayers (outer membrane continuous with endoplasmic reticulum), controls movement of materials and contains reactions

Question 7

structure of nucleus - nuclear pores?

Answer 7

allow passage of large molecules like ribosomes and mRNA out of nucleus, also means steroids and hormones can get in

Question 8

structure of nucleus - chromosomes?

Answer 8

lengths of protein-bound, linear DNA (DNA is tightly coiled so lots can be stored)

Question 9

structure of nucleus - nucleolus?

Answer 9

smaller sphere which is the site of rRNA production and makes ribosomes

Question 10

mitochondria - function?

Answer 10

site of aerobic respiration and ATP production

Question 11

structure of mitochondria - matrix?

Answer 11

fluid centre

Question 12

structure of mitochondria - cristae?

Answer 12

folded inner membrane which creates large surface area

Question 13

structure of mitochondria - mitochondrial DNA?

Answer 13

allows mitochondria to self-replicate so more can be made if cell’s energy needs to increase

Question 14

chloroplast - function?

Answer 14

site of photosynthesis in plants and algae

Question 15

structure of chloroplast - double membrane?

Answer 15

controls which molecules enter and leave

Question 16

structure of chloroplast - thylakoids?

Answer 16

folded membranes embedded with chlorophyll pigment

Question 17

structure of chloroplast - granum?

Answer 17

stacks of thylakoids which are site of light-dependent reactions

Question 18

structure of chloroplast - lamellae?

Answer 18

flat, thin parts of thylakoid membrane which join grana together so chemicals can pass between

Question 19

structure of chloroplast - stroma?

Answer 19

fluid-filled centre containing enzymes for photosynthesis

Question 20

structure of chloroplast - starch granules?

Answer 20

place for storing glucose produced in photosynthesis

Question 21

adaptions of chloroplasts?

Answer 21

grana create large surface area for light absorption, fluid of stroma contains enzymes for reaction, chloroplasts have DNA and ribosomes for quickly manufacturing proteins

Question 22

structure of Golgi apparatus?

Answer 22

• folded membranes (cisternae)
• secretory vesicles which pinch off from the cisternae

Question 23

function of Golgi apparatus?

Answer 23

• adds carbohydrates to proteins to form glycoproteins
• produces secretory enzymes
• secretes carbohydrates
• transports, modifies and stores lipids
• forms lysosomes
• ‘labels’ molecules with their destination
• finished molecules transported to cell-surface in Golgi vesicles where they fuse with the membrane and the contents are released

Question 24

function of lysosomes?

Answer 24

• hydrolyse phagocytic cells
• completely break down dead cells (autolysis)
• release enzymes to the outside of cells to destroy material (exocytosis)
• digest worn-out organelles for reuse of materials

Question 25

what are lysozymes?

Answer 25

hydrolytic enzymes found in lysosomes

Question 26

lysosomes - structure?

Answer 26

bags of digestive enzymes

Question 27

ribosomes - structure?

Answer 27

* small * made up of two protein sub-units and rRNA * large ribosomes (80s) found in eukaryotic cells * small ribosomes (70s) found in prokaryotic cells, mitochondria and chloroplasts

Question 28

ribosomes - function?

Answer 28

* site of protein synthesis * cytoplasm - proteins used inside cell * RER - proteins used outside cell

Question 29

function of rough endoplasmic reticulum?

Answer 29

produces and transports proteins (protein synthesis)

Question 30

structure of RER?

Answer 30

folded membranes called cisternae with ribosomes bound to cisternae

Question 31

structure and function of smooth endoplasmic reticulum?

Answer 31

cisternae with no ribosomes, produce, store and transport lipids which can be modified in Golgi apparatus

Question 32

function of cell wall?

Answer 32

provides structural strength to the cell

Question 33

structure of cell wall - middle lamella?

Answer 33

layer of material between plant cells made of polysaccharides, calcium and magnesium ions which acts as glue between cells

Question 34

structure of cell wall - plants/algae?

Answer 34

contain polysaccharide cellulose

Question 35

structure of cell wall - fungi?

Answer 35

made of polysaccharide chitin

Question 36

function of vacuoles?

Answer 36

* large, permanent vesicles in plant cells * makes cells turgid therefore providing support * temporary store of sugars and amino acids * pigments may colour petals to attract pollinators or contain chemicals to deter herbivores

Question 37

structure of vacuoles - tonoplast?

Answer 37

single membrane which surrounds plant cell vacuoles, helps control which chemicals enter and leave vacuole

Question 38

structure of vacuoles - cell sap?

Answer 38

weak solution of salts and sugars in vacuole

Question 39

how might a plant leaf palisade cell have organelle adaptations for its function?

Answer 39

large number of chloroplasts - this allows for greater rate of light absorption for photosynthesis Tall, thin shape - this means light can penetrate deeper before it reaches a cell wall which may absorb or reflect it, and the cells can be more densely packed

Question 40

how might a muscle cell have organelle adaptations for its function?

Answer 40

high density of mitochondria - the cristae and matrix contain the enzymes needed for aerobic respiration so large amounts of energy can be released for muscle contraction layers of protein filaments - the layers can slide over each other to enable muscle contraction

Question 41

how might a white blood cell have organelle adaptations for its function?

Answer 41

high density of lysosomes - they release hydrolytic enzymes which can digest bacteria during phagocytosis