Cell structures

Question 1

Prokaryotes examples

Answer 1

bacterial cells

Question 2

Eukaryotes examples

Answer 2

Animal, plant cells

Question 3

prokaryotes vs eukaryotes

Question 4

nucleus structure [4]

Answer 4

1. nuclear envelope (double membraned, continuous w ER)
2. nuclear pores
3. DNA
4. nucleolus (ribosomal subunits are synthesised)

Question 5

Nucleus f(x) [GEC]

Answer 5

G- contain genetic information
E- essential for cell division
C- control cell activities

Question 6

Cell surface membrane structure

Answer 6

• selectively permeable membrane
• Fluid mosaic model:
  + fluid: phospholipids are able to move freely and laterally along the phospholipid bilayer
  + mosaic: different proteins are randomly scattered and embedded among the phospholipids

Question 7

Cell surface membrane f(x) [3]

Answer 7

1. compartmentation and specialisation of cell
2. selectively permeable membrane
3. forms boundary that separates cell contents from the extracellular surrounding

Question 8

Cytoplasm

Answer 8

• semi-fluid structure
• 90% water + 10% dissolved solutes

Question 9

protoplasm

Answer 9

cytoplasm + cell surface membrane + nucleus

Question 10

cytoplasm f(x) [2]

Answer 10

• main site for metabolic activities
• where chemical reactions occur

Question 11

Ribosome structure [NEST]

Answer 11

N: non-membrane bound
E: exist as free ribosomes floating in the cytoplasm or attached to the rER
S: spherical in shape
T: 2 subunits(RNA + protein)

not organelle btw

Question 12

ribosome f(x) [5]

Answer 12

• site of p.p. synthesis
• translate gene carried by mRNA into p.p., p.p. folds into specific 3D conformation of protein

free ribosomes:
- synthesise proteins that function WITHIN cytoplams

ribosomes that are att. to rER synthesise proteins that are:
- meant to be secreted out of the cell
- packaged within lysosomes
- be embedded into the membranes

Question 13

Endomembrane system

Answer 13

1. endoplasmic reticulum
2. Golgi body
3. vesicles and lysosomes
4. outer membrane of nuclear membrane

Question 14

Rough endoplasmic reticulum (rER) structure [4]

Answer 14

1. continuous w nuclear envelope
2. 3D network of interconnecting flattened membranes
3. SINGLE membrane structure
4. ribosomes are att. to ER membranes

Question 15

rER f(x) [2]

Answer 15

1. folding p.p. into proteins
2. transport protein for secretion
   - transport vesicles containing protein bud/pinch off from rER and are transported to the Golgi body for further chemical modification

Question 16

sER structure [4]

Answer 16

1. SINGLE MEMBRANE STRUCTURE
2. 3D network of interconnecting tubular membrane
3. no ribosomes att. to membrane surface
4. could be continuous w rER or nuclear envelope

Question 17

sER f(x) [2]

Answer 17

1. synthesis of LIPIDS
   - enzymes in sER synthesise lipids (eg. phospholipids and steriods[eg. cholesterol])
2. detoxification
   - converts harmful/toxic substances into more soluble and less harmful substances (easier for secretion)

Question 18

Golgi body structure [3]

Answer 18

1. several stacks of flattened membrane-bound bodies
2. not continuous with nuclear envelope
3. vesicles can be seen fusing w the cis face, pinching off frm the trans face

Question 19

Golgi body f(x) [3]

Answer 19

1. CHEMICAL MODIFICATION:
   - modification of proteins that are transported from the rER and sER via transport vesicle
   - contain enzymes to catalyse the addition/removal of sugars frm proteins, addition of sulfate groups and phosphate groups
2. SORTING AND PACKAGING:
   - proteins/lipids that are SECRETED are sorted and packaged into SECRETORY VESICLES
3. FORMATION OF LYSOSOMES:
   - specialised vesicles containing LYSOSOMAL ENZYMES bud off frm the Golgi body
   - remains in cytoplasm

Question 20

types of vesicles

Answer 20

1. transport vesicles
2. secretory vesicles
3. lysosomes
4. vacuoles

Question 21

PROTEIN SYNTHESIS in cells (8 steps)

Question 22

Vesicles and lysosomes structure [3]

Answer 22

1. tiny sacs bound by a single membrane
2. formed when some membrane buds off to ENCLOSE A SUBSTANCE
3. formed frm sER, rER and Golgi body

Question 23

vesicle f(x) [1]

Question 24

vesicle f(x)

Question 25

lysosome f(x)

Question 26

lysosome structure

Question 27

types of endocytosis [3]

Answer 27

1. pinocytosis 2. phagocytosis 3. receptor-mediated endocytosis

Question 28

Mitochondrion structure [4]

Answer 28

- cylindrical shaped - double membrane: = outer membrane is smooth = inner membrane has numerous folds (CRISTAE) - membranes separated by intermembrane space - matrix is compartment enclosed by the inner mitochondrion membrane

Question 29

f(x) of cristae

Answer 29

to increase surface area to ratio, provides a larger surface area for chemical reactions

Question 30

Mitochondrion f(x)

Answer 30

site of respiration

Question 31

Chloroplast structure [5]

Question 32

Chloroplast f(x)

Question 33

Vacuole structure [2]

Answer 33

1. single membrane (tonoplast in plants) 2. contain cell sap in animal cells: they are small but numerous (temporary)

Question 33

Vacuole structure [2]

Answer 33

1. single membrane (tonoplast in plants) 2. contain cell sap in animal cells: they are small but numerous (temporary)

Question 34

vacuole f(x) [3]

Answer 34

1. helps develop turgidy 2. storage of starch, pigments and defensive compounds 3. deposition site

Question 35

Cell wall structure [4]

Question 36

cell wall f(x) [3]

Question 37

Root hair cell structure [4]

Question 38

Root hair cell f(x)

Question 39

Xylem structure

Question 40

xylem f(x)

Question 41

red blood cell structure [4]

Question 42

red blood cell f(x)