Eukaryotic and Prokaryotic organelles

Question 1

what is the structure of the nucleus?

Answer 1

nuclear envelope - double membrane
nuclear pores - within the envelope
nucleoplasm - granular, jelly like material
chromosomes - protein bound, linear DNA
nucleolus - small sphere inside which is the site of rRNA production and makes ribosomes

Question 2

what is the function of the nucleus

Answer 2

1) site of DNA replication and transcription (making mRNA)

2) contains the genetic code for each cell

Question 3

what is the structure of endoplasmic reticulum?

Answer 3

• Rough ER have ribosomes on the cisternae
• Both rough and smooth ER have folded membranes (cisternae)

Question 4

what is the function of the endoplasmic reticulum?

Answer 4

RER - protein synthesis
SER - synthesis and store lipids / carbohydrates

Question 5

what is the structure of the Golgi apparatus and golgi vesicles?

Answer 5

• cisternae created by folded membranes
• secretary vesicles pinch off from the cisternae

Question 6

what are the functions of the Golgi apparatus and golgi vesicles?

Answer 6

1) add carbohydrates to proteins to form glycoproteins

2) produce secretary enzymes

3) secrete carbohydrates

4) transport, modify, and store lipids

5) form lysosomes (the vesicles)

6) molecules are ‘labelled’ with their destination once processed and modified

7) finished products are transported to the cell surface in the golgi vesicles where they fuse with the membrane and the contents are released

Question 7

what is the role of the Golgi apparatus / vesicles?

Answer 7

to process packages and modify proteins

Question 8

what is the structure of lysosomes?

Answer 8

They are bags / vesicles of digestive enzymes which can contain up to 50 different enzymes

Question 9

what are the functions of lysosomes?

Answer 9

1) hydrolyse phagocytic cells ==> some contain the enzyme to digest pathogen inside the phagocyte

2) completely break down dead cells within an organism ==> autolysis

3) release enzymes to the outside of cell to destroy material ==> exocytosis

4) digest worn out organelles for reuse and recycling of materials

Question 10

what is the structure of mitochondria?

Answer 10

• double membrane
• cristae ==> formed by inner membrane folds
• matrix ==> fluid centre
• loop of mitochondria DNA

Question 11

what are the functions of mitochondria?

Answer 11

1) site of aerobic respiration

2) site of ATP production

3) DNA to code for enzymes needed in respiration

==> the inner membrane is folded to create a large surface area for one of the respiration stages

Question 12

what is the structure of ribosomes?

Answer 12

small - made up of two subunits of protein / rRNA

Question 13

what are the two types of ribosomes?

Answer 13

80s ==> large ribosomes found in eukaryotic cells (25nm)

70s ==> smaller ribosome found in prokaryotic cells, chloroplasts and mitochondria

Question 14

what is the function of ribosomes?

Answer 14

site of protein synthesis

Question 15

what is the structure of the vacuole?

Answer 15

fluid filled area surrounded by a single membrane = tonoplast

Question 16

what are the functions of the vacuole?

Answer 16

1) makes the cell turgid and therefore provides support

2) temporary store of sugars / amino acids

3) pigments may colour petals to attract pollinators

Question 17

what is the structure of chloroplasts?

Answer 17

• surrounded by a double membrane
• fluid filled stroma contains enzymes for photosynthesis
• highly folded membrane which is stacked and embedded with pigment
  ==> folded membrane = thylakoids
  ==> stacks = grana / granum

Question 18

what is the function of chloroplasts?

Answer 18

site of photosynthesis

Question 19

what is the structure of the cell wall?

Answer 19

plants - made up of microfibrils of the cellulose polymer

fungi - made of chitin, a nitrogen containing polysaccharide

==> not found in animal cells

Question 20

what is the function of the cell wall?

Answer 20

provides structural strength to the cell

Question 21

what is the function of the plasma membrane?

Answer 21

phospholipid bilayer - molecules embed within and attached on the outside
==> proteins, carbohydrates, cholesterol

Question 22

what cells is the plasma membrane found in?

Answer 22

all cells

Question 23

what is the function of the plasma membrane?

Answer 23

controls the entrance and exit of molecules

Question 24

what property determines whether a molecule can enter the plasma membrane?

Answer 24

whether it is lipid soluble
- if not, it cannot diffuse through the cell surface membrane and instead it has to be transported through a channel or carrier protein

Question 25

what three organelles do only some prokaryotic cells contain?

Answer 25

plasmids
capsule
flagella

Question 26

what is the structure and function of plasmids?

Answer 26

small loops of DNA which only carry a few genes
==> Where antibiotic resistant genes are found if a bacteria has one

Question 27

what is the structure and function of a capsule?

Answer 27

a slimy layer on the outside of the cell wall made of protein
==> prevents bacteria desiccating (drying out)
==> protects bacteria against host’s immune system by helping to cover the antigens on the outside

Question 28

what is the structure and function of the flagella?

Answer 28

tail like structure
==> rotate and the base to enable the bacteria to move

Question 29

what are the five differences between prokaryotic and eukaryotic cells?

Answer 29

1) prokaryotic cells are much smaller

2) prokaryotic cells babe no membrane-bound organelles

3) prokaryotic cells have smaller ribosomes (70s)

4) no nucleus ==> instead a single circular DNA molecule free in the cytoplasm which or not histone protein bound

5) prokaryotic cell wall is made of murrain which is a glycoprotein rather than the polysaccharide cellulose in eukaryotic cells