3.2.1.1 (eukaryotic cell structure)

Question 1

Describe eukaryotic cells

Answer 1

Contain DNA in a membrane bound nucleus
Eukaryote=true nucleus
Includes animals, plants, fungi, protists
Average cell diameter 10-100 μm - typically larger cells
Complex membrane bound organelles in cytoplasm with specific functions

Question 2

What are the 4 parts of the nucleus and their functions?

Answer 2

Nucleus- houses nearly all cell’s genetic material
Chromatin- consists of DNA and histone proteins
Nucleolus- makes rRNA which is made into ribosomes
Nuclear envelope- has nuclear pores to let molecules pass through, has nucleoplasm in

Question 3

Describe the mitochondria

Answer 3

Bound by a double membrane
-outer controls entry and exits of substances
-inner is folded inwards forming cristae
Site of aerobic respiration producing ATP
Number of mitochondria in cell depends on metabolic activity

Question 4

Describe ribosomes

Answer 4

Non membranous structure found in all cell types
~20nm in eukaryotes (80s)
-smaller in prokaryotes (70s)
Free in cytoplasm or associated with RER
Made from rRNA and protein
Site of protein synthesis

Question 5

Describe the golgi apparatus/ golgi body

Answer 5

Stacks of closely packed membrane bound sacs- cisternae
Sections of the golgi pinch off the membrane to form vesicles
Modify proteins eg adding carbohydrates and packaging proteins into vesicles
Form lysosomes- vesicles containing hydrolytic enzymes
Well developed in secretory cells

Question 6

Describe lysosomes

Answer 6

Vesicles containing hydrolytic enzymes
Made in golgi
Enzymes are isolated from cell to prevent acting on other chemicals/ organelles in cell
Abundant in secretory cells and WBCs
Destroys old/ surplus organelles
Responsible for autolysis after cell death
Break down material from endocytosis
Can be released to destroy nearby cells/tissues if required

Question 7

Describe the smooth endoplasmic reticulum

Answer 7

System of membranes found throughout cell
Membranes lack ribosomes
Lipid synthesis

Question 8

Describe the rough endoplasmic reticulum

Answer 8

System of membranes found throughout cell
Membranes lined by ribosomes
Protein synthesis and movement of proteins throughout cell

Question 9

Describe the chloroplast

Answer 9

Outer membrane- semi porous permeable membrane
Intermembrane space- thin space between outer and inner membrane
Inner membrane- forms border to stroma
Stroma- present within inner membrane, space outside thylakoid space
Thylakoid system- collections of membranous sacs called thylakoids suspended in stroma, chlorophyll found in thylakoids

Question 10

Describe cell wall

Answer 10

Mainly cellulose but also contains hemicellulose, pectin, lignin and polysaccharides
3 layers- primary and secondary cell wall, middle lamella
Plasmodesmata- channels through cell walls linking cytoplasm of adjacent cells
Strength and rigidity

Question 11

Describe the vacuole

Answer 11

Membrane bound fluid filled sacs
Filled with cell sap in plants
Important in keeping cell rigid/ turgid