cell structure topic 2

Question 1

describe the structure of nucleus

Answer 1

• Nucleus is a double membrane called the envelope containing ~3000 nuclear pores
  that enables molecules to enter and leave. It also contains chromatin and a nucleolus
  which is the site of ribosome production.

A granular jelly like material called
nucleoplasm makes up the bulk of the nucleus.

Question 2

function of nucleus

Answer 2

-site of Mrna transcription
-semi conservative replication
-mitosis
-gene expression

Question 3

describe the function of mitochondria

Answer 3

site of aerobic respiration which produces ATP

Question 3

describe the structure of mitochondria

Answer 3

Mitochondria are oval shaped, bound by a double membrane called the envelope.
The inner membrane is folded to form projections called cristae with a matrix on the inside
containing all the enzymes needed for respiration.

Question 4

describe the structure of chloroplast

Answer 4

surrounded by a double membrane
-had thylakoids ,folded membranes containing pigment)
-fluid filled stroma containing enzymes for photosynthesis

Question 5

describe the structure of lysomes

Answer 5

-bags of digestive enzymes

Question 6

describe the function of lysosome

Answer 6

hydrolyse phagocytic cells
break down dead cells (autolysis)
-exocytosis -release enzymes to outside the cell to defeat the material
-

Question 7

describe the structure of ribosomes

Answer 7

made up of two sub units -protein and Rna

80S - found in eukaryotic cells (larger ribosomes )
70S found in prokaryotes

site of protein synthesis

Question 8

describe the structure of endoplasmic reticulum

Answer 8

has folded membranes called cisternae
rough ER has ribosomes on the cisternae

Question 9

describe the structure of the Golgi apparatus

Answer 9

folded membranes making cisternae
Golgi vesicles pinch of cisternae

Question 10

describe the function of the golgi appararus

Answer 10

synthesises for glycoproteins
modifies proteins

produces lysosomes

Question 11

describe the function of the rough and soft endoplasmic reticulum

Answer 11

SER- stores lipids and carbohydrates

RER- synthesis of proteins

Question 12

describe the function of soft endoplasmic reticulum

Answer 12

SER- stores lipids and carbohydrates

Question 13

describe the cell surface membrane

Answer 13

begins with a phospholipid bi layer which forms due to the hydrophillic and hydrophobic interactions
hydrophobic inwards
hydrophilic outwards

Question 14

What is the function of the phospholipid bilayer

Answer 14

allow lipid-soluble substances to enter and leave the cell
• prevent water-soluble substances entering and leaving the cell
• make the membrane flexible and self-sealing

Question 15

what is found in the bilayer

Answer 15

intrinsic and extrinsic protein
glycoproteins
cholesterol
glycolipids

Question 16

what are intrinsic proteins

Answer 16

they bind to ions like glucose or amino acids ,change shape ,in order to move across membrane

Question 17

what is co-transport

Answer 17

occurs when two substances are simultaneously transported across a membrane

This occurs particularly in epithelial cells of the ileum.

Question 18

describe the process of co transport

Answer 18

1.sodium ions are actively transported into the blood from the epithelium cells causing lower concentration in epithelial cells (happens using protein carrier)
2.now there is a higher concentration in the lumen
3.sodium ions carry glucose /amino acids ,so now there is a higher concentration of glucose
4.glucose moves into blood by facilitated diffusion using blood plasma through carrier protein