cell structure

Question 1

What is the role of nucleolus

Answer 1

Produce ribosomal RNA

Question 2

What is the structure of mitochondria

Answer 2

Double membrane
Inner membrane is cristae
With interior fluid called matrix

Question 3

What does lysosome do

Answer 3

Contain hydrolytic enzyme
Break down waste and pathogens

Question 4

What are the roles of cytoskeleton

Answer 4

Provide mechanical strength
Scaffolding
Movement of cilia and filament
Movement of organelles

Question 5

What is the process of protein production [5]

Answer 5

1. Protein are synthesised on the ribosomes bound to the endoplasmic reticulum
2. They then pass into its cisternae and are packaged into transport vesicles
3. Vesicles containing the newly synthesised proteins move towards the golgi apparatus vis the transport function of the cytoskeleton
4. The vesicles fuse with the cis face of the golgi apparatus and the protein enter. the proteins are structurally modified before leaving the golgi apparatus in vesicles from its trans face.
5. The vesicles move towards and fuse with the cell-surface membrane, releasing their contents by exocytosis. Some vesicles form lysosomes - these contain enzymes for use in the cell.

Question 6

What are three components of cytoskeleton

Answer 6

Microfilaments
Microtubules
Intermediate fibres

Question 7

What is the structure of flagella

Answer 7

9+2
Two central microtubules
Surrounding by nine pairs of microtubules

Question 8

What is structure of endoplasmic reticulum

Answer 8

Fattened sacs of membrane called cisternae

Question 9

What is the structure of chloroplasts?

Answer 9

Fluid enclosed in the membrane is called stroma
Flattened sacs called thylakoids
Several thylakoids stacks together are called a granum
Starch grains

Question 10

What is microfilaments

Answer 10

Contractile fibres formed from actin
Responsible for call movement and cell contraction during cytokenisis

Question 11

What is microtubules

Answer 11

Globular tubulin proteins polymerise to form tubes that are used to form scaffold like structure that determines the shape of cell
Spindle fibres
Tracks movement of organelles

Question 12

What is intermediate fibres

Answer 12

Provide mechanical strength and maintain integrity of cell

Question 13

What is the difference between SER and RER?

Answer 13

SER: responsible for lipid and carbohydrate synthesis, and storage
RER: has ribosomes bound to the surface and is responsible for the synthesis and transport of protein

Question 14

What is the structure of ribosomes in eukaryotes?

Answer 14

80s
two small subunit

Question 15

What is the differences between prokaryotes and eukaryotes?

Answer 15

Prokaryotes
* Small cells (2um)
* DNA is circular
* No nucleus - DNA free in cytoplasm
* Cell wall made of peptidoglycan
* Few organelles and no membrane-bound organelles
* Small ribosome (70s)

Eukaryotes
* Large cells (10-100um)
* DNA is linear
* Nucleus present - DNA is inside nucleus
* Cell wall made cellulose (plant) or chitin (fungi)
* Many organelles - mitochondria and other membrane-bound organelles present
* Large ribosome (80s)