B2.2 Organelles and Compartmentalization

Question 1

Define organelles

Answer 1

Discrete subunits of cells adapted to specific functions

Question 2

Define the function of microvili (not discussed earlier)

Answer 2

Tiny hair-like structures that absorb nutrients better by giving the cell an increased surface area.
- To absorb the nutrients of the small intestines

Question 3

Why does the Nucleus “control the cell”

Answer 3

Contains the DNA that operates all the cellular functions (?)

Question 4

How does lysosome recycle old/damaged organelles?

Answer 4

They engulf it, “ingest it” w. their enzymes

Question 5

Outline the no-membrane, single membrane and double membrane-bound organelles in both prokaryotic and eukaryotic cells

Answer 5

Question 6

Do prokaryotes have compartmentalization

Answer 6

No

Question 7

Describe the compartmentalization of eukaryote cells

Answer 7

Due to the membrance-bound organelles, the organelles create a compartment with controlled conditions inside
- separates the the insides of an organelle from outside
- like a bag
- chloroplasts have double membrane — not as easily disturbed

Question 8

Are cell membranes organelles?

Answer 8

No

Question 9

Explain the three parts of cell that are not organelles

Answer 9

Cell wall
- extracellular (not inside the cell)

Cytoplasm
- not specialized to perform specific functions
- it is just where everything is happening

Cytoskeleton
- not a discrete structure
- CANNOT be differentiated from other cells
- why?
- discrete: specific and easily identifiable shape

Question 10

Explain the differential centrifugation

Answer 10

Purpose: to get the different the different organelles

1.) Cells in a homogenizer (blender)
2.) Puts in a centrifuge (spins around), turns into homogenate
3.) The denser materials will form solid pellets which could be removed easier
4.) Continue process removing denser pellets to get the parts you want

Question 11

Is cell membrane an organelle?

Answer 11

Yes because it has a specific function

Question 12

Outline the advantages of the separation of the nucleus and cytoplasm into separate compartments

Answer 12

• safeguards the DNA
  
  • DNA wouldn’t be compromised/affected by outside (e.g. chemical reactions in the cytoplasm)
  • THEREFORE translation cannot begin immediately after transcription thus, mRNA can still be modified (post transcriptional modification)
    
    • minimizes mutation
• makes functions more efficient
  
  • tailored to the specific functions of the organelle

Question 13

Define the process of translation

Answer 13

The process of making protein from RNA

Question 14

Explain transcription

Answer 14

RNA gets the code from DNA and can get in and out of the nucleus so it acts like a “secretary” to act as gene code for ribosomes to create protein (translation)

Transcription (AKA DNA to RNA) -> Translation (RNA to protein)

Question 15

Distinguish genes vs genomes

Answer 15

Genomes:
- total genetic composition of the cell

Genes:
- part of genes

Question 16

Advantages of compartmentalization

Answer 16

1.) Increasing chance of collision of enzymes and substrates
- creates a surface for them to touch the organelles (??)

2.) Protects cells from degradation

3.) Conditions, such as pH, can be maintained
- (no. 2 and no. 3 connect because of lysosomes)

4,) Large areas of membrane can become dense with proteins for a specific process
- see B2.1
- many proteins with diff. functions

Question 17

define hydrolyze

Answer 17

make simpler

Question 18

Explain why lysosomes need a membrane

Answer 18

They contain a high concentration of enzymes capable of hydrolyzing (breaking down) polymers (basically they have a lot of digestive enzymes that can break down stuff)

All of their enzymes are acid hydrolases which are active at an acidic pH.

If acidic hydrolases are released, everything outside would not work due to their acidity.
- that is why the lysosomes need a membane/proctection

Question 19

Describe the example of phagocytic vacuole and the following terms: phagocyte, phagocytosis and phagocytic vacuole

Answer 19

Definition:

Phagocyte - a cell that performs phagocytosis
- phagocytosis - a type of endocytosis that lets pathogens in to kill them
-phagocytic vacuole - phagosome, contains the pathogen/large molecule that entered the cell membrane.

Question 20

Phagocytosis

Answer 20

Cell uses the plasma membrane to engulf a large particle, giving rise to an internal compartment called a phagocytic vacuole (AKA the phagosome)

Question 21

Describe the inner membrane

Answer 21

contains the electron transport chains and ATP synthase (aka materials for ?? for creating ATP)

-> electron celectricity energy atp (to help me remember)

Question 22

Describe the intermembrane space of mitochondria

Answer 22

Where a high concentration of protons is generated by the electron transport chains

Question 23

Describe the matrix [2]

Answer 23

What?: The fluid filling the compartment inside the inner mitochondrial membrane.

Purpose: To contain enzymes and substrates for Krebs cycle and link reaction. Due to this, aerobic respiration can be performed more rapidly.

Question 24

Describe the nucleoplasm

Answer 24

semi-fluid matrix found inside the nucleus is called nucleoplasm.

Question 25

Give the term of DNA found within the nucleus

Answer 25

Chromatin

Question 26

Describe the nuclear envelope

Answer 26

• Two concentric membranes, called the inner nuclear and the outer nuclear membrane
• Allows only small non-polar (no charge) molecules due to their phospholipid bilayers.
• Continuous with ER

Question 27

Describe the nucleus during cell division (PROPHASE)

Answer 27

1.) Prophase
- chromosomes condense and the nucleolus disappears
- nuclear membranes fragmented into vesicles (so like a catabolic ver. of the first creation of the cell membrane).
- the nuclear pore complexes dissociate.
- because the membranes “fragment” to form tiny vesicles

Question 28

Outline the different parts in the mitochondria

Answer 28

Additional:
Krebs Cycle and Link Reaction takes place in the matrix bc:
- its like the cytoplasm of the membrane (mitochondria)??
- the link reaction is supposed to make the glucose usable for KC (so thats why its in the matrix)
ETC is in the inner membrane
- bc the ATP synthase (to create ATP — main purpose of ETC) is in there

Question 29

Outline the different parts in the nucleus

Answer 29

Question 30

Describe the nucleus during cell division (TELOPHASE)

Answer 30

-> Comes after prophase (so the nuclear membrane fragmented into the smaller vesicles)
During Telophase:
1.) The nuclear membrane vesicles bind to the chromosomes (the long line ones)
2.) The vesicles fused with one another and then absorbed the chromosomes.
3.) Then the fuse vesicles that absorbed the chromosomes will fuse again to make a complete single nucleus wherein the chromosomes decondense (aka unravel to like string) and the nuclear pore complexes reassemble