The cell ultrastructure

Question 1

Nucleus What does the nucleus do?

Answer 1

> stores genetic material
-> site of DNA replication
->transcription – tRNA, mRNA, rRNA

Question 2

nuclear envelope structure

Answer 2

Contains a nuclear envelope:
-> OUTER envelope contains ribosomes
-> INNER envelope contains Lamins - numerous mutations in the human A-type lamin gene (LMNA) cause Progeria.

Question 3

Nuclear pores role

Answer 3

Transport to and from cell to cytoplasm

Question 4

Nucleolus function

Answer 4

rRNA synthesis
-> combine proteins

-> important for making ribosomes

Question 5

type sof Chromatin (DNA + Histones) in nucleus

Answer 5

Euchromatin - loose and active
-> Heterochromatin – condensed and inactive

Question 6

nucleus definition and roles

Answer 6

The nucleus is the control centre of the cell and contains the genetic material, DNA. It directs cellular activities and is responsible for the replication and transmission of genetic information.

Question 7

Cell Membrane structure and role

Answer 7

Acts as a barrier which controls simple, facilitated and vesicular transport.

Structure:
1)Phospholipid Bilayer
Consists of a phospholipid head (hydrophilic)

2)Fatty acid tails (hydrophobic)

Question 8

where does cholesterol in the cell membrane come from and what’s its role in the cell membrane?

Answer 8

2) comes from SER (lipid synthesis) to golgi to Cell Memebrane

• Contains cholesterol which controls the fluidity and aids solubility of the membrane

Question 9

what is the function of proteins in the cell membrane?

Answer 9

ionic and molecular transport, electron transport, signal transduction, enzymatic reactions and intercellular communication.

Question 10

Rough Endoplasmic Reticulum function

Answer 10

a site of protein synthesis, lipid metabolism, and detoxification.

Question 11

Cell membrane definition

Answer 11

The cell membrane is a selectively permeable barrier that encloses the cell, separating its internal environment from the external surroundings. It regulates the movement of substances in and out of the cell.

Question 12

The RER has

Answer 12

ribosomes

Question 13

fate of protein synthesis in the RER

Answer 13

These proteins will become:
Lysosomes
To go to the Membrane proteins
Excretes proteins

Question 14

how does the RER assist with protein folding?

Answer 14

Assists with protein folding:

The RER also consists of enzymes that catalyze the formation of disulfide bonds necessary for a protein’s tertiary and quaternary structure. If the protein does not fold correctly, the molecular chaperons rebind onto the polypeptide and attempt to fold the protein into the correct shape.

Question 15

Glycosylation in the RER

Answer 15

Protein Glycosylation. Glycosylation, the attachment of sugar moieties to proteins, is a post-translational modification (PTM) that provides greater proteomic diversity than other PTMs.

Question 16

what is synthesised in the SER

Answer 16

1) Lipid Synthesis
-> fatty acids
->phospholipids
->cholesterol

Question 17

CYP540 Enzymes role

Answer 17

CYP enzymes are mainly found within the endoplasmic reticulum of liver cells.

detoxification from the liver e.g. alcohol, liver has high concentrations of these enzymes ->

Biotransformation – breakdown at the liver using these enzymes at the SMR

Question 18

what mineral does the SER store?

Answer 18

> stores calcium

Question 19

SER definition and roles

Answer 19

The ER is a network of membranous tubules and sacs involved in protein synthesis, lipid metabolism, and detoxification.

Question 20

Golgi Apparatus definition and role

Answer 20

the Golgi apparatus modifies, sorts, and packages proteins and lipids for transport to their specific destinations within or outside the cell.

Question 21

Where does the Golgi recieve vesicles (proteins and lipids) from?

Answer 21

1)Receives vesicles from the RER and SER

Cis Golgi – enters: closest to nucleus

Trans Golgi – leaves: furthest away to the nucleus

Question 22

what Post translational Modifications occur in the Golgi body?

Answer 22

> Glycosylation - N and O Type
->Phosphorylate

Question 23

What does the Golgi do with vesicles received from the ER

Answer 23

The Golgi apparatus, or Golgi complex, functions as a factory in which proteins received from the ER are further processed and sorted for transport to their eventual destinations: lysosomes, the plasma membrane, or secretion.

Question 24

Lysosomes definition and role

Answer 24

Lysosomes contain digestive enzymes that break down waste materials, cellular debris, and foreign substances.

They play a crucial role in cellular recycling and defence mechanisms.

Question 25

What type of enzymes do lysosomes contain?

Answer 25

They contain Hydrolytic enzymes which breakdown macromolecules
-> such as proteases
-> lipases
->nucleases
->glycosidases

Question 26

What organelle plays a key role in autophagy?

Answer 26

lysosomes - Plays a key role in autophagy of organelles

Question 27

What organelle plays a key role in Autolysis of Damaged cells

Answer 27

lysosomes

Question 28

explain why the membrane of lysosomes is highly glycosylated

Answer 28

The membrane is Highly glycosylated to protect the lysosomes from the hydrolytic enzymes inside

Question 29

what cells are lysosomes common in?

Answer 29

White blood cells

Question 30

Peroxisomes contain what enzymes?

Answer 30

1) Contain oxidative Enzymes
->catalase
->oxidase
->metabolic enzymes– alpha and beta

Question 31

what oxidation do peroxisomes play a role in?

Answer 31

2) Fatty acid oxidation

A major function of the oxidative reactions performed in peroxisomes is the breakdown of fatty acid molecules. In a process called β oxidation, the alkyl chains of fatty acids are shortened sequentially by blocks of two carbon atoms at a time, thereby converting the fatty acids to acetyl CoA.

Question 32

peroxisomes make what?

Answer 32

3)Make lipids and cholesterol

Peroxisome quality control and dysregulated lipid metabolism

In addition, peroxisomes contribute to the biosynthesis of essential lipid molecules, such as bile acid, cholesterol, docosahexaenoic acid, and plasmalogen.

->plasmalogen which is in white matter

Question 33

what kind of metabolism are peroxisomes involved in?

Answer 33

4)Alcohol metabolism

Catalase, located in peroxisomes, plays only a minor role in alcohol metabolism, possibly accounting for <2% of overall alcohol oxidation, although there is some evidence for increased metabolism of alcohol by peroxisomes in chronic drinkers.

Question 34

what is adrenoleukodystrophy

Answer 34

Adrenoleukodystrophy (ALD) is a genetic condition that damages the membrane (myelin sheath) that covers nerve cells in the brain and spinal cord. Myelin acts as insulation around the nerve fibers.

Impaired peroxisomal beta-oxidation of saturated very long chain fatty acids (VLCFA, >/=C22:0) results in increased VLCFA levels in the tissues and body fluids of patients with disorders of peroxisomal biogenesis (i.e., Zellweger syndrome and neonatal adrenoleukodystrophy) and single peroxisomal protein defects

Question 35

Mitochondria definition and role

Answer 35

Mitochondria are the powerhouses of the cell, responsible for generating energy in the form of ATP through cellular respiration. They have their own DNA and are involved in various metabolic processes.

Question 36

what synthesis occurs in the mitochondria

Answer 36

1) ATP Synthesis
-> electron transport chain
->oxidative phosphorylation

Question 37

pathways in mitochondria

Answer 37

Krebs Cycle and other pathways Urea, glucogenesis, ketogenesis

Question 38

what genetic material is contained in the mitochondria?

Answer 38

3) Mitochondrial DNA

Mitochondrial DNA is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate

Question 39

how does the mitochondria assist in apoptosis ?

Answer 39

assists in apoptosis by sensing cellular stress and release cytochrome C which can initiate apoptosis.

Bcl-2 family members regulate the release of proteins from the space between the mitochondrial inner and outer membrane that, once in the cytosol, activate caspase proteases that dismantle cells and signal efficient phagocytosis of cell corpses.