Cell compartmentalisation & organelles

Question 1

What are the major components of cells?

Answer 1

Small metabolites and macromolecules like proteins, DNA, and lipids

Question 2

What is the largest macromolecular component in cells?

Answer 2

Proteins

Question 3

How many distinct cell types exist in the human body?

Answer 3

200+

Question 4

What is the longest human cell?

Answer 4

Motoneurons of the sciatic nerve

Question 5

What is the key difference between different cell types in the same organism?

Answer 5

Gene expression

Question 6

What technologies are used to visualise cells and organelles?

Answer 6

Electron microscopy, optical microscopy, phase contrast, DIC, immunostaining, and fluorescence microscopy

Question 7

What is Phalloidin used for?

Answer 7

Staining actin filaments; it is a toxin from the death cap mushroom

Question 8

What does GFP tagging allow?

Answer 8

Tracking organelles and visualising membrane proteins

Question 9

What is the plasma membrane composed of?

Answer 9

Phospholipid bilayer with embedded proteins

Question 10

What maintains a cell’s shape?

Answer 10

The actin cortex beneath the plasma membrane

Question 11

Why are cells so small?

Answer 11

Maximise SA:V ratio
= efficient diffusion & material exchange

Question 12

What is the main function of the nucleus?

Answer 12

Stores chromosomal DNA and conducts transcription

Question 13

What is the function of the nucleolus?

Answer 13

Synthesises ribosomes

Question 14

What is the function of the rough ER?

Answer 14

Protein synthesis

Question 15

What is the function of the smooth ER?

Answer 15

Lipid synthesis and membrane expansion

Question 16

What does the Golgi apparatus do?

Answer 16

Modifies and packages proteins post-translation

Question 17

Function of lysosomes?

Answer 17

Breakdown of cellular waste and defective organelles

Question 18

What are peroxisomes responsible for?

Answer 18

Oxidative reactions using O₂, producing hydrogen peroxide

Question 19

What are lipid droplets?

Answer 19

Organelles for lipid storage and regulation, enclosed by a single phospholipid layer

Question 20

What do mitochondria do?

Answer 20

Produce ATP via oxidative phosphorylation; have their own DNA

Question 21

What do chloroplasts do (plants)?

Answer 21

Photosynthesis; also contain DNA

Question 22

What is the origin of mitochondria and chloroplasts?

Answer 22

Evolved from ancient purple bacteria and cyanobacteria through endosymbiosis

Question 23

What is gene expression?

Answer 23

Process of making proteins and enzymes from DNA via RNA intermediates

Question 24

What is a gene?

Answer 24

A segment of DNA that codes for a protein

Question 25

What is a proteome?

Answer 25

The full set of proteins a cell can express

Question 26

What separates gene expression in eukaryotes from prokaryotes?

Answer 26

Compartmentalisation – transcription in the nucleus, translation in the cytoplasm (in eukaryotes)

Question 27

Where does transcription occur?

Answer 27

In the nucleus

Question 28

Where does translation occur?

Answer 28

In the cytoplasm (ribosomes)

Question 29

What are key steps in mRNA processing?

Answer 29

Splicing (removal of introns), 5' methylation, and 3' polyadenylation

Question 30

What enzyme starts translation?

Answer 30

Ribosome – small subunit recognises start codon, large subunit completes assembly

Question 31

What is the function of ribosomes?

Answer 31

Protein synthesis

Question 32

Where are ribosomes found?

Answer 32

On the rough ER and freely in the cytoplasm

Question 33

What does SDS-PAGE do?

Answer 33

Separates proteins based on molecular weight

Question 34

What does mass spectrometry measure?

Answer 34

Protein composition of a sample

Question 35

What is cell fractionation?

Answer 35

Separates cellular components for analysis

Question 36

Why is translation localisation important in neurons?

Answer 36

Ensures proteins are made at synapses in response to signals

Question 37

What triggers translation in oocytes and neurons?

Answer 37

Specific stimuli like fertilisation or neuronal activity