Cells And Organelles

Question 1

What’s alopecia?

Answer 1

Hair loss

Question 2

What’s dysplasia?

Answer 2

Presence of abnormal cells in a tissue, preceding cancer development

Question 3

What’s a cell?

Answer 3

Semi-independent, living unit in which are sited mechanisms for metabolism, growth and replication. Membrane-bound aqueous solution of organic molecules

Question 4

What’s an organelle?

Answer 4

Subunit in a cell with a specific structure, performing specific integrated activities. May be membranous or non-membranous

Question 5

What’s a tissue?

Answer 5

Assembly of cells and their EXTRACELLULAR PRODUCTS which carry out similar and co-ordinated activities

Question 6

What’s an organ?

Answer 6

Assembly of tissues carrying out specific and coordinated activities

Question 7

What’s a system?

Answer 7

Assembly of organs performing specific, related activities, sharing REGULATORY INFLUENCES
OR
a diffuse network of cells in many body parts, sharing specific activities

Question 8

What’s a prokaryote?

Answer 8

Single called organism in which chromosome lies as a circular free strand in cytoplasm, no membrane bound organelles

Question 9

What’s a eukaryote?

Answer 9

One or more cells in which chromosomes lie in nucleus, DNA’s linear. Cytoplasmic, membrane bound organelles

Question 10

What’s a virus?

Answer 10

Assemblage of DNA/❗️RNA❗️ + proteins, parasitic on eukaryotes/prokaryotes. Operate chemically to subvert cell’s protein manufacturing mechanism, producing viruses instead of normal proteins. Escape to infect other cells. No membrane

Question 11

Differences between eukaryotes and prokaryotes in terms of genetic structures

Answer 11

1. Genetic material
   P: single circular chromosome
   E: linearly in paired chromosomes
2. Location
   P: nucleoid region
   E: nucleus
3. Nucleolus
   P: none
   E: present
4. Histones
   P: none
   E: present
5. Extrachromosomal DNA
   P: plasmids
   E: mitochondria/ plasmids

Question 12

Differences between prokaryotes and eukaryotes in terms of intracellular structures

Answer 12

1. Mitotic spindle
   P: absent
   E: present
2. Plasma membrane
   P: no sterols
   E: has sterols
3. Peroxisome
   P: absent
   E: present
4. Internal membranes
   P: photosynthetic organisms only
   E: many
5. ER
   P: absent
   E: present
6. Cytoskeleton
   P: absent
   E: present
7. Respiration
   P: at PM
   E: mitochondria
8. Lysosomes
   P: absent
   E: present
9. Golgi
   P: absent
   E: present
10. Ribosomes
    P: 70S
    E: 80S

Question 13

Differences between prokaryotes and eukaryotes in terms of extracellular structures

Answer 13

1. Cell wall
   P: peptidoglycan
   E: chitin in fungal
2. Flagella
   P: present
   E: only in some
3. Pili
   P: present
   E: absent
4. Cilia
   P: absent
   E: present in some
5. External layer
   P: slime layer
   E: absent

Question 14

Differences between prokaryotes and eukaryotes in terms of reproduction

Answer 14

1. Cell division
   P: binary fission
   E: mitosis/ meiosis
2. Mode
   P: asexual
   E: asexual/ sexual

Question 15

diff between SEM & TEM

Answer 15

TEM: subcellular features, electrons go through specimen

SEM: subcellular features, electrons scattered off cell surface

Question 16

What’s the maximum size of a cell, and why can’t it get any bigger

Answer 16

Less than 50 micrometres.
Volume increases > SA
Distance of diffusion from nucleus to periphery increases, slowing rate of diffusion of waste materials, metabolites and intermediates

Question 17

How do specialised cells overcome the problem of diffusion inefficiency due to size

Answer 17

1. Multinucleation: gene expression in more than one place
2. GAP junctions: movement of substances between cells
3. Thin processes: cytoskeleton

Question 18

What’s cytoskeleton made of? What are three types of it?

Answer 18

Protein filaments.
Thinnest: actin
Intermediate: mechanical strength eg keratin
Microtubules

Question 19

Function of cytoskeleton

Answer 19

1. Mechanical strength
2. Shape
3. Drives and guides movement of materials

Question 20

Cytosol vs cytoplasm

Answer 20

Cytosol: aqueous environment within PM

Cytoplasm: cytosol + organelles

Question 21

Function of nucleolus

Answer 21

Rdna transcribed, ribosome subunits assembled

Question 22

SER function

Answer 22

1. Synthesis of lipids and steroids
2. Start of N-linked glycolysation
3. Detox of xenobiotics

Question 23

RER function

Answer 23

1. Protein synthesis: membrane bound ribosomes synthesise proteins for secretion/ insertion into CM
2. Cys-CYs bridge formation
3. Vesicles bud off RER and are transported to Golgi

Question 24

Golgi function

Answer 24

1. Synthesises/packages materials for secretion
2. Directs new proteins to right compartment
3. Synthesis of lysosomes
4. Modification of proteins:
   N-linked carbohydrates
   Glycosylation of O-linked carbs&lipids
5. Transports membrane lipids

Question 25

What’s Golgi made of

Answer 25

4-8 closely stacked cisterna

Question 26

Peroxisome function

Answer 26

1. Oxidation of VLCFA
2. Phospholipid synthesis
3. Detoxification
4. Catalase

Question 27

Peroxisome-related illnesses

Answer 27

1. Zellweger syndrome

2. Adrenoleukodystrophy

Question 28

Number of enzymes in lysosomes? Requirements for lysosome function? Function of lysosomes?

Answer 28

> 50
Acidic
Autophagy

Question 29

Size of nucleus

Answer 29

‼️3‼️-10 micrometres