week 4 - cell compartmentalisation

Question 1

organisms are made up of…

Answer 1

many different types of cell

Question 2

do all cells have similar organisation and DNA

Answer 2

yes

Question 3

what is the longest cell

Answer 3

motorneurons of the sciatic nerve in humans

base of spine to toes

Question 4

erythrocytes

Answer 4

have no nucleus

some form a syncytium: cells share the same cytoplasm
- cell cytoplasm is connected / gap junctions LIKE skeletal muscles

Question 5

cells:
all connected together

Answer 5

cell junctions, connective tissue, ECM

some connected by synapses

Question 6

why are cells typically small

Answer 6

need efficient enough surface to exchange material with environment
- slow diffusion rate
- need maintaining adequate concentration of reactants and enzymes

Question 7

cell shape and organisation is..

Answer 7

not readily apparent

Question 8

optical microscopy

Answer 8

1) Contrast enhancing techniques (phase contrast and DIC
2) Cell staining
3) Immunostaining
4) Fluorescence microscopy and fluorescent protein tagging

Question 9

what we know about cells comes from…

Answer 9

microscopy

Question 10

epithelial cells

Answer 10

In mammals, many epithelial cells are ciliated in order to sweep materials across the tissue surface. For instance, huge numbers of cilia (more than 107/mm2) cover the surfaces of mammalian respiratory passages (the nose, pharynx, and trachea), where they dislodge and expel particulate matter that collects in the mucus secretions of these tissues.

Question 11

what does the plasma cell membrane do

Answer 11

demarks the cells boundary

• The boundary between the internal of the cell and the outside environment
• Phospholipid bilayer with embedded proteins
• selective permeability

Question 12

plasma membrane
made up of

Answer 12

The bio/plasma/cell membrane is made of two layer of phospholipids and proteins (around 50% in weight).
Most of the membranes are those of intracellular vesicles

Question 13

cell shape

Answer 13

cytoskeleton

cell wall (plants and yeast)

Question 14

what does the cytoskeleton do

Answer 14

gives the differing structures

Question 15

visualisation of cell structures:

Answer 15

Fluorescence labelling

Visualization techniques
Most cell are not round, Female rat egg: RED, F-Actin stained with Texas Red phalloidin; GREEN IS for a kinase known to cross link F-Actin.
The cell shape depends on the cortex on the inner side of the plasma membrane (part of the actin microfilaments cytoskeleton)
Spherical due to actin cytoskeleton

Question 16

the nucleus

Answer 16

contains the chromosomal DNA

Question 17

where are ribosomes made

Answer 17

nucleolus

(the most prominent structure/organelle in the nucleus)

Question 18

chromosomes

Answer 18

are very apparent in polytene nuclei

Polytene chromosomes were first described in 1881 by Balbiani but only at start 20th centuary theyy were linked to heredity.

the first observations of chromosomes were made in somatic (body) cells, specifically in the cells of salamander larvae.
Walther Flemming, who coined the term “chromosome” and described these structures in 1882, conducted his studies on the developing cells of salamander embr

How did scientist found out the genes (Mendelian hereditary factors then) are linked to chromosomes?
Sex determination.

Question 19

the nucleus is enclosed by a…

Answer 19

double membrane

nuclear envelope
- transport between nucleus and cytoplasm is critical

Question 20

membrane enclosed compartments/organelles

Answer 20

• Trafficking vesicles/endomembrane system
• Endoplasmic reticulum (rough ER and smooth ER)
• Golgi apparatus
• Lysosomes/peroxisomes/vacuoles
• Eukaryotic cell evolution

Question 21

how cells produce cell membrane? and lipids?

Answer 21

1) lipid synthesis

2) membrane expansion

3) vesicular transport

Question 22

how cells produce cell membrane? and lipids?
1) lipid synthesis

Answer 22

o Cells synthesize lipids, such as phospholipids, the in endoplasmic reticulum (ER)

Question 23

how cells produce cell membrane? and lipids?
- membrane expansion

Answer 23

o Cells increase lipid production when they need to expand their membranes (e.g. during cell division)

Question 24

how cells produce cell membrane? and lipids?
- vesicular transport

Answer 24

o Newly synthesized lipids are transported to different membrane compartments via vesicles
 Endocytosis and exocytosis
 These processes help expand to recycle cell membranes

Question 25

organelles are…

Answer 25

dynamic structures

Question 26

proteins delivery to the right location mediated by…

Answer 26

amino acid leader sequences

Question 27

pancreas

Answer 27

secretes insulin, glucagon, somatostatin, and function also as an exocrine gland by secreting digestive enzymes.

Question 28

how do cells form lipid droplets in an organised manner?

Answer 28

The close proximity of LDs to mitochondria allows for efficient energy regulation.
LDs can release stored lipids for oxidation in mitochondria when the cell requires energy.

Lipid droplets in fat tissues primarily store excess energy and play roles in metabolism, insulation, cushioning, and hormone regulation. They are critical for overall metabolic health.

Question 29

lysosomes carry out…

Answer 29

intracellular digestion of both external and internal bodies

Phagocytosis

Question 30

lysosomes are the…

Answer 30

primary catabolic compartments of cells

Question 31

lysosmes are repleated with…

Answer 31

enzymes

proteases, glycosidases, lipases

Question 32

defects in lysosomal function results in…

Answer 32

diseases

lysosomal storage disease

Question 33

lysosomes =

Answer 33

best example of compartmentalisation

tagging of lysosomal enzymes with mannose-6-phosphate in the Golgi apparatus
Lysosome internal enviroment is acidic to facilitate the breakdown of macromolecules.

Question 34

Lysosomes: are also…

Answer 34

recycling centres

– If key enzyme is not working, material accumulate in it causing LSD

Question 35

lysosomes pH

Answer 35

Low pH due to active pumping of protons by the H+-ATPase.

Question 36

autophagy

Answer 36

cells continuously eat themselves

Question 37

autophagy:
roles

Answer 37

plays specific roles in shaping immune system
development, fueling host innate and adaptive immune responses, and directly
controlling intracellular microbes as a cell-autonomous innate defense.

Question 38

mitochondria:
what

Answer 38

• Membrane enclosed organelles found in possibly in all eukaryotic cells

Question 39

mitochondria:
function

Answer 39

• Produce most of the ATP by oxidative phosphorylation

Question 40

mitochondria:
distinctive feature

Answer 40

• Have a DNA genome
• Have a secondary inner membrane

Question 41

each cell has …… mitochondira

Answer 41

many

Question 42

mitochondria:
shapes

Answer 42

Spermatozoon
spiral

Question 43

mitochondria:
fused together

Answer 43

Mitochondria are in fact fused together to for a retiulum/network, which is highly dynamic.

Question 44

origin of the eukaryotic cell

Answer 44

Mitochondria and chloroplast evolved from ancient purple bacteria and cyanobacteria
Genes that are conserved across eukaryotes leave no doubt that all extant eukaryotic forms evolved from a last eukaryote common ancestor (LECA
Such endosymbiosis still occurring in protozoa and invertebrates
Biologist Lynn Margulis, recipient of the National Medal of Science, first wife of Carl Sagan,
—– Meeting Notes (30/09/16 10:47) —–
Genes that are conserved across eukaryotes leave no doubt that all extant eukaryotic forms evolved from a last eukaryote common ancestor (LECA