Cells Lectures 1-5

Question 1

10 Angstrom

Answer 1

1nm

Question 2

1,000nm

Answer 2

1micrometer

Question 3

1,000,000micrometer

Answer 3

1m

Question 4

How many ribosomes make one meter

Answer 4

20,000,000

Question 5

Robert Hooke

Answer 5

Philosopher, astronomer and architect, Hook elasticity law
Micrographia - small things (insects), property of air, small stars and the moon
Looked at cork
Beginning of cells
Called cell because of the monk cell

Question 6

Antony Van Leeuwenhoek

Answer 6

Discovered bacteria, free living and parasitic microscopic protists, sperm cells and muscle fibres

Question 7

What is Scheleiden and Schwann’s cell theory say?

Answer 7

Cell is the unit of structure, physiology and organisation in living things
Cell retain a dual existence as a distinct entity and a building block in construction of organisms
Cells form by free cell formation, similar to the formation of crystals (WRONG) - all cells only arise from pre-existing cells

Question 8

What are the common features of a cell?

Answer 8

Cells gather material from environment and duplicate
Information is stored and inherited by DNA
Information is partially transcribed into an immediate form (RNA)
RNA serves for translation
Proteins put genetic info into action
All cells are enclosed by plasma membrane where material must pass

Question 9

What are the basic unit of life?

Answer 9

All cells come from pre-existing cells by division
Cells contain DNA which is passed from cell to cell during division
All cells are the same in chemical composition
All energy flow of life occurs in the cell

Question 10

How many cells does the human body contain?

Answer 10

10^14

Question 11

Describe the phases of the mitotic cycle

Answer 11

M phase - chromosome inheritance and cell division
S phase - DNA replication
G2 phase - cell growth
G1 phase

Question 12

How many cells are in the brain?

Answer 12

10^11

Question 13

Organisation of a bacterium

Answer 13

Pili, flagellum, cell wall, plasma membrane, nucleiod, ribosomes, cytoplasm

Question 14

Organisation of eukaryotic cells

Answer 14

Plasma membrane, Golgi, peroxisome, nuclear membrane, ER, lysosome, mitochondrium

Question 15

What is monera?

Answer 15

Bacteria and archae

Question 16

Organisation of pungi

Answer 16

mitochondria, cell wall, endomembrane system, nucleus

Question 17

What is the major difference between prokaryotes and eukaryotes

Answer 17

Prokaryote don’t have compartments

Question 18

Describe the central dogma

Answer 18

Francis Crick

3 molecules can interact to pass on detailed information(DNA –> RNA –> protein)

Question 19

Describe RNA

Answer 19

It can form a riboenzyme, it has enzymatic activity, can fold and form molecules that catalyse chemical reactions
Translate mRNA into proteins
Large and small subunit
Enzymatic activity of ribosomes depend on RNA part of the ribosomes

Question 20

How do ribonucleotides spontaneously polymerise?

Answer 20

On clay surfaces

Question 21

How can replicase be made

Answer 21

Ribozyme replicates an un-folded RNA strand of another replicase molecule
At high temp, both strands separate, one folds into a new replicase and one serves as a template

Question 22

What is needed to make a cell?

Answer 22

A bi-layer

Question 23

What is needed for a bi layer

Answer 23

Amphiphatic molecule, likes water at one end but not at the other,
Spontaneous assembly into lipids
Some minerals catalyse the formation of fatty acids from hydrogen and CO

Question 24

Describe Micelles

Answer 24

Polar fatty acids self organise into micelles

Question 25

How are vesicles formed?

Answer 25

Spontaneously formed from micelles, formation requires an acidic pH, larger than micelles and can grow by fusion with more micelles

Question 26

Describe lipid bilayer

Answer 26

Flexible molecules, flipping lipids can transport molecules over the membrane

Question 27

Which molecules accumulate within the vesicle?

Answer 27

Ribonucleotides, ribozymes and other molecules

Question 28

Describe a protocell

Answer 28

Vesicle has ribozyme and template strand, bigger so unstable and therefore can pop into two,

Question 29

Overall production of a protocell

Answer 29

RNA replicase uses ribonucleotides to make a copy of another RNA replicase, micelles fuse with the vesicle and enlarge it until it becomes unstable and divides Random mistakes could form better replicase and uptake of new RNA could incorporate new ribozymes - protocol grow and divide faster Protocells compete for resources and faster growing protocells are more competitive

Question 30

What is optical resolution limit?

Answer 30

minimum distance that allows recognition of object details, depends on wave length of light.beam smaller wavelength = better resolution

Question 31

Describe light microscopy

Answer 31

Visible light, glass lenses focus light, resolution limit 200nm, cells alive

Question 32

Describe electron microscopy

Answer 32

High resolution but material is always dead and fixed, electron beam

Question 33

Principle of fluorescent microscopy

Answer 33

Fluorescnce is the emission of light by a substance that has absorbed light Emission at a higher wavelength than excitation Sends electrons into a high energetic stages and then falls back

Question 34

GFP emits green light after excitation with

Answer 34

Blue light

Question 35

What is GFP used for?

Answer 35

Reporter to analyse proteins in the living cell | Fusion proteins allow us to visualise sub cellular structures

Question 36

Describe FRAP

Answer 36

Fusion protein is in the nucleus and cytoplasm, bleaching the nuclear population of fusion protein, fluorscence in the nucleus recovers because the cytoplasmic fusion protein enters the nucleus Reveals differences in membrane fluidity and protein motility - bleached area closes due to diffusion of integral membrane, unbleached don't close due to reduced membrane fluidity

Question 37

Describe FLIP

Answer 37

Photobleach the cytoplasmic population, fluorescence in the nucleus decreases as the fusion protein moves into the cytoplasm, visualise the nuclear population of fusion protein by photo-activation with a laser

Question 38

Describe photoactivation

Answer 38

400bm laser light induces a chemical reaction, about 100-fold increase in fluorescence after photo-activation, photoactivatable red fluorescent proteins available