W3 - The Cell

Question 1

Discovery of the cell

Answer 1

Robert Hooke, 1665

Looked at a thin slice of cork through his 2-lens microscope.

= Discovered tiny, hollow structures + called them cells.

Question 2

Who proposed the ‘cell theory’ and when?

Answer 2

Theodor Schwann

1839

Question 3

What does the ‘cell theory’ state?

Answer 3

All organisms are made up of 1 or + cells

Cell is the basic unit of life, the smaller unit that shows all characteristics of life

All cells come from pre-existing cells.

Question 4

Do prokaryotes have a distinct nucleus bounded by a membrane?

Answer 4

NO

Question 5

Do prokaryotes have membrane bound organelles?

Answer 5

NO

Question 6

What are plasmids?

Answer 6

Small circular extrachromosomal DNA mol

Question 7

How many cells does the human body contain?

Answer 7

Around 37.2 trillion

Question 8

Cytoplasm

Answer 8

Jelly like material in which organelles ‘float’

Question 9

Cytosol

Answer 9

Soluble part left of the cytoplasm if all the organelles were removed.

Question 10

What is the central dogma of molecular biology?

Answer 10

Flow of genetic info w/in a biological system.

Question 11

What are the 3 processes of central dogma of molecular biology?

Answer 11

Replication

Transcription

Translation

Question 12

Around how many genes do humans have?

Answer 12

25,000

Question 13

Give examples of structural proteins

Answer 13

Collagen

Elastin

Keratin

Question 14

Give examples of motility proteins

Answer 14

Actin

myosin

Tubulin

Question 15

Give examples of storage proteins

Answer 15

Ovalbumin

Casein

Question 16

Give examples of hormonal proteins

Answer 16

Insulin

Nerve growth factor (NGF)

Question 17

What % of cellular ATP is made in the mitochondria by oxidative phosphorylation?

Answer 17

Just over 80%

Question 18

Endosymbiotic theory

Answer 18

Mit were primitive bacterial cells.

Millions of years later… mit + eukaryotes became mutually beneficial.

NOW a permanent dependent relationship.

Question 19

Mitochondria DNA

Answer 19

Circular

Comes only from the mother

Question 20

How many genes roughly does mit DNA encode for?

Answer 20

37

Question 21

Where are SER more prominent in?

Answer 21

Adrenal cortex (secreting steroid hormones)

Hepatocytes

Sarcoplasmic reticulum of muscle cells

Question 22

Describe the Golgi apparatus

Answer 22

Stacks of membrane bound cistern between the ER + surface of cell.

Question 23

Function of Golgi apparatus

Answer 23

Processing of proteins synthesised in the RER

Question 24

What are ribosomes made of?

Answer 24

Protein

rRNA

Question 25

What does the ribosome do to make new protein?

Answer 25

Clamps over tRNAs + mRNAs

Question 26

What are the 3 main sites on a ribosome?

Answer 26

A P E

Question 27

A site on a ribosome

Answer 27

Receives new tRNA

Question 28

P site on ribosome

Answer 28

Receives peptide-bearing tRNA after peptide bond formation

Question 29

E site on ribosome

Answer 29

Where tRNAs exit

Question 30

What are the 4 major proteolytic systems?

Answer 30

Lysomomes - The 'bulk' protein breakdown ATP dependent ubiquitin proteasome - protein breakdown Calpains Caspases

Question 31

How are lysosomes created?

Answer 31

When early endoscopes from Golgi apparatus have hydrolytic enzymes added to them.

Question 32

At what pH do lysosomes work best at?

Answer 32

Around 5

Question 33

What are calpains?

Answer 33

Calcium activated degredated proteins.

Question 34

What do calpains do?

Answer 34

Cleave + breakdown proteins in elevated levels of Ca2+

Question 35

What are peroxisomes?

Answer 35

Membrane bound enzyme sacs

Question 36

What do peroxisomes do?

Answer 36

Carry out oxidation reactions to prod H202. (Hydrogen peroxide) + oxidative reactions for uric acid, aa + FAs

Question 37

What is the cytoskeleton?

Answer 37

Network of protein fibres

Question 38

What are the functions of the cytoskeleton?

Answer 38

Mechanical strength Locomotion Remodelling Chromosome separation in cell division Intracellular transport of organelles Cellular signalling

Question 39

What are microfilaments in the cytoskeleton?

Answer 39

Linear polymers of actin subunits.

Question 40

Characteristics of microfilaments in the cytoskeleton

Answer 40

Flexible Strong Resist buckling (compressive forces) Resist filament fracture (tensile forces)

Question 41

What are microtubules in the cytoskeleton?

Answer 41

Linear polymers of tubulin that act as conveyer belts in cells.

Question 42

What do microtubules in the cytoskeleton do ?

Answer 42

Move vesicles, granules, organelles + chromosomes via special attachment proteins.

Question 43

What do intermediate filaments in the cytoskeleton do?

Answer 43

W/stand mechanical stress.

Question 44

What are focal adhesions?

Answer 44

Multi-protein structures forming mechanical links between intracellular actin bundles + extracellular substrate. Large Dynamic Connects cytoskeleton of cell to ECM.

Question 45

How many protein components do focal adhesions comprise of?

Answer 45

At least 150

Question 46

What are signalling molecules (a.k.a ligands) ?

Answer 46

Mol that bind specifically to other mol i.e receptors. Message carried by the ligands is relayed through a chain of chemical messengers in the cell.

Question 47

Briefly lay out the signal transduction pathway

Answer 47

Ligand / extracellular signal mol Receptor Chemical messengers in cell to relay signal Response

Question 48

What is the result of a ligand binding to a cell-surface receptor?

Answer 48

Receptor's intracellular domain changes shape. = Sets off signalling events.

Question 49

Is signalling nonlinear?

Answer 49

YES