Genes and proteins: One gene-one protein hypothesis

Question 1

How can one gene be characterised?

Answer 1

As one protein hypothesis.

Question 2

What are the functions of DNA?

Answer 2

It encodes information in the form of genes.

It is transcribed and translated –> produce functional proteins.

Question 3

Where are genes linked?

Answer 3

To enzymes/functional proteins.

Question 4

What is an individual’s genotype?

Answer 4

Their genetic make-up.

Question 5

What is the phenotype of an individual?

Answer 5

The physical traits.

Characteristics.

Question 6

By what is the phenotype influenced?

Answer 6

By genotype.

Environment.

Question 7

How is the G-P map characterised?

Answer 7

Simple.

Direct.

Question 8

What does the interaction of regulatory systems and pathways form?

Answer 8

Complex networks.

Question 9

What do the complex networks formed by regulatory systems and pathways interactions, do?

Answer 9

Add additional complexity to G-P maps.

Question 10

How do genes act?

Answer 10

Through enzymes’ production.

Question 11

What is each gene responsible for?

Answer 11

Producing a single enzyme.

Question 12

What does a single enzyme produced by a gene affect?

Answer 12

A step in the metabolic pathway.

Question 13

Which hypothesis describes the relationship between genes and proteins?

Answer 13

‘one gene - one polypeptide’.

Question 14

Who formulated the Central Dogma of Molecular Biology?

Answer 14

Francis Crick.

Question 15

When was the Central Dogma formulated?

Answer 15

In 1957.

Question 16

What does the Central Dogma of Molecular Biology describe?

Answer 16

The flow of genetic information in a biological system from DNA to proteins.

Question 17

When was the Central Dogma updated?

Answer 17

In 1970.

Question 18

What did Crick said about the Central Dogma in 1970?

Answer 18

It deals with detailed residue-by-residue transfer of sequential information. Information cannot be transferred back from protein to protein or nucleic acid.

Question 19

Why did ‘exceptions’ or ‘adjustments’ were made to the dogma as biology developed?

Answer 19

To facilitate new discoveries.

To better understand systems.

Question 20

What does the dogma describe after all?

Answer 20

How information flows between DNA and RNA for replication.

How DNA via RNA makes produces proteins and gives a phenotype.

Question 21

How were metabolic changes recognised?

Answer 21

Through mating experiments.

Question 22

What was recognised in mating experiments responsible for metabolic mutations?

Answer 22

Phenotypes were not following Mendelian inheritance patterns.

Question 23

What else can be responsible for metabolic mutations?

Answer 23

Enzymes.

Not linked to genetics.

Question 24

What did Ephrussi and Beadle investigate in mid-1930?

Answer 24

The eye colour pigments of Drosophila melanogaster fruit flies.

Question 25

How were the 'genes' affecting eye colour appeared?

Answer 25

Serially dependent.

Question 26

What was the result of pigments through transformations?

Answer 26

Normal red eyes.

Question 27

What did different eye colour gene mutations disrupt?

Answer 27

Transformations at different points in series.

Question 28

What are the Drosophila eye-colour pigments?

Answer 28

Complex chemicals.

Question 29

How are Drosophila eye-colour pigments produced?

Answer 29

By a number of different enzymatic reactions.

Question 30

What do Drosophila eye-colour pigments produce when combined?

Answer 30

Hues = αποχρώσεις.

Question 31

What was each gene responsible for?

Answer 31

For an enzyme acting in metabolic pathway of pigment synthesis.

Question 32

How did they study the metabolic pathways of eye-pigment?

Answer 32

By isolating pigments from the eyes of flies.

Question 33

Which organism made genetic studies of biochemical traits much easier, as they started isolating fly eye pigments?

Answer 33

Bread mould = Neurospora crassa.

Question 34

What is the organism Neurospora crassa?

Answer 34

Red bread mould from the phylum Ascomycota. | Eukaryotic.

Question 35

When was Neurospora crassa organism first isolated?

Answer 35

In 1843.

Question 36

What are the characteristics of Neurospora crassa organism?

Answer 36

1. Grows easy and fast. 2. Haploid life cycle --> traits show in offspring. 3. Spores in sacks in order --> planted in media. 4. Mutated by X-rays when growing on different media.

Question 37

How can the sacks of spores in Neurospora crassa be removed?

Answer 37

By using micro-dissectors. | When planted in new media --> grow --> analysis.

Question 38

What can happen in Mapping experiments of Neurospora?

Answer 38

Different strains --> mated --> produce ascospores/sacks --> dissected out --> transferred to fresh agar plates.

Question 39

What can be determined from the Neurospora mapping experiments?

Answer 39

Offspring's phenotype.

Question 40

What did each offspring had inherited in mapping experiments?

Answer 40

2 different genes.

Question 41

What can we determine by separating the 2 different genes that inherit offspring?

Answer 41

Offspring's genetic recombination.

Question 42

What is the aim of using Neurospora crassa in Beadle and Tatum's experiment?

Answer 42

To link biochemistry of arginine biosynthesis to enzymes and genes.

Question 43

Where can Neurospora grow?

Answer 43

On minimal media without additional nutrients.

Question 44

What can Neurospora produce?

Answer 44

All compounds needed for growth. Amino acids. Arginine.

Question 45

What were scientists able to do by isolating arginine mutants in Beadle and Tatum's experiment with Neurospora crassa?

Answer 45

To place enzyme action into biosynthesis pathway --> produce arginine.

Question 46

What happens in Isolating arginine mutants process?

Answer 46

1. Neurospora --> exposed to --> X-rays --> mutations. 2. Ascospores --> isolated --> grow up on --> enriched media. 3. Strains --> tested on --> minimal media and minimal media + single amino acids.

Question 47

Where do strains of Neurospora not able to grow on minimal media, grow instead?

Answer 47

On minimal media + arginine.

Question 48

When did strains grown on media + arginine mutate?

Answer 48

In the arginine biosynthesis pathway.

Question 49

What happened in Complementing mutants with Neurospora?

Answer 49

Mutants assessed if they can grow on modified minimal media supplemented with arginine intermediates and arginine in biosynthesis pathway.

Question 50

What happened to Neurospora mutants when arginine intermediates and arginine in biosynthesis added?

Answer 50

They could be saved on minimal media.

Question 51

How many enzymes did Neurospora crassa use to produce arginine?

Answer 51

3.

Question 52

How did Neurospora crassa used 3 agents to produce arginine?

Answer 52

One after the other.

Question 53

What did Biochemists do during Neurospora crassa using enzymes?

Answer 53

They isolated the enzymes.

Question 54

Why did Biochemists isolate the enzymes that Neurospora was using?

Answer 54

To convert enzymes into products.

Question 55

In what was ornithine converted when enzymes were placed in the appropriate order?

Answer 55

To arginine.

Question 56

What did the mapping experiments with arginine mutants demonstrate?

Answer 56

Arginine mutants were coded by different genome parts/loci.

Question 57

How are loci recognised?

Answer 57

Genes.

Question 58

What hypothesis was developed further as molecular biology developed?

Answer 58

One gene - one protein/polypeptide - MULTIPLE POLYPEPTIDES.

Question 59

By how many proteins can enzymes be formed?

Answer 59

By multiple protein subunits.

Question 60

What else except protein subunits can enzymes include?

Answer 60

Non-protein factors. | RNA.

Question 61

What can genes produce once transcribed and translated?

Answer 61

Similar, different proteins.

Question 62

What shape do proteins/enzymes need to adopt?

Answer 62

A very precise 3-dimensional shape.

Question 63

Why do proteins need to have a 3-dimensional shape?

Answer 63

To interact with co-factors and substrates.

Question 64

What can structure changes affect in proteins?

Answer 64

Function. | Lose/generate new functions.

Question 65

What can the adding of functional domains to an enzyme change?

Answer 65

Functionality.

Question 66

Of what are eukaryote genes composed?

Answer 66

Exons and introns.

Question 67

Which part of eukaryote genes composition code for polypeptide to make a whole protein?

Answer 67

Exons.

Question 68

When do differences in splicing of genes occur?

Answer 68

After transcription. | Before translation.

Question 69

What do differences in splicing of genes alter?

Answer 69

Exons set.

Question 70

How are exons involved in protein production?

Answer 70

They are translated.

Question 71

What do variations in splicing affect in a protein?

Answer 71

Structure. | Function.

Question 72

Which are the key transitional controls in genes?

Answer 72

Start and stop codons.

Question 73

In what can modifications of key translational controls result in proteins?

Answer 73

Missing normal N-terminal = front section. | Longer C-terminals = end section.