Usin Genetics & storing it

Question 1

Phenotype?

Answer 1

Outward physical manisfestation of organisms genes

Question 2

Genotype?

Answer 2

Full hereditary info of organism (even if not expressed)

Question 3

Whats the difference between 2’-deoxyribose sugar & a ribose sugar?

Answer 3

On carbon 2 ribose has a hydroxyl group
On carbon 2 deoxyribose sugar has just a hydrogen

Question 4

Which way is the twist of the DNA double helix?

Answer 4

Right hand (to the right)

Question 5

How many H bonds join Cytosine & guanine?

Answer 5

3 H bonds between cytosine & guanine

Question 6

How many H bonds between adenine & thymine?

Answer 6

2 H bonds between thymine & adenine
(same for Adenine-Uracil)

Question 7

DNA is coiled around what protective protein?

Answer 7

Histones

Question 8

What is DNA called when wrapped round a histone?

Answer 8

A nucleosome

Question 9

List the stages of DNA packaging from smalledst to largest:

Answer 9

DNA
-> Nucleosome
-> Coils
-> Supercoils
-> Chromosome

Question 10

At what point do the supercoils form chromosomes?

Answer 10

Just before cell division occurs

Question 11

What makes up chromatin?

Answer 11

The DNA, proteins & RNA that packages DNA within the nucleus

Question 12

What are the 2 forms of chromatin?

Answer 12

Heterochromatic (condensed) form
Euchromatic (extended) form

Question 13

Why must the double helix strands seperate during transcription & replication?

Answer 13

To remove the histone & folding barriers so enzymes have access to the DNA

Question 14

In what two ways is the chromatin made more accessible to enzymes? (regarding histones)

Answer 14

By enzymatically modifying the histones or by displacing them with chromatin remodelling complexes.
Both are reversible

Question 15

How many new DNA molecules are made in replication?

Answer 15

2

Question 16

What does semi-conservative replication mean?

Answer 16

It means each of the 2 new DNA molecules contains 1 strand from the original & 1 new strand.

Question 17

In what direciton is the DNA replicated?

Answer 17

From 5 prime end to the 3 prime end.
(5’ to 3’)

Question 18

Why is DNA replication bi-direcitonal?

Answer 18

Because the DNA are anti-parallel, i.e. their prime ends are in reverse to eachother.
So ones built upward & one downward

Question 19

Which DNA template strand is the lagging & which the leading?

Answer 19

The laggine strand is the one trying to build in the opposite direction to the unzipping
The leading is the one building DNA in the same direction as the unzippin

Question 20

What are okazaki fragments?

Answer 20

Pieces of new DNA being made on the lagging template that will join together at the end.

Question 21

What are hte coding sections of DNA called?

Answer 21

Exons

Question 22

What are the ‘junk’ sections of DNA called?

Answer 22

Introns

Question 23

What do you call teh process of making mRNA?

Answer 23

TRanscription

Question 24

How is mRNA different to the DNA?

Answer 24

mRNA only uses the exons, stiching them together without hte introns in between

Question 25

What is the redundancy or degeneracy of the genetic code?

Answer 25

degeneracy refers to the fact that often the last base of a codon can be canged without changin the amino acid produced.

Question 26

What mutation caues sickle cell anemia?

Answer 26

Hydrophilic Glutamate is replaced by hydrophobic Valine in the haemoglobin gene

Question 27

Why has sickle cell anemia survived in the tropics?

Answer 27

It has a selective advantage of making you immune to malaria.

Question 28

What does mRNA do?

Answer 28

Carries exon info from DNA in nucleus to the cytoplasm

Question 29

People have many more proteins than genes, how can 1 gene produce multople proteins?

Answer 29

mRNA can be alternatively spliced to contain only some of the exons in a gene, giving many more options for DNA amino acid arrangment

Question 30

What are different proteins from the same gene called?

Answer 30

Protein Isoforms

Question 31

In what process is tRNA involved?

Answer 31

tRNA is involved in translation of mRNA into an amino acid sequence

Question 32

What does tRNA do specifically?

Answer 32

Acts as an adapter molecule between coded amino acid & mRNA. It brings the amino acid & joins it to the growing polypeptide chain

Question 33

What is rRNA?

Answer 33

A component of ribosomes

Question 34

What is a polysome?

Answer 34

A collection of ribosomes simultaneously translate one section of mRNA

Question 35

How do tRNA molecules reconise part of the mRNA chain?

Answer 35

tRNA molecules contain anticodons allowing them to match up to the right section of mRNA & amino acid.