Storing and Using genetic information

Question 1

What is the phenotype of an organism?

Answer 1

Outward, physical appearance

Question 2

What is the genotype of an organism?

Answer 2

Full hereditary information

Question 3

What is a nucleotide monomer?

Answer 3

Makes up chains for DNA

Made of a sugar, base and phosphate group

Question 4

How do the molecules bind in DNA?

Answer 4

• Phosphate bind to 5th and 3rd C of sugar

- Base binds to 1st C

Question 5

How are the bases structured in the double helix?

Answer 5

Bases are in the centre of the helix and bound by the outside to the sugar-phosphate backbone

Question 6

What is the name of the sugar used in DNA?

Answer 6

2-deoxyribose

Question 7

What is the name of the sugar in RNA?

Answer 7

Ribose - OH instead of H on 2nd C

Question 8

How many bases per turn of helix?

Answer 8

10

Question 9

What is meant by the chains of DNA running antiparallel to each other?

Answer 9

One runs from 5’ to 3’ from the top of the helix whilst the other is the opposite

Question 10

What structure contains most of the cell’s genetic material (DNA)?

Answer 10

Nucleus

Question 11

What occurs in the nucleus?

Answer 11

Replication of DNA and first steps in protein synthesis

Question 12

What are DNA molecules packaged into in the nucleus?

Answer 12

Chromosomes

Question 13

What are chromosome?

Answer 13

Single piece of DNA containing many genes, regulatory elements and other nucleotide sequences

Question 14

What is a nucleosome?

Answer 14

Bundles of histones (proteins) with DNA wrapped around it

Question 15

What is a chromatin?

Answer 15

Mixture of DNA, proteins and RNA that package DNA within the nucleus
Molecules that form a chromosome

Question 16

What are two types of chromatin?

Answer 16

Heterochromatin (condensed and euchromatin (extended) forms

Question 17

List stages of DNA packaging from smallest to largest

Answer 17

1. Nucleosome
2. Coils
3. Supercoils
4. Chromosome

Question 18

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

Answer 18

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

Question 19

What are two mechanisms which make chromatin maple accessible to enzymes?

Answer 19

• Histones enigmatically modified
• Histones displaced by chromatin remodelling complexes

Both reversibly

Question 20

What type of chromatin is more favourable for RNA polymerase and why?

Answer 20

Requires looser structure therefore euchromatin

Question 21

What does semi-conservative replication mean?

Answer 21

It means the 2 new DNA molecules contains 1 stand from the original and one from the new strand

Question 22

In what direction is the DNA replicated by DNA polymerase?

Answer 22

3’ to 5’ - the antisense strand

Question 23

What are the coding region in DNA?

Answer 23

Exons

Question 24

What is telomerase used for?

Answer 24

Replicating DNA strand from the 5’ to 3’ end

Question 25

What are the non-coding regions in DNA?

Answer 25

Introns

Question 26

What happens to introns and extols during transcription?

Answer 26

Introns spliced out and ends on exons join

Question 27

How many codons code for an amino acid?

Answer 27

3 but the number of codons is greater than the number of AA

Question 28

What are synonyms?

Answer 28

Condons which refer to the same AA

Question 29

How does degeneracy minimises effect of genetic mutations?

Answer 29

Variation of synonyms at 3rd codon means that changes to codon sequence are less likely to alter coded protein

Question 30

What is degeneracy?

Answer 30

Amino acids are encoded by more than one codon

Question 31

Which AA are an exception to degeneracy?

Answer 31

Methionine and tryptophan

Question 32

What type of mutation of codon sequence who alter the protein?

Answer 32

Codon that encodes for a stop or termination signal

Question 33

What disorder can single point mutations cause?

Answer 33

Sickle cell anaemia - Glu to Val - clumps haemoglobin together

Question 34

How can single point mutations cause dysfunctional proteins?

Answer 34

Base change = change in amino acid = change in structure = change in function

Question 35

mRNA role

Answer 35

Transcribes DNA in nucleus and moves to cytoplasm for protein synthesis

Question 36

What is the pre-mRNA strand?

Answer 36

Complement strand to DNA template which contains introns and exons

Question 37

What is alternative splicing?

Answer 37

Process where introns of pre-mRNA are spliced out and exon ends are brought together

Question 38

What is a strand of codons bound by in RNA?

Answer 38

An initiation codon and a termination codon

Question 39

Why are reading frames required in translation?

Answer 39

Reading frames required to read RNA strand by tRNA to deliver correct AA

Question 40

Role of tRNA?

Answer 40

Translate mRNA sequences into AA sequence

Question 41

Role of rRNA?

Answer 41

transported from nucleus to cytoplasms where they combine the proteins to form a ribosome