DNA to Protein I

Question 1

Define gene

Answer 1

Section of DNA / Chromosome which codes for one or more proteins.
Some are coding and some are non - coding blocks.

Question 2

Define gene expression

Answer 2

Genes can be switched on and off.

Genes can code for RNA too.

Question 3

Define genome

Answer 3

An organisms entire base sequence. (found in mitochondria of every cell. )

Question 4

Define exome

Answer 4

Part of genome which is made up of coding exons (this is the coding bit of the genome).

Question 5

What are 4 main types of centromere localisations?

Answer 5

Metacentric = Centromere is in the middle.
Sub - Metacentric = the centromere is slightly higher than it is in metacentric formation.
Acrocentric = forms rabbit ears style formation.
Telocentric = There are no upper arms to the structure.

Question 6

Which centromere localisation doesn’t exist in humans?

Answer 6

Telocentric

Question 7

What are the 3 key features used to identify chromosomes?

Answer 7

1) Size
2) Banding Pattern
3) Centromere Position

Question 8

What is the classic structure of ‘G - Banding’?

Answer 8

Classic structure of light and dark banding.
Light Band = Euchromatin
Dark Band = Heterochromatin

Question 9

What do chromosomes usually exist as?

Answer 9

Exists as chromatin.

Question 10

What happens to DNA during cell division?

Answer 10

DNA is complexed with various proteins and undergoes several levels of compacting via coiling and supercoiling.

Question 11

What is DNA normally wrapped around?

Answer 11

Histones.

Question 12

What is the structure of chromosome?

Answer 12

8 Histones

2 turns of DNA

Question 13

What is the formation of nucleosome?

Answer 13

Octamer of Histones.

Question 14

What does Histone H1 link to?

Answer 14

Linker DNA.

Question 15

What is the difference between euchromatin and heterochromatin in terms of function?

Answer 15

Euchromatin allows gene expression whereas heterochromatin DOES NOT allow gene expression.

Question 16

Explain heterochromatin in detail.

Answer 16

Inactive DNA due to NO genes present / genes aren’t expressed.
HIGHLY BOUND = No room for transcription.

Question 17

Explain euchromatin in detail.

Answer 17

Actively expressed DNA.

LOOSELY BOUND = Allows room for transcription.

Question 18

What is the function of centromeres?

Answer 18

Keeps sister chromatids together.
Attaches to microtubules during cell division.
Structurally intergral.

Question 19

What is the effect of having heterochromatin in the centromere structure?

Answer 19

Normally highly repetitive.

Question 20

What is the function of telomerase?

Answer 20

Repairs telomeres but is only ACTIVE in certain cell types.

= Can lead to cancer if switched on in the wrong cells.

Question 21

What happens to the structure of telomeres when they degrade?

Answer 21

They become shorter and thus, can affect the gene function and protein production.

Question 22

What are the stages in the cell cycle?

Answer 22

G0 
G1 
S
G2
Mitosis
Cytokinesis

Question 23

What happens in G1?

Answer 23

Cell makes a variety of proteins which are needed for DNA replication. (known as a single chromatid).

Question 24

What happens in G0?

Answer 24

Cell cycle arrest occurs.

Question 25

What happens in S?

Answer 25

Synthesis occurs = This is where chromosomes are replicated and therefore, each chromosome consists of two sister IDENTICAL chromatids.

Question 26

What happens in G2?

Answer 26

Synthesis of proteins.

Some cells don’t replicate though.

Question 27

What happens when the S - stage does not occur?

Answer 27

There would be a reducing number of chromosomes during cell division.

Question 28

What is a genome?

Answer 28

Combinaton of alleles at a single locus.

Question 29

What is contained within the nuclear genome?

Answer 29

22 pairs of autosomes.

1 pair of sex chromosomes.

Question 30

How are diseases passed onto children / inherited?

Answer 30

Mitochondrial disorders are passed down via the maternal side due to ova providing mitochondria.
Always MOTHER TO CHILD.

Question 31

What is the structure of a human mtDNA?

Answer 31

Circular DNA.
Heavy and Light Strand.
Heavy (H, outer ring) and Light (L, inner ring).

Question 32

What is the structure of a nucleotide?

Answer 32

Nitrogenous Base = Adenine / Cytosine / Guanine / Thymine
Phosphate
Sugar = Deoxyribose

Question 33

What are the two pyrimidines?

Answer 33

Cytosine

Thymine

Question 34

How many hydrogen bonds are there between A and T?

Answer 34

2 hydrogen bonds.

Question 35

How many hydrogen bonds are there between C and G?

Answer 35

3 hydrogen bonds.

Question 36

What is the procedures within the Central Dogma?

Answer 36

DNA -> RNA = Transcription
OCCURS IN THE NUCLEUS.
RNA -> Protein = Translation
OCCURS IN THE CYTOPLASM.

Question 37

What are introns?

Answer 37

Non - Coding Section of gene between exons.

Question 38

What is the UTR?

Answer 38

Contains regulatory elements which is IMPORTANT for control of protein synthesis.

Question 39

What is the sense and antisense strand?

Answer 39

Sense Strand = Same sequence as the mRNA molecule.

Antisense Strand = Used as a template to generate this identical mRNA strand.

Question 40

What is splicing?

Answer 40

Removing of introns.

Question 41

How is mRNA modified after transcription?

Answer 41

Capped at 5’ prime end.
Polyadenylated at 3’ prime end.
Introns are removed.

Question 42

What is mRNA?

Answer 42

Carries genetic information from nucleus to cytoplasm.

Question 43

What is rRNA?

Answer 43

Located in the cytoplasm.

It’s very important in directing translation.

Question 44

What is tRNA?

Answer 44

Located in the cytoplasm.

Transfers amino acids to ribosome to generate protein.