Chromosomes And Protiens

Question 1

In what type of cells does splicing occur to pre-mRNA

Answer 1

Eukaryotic cells

Question 2

What is the role of DNA helicase in transcription

Answer 2

Break hydrogen bonds in DNA molecule

Question 3

what joins to the DNA template strand during transcription

Answer 3

Free RNA nucleotides in the nucleus join there complementary base pair on the template strand and form hydrogen bonds

Question 4

What enzymes catalyses the formation of phophodiester bonds between the RNA nucleotides in transcription

Answer 4

RNA polymerase

Question 5

When does transcription stop

Answer 5

When a stop codon is reached

Question 6

What does pre-mRNA do with the template strand in transcription?and why ?

Answer 6

Dissociâtes from the DNA template strand because of the instability.
Therefore the hydrogen bonds are broken

Question 7

What is splicing?

Answer 7

The removal of introns from pre-mRNA

Question 8

What is a pre-mRNA strand made up of

Answer 8

Introns and exons

Question 9

What is an intron

Answer 9

A non coding section of a pre-mRNA strand

Question 10

What is a codon

Answer 10

A coding section of a pre-mRNA strand

Question 11

Name a disease caused by incorrect splicing

Answer 11

Cistic fibrosis

Question 12

What organelle is involved in the process of translation during protein synthesis

Answer 12

Ribosomes

Question 13

What is free floating in the cytoplasm that attaches to the ribosome with complementary bases in translation

Answer 13

tRNA

Question 14

What on the tRNA molecule is complementary to the mRNA

Answer 14

The anticodon

Question 15

What does a tRNA molecule carry

Answer 15

A specific amino acid

Question 16

What is used to hydrolyse the bonds between two amino acids in translation

Answer 16

ATP
An enzyme

Question 17

What bond forms between amino acids

Answer 17

Peptide bonds

Question 18

When does the ribosome stop doing translation

Answer 18

When a stop codon is reached

Question 19

What is formed during translation

Answer 19

A polypeptide chain of amino acids
The primary structure of a protein

Question 20

Define mutation

Answer 20

A change within the DNA usually the sequence or quantity of the nitrogenous bases

Question 21

What causes mutations

Answer 21

1. Natural copying errors
2. Exposure to mutagens

Question 22

What is a mutagen

Answer 22

A chemical or physical agent that is capable of inducing change in DNA known as mutations

Question 23

What is a substitution mutation

Answer 23

When one nucleotide is replaced by another nucleotide which will change the base within the triplet that codes for an amino acid 

Question 24

What is a silent mutation

Answer 24

When a change in base has no impact on the sequence of amino acids in the polypeptide chain 

Question 25

Why do silent mutations occur?

Answer 25

 the DNA code is degenerate

Question 26

What is a missense mutation?

Answer 26

When a change in the base causes a change in the amino acid that the triplet codon codes for which could change the overall 3D tertiary structure of the protein altering its function

Question 27

What is a nonsense, mutation

Answer 27

When a change in the nucleotide changes, the nitrogenous base, so therefore causes the amino acid to change. In this case it is a stop code on and makes the protein completely non-functional.

Question 28

What is a deletion mutation?

Answer 28

When one nitrogenous base is completely removed, which completely changes the triplet codon

Question 29

What is the name given to what happens when a deletion mutation occurs?

Answer 29

Frame shift

Question 30

What is a nondisjunction mutation?

Answer 30

When the chromosomes fail to separate during meiosis, which causes the gametes to have one more or one less chromosome E.g. down syndrome

Question 31

What are the benefits of mutations?

Answer 31

It produces genetic diversity It helps with natural selection It has helped with evolution

Question 32

What are the disadvantages of mutation?

Answer 32

Most mutations produced organisms that are less suited to the environment 

Question 33

Give some features of prokaryotic DNA

Answer 33

Found in the cytoplasm of bacteria The DNA is circular and non linear It is not associated with proteins / histones It does not contain introns (non coding sections) Shorter than eukaryotic DNA