Chromosomes And Protiens Flashcards
In what type of cells does splicing occur to pre-mRNA
Eukaryotic cells
What is the role of DNA helicase in transcription
Break hydrogen bonds in DNA molecule
what joins to the DNA template strand during transcription
Free RNA nucleotides in the nucleus join there complementary base pair on the template strand and form hydrogen bonds
What enzymes catalyses the formation of phophodiester bonds between the RNA nucleotides in transcription
RNA polymerase
When does transcription stop
When a stop codon is reached
What does pre-mRNA do with the template strand in transcription?and why ?
Dissociâtes from the DNA template strand because of the instability.
Therefore the hydrogen bonds are broken
What is splicing?
The removal of introns from pre-mRNA
What is a pre-mRNA strand made up of
Introns and exons
What is an intron
A non coding section of a pre-mRNA strand
What is a codon
A coding section of a pre-mRNA strand
Name a disease caused by incorrect splicing
Cistic fibrosis
What organelle is involved in the process of translation during protein synthesis
Ribosomes
What is free floating in the cytoplasm that attaches to the ribosome with complementary bases in translation
tRNA
What on the tRNA molecule is complementary to the mRNA
The anticodon
What does a tRNA molecule carry
A specific amino acid
What is used to hydrolyse the bonds between two amino acids in translation
ATP
An enzyme
What bond forms between amino acids
Peptide bonds
When does the ribosome stop doing translation
When a stop codon is reached
What is formed during translation
A polypeptide chain of amino acids
The primary structure of a protein
Define mutation
A change within the DNA usually the sequence or quantity of the nitrogenous bases
What causes mutations
- Natural copying errors
- Exposure to mutagens
What is a mutagen
A chemical or physical agent that is capable of inducing change in DNA known as mutations
What is a substitution mutation
When one nucleotide is replaced by another nucleotide which will change the base within the triplet that codes for an amino acid 
What is a silent mutation
When a change in base has no impact on the sequence of amino acids in the polypeptide chain 
Why do silent mutations occur?
 the DNA code is degenerate
What is a missense mutation?
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
What is a nonsense, mutation
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.
What is a deletion mutation?
When one nitrogenous base is completely removed, which completely changes the triplet codon
What is the name given to what happens when a deletion mutation occurs?
Frame shift
What is a nondisjunction mutation?
When the chromosomes fail to separate during meiosis, which causes the gametes to have one more or one less chromosome
E.g. down syndrome
What are the benefits of mutations?
It produces genetic diversity
It helps with natural selection
It has helped with evolution
What are the disadvantages of mutation?
Most mutations produced organisms that are less suited to the environment 
Give some features of prokaryotic DNA
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
