Unit 4 Topic 2 PART 2 Flashcards
What are the three types of point mutations
Silent mutation, nonsense mutation, missense mutation.
Mutation Definition:
A change in a gene or a chromosome relative to the original. Essentially an error in the the copying process of genetic information.
Silent Mutation Definition.
These mutations do not affect the sequence of amino acids during translation.
Nonsense Mutation Defintion.
A nonsense mutation occurs in DNA when a sequence change gives rise to a stop codon rather than a codon specifying an amino acid.
What is the result of a nonsense mutation occurring?
The presence of the new stop codon results in the production of a shortened protein that is likely non-functional.
Missense Mutation Defintion.
Change the amino acid specified by a codon, (the amino acid sequence has changed).
What will happen if errors in the genetic sequence occur.
The errors can accumulate and thus accumulated over generations and passed down to future generations.
Frameshift mutation definition
A mutation that dislocates the translational reading frame.
2 types of frameshift mutations:
Insertion and deletion.
Insertion mutation def
One or more bases are added to the DNA sequence.
Deletion mutation def
One or more bases are added to the DNA sequence.
How is genetic information read?
The info is read in codons, three bases at a time.
DO frameshift mutations affect the speed of which genetic information is read?
YES
How do environmental mutagens affect mutation rates?
They can speed up mutation rates.
Can particular mutations be influenced mutagens Y/N
No
What are the three broad categories of mutations
Chemicals, radiation and infectious agents
X rays are a physical mutagen. What can affect can they have on DNA?
They can causes the DELETION of A and G bases, which disrupts the DNA and potentially cause serious damage.
What affect does nuclear radiation have on chromosomes?
Causes double-strand breaks which results in large segments of chromosomes being rearranged?
Mechanism used for programmed cell death.
Apoptosis
Name 3 forms of (potential) physical mutagens?
Gamma rays, X-rays and nuclear radiation.
Definition for aneuploidy
Aneuploidy is a condition where one or more chromosomes are missing from or added to the normal somatic cell chromosome number.
What are aneuploidies usually a result of?
Non-disjunction during meiosis.
What does Trisomy 21 cause?
This condition causes Down Syndrome, where the offspring has two extra female chromosomes.
What is the most common cause of down syndrome?
Non-disjunction of chromosome 21 during meiosis (95% of all cases)
