Mutations

Question 1

What is a Mutation?

Answer 1

A permanent change to the genetic code or the nucleotide sequence in DNA

Question 2

Mutation specs

Answer 2

All mutations are inheritable - they are copied during DNA replication and passed onto daughter cells
Only mutations that affect genetic info in gametes are passed on to the organisms offspring
Mutations that occur in body cells are called SOMATIC CELL MUTATIONS, those that occur in reproductive cells are GERM LINE MUTATIONS

Question 3

Point Mutation

Answer 3

A chemical change that affects just one or a few nucleotides
Substitution of one nucleotide for another
Insertion or deletion of one or more nucleotides
May or may not affect the cell as a change in 1 nucleotide might no change the aa
ie. CUU and CUC both code for leucine
AKA: Silent Mutation

Question 4

Mis-Sense Mutation

Answer 4

Results in a slightly altered protein
Can be harmful - change in one aa in one of the polypeptides that makes up haemoglobin can cause sickle cell disease
Can be beneficial - may also help organisms develop new forms of proteins (ie, antibodies to fight infections)

Question 5

Nonsense Mutations

Answer 5

Renders the gene unable to code for a functional polymerase
ie. deletion of start signal or premature stop signal

Question 6

Frameshift Mutation

Answer 6

Causes the entire reading frame of the game to be altered (insertion or deletion of two or more nucleotides)
Usually results in a nonsense mutation

Question 7

Chromosomal Mutations

Answer 7

Changes on more than one gene
Crossing over - recombines Genetic Material from different chromosomes
Lisa’s or duplication of portions of chromosomes during DNA replication
Many mutations are caused by molecular interactions that take place naturally within cells - SPONTANEOUS MUTATIONS
Incorrect base pairing by DNA polymerase during DNA replication

Question 8

What can cause some mutations?

Answer 8

Exposure to certain environmental factors can INDUCE MUTATIONS

Question 9

What is a Mutagen?

Answer 9

Physical or chemical facotors that cause mutations
They cause incorrect nucleotides to be inserted during DNA replication
Eg. Nitrites, gasoline fumes, 50 compounds found in cigarettes (most are carcinogenic)
Could cause a different aa to be coded
Could cause a stop codon to appear and make a shorter aa chain

Question 10

Physical Mutagens

Answer 10

X-rays, gamma rays, UV rays

Question 11

Chemical Mutagens

Answer 11

Molecule that can enter the nucleus and induce mutations by reacting chemically with the cell

Question 12

Mitochondrial DNA

Answer 12

Mitochondria has its own DNA that is replicated, transcribed, and translated independent from the DNA in the nucleus
REMEMBER: cytoplasm in a zygote comes from the ovum, so where does everyone get their mtDNA from?
Mutation can happen in mtDNA sequences, they likely share a maternal ancestor