Genetics: Mutations Flashcards
Test review
What is a mutation?
An error replicating genetic material which becomes part of the cell’s genotype and it’s descendants. Some are harmful, but many have no effect. Some are also beneficial, which fuels variation for evolution.
What are the two types of mutations?
Chromosome mutation: Abnormal change in the structure of a whole or parts of a chromosome, or an organisms chromosome number
Gene mutation: Abnormal change that affects the gene on a chromosome
How must mutations be passed down?
Inherited mutations may only be received from organisms with gene mutations, as they are in the genetic material. Body mutations develop only for the organism which has them, and may not be inherited.
What are spontaneous mutations?
Mutations caused by molecular interactions taking place naturally in cells.
What is a cause of spontaneous mutations?
Incorrect base pairing by DNA polymerase during DNA replication.
What are induced mutations?
Mutations caused by agents outside the cell.
What are mutagens and their two types?
A substance or event that increases the rate of mutation in an organism.
1: Physical mutagens
2: Chemical mutagens
What are physical mutagens?
Causes physical changes in DNA structure. They are high energy radiation. (X-rays, gamma rays, UV radiation)
What are chemical mutagens?
A molecule entering a cell’s nucleus, inducing mutation via chemical reaction with DNA. (Nitrites, gas fumes, carcinogens)
What are the two types of gene mutations?
1: Frameshift mutation
2: Point mutation
What is Frameshift mutation?
Insertions or deletions of a particular nucleotide, changing the entire amino acid sequence. Shifts reading frame.
What is Point mutation?
One nucleotide replaces another (substitutes) in a triple. Codes for a different amino acid, changing the protein.
What are the three types of point mutation?
1: Silent - No effect
2: Mis-sense - Changes a single amino acid. May be insignificant (No change)
3: Non-sense - Early stop message. No functional protein
What is it called when a cell has an has one extra chromosome? one less?
Trisomy: One extra
Monosomy: One less
(Monosomy is more harmful due to missing genetic info)
What is nondisjunction?
Addition or loss of a whole chromosome. Occurs during meiosis when when chromosomes don’t separate.
What are some conditions connected to nondisjunction?
- Downs syndrome (3 #21) - Trisomy 21
- Turner’s syndrome (XO) - Female
- Klinefelter’s syndrome (XXY) or (XXXY) - Male
- Jacob’s Syndrome (XYY) -Male
- XXX - (no effect) Female
- Patau - Trisomy 13
- Edwards - Trisomy 18
What is polyploidy?
Having an extra set(s) of chromosomes. Occurs when nuclei don’t undergo meiotic division. Produces diploid gametes, not haploid. Zygote will be multiple haploid number (3n, 4n, 5n). Lethal in most animals, but common in plants. Polyploid plants are usually healthier.
What is translocation?
Non-homologous chromosomes exchange fragments/pieces of a chromosome and they attach to non-homologous chromosomes without receiving anything in return.
What is inversion?
Occurs when a piece of a chromosome is rotated which reverses the order of genes in that segment.
What is addition/duplication?
Occurs when a piece of a chromosome breaks and attaches to a homologous chromosome. Results in a repeating sequence.
What is deletion?
Occurs when a piece of a chromosome breaks off, resulting in the loss of genes.
What is epigenetics?
The study of how your behaviours/environment may cause changes that affect how your genes work. These changes are reversible and don’t change your DNA sequence, rather changes how your body reads a DNA sequence.
