Multiple Alleles/ Mutation Flashcards
Multiple alleles
3 or more of the same gene that code for a single trait
In humans blood is determined by
3 alleles A,B and O
Humans can only inherit
2 alleles
Which are recessive and which are dominant
A and B is dominant and O is recessive
Blood type A is
Blood type B is
Blood type AB is
Blood type O is
An antigen
an antigen
an antigen/ universal recipient
universal donor
Mutation is
a sudden genetic change in the base pair sequence of DNA
Mutation can be
harmful, beneficial, neutral
If it is:
Harmful
Beneficial
Neutral
Organism is less able to survive
genetic disorders, cancer, death
Allows organism to better survive
provides genetic variation
neither harmful nor helpful to organisms
Mutations can occur in these two ways
Chromosomal or gene/point
chromosomal mutation
- Less common than a gene mutation
- Affects many genes rather than just one
- Caused by failure of the homologous
- Chromosome pairs no longer look the same
Examples of chromosomal mutation
Down’s syndrome(trisomy 21)-47 chromosomes 1 extra chromosome at pair #21
Turner’s syndrome
Klinefelter’s syndrome
Turner’s syndrome
only 45 chromosomes, missing a sex chromosome
girls affected- short, slow growth, heart problems
Klinefelter’s syndrome
47 chromosomes, extra X chromosome (XXY)
boys affected- low testosterone levels, underdeveloped muscles, sparse facial hair
Down’s syndrome(trisomy 21)
47 chromosomes 1 extra chromosome at pair #21
What happens if an animal has an extra chromosome compared to plants
it is fatal for animals but it makes plants hardier and larger
Gene/Point Mutation
Most common type of mutation and least drastic, only one gene is altered
Substitution occurs when
one base pair is substituted
Ex: one nucleotide containing cystine is substituted for one with guanine
Insertion occurs when
an extra base pair is added to a sequence of bases
Deletion occurs when
a base pair is deleted from a sequence. A single nucleotide or entire sequences of nucleotide can be removed.
Codon
When a group of three base pairs that codes for a DNA or RNA sequence
Frameshift mutation occurs when
there is an insertion or deletion of the base pairs from the DNA structure
Ex: Recessive gene mutations
Sickle Cell Anemia
Red blood cells are sickle shaped instead of round and cannot carry enough oxygen to the body tissues -
What does Sickle Cell protect people from
it protects people from malaria (heterozygous condition)
Cystic fibrosis
mucous builds up in the lungs
Tay-Sachs Disease
deterioration of the nervous system
Phenylketonuria (PKU)
An amino acid in milk that cannot be broken down and it builds up
What does PKU cause and who is tested for it
it causes mental retardation, newborns are tested for it
Dominant gene mutation:
Huntington’s Disease, Dwarfism
Huntington’s Disease
gradual deterioration of brain tissue, shows up in middle age and is fatal
Dwarfism
variety of skeletal abnormalities.
