Chapter 15 Flashcards
Polymorphism
Any genetics difference among individuals that is sufficiently common
Genotype
Genetic makeup of a cell or organism
Phenotype (3)
- An individual’s observable characteristics or traits
- seen either physically or in development, physiology, or behavior
- results from interaction b/w genotype and environment
Alleles
Different forms of any gene
Subunit of hemoglobin with A, S, and C allele
- A most common
- S associated with sickle cell anemia
- C glutamic acid replaces with lysine
Homozygous
An individual w/ an allele of the same type from each parent
Heterozygous
An individual w/ different types of alleles from their parents
2 important principles about the connection b/w genotype and phenotype
- Depends on whether mutation is homozygous or heterozygous
- Effect of a particular genotype may depend on environment
Harmful mutations (2)
- often eliminated through generations
- ex. Emphysema
Genotype-by-environment interaction
Phenotype is the result of an interplay b/w genes and the environment
Neutral mutations (3)
- Have no effect on the organism
- Often found in noncoding DNA
- occur especially in organisms w/ large genomes
PTC (3)
- chemical some can taste and some can’t
- example of taster polymorphism
- neutral mutation
Beneficial Mutations
- Protecting against infectious disease
- in rare cases permit organisms to become adapted to their environment
No disjunction
- Failure for a pair of chromosomes to separate during anaphase of cell division
- one cell receives extra copy of chromosome, one has no copy of that chromosome
1st division non-disjunction
Chromosomes not genetically identical
2nd division non-disjunction
Genetically identical chromosomes
Down syndrome
- Presence if an extra chromosome 21
- AKA trisomy 21
- short b/c of delayed maturation
- muscle tone low
- characteristic facial appearance
Extra/Missing chromosomes
- common
- usually remain undiscovered
- males and females remain healthy
XXY (7)
- very small testes but normal penis and scrotum
- some degree of mental impairment
- testes fail to enlarge
- voice remains high pitched
- pubic and facial hair sparse
- some enlargement of breasts
- sterile
Turner syndrome (7)
- only one X chromosome
- short
- webbing of the skin
- no sexual maturation
- external sex organs remain immature
- breasts fail to develop
- pubic hair fails to grow
Spontaneous Abortion
- Most fertilized eggs with abnormalities fail to complete embryonic development
- often triploid or tetraploid
