AP110 Chp 25 Heredity Flashcards
1
Q
Genes and Chromosomes
A
Genes
- Units of heredity encoded into DNA
- Each gene is located on discrete segments of DNA
Chromosomes
- Highley folded DNA (and genes) found during cell division.
- 46 chromosomes in humans
- 22 autosome pairs
- 1 sex chromosome pair
2
Q
Dominate and recessive genes
A
Dominate gene
- Always expresses affect
- Heterozygous or homozygous
- Need to inherit from one parent only
Recessive gene
- Only expressed if homozygous
- Need to inherit from both parents
Phenotype
-Any characteristic that can be observed (eye color, blood type)
Genotype -A persons genetic makeup (Heterozygous dominant Bb (a carrier) Homozygous dominant BB Homozygous recessive bb)
3
Q
Chromosome distribution
A
Meiosis
- Produces gametes with 23 chromosomes
- Cells receive chromosomes at random from parents
-Punnett square
(show combinations of genes that can result from a given parental cross, that is, a mating that produces offspring)
4
Q
Sex determination
A
Sex chromosomes not matched in size or appearance
- Female (X) chromosome larger
- Male (Y) chromosome smaller
Sex
- Females: Two X chromosomes XX
- Males: An X and a Y chromosome XY
Sex linked traits
- Traits carried on sex chromosomes (mostly X)
- Most are recessive
- Usually males exhibit trait
- Heterozygous females are carriers
5
Q
Hereditary traits
A
Types of inheritance
- Single gene inheritance, less common
- Multifactorial inheritance (multiple gene) inheritance; most common
Factors affecting gene expression
- Sex
- Other genes (Codominance, Incomplete dominance)
- The environment
6
Q
Gene mutation
A
- When genes or chromosomes do not replicate exactly
- Results in changes in genes or chromosomes
May be caused by
- Chromosomal breakage or loss
- Gene fragment rearrangement
May occur during cell division
- Spontaneous
- Induced by mutagen
7
Q
Gene diseases
A
Congenital disease
- Present at birth
- May or may not be hereditary
Causes
- Teratogens (drug or infection)
- Nutrient defeciencies
Hereditary disease
