Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
13 Cards in this Set
- Front
- Back
|
Mendel's first law
|
Law of segregation
anaphase I of meiosis Alternative versions of genes account for variations in inherited characteristics. For each characteristic, an organism inherits two alleles, one from each parent. The two alleles for each characteristic segregate during gamete production. -variation |
|
|
Mendel's second law
|
Law of Independent Assortment
the inheritance pattern of one trait will not affect the inheritance pattern of another chromosomes in gamete formation are randomly sorted from all possible combinations of maternal and paternal chromosomes |
|
|
How many possible combinations of chromosomes are possible for human gametes?
|
with 23 pairs of chromosomes, the number of possibilities is 2^23 or 8,388,608 possible combinations
|
|
|
How does incomplete dominance modify Mendelian ratios?
|
2 possible heterozygous genotypes express an intermediate phenotype e.g.
red:2 pink:white 1:2:1 phenotype ratio instead of the 3:1 phenotype ratio |
|
|
How does codominance modify Mendelian ratios?
|
2 possible heterozygous individuals express both phenotypes
1:2:1 phenotype ration instead of 3:1 |
|
|
How does lethality modify Mendelian ratios?
|
Alleles that cause an organism to die are called lethal alleles, where the gene involved is an essential gene.
If the mutation is caused by a dominant lethal allele, the homozygote and heterozygote for the allele will show the lethal phenotype. If the mutation is caused by a recessive lethal allele, the homozygote for the allele will have the lethal phenotype. |
|
|
Cystic fibrosis, Tay-Sachs Disease, sickle cell anemia, and Brachydactyly occur in which genotypes?
|
Recessive lethal allele
-Homozygous (lethal) -Heterozygous (mutant phenotype) |
|
|
What is the genotype involved in Huntington’s Disease?
|
Dominant lethal allele
-One copy of allele results in death -late onset |
|
|
How does epistasis modify Mendelian ratios?
|
Several genes control one phenotype:
A ratio expressed in 16 parts (9:3:4) when studying inheritance of a single character = two gene pairs are interacting. |
|
|
Examples of epistasis?
|
A genotype mask /suppresses expression of an allele.
A dominant allele at one locus masks expression of alleles at a second locus. The homozygous condition of either recessive allele mask the expression of the dominant allele at the other locus. New phenotype in the F2 generation. |
|
|
What is the pattern of inheritance found with X-linkage?
|
Transmission of genes located on the x-chromosome.
Crisscross pattern of inheritance for reciprocal crosses (white male x red female get different ration for red male x white female). Males are hemizygous for all alleles on the x-chromosome - higher incidence of recessive traits. |
|
|
Hemophilia, colour blindness and muscular dystrophy are
|
x-linked traits
|
|
|
What are possible phenotypic ratios found in Morgan's crosses? (x-linkage)
|
Ww x wY :1/2 Ww female, 1/4 WY male, 1/4 wY male
ww x WY :1/4 Ww female, 1/4 ww female, 1/4 WY male, 1/4 wY male |
