Chapter 14 & 15 Flashcards
Define alleles
different versions of genes
define genes
genetic information that codes for a specific trait
define traits
a specific characteristic of an individual
Define true breeding
homozygous dominant → AA
homozygous recessive → Aa
Define heterozygous
Aa
Define phenotype
physical expression of a gene
Define genotype
the genetic makeup→ the combination of inherited allele
What are the four parts of Mendel’s Model
1.Alternate versions of genes → ALLELES
2.Organisms inherit two copies of a gene
3.Dominant Allele and Recessive Allele
4.Law of Segregation
Define Law of segregation
Two alleles will separate into two gamete cells
Define Law of Independent assortment
2 alleles will independently separate into two gamete cells
Define F2
cross between two individual from F1 generation
define a testcross
breeding of a unknown genotype with recessive homozygous
To find the genotype of a dominant phenotype
What are the steps to read a pedigree?
- Determine if the trait is dominant or recessive:
Dominant: will not skip a generation; one parent MUST have the trait
Recessive: neither parent is required to have the trait- heterozygous
2.Determine if the trait is autosomal or sex-lined
X-linked recessive= males are much more commonly affected than females
Autosomal traits: both males and females are equally likely to be affected
During what phases of meiosis will the law of segregation take place?
In Anaphase 1: the homologous chromosomes will separate into two gamete cells
In Anaphase 2: the sister chromatids will separate into two gamete cells
During what phases of meiosis does the law of independent assortment take place?
Anaphase 1- homologous chromosomes
Anaphase 2 sister chromatids
During metaphase 1 & 2 , alleles will independently orient on the metaphase plate
What is a wild type?
phenotype most commonly observed
w+
What is a mutant?
phenotype due to alleles that have changes
w
What are some sex-linked diseases?
Colorblindness, hemophilia, and duchenne’s muscular dystrophy
What is nondisjunction?
Homologous chromosomes do not move apart during during meiosis 1 & sister chromatids do not separate during meiosis 2;
can also affect autosomal chromosomes
What are some autosomal nondisjunction disorders?
trisomy 21(down syndrome)
Trisomy 18
Trisomy 13
In which chromosomes do autosomal nondisjunction disorders take place?
autosomes- 22 pairs
What do people with sex chromosome nondisjunction have trouble with?
childbearing
What are some sex chromosome nondisjunction disorders?
Kleinfelters, Turners
What is kleinfelters disorder?
XXY → male
Sterile; Some female body characteristics
