Chapter 17: Inherited Change Flashcards
Gene
Length of DNA that codes for a particular polypeptide.
Allele
Different forms of a gene.
Genotype
Genetic make up of an organism. It describes the alleles an organism has.
Phenotype
Observable characteristics of an organism.
Homozygous
Alleles on each chromosome are the same.
Heterozygous
The two alleles are different.
Codominant
When two alleles contribute to the phenotype.
Multiple alleles
When a gene has more than two allelic forms.
Law of segregation.
In diploid organisms, characteristics are determined by alleles that occur in pairs. Only one of each pair of allele can be present in a single gamete.
F1
First filial
Ratio
Measure of the relative size of two classes that is expressed as a proportion.
What is dihybrid inheritance?
Shows how two characters, determined by two different genes located on different chromosomes, are inherited.
Law of independent assortment.
Each member of a pair of alleles may combine randomly with either of another pair.
Sex chromosomes in females
XX
Sex chromosomes in males
XY
What name is given to any gene carried on the X or Y chromosome?
Sex-linked.
Is the X or the Y chromosome longer?
X (So for most length of the X chromosome, there is no equivalent homologous portion of the Y chromosome. Those characteristics that are controlled by recessive alleles on this non-homologous portion of the X chromosome will appear more frequently in the male. This is because there is no homologous portion on the Y chromosome that might have the dominant allele, in the presence of which the recessive allele does not express itself).
What is an X-linked genetic disorder?
Disorder cause by a defective gene on the X chromosome.
Why are pedigree charts useful?
Trace the inheritance of sex-linked characters.
What is a male represented by in a pedigree chart?
Square
What is a female represented by in a pedigree chart?
Circle
What does shading in a pedigree chart represent?
Indicates the presence of a character in the phenotype.
What name is given to any two genes that occur on the same chromosome?
Linked.
What are the remains 22 chromosomes called?
Autosomes.
Autosomal linkage
Name given to the situation where two or more genes are carried on the same autosome.
When does epistasis arise?
When the allele of one gene affects or masks the expression of another in the phenotype.
What is the chi-squared test used to test?
The null hypothesis.
What is the null hypothesis used to examine?
The results of scientific investigations and is based on the assumption that there will be no statistically significant difference between sets of observations, any difference be due to chance alone.
The chi-squared test can only be used if certain criteria are met…
- Large sample size
- Only raw counts can be used, not percentages and rates etc
- Data must fall into discrete categories
- Used to compare experimental results with theoretical ones
Chi-squared formula…
(Observed - Expected)^2 /
Expected numbers
Degrees of freedom
Number of classes minus one.
If the probability that the deviation is due to chance is equal to or greater than 0.05/5%, the deviation is said to be…
…not significant.
If the deviation is less than 0.05/5%, the deviation is said to be…
…significant.
Some factor other than chance is affecting the results and the null hypothesis must be rejected.
