10.2 Inheritance Flashcards
What is segregation?
The alleles of the same gene separating during meiosis.
What is independent assortment?
Different genes located on different chromosomes move independently from each other.
What genes are unlinked?
Found on different chromosomes and segregate independently as a result of meiosis.
What genes are linked?
On the same chromosome and do not segregate independently.
What is an exception for linked genes that are far apart on chromosomes?
Crossing over between genes occurs frequently causing separation of genes, making it seem like they’re unlinked.
What is a dihybrid cross?
The inheritance of two genes is investigated together. Founded by Mendel.
What was the exception to Mendel’s rule?
Discovered by Thomas Morgan with experiment with the fruit fly. Believed that variations seen in organisms is explained by environmental influence.
How did Thomas Morgan discover non-Mendelian ratios.
He bred thousands of fruit flies. Notice one fruit fly with abnormal white eyes instead of normal red eyes.
- He mated the white-eyed fruit fly with a red-eyed fly.
- F1: Most of the offspring were red-eyed with minimal white-eyed flies.
- F2: White-eyed flies appeared in larger numbers.
What is the gene locus?
Each particular gene is found in a specific position on one chromosome type.
What is homologous genes?
When two chromosomes have the same sequence of genes. Not identical because some alleles can differ.
What is an autosome?
Any chromosome that is not a sex chromosome (in humans, number 1-22).
What is a sex chromosome?
A chromosome involved with determining the sex of an organism (in humans, X and Y).
How many autosomes to diploid nuclei have?
They have two of each type of autosome.
What are the two types of linkage?
Autosomal gene linkage and Sex Linkage.
What is autosomal gene linkage?
When the genes are on the same autosome.
What is sex linkage?
When the genes are located on the X chromosome.
What makes genes linked?
Genes that do not independently assort because they’re located near each other on the same chromosome. The genes travel together during meiosis and alleles end up on the same gamete.
What is variation?
Differences between individual organisms. When individuals fall into a number of distinct categories, variation is discrete or continuous.
What is discrete variation?
Individuals fall into a distinct category. There isn’t a continuous range, you either “are or are not”.
What is continuous variation?
There is a range of measurements from one extreme to the other. Due to polygenic (combined effect of many genes) and often influenced by environment.
What is an example of discrete variations?
Blood types: there are several and no in-between category.
What is an additive effect?
Examples of inheritance in which two or more genes affect the same character.
What is a polygenic characteristic?
Characteristics determined by many genes. Each gene has an additive effect on the overall phenotype.
What is an example of polygenic inheritance?
Two gene cross with codominant alleles.
