✅17 - Inherited Change Flashcards
What is a genotype?
The genetic makeup of an organism, all the alleles that it has
What is a phenotype?
The observable or biochemical characteristics of an organism. The result of the interactions between expression of the genotype and the environment
What is a gene?
A length of DNA
What are alleles?
Different forms of genes
What is a locus?
The position of a gene on a particular DNA molecule
What are homologous pairs of chromosomes?
Pairs of chromosomes with approximately the same length, gene position and centromere location
What is homozygous?
When an individual has two of the same allele
What is heterozygous?
When an individual has two different alleles
What does codominant mean?
Where two alleles both contribute to the phenotype
What are multiple alleles?
When a gene has more than two allelic forms, of which only two may be present at the loci on an individual’s homologus chromosomes
What is monohybrid inheritance?
Inheritance of a single gene
What is the F1 generation?
First filial - two different pure breed organisms crossed to give hybrid offspring
What is the F2 generation?
Second filial - heterozygous offspring from F1 generation crossed together to produce more offspring
What is the law of segregation?
In diploid organisms, characteristics are determined by alleles that occur in pairs. Only one of each pair of alleles can be present in a single gamete.
Why are actual results of genetic crosses rarely the same as predicted?
Due to statistical error
How can results of genetic crosses be made to be closer to predicted ones?
By using a very large, representative sample
What is dihybrid inheritance?
Two characteristics, determined by two different genes located on different chromosomes are inherited
What is the law of independent assortment?
Each member of a pair of alleles may combine randomly with either of another pair
What is an example of codominance?
The snapdragon plant, which has one allele for an ezyme that catalyses the formation of red pigment and one which produces no pigment - red and white. However, the two colour combine to give pink flowers
What is an example of multiple alleles?
Blood group
Which sex chromosomes do females have?
XX
Which sex chromosomes do males have?
XY
How many different types of gamete do males produce?
2, one X and one Y
What are sex-linked genes?
Any gene carried on wither the X or Y chromosome
Why can some genes be more prevalent in males than females?
The X chromosome is much longer than the Y, so more most of the X chromosome, there is no homologous equivalent and those recessive characteristics on the X chromosome will be more frequent in males
What is an X-linked genetic disorder?
A disorder caused by a defective gene on the X crhomosome
What is an example of an X-linked genetic disorder?
Haemophillia
What are autosomes?
Any chromosome which is not a sex chromosome
What is autosomal linkage?
When two or more genes are carried on the same autosome
Why do linked genes remain together when passed onto offspring?
Because, assuming that there is no crossing over, they do not segregate in accordance with Mendel’s law of independent assortment
What is epistasis?
When the allele of one gene affects or masks the expression of another in the phenotype
What is an example of epistasis?
In mice, where several genes determine coat colour
How does epistasis in mice work?
Gene A controls distribution of black pigment and whether they are banded or not. The dominant allele of A leads to hairs with black bands, which recessive a produces uniform black hairs.
Gene B controls expression of A. Dominant B leads to production of the pigment while recessive b leads to no pigment
Which statistical test is used for genetics?
Chi Squared
