Topic 7 - Inheritance Flashcards
What does heterozygous mean?
Describes an individual where both alleles of a gene are different
What is a sex chromosome?
Chromosomes that contain genes that determine the sex of an organism
What is the genotype of an organism?
The genetic constitution of an organism, the total combination of alleles an organism has inherited and carries on its chromosomes.
Define diploid
A cell containing half the number of chromosomes
What is a recessive allele?
An allele that is not expressed in the phenotype of heterozygous organisms
What is an allele?
Different forms of a particular gene, found at the same locus on a chromosome. A single gene could have many alleles.
What is a homologous pair?
Two chromosomes containing the same genes at the same loci but potentially containing different alleles
Define haploid
A cell containing half the diploid number of chromosomes
What is the phenotype of an organism?
Observable or measurable features of an organism which are the result of the genotype as well as environmental factors
What is a zygote?
A diploid cell formed from fusing two haploid nuclei
Define recessive
An allele only expressed in homozygous individuals and the characteristic is only expressed if there is no dominant allele present.
Define dominant
An allele that is expressed in the phenotype of heterozygous organisms
What is an autosome?
Chromosomes that are not sex determining chromosome
What is a sister chromatid?
Identical copies of a chromosome formed in DNA replication. Containing the same alleles in the same locations
What is a gene?
A length of a DNA coding for the production of a polypeptide or protein and occupying a specific locus on a chromosome
Define homozygous
Describes an individual where both alleles of a gene are the same
What is DNA?
A polynucleotide chain
What is a chromatin?
Loosely packed molecule of DNA and proteins
What is a chromatid?
One half of a duplicated pair of chromosomes (sister chromatids)
What is a chromosome?
A structure that forms when chromatin condenses
What does codiminant mean?
Both alleles are expressed equally and contribute to the phenotype, with there being either a blend of the two characteristic or both characteristics being seen together.
What is a locus?
The specific position of the gene on the chromosome.
What is pure breeding?
Homozygous pair of alleles.
What is sex linkage?
Sex linkage is the expression of an allele dependent on the sex of the individual as the gene is located on the sex chromosome.
What is an autosomal linkage?
In an autosomal linkage two or more genes are on the same autosomal chromosome
What is recessive epistasis?
Occurs when the presence of a recessive allele prevents the expression of another allele at a second locus. 9:3:4
What is dominant epistasis?
When a dominant allele at one locus completely makes the alleles at a second locus. 12:3:1
What is monohybrid inheritance?
When a phenotype or trait is controlled by a single gene. For instance, cystic fibrosis is where the individuals with doubly recessive phenotype are affected.
What is dihybrid inheritance?
When two characteristics are studied and is determined by two different genes that are present on two different chromosomes at the same time.
What is an example of codiminance?
Human ABO blood groups.
