4.3 - Inheritance Flashcards
Define what an allele is
A version of a gene that occurs at the same locus on homologous chromosomes
What is autosomal linkage?
When two or more genes are positioned on the same autosome. They are unlikely to be separated by crossing over during meiosis so are often inherited together
Define autosome
A chromosome that is not an X or a Y chromosome
Explain what carcinogen is
A type of mutagen that causes cancer
What is the Chi-squared test?
A statistical test used to determine whether a pattern of inheritance is statistically significant
What is chromosome mutation?
A change in the structure or number of chromosomes. This affects many genes
What is co-dominance?
When both alleles for a gene in a heterozygous organism equally contribute to the phenotype
What is the degrees of freedom (X2 test)?
The number of categories minus one
What is the dihybrid mandelian inheritance?
The determination of a trait by the inheritance of two genes
Define the meaning of dominant
Describes an allele that is always expressed. Represented by a capital letter
Explain what Down’s syndrome is
A genetic disorder characterised by delayed development and learning disabilities. Due to non-disjunction, an affected individual possesses three copies of chromosome 21
What is Duchenne muscular dystrophy (DMD)?
An X-linked recessive condition characterised by muscle degeneration and weakness. It is more common among males because they only inherit one X chromosome.
Define what epigenetics are
The study of changes in gene expression that are not due to alterations in the nucleotide base sequence of DNA
What is F1 generation?
The first generation of offspring resulting from the cross of two individuals in the parental generation
What is F2 generation?
The second generation of offspring resulting from the cross of two individuals in the F1 generation
Explain what a gene is
A length of DNA on a chromosome that codes for the production of one or more polypeptide chains and functional RNA
What is gene mutation?
A change to at least one nucleotide base in DNA or the arrangement of bases. Gene mutations can occur spontaneously during DNA replication and may be beneficial, damaging or neutral
Define what a genotype is
An organism’s genetic composition. Describes all alleles
What is haemphilia?
An X-linked recessive condition that results in excessive bleeding and blood that is slow to clot. It is more common among males because they only inherit one X chromosome
Define what heterozygous means
When someone has two different alleles of a gene e.g. Ff
What is histone modification?
The alteration of histones by the addition of methyl, acetyl, or phosphate groups. This can increase or decrease gene expression by making the DNA more or less accessible to transcription factors
Define what homozygous means
When someone has two identical alleles of a gene e.g. ff
Explain what locus means
The position of a gene on a chromosome
What is methylation?
The transfer of methyl groups to cytosine bases of DNA. Methylation inhibits transcription by making the DNA less accessible to transcription factors or preventing transcription factors from binding. This deactivates the gene
