Alleles Flashcards
What is a gamete?
An organism’s reproductive cell (egg in female and sperm in males), which has half the number of chromosomes (23)
Gametes are crucial for sexual reproduction and genetic diversity.
What is a chromosome?
A structure found in the nucleus which is made up of a long strand of DNA
Chromosomes carry genetic information and are essential for cell division.
What is a gene?
A short section of DNA that codes for a protein, and therefore contributes to a characteristic
Genes are the basic units of heredity.
What are alleles?
The different forms of the gene
Humans have two alleles for each gene as they inherit one from each parent.
What is a dominant allele?
Only one (out of the two alleles) is needed for it to be expressed and for the corresponding phenotype to be observed
Dominant alleles mask the effect of recessive alleles in the phenotype.
Fill in the blank: Some characteristics are controlled by a _______ gene, such as fur colour in mice and red-green colour blindness in humans.
single
However, most characteristics are the result of many different genes interacting.
True or False: Most characteristics in organisms are controlled by a single gene.
False
Most characteristics result from many different genes interacting.
What is a recessive allele?
Two copies are need for it to be expressed and for the corresponding the phenotype to be observed
What does homozygous mean?
When both inherited alleles are the same
What does heterozygous mean?
When one of the inherited alleles is dominant and one is recessive
What is a genotype?
The combination of alleles an individual has, e.g. Aa
What is a phenotype?
The physical characteristics that are observed in the individual, eg. Eye colour
What is a zygote?
The stage of development immediately after fertilisation - a diploid (2n) cell formed from the fusion of two haploid gametes
What is an allele?
Different forms of the same gene
What do alleles lead to?
Different inherited characteristics
