unit 2 Flashcards
What is genetics?
The scientific study of heredity.
What is a chromosome?
A unit of DNA containing many genes.
What are alleles?
Different versions of the same gene.
Who is known as the father of genetics?
Gregor Mendel.
What is the Law of Segregation?
Two alleles for each trait separate when gametes form; parents pass only one allele for each trait to each offspring.
What is the Law of Independent Assortment?
Genes for different traits are inherited independently of each other.
Define phenotype.
Physical appearance of offspring.
Define genotype.
The combination of alleles which you carry for a particular gene.
What is a dominant allele?
An allele which is always expressed when present and cannot be masked by another allele.
What is a recessive allele?
An allele which can be masked by another allele; it is only expressed when two copies are present.
What does homozygous mean?
Two copies of the same allele of a gene.
what were gregor mendal’s conclusions
the law of segregation and the law of independent assortment
what is heredity
the passing on of traits from one generation to the next
what is the difference between a gene and an allele
gene is the basic unit of heredity (passed from parent to child) and an allele is different versions of the same gene
what is heterozygous
-an individual that has two different alleles of a gene on a pair of chromosomes
what is a punnet square
used to work out the probability of different geneotypes and phenotyoes in a genetic cross
what are the types of dominance
complete dominance, incomplete dominance, and codominance
what is incomplete dominance
- the phenotype of a heterozygous individual is intermediate (a blend) between those of the parents
-on allele is not complete dominant over another
ex. red and white make pink
what is codominance
-the condition in which both alleles in a heterozygous organism are expressed
-ex. red and white make red and white stripped
why do X-linked recessive traits show up more in males
-males only carry one x chromosome
what is a hybrid cross
-a cross that shows the possible offspring of two traits
