Transcript Genetics Terms

Genetics Terms
Genetics
• Heredity – passing of traits from one generation to
the next.
• Genetics – “study of heredity”
• Traits – inherited characteristics
Genetics
• Allele – different copies or forms of a gene
controlling a certain trait (eye, hair color)
• Dominant – the observed or expressed trait
(prevents the expression of a recessive allele)
• Recessive – trait that can be hidden by a dominant
gene. * not expressed unless homozygous
Genetics
• Gene – “basic unit of heredity”
• Gamete – egg or sperm cells with haploid # of
chromosomes (sex cells)
• Homozygous – when alleles for a specific trait are the
same (BB/bb)
• Heterozygous – when alleles for a specific
trait are different (Bb)
Genetics
• Genotype – genetic makeup of an organism. The
combo of alleles that an organism inherits for a
certain trait. “Letters” (BB, Tt, Dd)
• Phenotype – the expression of the genotype or
physical appearance that an organism shows.
“Look like” (brown, tall, dimples)
Genetics
• Haploid – (n) ½ the # of chromosomes
*having 1 set of chromosomes
• Diploid – (2n) 2x’s the haploid # of chromosomes
*having 2 sets of chromosomes
• Chromosome – a strand of DNA that functions in the
transmission of traits.
• Zygote – a cell resulting from the union of the gametes
*fertilized egg
Genetics
• Hybrid – organisms that are heterozygous and result
from two different pure lines.
• Parent generation – 1st generation of parents
• F1 generation – 1st generation of offspring
• F2 generation – 2nd generation of offspring
Genetics
• Law of Dominance – when pure organisms are
crossed with contrasting traits, all offspring
will show the dominant trait.
• Law of Segregation – during egg/sperm
formation, the pair of genes/alleles for a trait
separate so that each gamete has only one of
the genes for the trait.
Genetics
• Law of Independent Assortment – as gametes are
formed the genes for various traits separate
independtly of each other. Exp….eye color does not
influence hair color
• Punnett square – indicates ratio of genotypes and
phenotypes of possible offspring.
• Cross – an exchange of genetic information.
Genetics
• Test cross – cross an unknown genotype with
a known genotype (an individual showing the
recessive trait, homozygous recessive)
– # 8 in your monohybrid cross
List 3 reasons why Gregor Mendel used pea plants
1. Easy to grow/grow fast
2. Easy to pollinate b/c produce 2 distinct sex cells
3. Show sharply contrasting traits (round vs
wrinkled, green vs yellow, tall vs short)