Ch 11 Flashcards
True breeding
All children have same traits
Genetics
Study of heredity
Hybrid
Kids whose parents had different traits
Trait
A specific characteristic
Gene
DNA code for a trait
Allele
The gene options
Fertilization
Sperm meeting egg
Gamete
Sex cell (sperm or egg)
Zygote
Cell when sperm and egg meet
Gregor Mendel
Austrian monk born 1822
Studied genetics and taught high school
Keep meticulous quantitative data
Gregor Mendel’s experiment on pea plants
Very short reproductive lines
Simple control of offspring
Many obvious traits
Able to selectively breed or self pollinate
(Mendel’s crosses) p
The two parent plants
Two different true breeding (yellow and green)
(Mendel’s crosses) F1
The first generation (p x p)
All offspring have same allele (green)
(Mendel’s crosses) f2
Second generation (f1 x f1) 1/4 of offspring have a different allele than parents (3/4 green and 1/4 yellow)
(Mendel’s conclusions) An individuals characteristics (traits) are determined by
Factors (genes) that are passed from one parent generation the next
(Mendel’s conclusions) an individual gets
One allele from each parent
(Mendel’s conclusions) principle of dominance
Some alleles are dominant (always appear) and others are recessive (hidden by the dominant)
(Mendel’s conclusions) Law of segregation
During gamete formation the alleles for each gene separate from each other, so that each gamete carries only one allele for each gene
Homozygous
Having two of the same alleles
Heterozygous
Having two different alleles
Phenotype
The appearance of the individual
Genotype
The allies in their genes (DNA)
Probability
The chance that a particular event will occur
Allies are represented by
Letters
Alleles (referring to Punnett square)
= genotype = phenotype = probability
Genotype ratio 1:2:1
Always homozygous dominant : heterozygous: homozygous recessive
Phenotype ratio
Dominant to recessive
Two factor cross
A huge Punnett square with 4 columns and 4 rows
Looks at how two different traits are inherited together
Dihybrid
Both parents are heterozygous for both traits
Phenotype ratio 9:3:3:1 ratio
Independent assortment
Genes for different traits can segregate independently during formation of gametes (this gets way more complicated)
Mendel’s principles
Inheritance of biological characteristics is determine by individual units called genes which are passed from parents to offspring
Where two or more forms (alleles) of the gene for a single trait exits, some alleles may be dominant and others may be recessive
In most sexually reproducing organisms each adult has two copies of each gene - one from each of their parents. These genes segregate from each other when gametes are formed
Alleles for different genes usually segregate independently of each other
Incomplete dominance
Neither allele is dominant
Heterozygous phenotype is a mix
Example: red and white = pink
(Allele letters are both capital)
Codominance
Neither allele is dominant
Heterozygous phenotype is a mix
Example: red and white = roan(candy cane)
(Allele letters are both capital)
Multiple alleles
There are more than two options
Example = rabbit coat color
Polygenic traits
Several genes produce many different traits
Human skin color
Four different genes control the trait
Environmental affects
The environment can affect gene expression and influence genetically determine traits
Meiosis
Process by which gametes are formed
Contain half the normal number of chromosomes as somatic cells
Known as “haploid” and number of chromosomes in this state is represented as “n = ____”
Diploid number is represented as “2n = ______”
Mechanics of meiosis
Cause genetic reshuffling to occur at random and can result in genetic reshuffling producing new allele combinations
