Ch.11, Genetics Flashcards
What are the different forms of a gene called?
Alleles
What is a factor that determines traits?
A gene.
What is a specific characteristic that may vary among individuals?
A trait.
What is the offspring of true–breeding parents with different traits called?
A hybrid.
Why did Mendel choose to use pea plants in his experiments?
- they mature quickly
- they produce lots of offspring
- they have seven easily recognizable traits
How did Mendel cross–pollinate flowers?
He used a paintbrush to transfer pollen from the stamen of one flower to the pistol of another.
What is the difference between a gene and and allele?
Alleles are different forms of a gene.
State the principle of dominance.
Some alleles are dominant and others are recessive.
What is segregation?
The separation of alleles.
What is the result of segregation?
An offspring that has some genes from the father and from the mother.
What is probability?
The likelihood that a particular event will occur.
State the principle of independent assortment.
Genes from different traits segregate independently during the formation of gametes.
What are the units that determine the inheritance of biological characteristics?
Genes
What is an allele?
A form of a gene.
Alleles from different jeans usually _____ independently from each other when gametes form.
Segregate
What are the traits that Mendel’s experiments cannot predict?
Incomplete dominance, codominance, multiple alleles, and polygenic traits.
Give an example of incomplete dominance.
Red rose + white rose = pink rose
Given example of a trait with multiple alleles.
Rabbits have more than two alleles for each furr color trait.
Given example of a polygenetic trait.
Variety of skin color in humans.
Traits produced by two or more genes are ____.
Polygenic traits
Explain the difference between multiple alleles and polygenic traits.
Multiple alleles are genes controlled by more than two alleles, while polygenic traits are controlled by more than one gene.
What is heredity?
The passing of genes from parents to offspring.
What is genetics?
The study of heredity.
Who was Gregor Mendel?
An Austrian monk who loved to garden and did several experiments on pea plants to learn about heredity.
What is the function of the petal?
It is a specialized leaf that is colorful.
Distinguish between pollination and fertilization.
Pollination is the when the pollen lands on the stigma and fertilization is when the pollen nucleus meets the egg.
What is the purpose of the anther?
It is the male part of the flower that produces pollen (sperm).
What is the purpose of the filaments?
They support the anthers.
What is the purpose of the stem?
It supports the plant/flower.
What is the stamen?
The anther and filament combined.
What is the purpose of the stigma?
It is the tip of the pistol that “collects” pollen.
What is the purpose of the style?
It supports the stigma and is the middle of the pistol.
What is the purpose of the ovule?
It is at the bottom of the pistol and it is where the egg is housed/produced.
What is the purpose of the sepal?
It protects the flower bud.
What is the pistol?
The stigma, style, and ovule combined.
What is a perfect flower?
A flower with both male and female parts (it can self pollinate).
What is an imperfect flower?
A flower that only contains a female part.
What is another name for an imperfect flower?
A pistillate.
What is pollination?
The process by which pollen is transferred from male to female parts.
What is fertilization?
The process by which the sperm and egg unite to form a zygote.
Describe the process of double fertilization.
First a pollen grain starts germinating in response to a chemical on the stigma, then a pollen tube grows down the style which allows the male gametes do for fuse with the female gametes, finally a second pollen nucleus fuses with two egg nuclei to form a triploid endosperm (food for the seed).
Did Mendel’s pea plants have perfect or imperfect flowers?
They had perfect flowers.
Where Mendel’s original plants pure breed or hybrids?
They were pure breed.
Describe Mendel’s experiment with monohybrid crosses.
First he crossed a true breeding tall and true breeding short plant, which he called his P1 generation, then he planted those seeds and got the F1 generation (hybrids), after that he planted the seeds from those hybrids to get his F2 generation.
What were Mendel’s results for his F1 generation.
All of them were tall.
What were Mendel’s results for his F2 generation.
3/4 tall, 1/4 short
What did Mendel conclude from his results from his monohybrid cross experiment?
Mendel concluded that inheritance of traits were determined by”factors” that are passed from parent to offspring.
What are Mendel’s “factors” now called?
Genes
Why and when do alleles segregate?
Alleles segregate during the formation of gametes; they segregate so that each resulting gamete only receives one copy of the trait.
What is the genotype of a gene?
It’s genetic makeup.
What is the phenotype of a gene?
It’s physical characteristics.
What is the difference between a monohybrid cross and a dihybrid cross?
Monohybrid crosses only predict a single trait, while dihybrid crosses predict two traits.
What is a homozygous trait?
Two identical alleles for the same trait.
What is a heterozygous trait?
Two different alleles for the same trait.
Describe Mendel’s experiment with dihybrid crosses.
First he crossed a true breeding round yellow seed plant with a wrinkled green seed plant, this was his P1 generation, then he planted those seeds (F1), next he allowed the F1 generation to self pollinate and then he planted those seeds.
Describe Mendel’s results from his dihybrid cross experiment.
- 315 round and yellow
- 32 wrinkled and green
- 209 had combinations not found in the parents
What are the four exceptions to Maedel’s principles?
- incomplete dominance
- codominance
- multiple alleles
- polygenic traits
Describe incomplete dominance.
Occurs when one allele is not completely dominant over the other.
(Ex. Red rose + white rose = pink rose)
Describe codominance.
Each alleles expressed equally.
Ex. White chicken + black chicken = white and blacked speckled chicken
Describe multiple alleles.
Genes controlled by more than two alleles. (Ex. Rabbit coat color is controlled by 1 gene with 4 possible alleles)
Describe polygenic traits.
Traits controlled by more than one gene. (ex. Human skin color)
Give some examples of environmental factors that can affect genes.
Diet, exposure to sunlight, temperature, and hormone levels.
Describe Mendel’s idea of segregation.
He hypothesized that during the formation of gametes alleles segregate so that each resulting gamate only receives one copy for that trait.
How are punnet squares used in genetics?
They are used to predict the offspring of two parents.
What is the genotype for an individual that shows the recessive form of a trait?
Two recessive alleles (ex. bb)
What structure forms the fruit?
The ovary.
