Unit 3 (Mendelian Genetics) Flashcards
What are Mendelian Genetics?
The study of patterns of inheritance.
Who is the father of genetics? When did he live?
- Gregor Mendel
- (1822-1884)
What is Gregor Mendel known for? Why is he so impressive?
- He discovered the basic patterns of inheritance by studying pea plants.
- He did this without any knowledge of DNA, chromosomes, or genes.
What were the studied traits of Mendel’s pea plants?
The flowers were either red/white.
The pea seeds were either round/wrinkled.
Explain Mendel’s First Experiment.
He began by true breeding and then bred the offspring with each other for the following generation.
(P) RR x ww= Rw, Rw, Rw, Rw
(F1) Rw x Rw=RR, Rw, Rw, ww
(F2) RR, Rw, Rw, ww (he didn’t bred these)
What were the two statements Mendel concluded from his first experiment?
- Organisms contain two hereditary factors (genes) for each character (phenotype).
- Each gamete contains 1 of the 2 genes. Known as the “particulate nature of inheritance”
(two genes for each trait, one gene from each parent)
What is a locus?
The specific place on a chromosome where a gene is located. (The location of a gene on a chromosome)
What is a genotype?
The combination of alleles that make up the genetic code. (ex. RR)
What is a phenotype?
An observable characteristic (green vs. blue eyes are the same genotype but different phenotype)
What is an allele?
A “version” of a gene.
What is Incomplete Dominance?
This is when neither allele is dominant. (like a halfway point)
What does “true breeding” refer to?
This refers to when one crosses two individuals with homozygous genes.
What does “hereditary factors” refer to?
This is how Mendel referred to what we now call, “genes.”
What does Mendel’s theory of the “particulate nature of inheritance” refer to?
Mendel’s theory of how traits are passed from parent to child. This theory contradicted the current “blending” theory of the time.
- Particles (genes) are passed on from parent to child. They can be carried even if they are not visible.
(ex. he made two red plants have a white child, this contradicts the blending theory)
What does it mean for a genotype to be homozygous? What are two ways a gene can be homozygous?
What does it mean for a genotype to be heterozygous?
- It means the genotype is comprised to two of the same alleles.
(RR, rr) This is the same allele on both chromosomes of a homologous pair. - It means the genotype is comprised of two different alleles. (Rr)
What is a Monohybrid Cross?
Fertilization between two true-breeding parents that differ in only one characteristic is called a monohybrid cross.
What is cystic fibrosis? What are the three possible genotypes regarding cystic fibrosis?
- Cystic fibrosis is a recessive genetic disorder that is quite lethal.
- He explained that there are three genotype options.
-You are healthy and not a carrier. (RR)
-You are healthy and a carrier. (Rr)
-You have cystic fibrosis (rr)
What are the alleles of the parent generation that leads to a dihybrid cross? What is a Dihybrid Cross?
- Parent Gen.= A homozygous dominant and homozygous recessive parent (YYRR x yyrr)
- A dihybrid cross is the F1 generation, the crossing of two heterozygous (YyRr x YyRr) organisms.
What is the difference between a Dihybrid and a Monohybrid Cross?
These are both the crossing of parents in the F1 generation. HOWEVER, a monohybrid cross is the crossing of one trait, and dihybrid is the crossing of two traits.
What are the four possible gametes Rr x Yy can make?
(RY) (Ry) (rY) (ry)
What is the numerical pattern dihybrid crosses follow genotype wise?
9 (shows both dominant traits)
3 (shows one of both)
3 (shows one of both)
1 (shows both recessive traits)
What did Mendel conclude after conducting his dihybrid cross experiment on the pea plants?
The gametes occur in equal proportion and the different traits pass to the gametes independently. (slide 25-26🧡)
What is Independent Assortment?
The rule that genes for different traits are inherited independently of each other.
What is the difference between linked and unlinked loci?
Linked Loci= on the same chromosome
Unlinked Loci= on seperate chromosomes
