Ch. 1 & 2 & 6 Flashcards
Mendel crossed pure strains of peas which differed in only one trait. Name one of the traits he used, and the two forms or alleles of that one trait.
Visible traits:
He used seed shape: Round and Wrinkled
some other visible traits are listed below.
Spherical seeds x Wrinkled seeds Yellow seeds x green seeds Purple flower x white flowers Inflated pods x constricted pods green pods x yellow pods axial flowers x terminal flowers Tall stems x dwarf stems
In what generation did Mendel observe the 3:1 ratio of dominant versus recessive phenotype?
From the F2 generation.
in the f1 generation, phenotype was all round, in the f2 generation phenotype was 3round:1wrinkled
Mendle’s first las is callsed the principle of?
Independent Segregation
- traits are controlled by two factors
- during gamete formation, the two factors separate or segregate so that each gamete has on factor.
- when a male gamete fertilized a female gamete, the two factors are united in a new individual.
In dihybrid crosses, Mendel observed a phenotype ratio of 9:3:3:1. This was interpreted as? It is also his second law.
Independent Assortment, the second Mendel law.
-the sets of factors separate from each other independently.
Mendel’s work was reuinited with behavior of chromosomes during meiosis. It was determined that chromosomes carry the factors that control inherited traits, what is this theory?
Chromosomal Theory of Inheritance
The chromosomal theory of inheritance states that genes are carried on chromosomes and that the behavior of chromosomes durring ______ accounts for Mendel’s first and second laws.
During Meiosis.
-separation into haploid gametes.
Name the three helical forms of DNA?
B-Form, A-Form, Z-Form
In the most common helical form of DNA, what is the spacing between bases, and what is the pitch of the helix, pitch being the rise of the helix in one full turn?
Space between bases = 0.34 nm or 3.4A
Pitch of one full turn = 3.4 nm or 34A
1 nm = 1x10^-9 m
1 A = 1x10^-10 m
ie: 10 base pairs per turn
Meselson-Stahl are the two names associated with what model of DNA replication?
Semi-conservative
after on round of replication, one strand from the original double stranded dna could be found on each of the two separate new strands, along with a new complimentary strand. Half of the original was conserved.
What was Chargaff’s Rules?
A=T
G=C
A+G=C+T
What density indicator suggested two nucleotide strands in each molecule of DNA?
The 20A diameter and the density of DNA
What was the Hershey-Chase Experiment?
A virus is a very simple life form consisting of a DNA molecule surrounded by a protein coat.
used bacteria phages and bacteria to measure transfer of dna
Who separated all classes of biomolecules in the heat-killed s strain debres, tested for transforming ablility one at a time?
Avery, Macleod & McCarty 1944
the found Polysaccharides, lipids, proteins, RNA and DNA
What was the “Transforming Principle”?
principle from the latin princeps “take as first”- a distiguishable ingrediant that imparts a characteristic quality.
Some ingredient in the cell debris of the heat killed S strain imparted the polysaccharide capsule trait to the R strain pneumonia. This trait was the passed to all transformed R strain progeny. A Mendelian gene had been passed from the S strain to the R strain.
Who was Frederick Griffith, and in 1928 what was he looking for?
-He was looking for a more effective vaccine for S. pneumonia, the “transforming principle” was what he was searching for. Since:
- Virulant S strain makes a polysaccharide capsule that makes its colonies look “smooth”.
- Nonvirulent R strain has no capsule and colonies look “rough”
What was the Fruit Fly Drosophilia Melanogaster used for?
To study inheritance of traits on chromosomes.
This is a sex-linked trait, white eyes vs. wild type red eyes.
If two events are independent, what is the probability of the two happening simultaneously, for a 3:1 event and a 3:1 event?
3:1
3:1
x
=9:3:3:1
Mendel’s second law
What cellular body carries factor which carry traits?
Who discovered this?
Chromosomes in gametes
3 at the same time, which also discovered Mendel’s work.
How did R (non-virulent) strain kill the mouse?
When Frederick Griffith, 1928, mixed R strain with heat killed S strain, the R strain took up genetic info on S strain which made it virulent-R strain, now called S strain again but it came from R strain.
He called it “transformation”, it is a genetic event.
McCarty (famous jhu dad of AAP). They were testing different componenets of bacteria to figure out what Frederick was talking about with “Transforming Factor”. What did they find and what did the test?
The tested separately, Polysaccharides, Lipids, Proteins, Ribonucleic acids, Deoxyribonucleic acids.
The only one that transformed was Deoxyribonucleic acids, which is where this “transforming factor” existed. This inspired the questions “what does DNA look like”?
Two black guinea pigs were mated, and over the next few years, produced 28 black and 9 white offspring. Explain these results giving the genotypes of the parents and offspring.
B:w B:w would make a 3:1 black:white phenotype. If you simply break down 28:9, it reduces to about 3:1.
You are given three yellow, round peas, labeled A, B and C. Each was grown into a plant and crossed with a plant grown from a green wrinkled pea. The following results are observed:
A: 51 Yellow round
49 Green round
B: 100 Yellow round
C: 24 Yellow round
26 Yellow Wrinkled
25 Green round
25 green wrinkeld
What are the genotypes of A, B and C?
A: Y?R? x gg:ww = A must be YgRR
B: Y?R? x gg:ww = B must be YYRR
C: Y?R? x gg:ww = C must be YgRw
Who discovered the “Transformation Factor” which changed “non virulent” R-Strain pneumococcus to “virulent” S-Strain pneumococcus?
Frederic Griffith
Avery, MacLeod McCarty found what?
that the “transformation factor” was in fact DNA which changes R-strain to S-strain pneumococcus.
