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Mendelian genetics, pedigree analysis is applied for humans


Genes can have incomplete dominance or codominanance, resulting in new phenotype ratios

Mitosis -- Chapter 3

Interphase gap -- cells are activitly creating whatever they should be creating in the biological role

Interphase Gap 2

Mitosis: Prophase


unipartite, bipartite?


Germ cells divide to produce gametes through meiosis.

Germ cells go through Meiosis. First the chromosomes go through duplication.

Prophase I:

Metaphase I:

Anaphase I:

Meiosis II:


Oogenesis is egg formation in humans. The egg need lots of cytoplasm with mitochondria

Looking at Drisophila:

Changes in Chromosome Number

Aneuploidy - individual whose chromsome number is not a multiple of n

Autosomal aneuploidy is generally lethal

Aneuploidy for the X chromosome

Sex Chromosome Aneuploidy

Kleinfelter's results from non-disjunction in female in Meiosis I or Meiosis II

Kleinfelter's results from non-disjunction in males in only Meiosis I.

Aneuploid mosaics like Turner's Syndrome result from mitotic nondisjunction

Gynandromorph is a special case where nondisjunction occurs in the first mitosis division.

Euploids contain only complete sets of chromosomes

Whiptail lizards are only females.

Polyploids (like Triploids and Tetraploids) are almost always sterile, since during cell division, chromatids do not segregate correctly

Linkage and Recombination

If genes are on different chromosomes, they will assort independently

To keep track of parental allelic combinations, we can represent genotypes:

The Chi Square Test is a statistical test to evaluate hypotheses that two genes assort independently

  1. Use the data from an experiment, to determine total number of offspring and classes, and the given distribution
  2. Calculate the expected number (based on 1:1 ratio for null hypothesis).
  3. Χ^2 = ∑ (observed - expected)^2/expected
  4. Determine the degrees of freedom (df) = number of classes - 1
  5. Use the chi-square value and number of degrees of freedom to determine a p value = probability that a deviation from the predicted numbers at least as large as that observed in the experiment will occur by chance
  6. Evaluate the significance of the p value. 0.05 p value is the boundary between accepting and rejecting null hypothesis

Map distances

Recombination was demonstrated using physical markers that were visible under the mircoscope. In the example, there was discontinuity and a bend.

Two Point Crosses

Three Point crosses

Double crossovers might not occur because they are rare.


What component is responsible for this phenomenon of transforming cells?

Chase and Hershey Experiments with infecting bacterial cells with bacteriophages

Structure of DNA: Deoxyribose sugar is a pentagon of carbons

DNA is a double helix, first proposed by James Watson and Francis Crick

DNA Replication

Watson-Crick model of replication is semiconservative; one strand is from the parental molecule and other is newly synthesized

Meselson-Stahl Experiment: use atomic weights to show how DNA replicates.

  1. E coli is grown on 15N for several generations (so that the DNA itself is atomically heavier)
  2. DNA is extracted and density is analyzed through centrifugation (visible bands determine atomic weight)
  3. Cells are transferred to a lighter medium 14N for one generation.
  4. DNA is analyzed again, but this time it is precisely 14N and 15N on the gradient. "Hybrid"
  5. More generations, less and less hybrid and more 14

This proves the semiconservative model.

Two steps; initiations and elongation

Elongation: DNA polymerase must have

One kind of E coli DNA polymerase, III, type of enzyme that is used to extend DNA using RNA primers

DNA polymerase I removes RNA primer and fills in gaps, still from 5' to 3'

DNA ligase joins leading and lagging strands by the phosphodieseter

E coli DNA Polymerase adds nucleotides to the end of a DNA stand

Three activities for our two types of E. coli DNA polymerase

  1. 5' to 3' polymerase activity
  2. 3' to 5' exonuclease activity (chewing it off) and fixing mistakes
  3. 5' to 3' exonuclease primer degradation

Problem with circular chromosomes: positive supercoils, tension opened by topoisomerases

Eukaryotes have linear chromosomes

DNA Replicaiton Process

  1. Two Helicases, one at each replication fork of the DNA
  2. Primase make exactly two RNA primers
  3. DNA Polymerase III extends out, copying DNA to mRNA
  4. Repeat 2 & 3
  5. DNA Polymerase I fixes RNA primers, leaving a nick at the end
  6. Ligase mends the nicks

Genetic Code

DNA acts as a template for RNA

Researchers used radioactive labelling (C14 instead of C12) which makes no difference in DNA structure


The process by which the polymerization of ribonucleotides is guided by complementary base pairing (template?) to produce and RNA transcript of a gene

Terminator signal is encoded in the gene


The process in which the genetic code carried by mRNA directs the synthesis of proteins from amino acids

Mutations: silent, missense (wrong amino acid), nonsense (cause a stop, truncation), frameshift, or in promoter

Gene Regulation in Prokaryotes

DNA regulation determines which genes are transcribed and translated (think immune cell vs muscle cells have same DNA but different funcitons)

Glucose is another sugar preferred by the bacteria over lactose

I- mutation that signals repressor, cannot bind to the operator

Lac Operon


Hardy Weinberg Equalibrium

Restriction Enzymes/Cloning

Restriction REN

Cancer Genetics

Genetic disorder involving mutations in cells