found that genetic information of a heat killed "s-type" could be passed onto a "r-type"
Avery, MacLeod, and McCarty
Found that "s-type" (lethal) inheritance was lost when treated with DNase. Therefore concluded that DNA was genetic material
Hershey and Chase.
Radioactively labled the protein (Sulfur) and DNA (Phosphorus) of a virus. Determined that only the radioactive phosphorus was passed into the host bacteria and therefore proved DNA is genetic material
Beadle and Tatum
took a single mutagenized fungus spore and incubated it in different minimal media (MM). Their results lead to the "One gene One protein" principal and demonstrated mutant screening.
able to synthesize amino acids from minimal medium
a mutant strain unable to grow on minimal medium but can grow on medium supplemented with amino acids
observations that the amount of A nucleotides is the same as T and the number of G is the same as C. A=T & C=G
2 strands of DNA bases connect through covalent bonds to a sugar-phosphate backbone. The bases of each strand form hydrogen bonds. the strands run anti-parallel (5' to 3'). The helix has a right handed twist.
Each gene is encoded in DNA---> transcribed into RNA (can also go back to DNA "reverse transcription")---> Translated into protein
The complete set of DNA within the nucleus of any organsim
c-value and c-value paradox
The nuclear DNA content of a genome. surprisingly not correlated to the physical size or complexity of an organism, because not all DNA encodes genes.
Have short generation time and produce many progeny. Usually have small genomes (c-value), and are diploid.
core histones (proteins) that have DNA coiled around them twice. help package/compact DNA (1st level of structural organization)
compacts DNA strands and nucleosomes into a 30nm fibre (2nd level of structural organization)
wind up 30nm fibre into coils, which wrap around other scaffold proteins. (3rd level of structural organization )
The material that makes up chromosomes (proteins and DNA). 2 main types: Euchromatin and heterochromatin
loosely packed chromatin which contains more genes that are being transcribed
densely compacted chromatin containing highly-repetative sequences called "satellite DNA"
Heterochromatic sequences bound by centromeric proteins that link to microtubules. aka primary constrictions
repetitive sequences near the ends of linear chromosomes. important in maintaining consistent length and preventing alteration of chromosomes during replication.
centromere is located near the middle of a chromosome
Centromere is closer/ish to the end of a chromosome
Centromere is at, or near the very end of a chromosome
pairs of similar, but not identical, chromosomes where one member comes from the male parent and the other from the female.
genetically identicle and physically connected chromatids at the centromere until cell division
contain a different gene loci and may appear different physically as well
physically separate chromatids but come from homologous chromosomes (contains the same genes but will have allelic differences)
Enzyme that synthesize new nucleic acid strands by attaching nucleotides to the 3' OH group of the previous nucleotide.
Special RNA directed DNA polymerase which contain a RNA template that attaches to new DNA strands and adds repeats of AAUCCC which will then become TTAGGG when DNA polymerases come and finish off the new strand of DNA.
Condensing of replicated chromosomes.
chromosomes migrate to the middle of the dividing cell
sister chromatids detach and migrate to poles of dividing cell
identical sets of chromosomes are completely separated within the new nuclei of each daughter cell.
completion of cell division and of cytoplasm.
Purpose is to create genetically identical daughter cells
purpose is to create gametes (1/2 genetic info) for genetic recombination.
instead of of sister chromatids being split it is just homologous chromosomes that get paired up then split.
attachments formed between the homologous chromosomes during Meiosis 1 to create the bivalent's that form before being split during anaphase 1.
In the synaptonemal complex forming bivalent's during meiosis 1 crossovers are places where DNA repair enzymes break the DNA and attach non-sister chromatids together. This helps create added variation in inherited genes.
reductional cell division
description of Meiosis 1 because the # of chromosomes per cell is being decreased.
equational cell division
description of Mitosis and Meiosis 2 because the # of chromosomes doesn't change.
G1 phase: the lag portion after cell division
S phase: Dna synthesis/chromosome replicate
G2 phase: lag portion after DNA synthesis (doesn't occur during meiosis)
M phase: mitosis and cytokinesis
describes G1, S, and G2 phase all grouped together. (everything except M phase)
the DNA content in a cell
the number of chromosomes in a cell
a written description of chromosomes
any non-sex chromosome. typically shown by homologous chromosomes having the same length, centromere location, and banding pattern.
organism with the normal # of chromosomes
organisms with a mssing or and extra chromosome
organism with the absence of one member of a pair of homologous chromosomes. (2n-1)
organism with three rather than two of a particular chromosome (2n+1)
failure of chromosomes to separate during mitosis, meiosis 1, or meiosis 2.
types of defects in chromosomes
deletions: loss of chromosome region
duplications: gain of chromosome region
inversions: moving of chromosome region within a chromosome
insertions: moving/addition of chromosome region from one chromosome to another
translocation: reciprocal exchange of chromosome regions
organism contains the normal two copies of each autosome
any organism that has more than two copies of each chromosome sets.
notation used to describe ploidy. ex diploid=2x=2n. hexaploid=2n=6x.
(remember that n is only used to depict the stage of the cell cycle so will be the same for all organisms in the same stage)
all triploids are sterile because of unequal pairing/segregation during meiosis 1. so viable gametes are not created (banana's). they can be created through "cuttings" or by crossing tetraploid with diploid organisms.
tissue specific genome amplification that allows for extra rounds of DNA synthesis (s-phase) without mitosis or cytokinesis. The pourpose of this is to allow extra production of enzymes and proteins.
organelles contain chomosomes much like prokaryotes. mitochondria=inherited from mother.
salivary gland which has extreme endoreduplication resulting in over 1000 chromatids aligning together and therefore very easy identifying and study of chromosomes.
alternative versions of the same gene
Mendel's 1st law.
The Law of Equal Segregation: during gamete formation, the two alleles at a gene locus segregate form each other; each gamete has an equal probability of containing either allele. disproved previous blending inheritance theory.
both alleles of a gene are identical
alleles are different for a gene
when there is only one copy of a gene present (deletion on the homologous chromosome)
the most common allelic form in a natural population
a specific position on a chromosome. aka gene.
the entire set of alleles in an individual
the visible/detectable effect of alleles on an individual
(aka Semi-dominance) both alleles affect traits additively, and heterozygote phenotypes show intermediate expression between the homozygotes (often labelled using A1 and A2)
heterozygous individuals express the phenotype of both alleles simultaneously Ex. ABO blood groups
one normal allele produces enough protein to have normal biological function (wild type)
a diploid organism that has only one functional copy of a gene (other is inactivated by mutation) and that one copy is insufficient to provide normal biological function (wild type)
solving question using matings of model organism (mendel)
solving biological questions using DNA, RNA and proteins.
True breeding lines
in-bred populations which all parents and offspring have the same phenotypes for a particular trait. useful because they are assumed to be homozygous.
individual with uncertain genotype is crossed with homozygous recessive for loci being tested. by looking at the ratio's of F1 progeny showing each phenotype we can determine the genotype of the unknown.
genes on sex chromosomes that are inherited together with the sex determining system
males with only one x chromosome express genes on the x at twice the normal rate to restore balance of proteins. (y chromosome doesn't do much)
crossing a male and female with different phenotypes and then doing the same thing, but with the phenotypes swapped. when the two crosses show differences and the male and females show differences in one of the crosses it can be determined that the trait is x linked.
Z linked gene
same as sex linked genes in humans except with turkeys! females will have two E alleles and males only one. so females will have a better chance of being bronze (cause by dominant E allele) compared to the males which will either be E or e because they only have a single E allele then a W chromosome.
what % of individuals with the mutant genotype have the mutant phenotype. you either have complete penetrance or incomplete
what is the difference in intensity of the phenotype between individuals? this can be variable but is described as Narrow (no difference) or Broad (large variability).
the random selection of a non-representative group of individuals for observation. AKA the fact that there may be some sort of bias in your sampling.
(X^2) determines whether deviation between observed and expected ratios is due to sampling or if there is something else happening.
changes in DNA sequences. Do not always result in mutant phenotypes and are more likely to cause loss of function than gain.
when a mutation changes the phenotype of an individual.
variations of DNA sequences (and phenotypes) that exist in populations in relative abundance. essentially the same as a mutation, just is more common.
agents that cause mutation
stand slippage that causes bases to be displaced and form a "loop" of bases that is connected, but not paired, and can result in additions or deletions.
Short-Sequence Repeats: areas of DNA with repeats of the same nucleotides. especially prone to forming loops or other strand slippage. Also very useful because they hare highly polymorphic. AKA microsatellites
a transposable element used as a biological mutagen in Drosophila
An insertional element modified from a bacteria used as a mutagen in plant species.
a chemical mutagen that uses alkylation (addition of alkyl group to G bases). This results in a T instead of a C being paired with the alkylated G base.
a chemical mutagen that can insert itself between the stacked bases at the centre of the DNA double helix, possibly causing a frameshift mutation.
Ethane Methyl Sulfonate: example of commonly used alkylating agent.
Transposable elements: naturally occurring DNA sequences that are able to be inserted into new locations in the genome after being cut out. AKA mobile genetic elements or jumping genes.
types of TE's
Class 1 (retrotransposons): normal transcription into RNA then reverse transcription back into DNA allows for insertion of this new sequence into a new location. families called LINEs and SINEs
Class 2 (transposons): use an enzyme called transposase to cut out the TE and then this dsDNA is inserted into a new loaction.
TEs that do not encode any proteins. They can only transpose if enzymes are provided.
TEs that can produce their own enzymes or even provide enzymes to other TEs. These enzymes recognize conserved nucleotide sequences in the TE to determine where to cut.
a component of wood and tobacco smoke that is also an intercalating agent (insert themselves into the middle of double helix)
an intercalating agent that is used to stain DNA in laboratories.
anything damaging DNA by transferring energy. radioactive particles, x-rays, or UV light. Smaller particles=small effect larger particles=breaking double stranded helix.
used to understand molecular components and processes by inducing random mutations and then looking for phenotypes with a mutation.
AKA null: loss of function mutation resulting in an allele that produces no active protein. compared to a hypomorphic which has only lost partial function.
gain of function mutation resulting in increased amounts of active protein
gain of function mutation resulting in a protein with a new function
mutation resulting in activity that is dominant and opposite to normal (wild type) function. aka dominant negatives.
changes in the DNA occur at a non-coding region or changes a base without changing the actual amino acid produced.
encoding of similar genes at multiple locus in the genome. makes mutational analysis difficult because no phenotypic difference will occur
two homozygous individuals with similar mutant phenotypes are crossed. If the F1 progeny all have the mutant phenotype then it is assumed the mutations are the same but if anything else appears then it is likely the mutations are on different genes.
when two homozygous mutants produce F1 progeny with a wild type phenotype. The mutants where able to "complement" each other.
any mutants that fail to complement each other are said to be in the same "complementation group"
modes of inheritance and descriptions
autosomal dominant (AD): everyone with the dominant allele will show symptoms thus every affected individual must have an affected parent
autosomal recessive (AR): requires two alleles to show phenotype. requires both parents of affected individuals to have at least one affected allele
x-linked dominant (XD): affected allele is located on the X-chromosome and is dominant. It is NOT possible for an affected father to pass effect onto son (X inherited from mother)
x-linked recessive (XR): need 2 affected (female) or 1 affected (male) allele for phenotype to show. It is NOT possible for a affected daughter to inherit from an unaffected father.