BIOL1003 Lecture Notes - Lecture 2: Turner Syndrome, Meiosis, Barramundi
Chromosomal Basis of Inheritance
To understand the material nature of inheritance, you need to understand where
heritable material can be found
The Chromosome
It was observed under the first microscopes that all organisms were made of cells
It was also observed that all cells have black dots in them- the nucleus
Began to cut up cells to look at them without killing them- when they studied them
for a while they noticed cell division
Dividing cells scramble of all their internal bits, then put them together again,
starting with the nucleus- must be important
The nucleus breaks up to form dark, easily stainable coloured bodies- chromo somes
Only present during cell division
Gene
Mendel hypothesised a factor that conveys traits from parent to offspring (1860s)
Darwin used the phrase “pangenesis”
Mendel’s theory of inheritance and Darwin’s theory of natural selection was
combines by someone who understood both languages
Shortened to “pangen” in 1880
oPangen: the smallest particle (representing) one hereditary characteristic
Gene first used in 1909
oGene: he fundamental physical and functional unit of heredity
Genes and chromosomes
Morgan- used beams of electrons to see bands and stripes on the chromosome- saw
if traits corresponded to the bands of fruit flies, fruit fly chromosomes bloat and
inflate making it easier to study than humans
Through the observation of cell division, chromosomal bands and their correlation to
inherited traits, Thomas Hunt Morgan established in 1920 that genes can be found
on chromosomes
He had no idea what chromosomes were made of
Chromosome
Chromosome: a condensed form of proteins and nucleic acids
carrying genetic information (DNA), visible only during cell division
Chromosome is a unit to make sure that the information is going to
be packaged in an equal way in the daughter cells
When the cell is not dividing it is relaxed, spread out in the nucleus
and is called chromatin, it is still made up of nucleic acids and proteins
but looks different
Image:
oDarker and lighter bits correspond to more active and less active parts of the
genome
oGenes that are active in transferring their content and information to make
proteins and coordinate biological processes in the cell
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Document Summary
To understand the material nature of inheritance, you need to understand where heritable material can be found. It was observed under the first microscopes that all organisms were made of cells. It was also observed that all cells have black dots in them- the nucleus. Began to cut up cells to look at them without killing them- when they studied them for a while they noticed cell division. Dividing cells scramble of all their internal bits, then put them together again, starting with the nucleus- must be important. The nucleus breaks up to form dark, easily stainable coloured bodies- chromo somes. Mendel hypothesised a factor that conveys traits from parent to offspring (1860s) Mendel"s theory of inheritance and darwin"s theory of natural selection was combines by someone who understood both languages. Shortened to pangen in 1880: pangen: the smallest particle (representing) one hereditary characteristic. Gene first used in 1909: gene: he fundamental physical and functional unit of heredity.
