Genetics: Chromosomes Flashcards
(34 cards)
While cell division in plants and algae was observed in the 1830s, why was cell division in animal cells only observed in 1873?
They were harder to grow in cultures, leading difficulties to getting good samples
The germ plasm theory states that we have 2 types of cells. What are they?
Somatic (liver, brain, etc) and germ (reproductive) cells
in homologous chromosomes,
traits line up
What is genetic drift?
Mutations dying because of random events
What is the process of cell division called?
Mitosis
What was the process of discovering nucleic acides?
1860s - Isolated phosphorous rich chemicals from leukocytes. Named nuclein, because they were isolated from the nuclei of the cells
1880s - Renamed nucleic acid because of their acidic nature
1890s - Isolated 5 distinct nucleotide bases: Adenine, guanine, cytosine, thymine (for DNA), and uracil (for RNA)
When and who identified chromatins to be the threadlike structures in nuclei?
1880s - Walther Flemming
Who first used the term chromosome?
1888 - Waldeyer- Hartz
When do nuclear chromosomes become visible?
When they are condensed
What occurs during mitosis?
Replicated chromosomes are separated into two new nuclei during the process of cell division
Cells undergo ____ _______ as the organism grows, and also to replace damaged cells.
Dividing cells undergo ______ to allocate chromosomes to each daughter cell
cell division, mitosis
What is germ plasma theory? When and who proposed it?
Inheritance in multicellular organisms takes place via the germ cells in the gonads such as egg cells and sperm cells (gametes). Other cells (somatic cells) are not the agents of heredity.
1892, August Weismann
In germ plasma theory, what is germplasm?
The essential element of germ cells that is passed from one generation to the next
In eukaryotic cells, where can DNA be stored?
nuclear chromosomes, mitochondria, and chloroplasts
When and who developed parts o the chromosome theory of inheritance? What did their work show?
1902, Walter Sutton and Theodor Boveri
Chromosomes are seen in all dividing cells and pass from generation to the next. Stated that chromosomes might be the basis of genetic inheritance, but was controversial at the time
Scientists first thought that _______ carried the genetic material. Why?
Proteins
It was known that chromosomes also contained proteins. They though the structure of DNA was too simple to give rise to the traits, unlike proteins with over 20 amino acids
What is the basic building block of DNA?
phosphate, sugar (deoxyribose), and 4 bases (AGCT)
Which two bases are purines?
Adenine and guanine
Which two bases are pyrimidines?
Cytosine and thymine
What is the length of DNA from the largest human chromosome?
10 cm (250*10^6 base pairs)
Early scientists incorrectly insisted that DNA was probably only __ nucleotides long and that the amounts of the four bases were the same in all DNA molecules
10
When and who conducted Experiment 1? What was the conclusion?
1928, Frederick Griffith.
He discovered that bacteria are capable of transferring genetic information though a process called transformation
Describe the process of Experiment 1
Griffith was trying to make a vaccine for pneumonia with the bacteria.
He experimented with 2 strains: Rough and Smooth.
Only Smooth was virulent, causing pneumonia and death in mice
He then showed the heat-killed Smooth were no longer virulent
However, if he mixed the dead Smooth with live Rough, the Rough transformed into Smooth bacteria
This meant dead Smooth could still transfer genetic material into Rough
When and who conducted Experiment 2? What was the conclusion?
1944, Avery, Macleod, and McCarty
They discovered that DNA likely caused the bacterial transformation reported in Griffiths experiment
