Lecture 1- Structure Of DNA and Chromsomes Flashcards
What are the requirements for genetic information?
Stable for storage, available for cellular processes, faithfully replicated, able to control expression of traits, change in a controlled way
Genetic information must be stable for storage, available for cellular processes, faithfully replicated through semi-conservative replication, able to control expression of traits, and able to change in a controlled way, such as through point mutations.
Who isolated nuclein and when?
Friedrich Miescher in 1868
Miescher focused on proteins and found nuclein in human pus from bandages, discovering a non-protein substance due to its high molecular weight and acidity.
What did Avery, Macleod, and McCarty discover in 1944?
Transforming principle
Their work contributed to the understanding of DNA as the carrier of genetic information.
What was the key finding of Hershey and Chase in 1953?
Only DNA was present in bacterial cells
They used bacteriophages labeled with radioactive isotopes to demonstrate that only phosphorus (from DNA) entered the bacterial cells.
What technique did Rosalind Franklin use to study DNA?
X-ray crystallography
Franklin’s work suggested that DNA was likely helical with phosphate groups on the outside.
What did Watson and Crick report in 1953?
Base pairings and two helical chains
They described the structure of DNA as two coiled helical chains.
What was a controversial aspect of Watson’s career?
Pseudoscientific racism
Watson was suspended from his position at Cold Spring Harbor Laboratory in 2007 due to his views.
What was Dr. Dunston’s research focus?
Type 2 diabetes differences in populations
He acquired samples from African populations for the Human Genome Project.
What is the structure of DNA described as?
Right-handed helix
DNA structure includes pyrimidines (CTU) and purines (AG).
How are nucleosides and nucleotides formed
Nucleoside: sugar + base; Nucleotide: sugar + base + phosphate
What is the significance of 3’ and 5’ ends in DNA?
Directionality of DNA strands
DNA strands run antiparallel, with each strand having a 3’ and a 5’ end.
How many hydrogen bonds do AT and GC pairs have?
AT: 2 H bonds; GC: 3 H bonds
The number of hydrogen bonds affects the stability of the DNA structure.
What are major and minor grooves in DNA?
Result from angles between sugar-phosphate backbone
These grooves are important for protein binding and DNA interaction.
What is a genome?
All the DNA in the nucleus of a cell or organelle
This includes the mitochondrial or chloroplast DNA.
What is a karyotype?
Discrete units of chromosomes
A karyotype is an image showing the number and appearance of chromosomes in a cell.
How is DNA stored in the cell?
As chromatin strands
DNA wraps around histone proteins to form nucleosomes.
What is euchromatin?
Less compact DNA containing frequently expressed genes
Specific acetylation and methylation marks are associated with euchromatin.
What is heterochromatin?
More compact DNA with less frequently expressed genes
Heterochromatin is typically associated with gene silencing.
What is a nucleosome?
DNA wrapping twice around 2 histones
What is Artemisinin?
An anti malarial compound discovered by Tu Youyou made from sweet wormwood
