DNA and Chromosomes Lecture Notes

This set of flashcards covers key concepts, experiments, and findings related to DNA and chromosomes, including the characteristics of genetic material, historical experiments, and the structure and function of DNA.

What are the key characteristics of genetic material?

Genetic material must contain complex information, replicate faithfully, and encode the phenotype.

What did Frederick Griffith discover in his 1928 experiment?

A substance from dead cells of one strain could produce a heritable change in another strain of bacteria.

What was the conclusion of Avery, MacLeod, and McCarty's experiments in 1944?

They identified DNA as the hereditary substance after treating samples to destroy different molecules.

What did Hershey and Chase use to determine the genetic material of bacteriophages?

They labeled bacteriophage DNA with radioactive phosphorus and protein with radioactive sulfur.

What did Chargaff's data reveal about DNA base composition?

The base composition of DNA varies between species, and within a species, A = T and G = C.

How did Watson and Crick deduce the structure of DNA?

They used X-ray crystallography data, notably from Franklin, to conclude that DNA is helical with a double-stranded structure.

What are the primary structural components of DNA?

DNA is composed of nucleotides made of a deoxyribose sugar, a phosphate group, and a nitrogenous base.

What are the differences between heterochromatin and euchromatin?

Heterochromatin is more condensed, found at specific locations with fewer genes, while euchromatin is less condensed with many genes.

What role do histone proteins play in chromatin?

Histones are positively charged proteins that interact with negatively charged DNA and help package it into chromatin.

What is the impact of epigenetic changes on gene expression?

Epigenetic changes, like DNA methylation and histone modification, can regulate gene expression and influence traits.

What happens to one of the X chromosomes in mammalian females?

One X chromosome is inactivated by heterochromatin formation, leading to mosaicism in tissues.

How do maternal behaviors influence DNA methylation in offspring?

Maternal licking and grooming lead to differences in DNA methylation that affect stress-related gene expression.

What are epimarks and their significance in gene expression?

Epimarks are reversible modifications that can affect gene expression, often 'erased' in gametes but maintained in somatic cells.