Molecular Flashcards
What are the purines?
- Adenine
- Guanine
What are the pyrimidines?
- Cytosine
- Thymine
- Uracil
How many times does DNA loop around histone?
Twice
What does H1 act as?
A histone linker
During what phase does DNA and histone synthesis occur?
S phase
What are Barr Bodies?
Inactive X chromosomes
What gives DNA a negative charge?
Phosphate
What amino acids give histones a positive charge?
- Lysine
- Arginine
What does histone acetylation do?
- Increases transcription
- Removes histone’s positive charge, relaxing coiling
- Attaches to lysine
What sequence of genes represses transcription?
CpG islands (C, G) - Methyl group attaches to Cytosine
What processes involve DNA methylation?
- Aging
- X chromosome inactivation (lyonization)
- Carcinogenesis
- Genomic imprinting
- Transposable element repression
What disease is thought to be due to dysregulated acetylation?
Huntington’s
What do nucleosides lack?
A phosphate group
How many rings do purines (A, G) contain?
2
How many rings do pyrimidines (CUT) contain?
1
How many H bonds do the bases have?
- C-G bond has 3 (higher melting point)
- A-T bond has 2
What does deaminated Cytosine become?
Uracil
What does deaminated Adenine become?
Hypoxanthine
What does deaminated Guanine become?
Xanthine
What does deaminated 5-methylcytosine become?
Thymine
What does methylation of uracil make?
Thymine
What amino acids are necessary for purine synthesis?
- Glycine
- Aspartate
- Glutamine
What makes up a nucleoside and a nucleotide?
- Nucleoside = base + sugar (ribose/deoxyribose)
- Nucleotide = base + sugar + phosphate