Lecture 1 Flashcards
What does euchromatin consist of?
Beads on a string, genes can be expressed in this form
What does heterochromatin consist of?
Solenoid fibres, genes cannot be expressed in this form.
What does a nucleosome consist of?
Histone core with DNA wrapped around it. Also termed beads on a string.
What are chromosomes made from?
Chromatin which consists of nucleosomes in the form of solenoids. DNA, RNA and protein are involved.
What is the genome?
The genome is the entire DNA sequence.
What is the difference between a nucleotide and nucleoside?
A nucleotide consists of a base, sugar and phosphate. A nucleoside is just a base and sugar.
What is a nuclei acid?
DNA and rna are nuclei acids which are polynucleotides. Ie lots of nucleotides together.
What bonds join nucleotides together?
Phosphodiester
Which base pairing has three hydrogen bonds?
Guanine and cytosine
What way are the strands arranged in a double helix?
Anti parallel
What direction is DNA read?
5 prime to 3 prime
DNA replication occurs in what direction?
DNA polymerase extends it from 3 prime to 5 prime of template strand. However this means that the newly synthesised strand is made 5 prime to 3 prime.
What are Okazaki fragments?
Small sections of replicated DNA that when joined together make up the lagging strand. DNA helical unwinds a section of DNA and ligand can replicate DNA from that section. Lagging strand is 5 prime to 3 prime so dna must be replicated from the 3 prime end in multiple fragments.
What enzyme unwinds DNA
DNA helicase
What happens to chromosome in DNA replication?
One chromosome which is one DNA molecule becomes two DNA molecules or chromatids.
