Lecture 29 Flashcards
(34 cards)
How does bacteria store compact DNA?
negative supercoiling and by organizing the genome into separate loops of supercoiled DNA, whereby each loop is bound to protein
What is the compact structure of storing DNA in bacteria cell called?
nucleoid that exist in the cytosol
Where is DNA stored in eukaryotes?
nucleosomes that are formed from histone core proteins
What are bacteria considered?
Bacteria are considered haploid because they only have one copy of each chromosome per nucleus
What are eukaryotes considered?
diploid because they have two homologous sets of chromosomes per nucleus (except sex chromosomes)
What type of chromosomes do bacteria and eukaryotes have?
Bacteria= circular
eukaryotes= linear
What do genes comprise of?
coding(exons) and non-coding(introns), also 37.5% of the genome
What are inter-genes?
DNA sequences that are present between genes such as promoter regions, transposons and microsatellite repeats. Also, 62.5% of the genome
What is true about gene density?
It is the ratio between the number of genes per number of base pairs. Therefore, bacterial genomes have a higher gene density than eukaryotic genomes
What happens during the process of transcription?
DNA is used as a template for the synthesis of an RNA copy of the gene
What do nuclear pores allow? How do genes move around?
small molecules to diffuse between the nucleus and cytoplasm such as RNA and proteins
How is pre-mRNA processed?
- the addition of a 5’cap
- the addition of a poly A tail at the 3’ end
- intron splicing and joining of exons together to form the mature mRNA
What makes up inter-genes?
Regulatory elements, genome-wide repeats, and microsatellite repeats
How is eukaryotic genome organized?
DNA sequence, chromatin when associated with proteins, then chromosomes
How do nucleosomes compact DNA?
about 6 fold and DNA is wound 1.65 times around the histone core. Super abundant and also the most conserved proteins in evolution
What is histone 1 or H1?
It is the linker histone that tightens the nucleosomal structure. Works like tape to keep DNA stable
What is true about histone1?
It is a small and positive charged protein. It is also made up of lysine and aginine. Also, associate tightly and non specific with the DNA because it is neg charged
What is true about histone modifications?
They can be modified and also add methyl, phos, acetyl groups
What happens if you add methyl, acetyl, etc. groups to histone?
They can loosen or tighten the DNA to be compacted. It also can be reversible and alter the biological functions
What type of bond happens when histone bonds with acetyl, ubo, methyl groups?
covalent bonds
What further compacts DNA?
protein scaffold that further loop DNA
What does histone do to DNA?
They reduce the access to DNA specific binding proteins. Due to this, it unwraps a bit.
What are the two types of chromatin?
Euchromatin and heterochromatin
What distinguishes euchromatin?
It is loosely compact and stains light. It is also has unique sequences, active chromatin, and gene rich, recomb
