Lecture 9-10 Flashcards
what chromosome is the beta globin gene on?
chromosome 11
what chromosome is the alpha globin gene on?
chromosome 16
what happens in thalessemia?
- either the alpha or beta globins are not produced
what happens with methemoglobin?
- can’t deliver oxygen
- FE3+ instead of 2+
what are some signs of beta thalessemia?
- microcytic anemia
- inefficient erythropoiesis
- splenic enlargement
- gall stones
what is Beta + thalessemia?
- some partially functional beta globin is made
what is beta 0 thalessemia?
- no functional beta globin is made
what is A form?
DNA-RNA hybrid, thick, shorter distance between base pairs
what is B form?
most genomic DNA
all natural DNA contains ____ at the 5’ end and _____ at the 3’ end.
A phosphate group; a hydroxyl group
why is dna negative?
phosphate groups on the outside
what determines the stability of a DNA helix?
- G:C content
- length
what are the four core histones?
H2A, H2B, H3, H4
- linker is H1
describe the steps of DNA organization in regards to coiling.
1) naked DNA is wrapped around an eight histone core making a nucleosome.
2) nucleosomes are packed into a nucleofilament
3) nucleofilaments are organized into a loop and wrapped around a nuclear scaffold protein.
when is nucleosomal DNA most densely packed?
- 10 times more packed during metaphase
what makes up a centromere?
- multiple repeats of an A:T rich 171 bp sequence of DNA called alpha satellite DNA.
what are telomeres?
- 5-15kb in size
- bunch of TTAGGG repeats
- helps in maintenance of chromosome ends
what is epigenetic regulation?
regulation of transcriptional activity of chromosomal genes through the modification of histone tails
what are the 4 main types of epigenetic modifications found on histones?
1) acetylation - removes positive charge on histones, reduces interaction b/t it and negative phosphates on DNA.. makes it looser (euchromatin)
2) methylation - causes contraction of DNA into chromosome
3) demethylation
4) phosphorylation
which is denser, euchromatin or heterochromatin
heterochromatin.
tell me about euchromatin.
- less condensed.
- replicated throughout S phase
- recombines during meiosis
- many genes
- transcriptionally active
tell me about heterochromatin.
- highly condensed
- few genes
- replicates in late S phase
- no meiotic recombination
- not very transcriptionally active
what are the three mechanisms of chromatin regulation/assembly?
1) chromatin modifiers (acetylation, methylation, etc)
2) ATP dependent chromatin modifiers (move/exchange nucleosomes within DNA)
3) recruitment of proteins to modified histones
what does the HP1 protein do?
- causes repression of transcription
- enriched in heterochromatin
what is the general characteristic about thalessemias?
they are a usually deletion mutations that results in a quantitative change in normal hemoglobin production.
what is the average life of a RBC and how long does it take a RBC to circulate completely?
- 120 days
- 3 minutes
what is the purpose of the spleen and how long does it typically take it to do its job?
- filters the blood, usually RBCs are only in the spleen for 15 seconds. If sickled, RBCs can stay in it for up to an hour.
what is a reticulocyte count?
measure of new red blood cells
