Lecture 9-10

Question 1

what chromosome is the beta globin gene on?

Answer 1

chromosome 11

Question 2

what chromosome is the alpha globin gene on?

Answer 2

chromosome 16

Question 3

what happens in thalessemia?

Answer 3

• either the alpha or beta globins are not produced

Question 4

what happens with methemoglobin?

Answer 4

• can’t deliver oxygen

- FE3+ instead of 2+

Question 5

what are some signs of beta thalessemia?

Answer 5

• microcytic anemia
• inefficient erythropoiesis
• splenic enlargement
• gall stones

Question 6

what is Beta + thalessemia?

Answer 6

• some partially functional beta globin is made

Question 7

what is beta 0 thalessemia?

Answer 7

• no functional beta globin is made

Question 8

what is A form?

Answer 8

DNA-RNA hybrid, thick, shorter distance between base pairs

Question 9

what is B form?

Answer 9

most genomic DNA

Question 10

all natural DNA contains ____ at the 5’ end and _____ at the 3’ end.

Answer 10

A phosphate group; a hydroxyl group

Question 11

why is dna negative?

Answer 11

phosphate groups on the outside

Question 12

what determines the stability of a DNA helix?

Answer 12

• G:C content

- length

Question 13

what are the four core histones?

Answer 13

H2A, H2B, H3, H4

• linker is H1

Question 14

describe the steps of DNA organization in regards to coiling.

Answer 14

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.

Question 15

when is nucleosomal DNA most densely packed?

Answer 15

• 10 times more packed during metaphase

Question 16

what makes up a centromere?

Answer 16

• multiple repeats of an A:T rich 171 bp sequence of DNA called alpha satellite DNA.

Question 17

what are telomeres?

Answer 17

• 5-15kb in size
• bunch of TTAGGG repeats
• helps in maintenance of chromosome ends

Question 18

what is epigenetic regulation?

Answer 18

regulation of transcriptional activity of chromosomal genes through the modification of histone tails

Question 19

what are the 4 main types of epigenetic modifications found on histones?

Answer 19

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

Question 20

which is denser, euchromatin or heterochromatin

Answer 20

heterochromatin.

Question 21

tell me about euchromatin.

Answer 21

• less condensed.
• replicated throughout S phase
• recombines during meiosis
• many genes
• transcriptionally active

Question 22

tell me about heterochromatin.

Answer 22

• highly condensed
• few genes
• replicates in late S phase
• no meiotic recombination
• not very transcriptionally active

Question 23

what are the three mechanisms of chromatin regulation/assembly?

Answer 23

1) chromatin modifiers (acetylation, methylation, etc)
2) ATP dependent chromatin modifiers (move/exchange nucleosomes within DNA)
3) recruitment of proteins to modified histones

Question 24

what does the HP1 protein do?

Answer 24

• causes repression of transcription

- enriched in heterochromatin

Question 25

what is the general characteristic about thalessemias?

Answer 25

they are a usually deletion mutations that results in a quantitative change in normal hemoglobin production.

Question 26

what is the average life of a RBC and how long does it take a RBC to circulate completely?

Answer 26

- 120 days | - 3 minutes

Question 27

what is the purpose of the spleen and how long does it typically take it to do its job?

Answer 27

- 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.

Question 28

what is a reticulocyte count?

Answer 28

measure of new red blood cells