Genomic DNA and Nucleic Acids Prework 1 Flashcards Preview

MCM Test 1 > Genomic DNA and Nucleic Acids Prework 1 > Flashcards

Flashcards in Genomic DNA and Nucleic Acids Prework 1 Deck (16):
1

how many base pairs are in the human genome?

3.2 billion

2

how many protein coding genes?

20,000

3

how many non coding genes

25,000

4

how many pseudogenes?

14,000

5

how many gene transcripts?

200,000

6

how many nucleotide differences between individuals?

3-3.5 million

7

how many chromosomes are there in each human cell?

46
22 autosomes x 2 copies
2 sex chromosomes

8

what is the difference between euchromatin and heterochromatin?

euchromatin is gene rich, structurally open, and contains actively transcribed genes
heterochromatin is repetitive and gene free and structurally compacted

9

what is the difference between constitutive and facultative heterochromatin?

constitutive heterochromatin contains repeats, telomeres and centromeres
facultative contains developmentally silenced genes

10

what does DNA methylation do?

causes irreversible packaging of DNA into heterochromatin

11

what are some reasons why DNA methylation is so important?

silences tissue specific genes in other tissues, methylation of tumor suppressor genes can cause cancer, females have a silenced X chromosome

12

what makes up a nucleosome?

about 200 bp of DNA wrapped around a histone octamer protein core

13

what are some characteristics of histone proteins?

rich in lysine and arginine, highly basic
electrostatic interactions with phosphates on DNA backbone
globular core with flexible tails (tails are the site of modifications)

14

what are modifications that can be enacted on histone protein tails?

small: acetylation, phosphorylation, methylation
large: ubiquitylation, sumoylation, ADP-ribosylation

15

how do histone modifications differ from DNA modifications?

more dynamic; DNA mods are more long term

16

what does the word "epigenetics" refer to?

information in DNA not based upon the nucleotide sequence, but still inherited
ex: maternal/paternal allele specific patterns of DNA methylation at some loci