Biochemistry Lecture 4

Front 1

Nuclesome

Back 1

histone octamer and ~150 DNA base pairs + H1 bundled at the side to maintain stability and bind bundles together

Front 2

Histone

Back 2

- acts as a docking/coiling site for the DNA
- rich in positively charged amino acids (lysine and arginine)

Front 3

Histone Modification

Back 3

Enzymes can act on histone to alter Histones
- acetylation - most important, acts on histone tails
- methylation
- ubuiquination
- phosphorylation

Front 4

Histone Acetyltransferase (HAT)

Back 4

Histone acetylation acts on histone tails, bonds to them and makes them slightly more negative which in turn opens up nucleosome to allow DNA to be accessible for transcription

Front 5

Histone deacetyltransferase (HAT)

Back 5

subtracts acetyl group from histone tails, makes the nucleosome tighter and more compact

Front 6

Ploidy

Back 6

The number of sets of chromosomes in a biological cell

Front 7

Diploid

Back 7

Two complete sets of chromosomes in every somatic cell (not sex cell)

Front 8

Centromere

Back 8

Constricted region of chromosome that links the sister chromatids

Front 9

Kinetochore

Back 9

Tightly packed region where spindle fibers attach on chromosome

Front 10

Metacentric
Subcentric
Acrocentric

Back 10

Front 11

Genetic location

Back 11

Use of 3 key features to identify chromosome recognition
- size tells you which chromosome it is
- arm P - petite, Q -long
- position - banding pattern
can give types of disease and location on the chromosome

Front 12

Telomere

Back 12

repeated elements of heterochromatin DNA sequence placed at the ends of chromosomes. The sequence is repeated thousands of times to protect from recombination, degradation, and fusing with other chromatids.
Sequence IS: 5' - TTAGGG - 3'

Front 13

End of replication problem

Back 13

Where RNA primer was on DNA chain during replicaiton there is no -OH to add onto so space is left empty => Enter telomerase

Front 14

Telomerase

Back 14

Ribonucleoprotein that uses its own RNA template to extend the 3' end of DNA to fill in the gap left behind by RNA primer. Uses repeat after repeat after repeat 5' - TTAGGG - 3'

Front 15

Senescence

Back 15

If a cell goes through to many cellular divisions it will eventually reach its limit of division (Hayflick limit) and the cell will shut off - it does not respond to its environment and basically experiences cell death. Referred to as biological aging. Telomerase is said to be turned on in cancer cells, effectively allowing for the continuation of cellular replication.