Genetics Ch 11

what is the difference between an organelle and a membrane-bound organelle

an organelle can be a ribozyme. and a membrane bound organelle is attached to membrane such as the ER or the mitochondria

telomerase shortening due to childhood diversity

studies have shown that an abused/neglected child who has had a tough life has a shorter line of telomers

what do telomers affect

the longevity of life, how many times a cell divides

how does cancer use telomers

cancers have over-active telomerase meaning cancer cells can divide uncontrollably and more than other normal cells can

how many divisions of telomer occur before you grow up and the telomerase activity is stopped

60 divisions

if you were to cut open your skin and muscle which cells would re-generate

the skin cells like gut cells replicated constantly, but muscle cells will never re-grow because after you stop growing those cells never turn back on. Once you reach a certain age re-growth isn't often. Body builders make their muscles bigger but then do

super coiling

when DNA rounds around itself

types of super coiling

positive, negative,

topoisomerase

type 1 and type 2

type 1 topoisomerase

cuts one strand of DNA to enable twisting

type 2 topoisomerase

cut two strands of DNA

what does topoisomerase do

the enzyme responsible for adding and removing turns in the coil

how does DNA supercoil around itself

it normally wouldn't seem like this was possible due to the negative charges on phosphates but the proteins allow this to be possible

over-wound DNA can't be

transcribed

positive DNA

is usually over-wound

negative DNA

is looser, or under-wound which is more likely for the DNA to be transcribed because hydrogen bonds break easily

how is bacteria DNA

highly folded in E.coli

heterochromatin

highly condensed such as mitotic chromatin, "non-moveable" histones

euchromatin

less condensed "moveable" histones

histone proteins

form nucleosomes

constitutive heterochromatin

constant

facultative heterochromatin

in interphase it is transcripable

eukaryotic chromatin

has a highly complex structure with several levels of organisms

in the most condensed form of DNA

no transcription occurs. transcriptional proteins need to be able to get to the DNA nucleotides to transcribe another strand

HAT proteins

acetylate the tails and activate transcription

Histone D acetylates

chromatin becomes fixed or stuck heterochromatin

salamanders have more complex DNA than corn

corn has more complex DNA than humans

why does corn have such complex DNA

because if doubles it's chromosome

generally besides mammals

organisms become more complex with the more DNA they have

A lot of experimental data come from which organism

the fruit fly

what does C equal

the number of nucleotides in a genome

What are chromosome puffs

they are sensitive to DNAase that are transcriptionally active

endonuclease is able to cut DNA from the form of a

circle

exonuclease is able to cut DNA from the form of a

line

why is euchromatin more likely to be cut

because it is less condensed, and the looseness leads to easier cutting

chromosome puffs

are regions of relaxed chromatin where active transcription is taking place

variation in DNA methylation

an epigenetic change at the agouti locus produces different coat colors in mice

What is a DNA if it had two turns added

Over turned super coiled

What's DNA when it has two turns removed

Under rotate, negative supercoil

each loop of DNA is a domain and each DNA Can have

A different amount of supercooling

Histone proteins

Form nucleosomes in eukaryotes. A chromatid one equals nucleosomes plus histone. Linker DNA. High order chromatin structure for example packaging DNA

Eu chromatin general overview

Less condensed, on chromosome arms, unique sequences, many genes present, transcription occurs often and cross over is coming

Hetero chromatin

Highly condensed, transcription is infrequent, few genes are present, repeated sequences and they are located at centromers, telomeres, and other specific places

How would neutralizing the positive charges effect histone proteins

it would make them bind less tightly to the negatively charged DNA

Eukaryotic chromatin

Has a highly complex structure with several levels of organization

Genome sizes in order of smallest to largest

Bacteriophage, ecoli bacterium, yeast, plant, insect, human, corn, and salamander

Changes in chromatin structure

Polytene: chromosome puffs, DNA I sensitivity, epigenetic changes.

Chromosomal puffs

Region of relaxed chromatin where active transcription takes place

DNAase 1 sensitivity

Correlates gene activity

Epigenetic changes

Methylation, capable of being reversed and often due to environmental factors

An epigenetic change example

Variation in DNA methylation at the agouti locus produces different colors in mice fur

all E.Coli DNA is

unique

mitochondrial and chloroplast DNA differs in certain life why

possibly from aerobic respiration

Do humans have mitochondrial DNA

humans have mitochondrial DNA. this DNA is commonly received from the mother but may be from the father

heteroplasmic cells

can produce homoplasmic cells through the process of appreciative segregation