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Chromatin
complex of DNA and proteins in eukaryotic chromosomes
Euchromatin
genetic material that is slightly stained when dyed.

believed to be genetically active
Heterochromatin
genetic material that is darkly stained when dyed

believed to be gentically inactive with numerous chunks of repetitive DNA
Haploid
one complete set of chromosomes (n)
Diploid
two complete sets of chromosomes (2n)
Tetraploid
Octoploid
(4n)
(8n)
Sex Chromosomes
chromosomes connected with determination of sex
SRY gene
y linked gene in humans and mammals which codes for a protein (testes determining factor) that plays a role in male development
testes determining factor
protein produced in embryoonic development which stimulates the differentiation of testes from embryonic glands
haplo-diploid
form of sex determination in bees. fertilized eggs become females and unfertilized eggs (n) become males
dosage compensation
the increase or decrease in the activity of a gene depending on the number of copies of taht gene in the cell. sex chromosomes.
genetic linkage
relationship among genes in same chromosomes

tend to be inherited together
independent assortment
random segregation and assortment of chromosomes during meiosis resulting in unique games only for genes on different locations
centimorgans
unit of measurment of genetic recombination frequencies

1 cM=1% chance separation
recombination frequency
used to measure intensity of linkage between genes

total #recombinant
total #progenies
DNA
deoxyribonucleic acid
information carrying genetic material comprises of genes.
phosphate-5c sugar-nitrogenous base
double stranded antiparallel
RNA
ribonucleic acid
carries genetic information in some viruses
single stranded
different types
Nucleosomes
spherical subunits of eukaryotic chromatin
composed of histones and 146 nucleotide pairs
Histone
proteins that are used for coiling of DNA in chromosomes

also used fo regulation of gene activity
Chromosome
supercoiled linear DNA that stains darkly during cell division
Pedigrees
dominant- seen in every generation
recessive- unaffected parents

Inbreeding coefficient
  1. common ancestor
  2. count # of relatives in loop (n)
  3. (1/2)n sum for each loop

Coefficient of relationships- multiply inbreeeding coefficient by 2
liklihood of inheriting x-linked trait
xaxA   (x)   xay
xAxa            xay
xAxA            xAy
SRY mutants
SRY gene triggers development of testes

formation of testes
testosterone secreation --> male characteristics
hormone binds to receoptor to instruct cell how to differentiate
if system fails, female characteristics are formed

inability to make testosterone receptor
testicular feminization (Tfm) mutation in x linked gene encodes receptor, mothers ot xy hemizygous
dosage compensation
the increase or decrease in activity of a gene dependign on teh number of copies of that gene in a cell. x linked genes

1) hyperactivity- one gene work 2x hard in drosophila
2) inactivity- one copy of gene is inactivated (humans)
3) each x linked worked half as hard c. elegans
linked gene discernment
phenotype data

#recombinant/total

very small <50 =linked gene
~ 50 = nonlinked
recombination frequency probablities and map distribution
recombination frequence = map distance

.42 = 42 cM
gene order
look at least # represented and compare to parent strains for middle gene
why is recombination important?
recombination is importate because it allows for new genotypes and phenotypes that may be better adapted to the environment. thus aiding in evolutionary process.
DNA vs RNA structure
DNA
double stranded, anti parallel
thymine

RNA
single stranded
uracil
What are the major characteristics of RNA
Single stranded
ribonucleic acid
contains uracil instead of thymine
codes for proteins
many forms
in what direction is DNA assembled, and why?
DNA is assembled in the 5' --> 3' direction.

phosphodiester bonds can only be synthesized by the DNA polyermase on the 3' Carbon containing the -OH
Understand the base pairing rules
Adenine and thymine
guanine and cytosine
Levels of chromosome organization
Process is condensing the DNA
1- 3nm DNA is coiled around a protein histone complex. This produces what is known as teh beads on a string, complex

2- the DNA that is wrapped around the histone is now 11 nm in length. It coils further to form a chromosome thread 30 nm in length

3- the thread wraps around a non histone protein scaffold which gives the distinct chromosome shape and makes DNA easier to manage during replication
Why is DNA supercoiling important?
It makes DNa easier to manage in the cell, by making the super long threads into compact structures
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