-
what is the bonds btwn base portions of nucleotides in DNA?
hydrogen
-
backbone of DNA
sugar-phosphate
-
how many base pairs per helical turn
10
-
what on DNA differs organisms?
nucleotide sequences
-
the 20 letter amino acid alphabet spelt out with 4 letter nucleotides
genetic code
-
nucleotide sequence of gene transcribed and then translated
gene expression
-
what is the DNA molecules packaged into?
chromosomes
-
how many different types of chromosomes is in a human nucleus?
23 or 24 for Y chromosome
-
DNA + proteins that fold and pack
chromatin
-
what type of cells are sperm and eggs?
germ cells
-
maternal and paternal chromosomes of a pair
homologous chromosomes(homologs)
-
whats the only nonhomologous chromosome pairs
sex chromosomes
-
chromosomes distinguished with different fluorescent dyes
DNA hybridization
-
ordered display of all 46 human chromosomes
karyotype
-
segment of DNA that contains the instructions for making a protein or RNA molecule
gene
-
total genetic information in all chromosomes in a cell
genome
-
large excess of interspersed DNA
junk DNA
-
when chromosomes are duplicated
interphase
-
when chromosomes are distributed or segregated to two daughter nuclei
mitosis
-
chromosomes are extended
interphase
-
type of nucleotide sequence that acts as a begin site for DNA replication
replication origin
-
* located at each end of chromosome
* contain repeated nucleotide sequence required for chromosomes to be replicated
* cap DNA ends
telomers
-
allows duplicated chromosomes to be separated during M phase
centromere
-
stage DNA coils up, compacts into a structure of chromosomes
- M phase
- mitotic chromosomes
-
two places chromosomes tend to attached to
- nuclear envelope
- nuclear lamina
-
the two DNA forming chromosomes classes
histones and nonhistones
-
Histone responsible for the first and most fundamental level of chromatin packing
nucleosome
-
series of "beads on the string" string being DNA and beads being
nucleosome core particle, DNA wound around a core of proteins formed from histones
-
DNA wound around a core of proteins formed from histones
nucleosome core particle
-
enzymes that break down DNA by cutting phosphodiester bonds between nucleotides
nucleases
-
exposed DNA between core particles
linker DNA
-
nucleosome core particle + adjacent DNA linkers
nucleosome
-
what helps the histones bind tightly to the negatively charged sugar-phosphate backbone of DNA?
positively charged amino acids(lysine and arginine)
-
nucleosome core particle structure
- 2 of each histones
- DNA, 147 nucleotide pairs long
- histone octamer
- linker DNA
-
long, unstructured N-terminal amino acid
- histone tail
- each histone has one
-
what controls many aspects of chromatin structure and how
histone tails, subjected to several types of reversible, covalent chemical modifications
-
histone that changes the path the DNA takes as it exits the nucleosome core-to form a more condensed chromatin fiber
linker histone/H1
-
levels of chromatin fiber folding
- folded into loops
- loops condensed-interphase chromosome
- compact string of loops-mitotic chromosome
-
what allows access to DNA
changes in nucleosome structure
-
protein machines that use energy of ATP hydrolysis to change position of DNA wrapped around nucleosomes
chromatin-remodeling complexes
-
what is attached to both the histone octamer and DNA which controls access to DNA and remaining inactive during mitosis
chromatin-remodeling complexes
-
what can be added or removed to histone tails that would alter chromatin structure
- acetyl
- phosphate
- methyl groups
-
this can reduce the affinity of tail for adjacent nucleosomes thereby loosening chromatin structure
acetylation of lysine
-
rxns from proteins on docking site of histone tails
- promote chromatin condensation
- decondense & facilitate access to DNA
- indicates newly replicated chromatin
- indicates genes in stretch of chromatin that should be expressed
- indicate nearby genes that need to be silenced
-
2 interphase chromatins
- heterochromatin-most highly condensed
- euchromatin
-
what happens when histone tail modification attracts a set of heterochromatin-specific proteins?
- heterochromatin spreads out
- causes a wave of condensed chromatin to propagate
- propagation continues spread until barrier DNA sequence
-
where in a chromatin does DNA not contain genes and why
- heterochromatin
- bc its so compact genes usually fail to be expressed
-
2 alternative RNA's we're learning about
- Small interfering RNA
- MicroRNA
-
quicker alternative to feedback loops
Proteasome
-
shorten mRNA life span by adding extra sequences to which prime end?
3'
-
what type of specialized cell is most embryos composed of?
iPS cells
-
Part of DNA that expresses specific tissues
transcription factors on Enhancer region
-
What do transfactors recruit?
- HAT-Histone acetylases-loosening chromatin
- HDAC-histone deacetylases-compacting chromatin
-
Cis vs. trans
- postivie Cis elements are bound by trans factors called activators
- Negative Cis elements bound by trans factors called repressors
-
2 steps at pre-transcription
- closed chromatin
- chromatin remodeling
-
1 thing that happens at transcription
chromatin opens
-
3 things at post-transcription/pre-translation
- hetereonuclear
- mRNA
- cytoplasmic mRNA
-
entire stretch of DNA that includes operators, promoters, and genes that they control in bacteria
operons
-
operon that is usually on until bonded w/molecule from negative feedback
example
-
operon that is usually off, for catabolic pathways
what turns it on and example
- inducible operon
- inducer inactivates repressor
- Lac operon
- positive feedback
-
stimulatory protein that positively controls operons
- catabolite activator protein
- activator of transcription
-
When is CAP (catabolite activator protein) activated?
- glucose is scared
- activated by binding with cAMP
-
RXN that happens when CAP is activated by cAMP
- lac operon increases affinity of RNA polymerase, accelerates transcription
- when glucose levels increased, CAP leaves LAC, resumes normal activity
-
2 ways a cell can regulate the activity of enzymes
- feedback inhibition
- gene regulation
-
what controls gene expression in bacteria?
operon model
-
how does feedback pathways work?
final end product binds to block rest of steps
|
|
