genome structure Flashcards
the dna in genes turns into rna through — in the — and the rna becomes poplypetide product through —- in —- and this polypeptide leads to structure and biological activity of the cell
- transcription
- nucleas
- translation
- cytoplasm
—- is the length of the cell
—- is the full complement of dna an organism and has 25,000 genes
- gene
- genome
the building blocks are —-
the c atoms in the sugar are numbered from —–
the dexoribose - the hydroxyl OH at carbon 2 is replaced by —-
- nucleotide
- 1’-5’
- H
—- are the genetic code
pruine bases have — interlock rings
pyridine has —-
- bases
- 2
- one ring
nucleotide triphosphate components are:
- base + 3 phosphate + sugar
nucleotidetriphosphate join together to make —- , the covelent bond is in —– direction
- long strand aka polymer
- 3’ to 5’ phosphodiser
( c5 and c3 are not linked to a neighbouring sugar )
dna structure:
- double helix w/ —– orientation
- —— backbone on the exterior
- —— on the interior
- ——–
-anti-parrel ( bc 5 and 3 go in the opposite direction )
- sugar phosphate
- purine and pyridine
- complementary base paring :
A-T ( 2 h bonds )
C-G ( 3 h bonds )
—- means the dna strands are complementary
base pairing ( so basically the reflect example:
strand : 5’ AAT 3’
complementary strand: 3’ TTA 5’
the sequence of the bases is the — form of genetic info
storage
forces that hold the dna together are:
1- covelant bonds from 3’-5’ phosphodiser bonds along the dna backbone
2- non-covelent bond :
- base stacking: van der Waals interactions between the stacked base pairs is the strongest non covalent force in the structure
3- hydrogen bonds between the nucleotides:
g-c 3 h bonds ( are rich regions and more stable thermodynamically ) , a-t 2 h bonds ( rich regions that open for replication and transcription )
—- looks like a string of beads , by which the dna wraps around 8 histones to make it
nucleosome strcuture
8x histones ( H2A,H2B , H3 , H4)X2 are — charged and have — core particles while dna is — charged and have —- interactions
the H1 sites sits on —- od the core particles
- positivly
- octamer
- -ve
- ionic
- outside
dna is highly organised and it wound around the nucleosome to make —- which is a highly copact organisation
- chromatin
to make the chromosome this following steps must occur:
basic helix 1;1 —> nucleosome 1;6 —-> chromatin 1:36 —-> scaffold 1:6 —> loops of chromatin —> chromosome
histones have — that aren’t involved in nuclease structure but are important for chromatin structure
tails
—– tails are rich in — charged — residue and the modification of this — changes the chromatin structure
H3 + H4 , +ve , lysines , lysins
histone modification facilitates —-
transcription
the role of chromatin structure in regulating transcription is accessibility to —–
promotors and game sequence
lysines are — charged and dna is — which will interact together o nigh neighbouring nucleosome and —- together , if they are acetylated then the positive charge becomes —-
- positive
- negative
- condense
- neutral
—– promotes looser dna structure and aids transcription
acetylation
( enviornmental cues activates HATs and unwind dna , gene expressed then when no longer needed repressor activate HDACs)
ppl have — individual molecules of chromosomes
giemsa stain is a — banded karyotyping during — is most condensed
—- the consisition aka no. of chromosome
- 46
- g banded
- metaphase
- karyotype
elements of chromosomes:
—– essential for replicating - miotic spindle m characterised by repetitive dna and some specific to c/somes
—- points at which dna sythesis initiates and is essential for dna replication , multible For on human chromosome, speeds replication
—- caps the end of chromosome acts as a buffer and maintains the structural integrity
- centromer
- origin of replication
- tolemer
( check structure slide: 21)
after — phase and before mitosis the chromosomes consist of —-
2 sister chromatid
—- dark/light bands ( density of chromatin foldings)
—- highly condensed no transcription , dark , gene poor
—- extended , light , active transcprtion , gene rich
- banding ( trypsin / giemesta stain )
- hetrochormatin
- euchromatin
true or false:
human genome consists of 30-35k genes and less than 5% of sequence is exonic
trueee
what makes up the human gene? ( conserved about 5%)
1- promoter element ( proximal and core ) —> recruits proteins as RNAPOL2
2- 5’ untranslated region UTR —> era stability
3- exons —> amino acids coding sequence
4- introns —> splicing , poor undertsandig
5- 3 UTR —> mrna stability
what makes up the non conserved part of the genome? ( non conserved refers to not under strong selection , can evolve relatively quick )
1- transpoons about 40% , mobile dna sequence that can migrate to diff regions of the genome
2- microstailities 5%
3- other repear dna about 50%
