molecules to cells section 2 genetics

what is the central dogma

DNA→RNA→Protein

what are the three things DNA must do

1. replicated faithfully

2. have the coding capacity to generate proteins for cellular functions

3. transmit from parent cell to daughter cell

4. orchestrate any organismal functions

where are genes located

on chromosomes in the nucleas

what is DNA made of

nucleaotides, phosphate+sugar+base

what are the purine versus pyrimidine bases

A and G=purine

C and T=pyrimidine

how are phosphodiester bonds formed

5’ phosphate to 3’ hydroxyl

how was DNA structure determined

x-ray crystallography→DNA precipated from a solution by adding ethanol providing the fibres for crystallography

what is Chargaffs rule

A=T and C=G

how are bases paired in DNA replication

hydrogen bonding; C and G have 3 compared to and A and T with 2

job of helicase

to unwind and open up DNA

job of topoisomerase

deals with overwinding with nucleases to snip DNA while ligase reconnects

what is the main enzyme in DNA replication

DNA polymerase III

what is required for DNA polymerase initiation

RNA primers→created by primase

what can DNA pol I do

removes RNA primers

what directino does DNA synthesis occur

5’ to 3’ direction

how is the lagging strand created

Okazaki fragments→multple primers involved so DNA synthesis can still move from 5’ to 3’ direction

what are the enzymatic activities of DNAP I

1. 5’ to 3’ dna polymerasation

2. 3’ to 5’ exonuclease activity; backwards correcting base errors

3. 5’ to 3’ exonucleasing removing RNA primers

whatis Rifamipicin

RNA polymerase inhibitor

what is the Nick translation

DNA polymerase I taking over from DNA polymerase III and removes the RNA primer replacing it with new DNA and then ligase seals the nicks between the DNA

what is the Haflick limit

telomere shortening→indicator of aging that cells can only divide a certain number of times

what is the role of transfer RNA

translocation protein synthesis

what is meant by +1 in transcription

intiaition site

what is upstream versus downstream

upstream=-5

downstream=+5

what is the purpose of sigma subunits

in prokaryotes they are required for specific promoter recognition

does RNAP bind specifically or nonspecifcally

nonspecifcally→binds then scans looking for promoter sequence

simple versus complex termination of transcription

simple means without a protein factor and a hairpin structure forms near mRNA end causing RNAP dissociation

complex is rho depednent so a helicase protein called rho is required to terminate transcription

how is RNAP acitivate

through phosphorylation of C-terminal tail domain

how is mature mRNA produced

1. splicesomes remove introns

2. 5’ cap and 3’polya tail are added

3. mature mRNA is transported from nucleas to cytoplasm via nuclear pores

what are the two components of a gene

1=coding sequence; what gets transcribed

2=DNA regulatory elements such as the promoter

are gene products always proteins

no they can function as RNA

what are the cell types that cannot still express all nessecary genes to build a new organims(Wilmut sheep)

cells that have lost there nucleai(erythrocytes)

senescent cells that lost telomeres such as skill cells and neurons

what are housekeeping genes

genes expressed in every cell type

job of small nuclear RNAS

splice mRNA to remove introns

what are mendelles principles

principle of dominance→allele can be cominant or recessive with dominant always being expressed when hetereozygous

principle of segregation→allelles of genes seperated during gametogensis

law of independant assortment→genes encoding different traits segregate indepednetly of one another

Huntingtons disease

autosomal dominant

what cells are assoicated with cancer and expressed in breast cells

BRCA

epidermolysis bullosa

mutation in keratin gene that is austosomal dominnant and causes blistering

describe DNA replication

always occurs 5’→3’

the origin of replication is thymine and adenine rich since they only have two hydrogen bonds

pre initiation complex binds to DNA and opens up creating replication bubble

helicase unwinds DNA and SS binding proteins prevents reannealing and protects nucleotides from nucleases which want to break phosphodiester bonds

as it super coils topoisomerase uses nuclease to snap and then ligase to repair dna to un super coil

then the elongation stage involes primase which is an enzyme that attaches RNA primers allowing DNAP III to create DNA

the lagging strand gets multiple primers

DNAP I removes the RNA primers

polio

FLU

Polio=+ssRNA acts as mRNA so it immedicatly translated in cytoplasm using host ribosomes

FLU=-ssRNA so it gets transcribed in the nucleas by virion polymeriases and then translated

VSV chicken pox=dsDNA so it gets transcribed in the nuclease by host RNAP II

how do virusues move inside of cells

through microtubules and dyneines moving towards the nuclease

what info is versus is not contained in viral genomes

IS: virus genome replication, assembly and packing of genome, reuglating virus replication, modulation host defences, and spreading to other cells

NOT: genes for complete protein synthesis and those nessecary for energy production or membrane synthesis