3.1_genes

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Genetics

3.1 Genes

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Essential Idea: Every liviorganism inherits a bluepr

for life from its parents.

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Nature of Science: Developme

in scientific research follow

improvements in technology – g

sequencers are used for thesequencing of genes.

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∑ - A gene is a heritable factor that cona length of DNA and inuences a spe

characteristic.• umans ha!e bet"een

#1,$$$%#3,$$$ proteincoding genes

• The number of genes in an

organism&s genome doesnot indicate ho"complicated an organismis, as indicated by thetable in your notes.

β - Comparison of the numbein humans with other species

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∑ - A gene occupies a specic position onchromosome.

•'ach chromosomecontains many di0erentgenes often lined in

groups.

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∑ - he !arious specic forms of a gene aalleles.

• Allele: 2ne specic form of a gene,di0ering from other alleles by one ora fe" bases only and occupying thesame gene locus as other alleles of

the same gene.

• There can be t"o or more alleles of aspecic gene depending on the gene.

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∑ - he !arious specic forms of a gene aalleles.

• The gene that inuences human blood type has thrdi0erent alleles that code for blood types A, 4 and 5hen there are more than t"o alleles, this is calledmultiple alleles.

• *ince each human cell consists of # copies of eachchromosome (e6cept - and ), there are t"o copieseach gene. *ometimes a person can ha!e t"o of thesame allele (homo7ygous) or t"o di0erent alleles(hetero7ygous)

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∑ - Alleles di"er from each other b# one or ofew bases.

•Genes consist of a certain se8uence oDNA bases "hich can be 1$$&s to 1$$bases in length

•9sually di0erent alleles of the gene !by only one to a couple of di0erent ba

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∑ - Alleles di"er from each other b# one or ofew bases.

• or e6ample, the allele for *icle ;ell Anemia icreated by a mutation of a single nucleotide.

• Adenine is s"itched to Thymine (;T; to ;A;)"hich results in glutamic acid being substitute

!aline at position in the aemoglobin polype

• This !ariation "hen one nucleotide is s"itchedanother is called a single nucleotide polymorph(*N<s for short)

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β - $se of a database to determine di"erenin the base se%uence of a gene in two spec

• http:==""".digital"orldbiology.com>A*T=#$$$se8uences.html

• http:==digital"orldbiology.com=d"b=4>A*

• www.ncbi.nlm.nih.go!&genban'

• http(&&wor'bench.sdsc.edu&

http://digitalworldbiology.com/BLAST/62000sequences.html


http://digitalworldbiology.com/dwb/BLAST


http://www.ncbi.nlm.nih.gov/genbank

http://workbench.sdsc.edu/



http://www.ncbi.nlm.nih.gov/genbank






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∑ - New alleles are formed b# mutatio

• As stated abo!e, ne" alleles arecreated by random changes in the bse8uence called mutations.

•There are a !ariety of di0erent typemutations that can be either harmfuneutral or benecial

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β - Application( he causes of sic'le cell anemia) inclubase substitution mutation) a change to the base se%um*NA transcribed from it and a change to the se%uen

pol#peptide in hemoglobin.

• A base substitution mutation causes thereplacement of a single base nucleotide "itanother nucleotide in DNA.

• 5hen one of the bases is changed, this"ill cause a change in the m?NA se8uence the DNA is copied during transcription of thgene.

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β - Application( he causes of sic'le ceanemia++.

• This change in the m?NA se8uence may change thamino acid in the polypeptide coded for by the genthe process of translation.

• *icle%cell anemia is a disease that causes red blooto form a sicle shape (half%moon). These sicled bcells cannot carry as much o6ygen as normal red bcells. They can cause clots in blood !essels becaustheir abnormal shape and ine6ibility caused bycrystalli7ation of the abnormal hemoglobin.

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• *icle cell is caused by a base%substitution "hen the adenine base in GAGreplaced by a thymine base, changing the

triplet to GTG.• The normal triplet "hen transcribed andtranslated codes for the amino acid glutamacid.

β - Application( he causes of sic'le cellanemia++

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•5hen the base substitution occurs, thamino acid that is translated is no" !aline.

•*ince !aline has a di0erent shape andcharge, the resulting polypeptide&s shand structure changes.

β - Application( he causes of sic'le cellanemia++

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• As a result, hemoglobin&s shap"ill change, as does the shape

the red blood cell, resulting in problems associated "ith siclcell anemia listed abo!e.

β - Application( he causes of sic'le cellanemia++.

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•https:==""".youtube.com="atch!B1fNCr2"DyE

,ic'le Cell Anemia in Africa

https://www.youtube.com/watch?v=1fN7rOwDyMQ




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∑ - he genome is the whole of the genetinformation of an organism.

•enome: The "hole of the genetic informatioan organism

• Fn humans, the genome consists of +

chromosomes plus the mitochondrial DNA • Fn plants, the genome also consists of chloropDNA on top of their chromosomes andmitochondrial DNA

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∑ - he genome is the whole of the genetinformation of an organism.

•<roaryotesha!e a circular

chromosome andplasmids in theirgenome

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∑ - he entire base se%uence of human ge was se%uenced in the uman enome /ro

• 5hat they found: ost of the genome does code for proteins (originally labeled Hun D*ome of these regions consist of areas that a0ect gene e6pression or are highly repetitise8uences called satellite DNA. *cientists calso predict "hich se8uences do code for pr(appro6imately #1$$$%#3$$$ se8uences)

3.1_genes

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