Aula 2- genes e DNA

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O que são os genes? 
Estrutura da molécula de DNA (ácido dessoxiribonucléico)
É um polímero (cadeia) de nucleotídeos.
4 tipos: 
Desoxiadenilato 
Desoxiguanilato
Desoxicitidilato
Desoxitimidilato
Nucleotídeos da molécula de DNA 
Grupamento fosfato
Carbohidrato: Pentose do tipo Desoxiribose
As bases nitrogenadas são diferentes.
3
Nucleotídeos da molécula de DNA
Poderemos chamá-los, em sala de aula, pelo nome das bases nitrogenadas: 
Adenina
Guanina
Timina 
Citosina
Como polimerizam?
Ligação fosfodiéster entre
nucleotídeos adjacentes
Ligação fosfodiéster 
O posicionamento do grupo fosfato e da hidroxila dá orientação à fita de DNA.
5´
3´
A molécula de DNA é composta por duas fitas nucleotídicas. 
As fitas se mantém unidas por pontes de hidrogênio entre as bases nitrogenadas A-T; C-G.
As fitas são antiparalelas.
Pontes de hidrogênio
8
Bases nitrogenadas
Purinas
Pirimidinas
9
Pontes de Hidrogênio
11
Representação da fita de DNA
5´GTGAGGGCTTTGCTCTCCTGGAGACATTTGCCCCCAGCTGTGAGCAGGGACAGGTCTGGCCACCGGGCCCCTGGTTAAGACTCTAATGACCCGCTGGTCCTGAGGAAGAGGTGCTGACGACCAAGGAGATCTTCCCACAGACCCAGCACCAGGGAAATGGTCCGGAAATTGCAGCCTCAGCCCCCAGCCATCTGCCGACCCCCCCACCCCGCCCTAATGGGCCAGGCGGCAGGGGTTGACAGGTAGGGGAGATGGGCTCTGAGACTATAAAGCCAGCGGGGGCCCAGCAGCCCTCAGCCCTCCAGGACAGGCTGCATCAGAAGAGGCCATCAAGCAGGTCTGTTCCAAGGGCCTTTGCGTCAGGTGGGCTCAGGGTTCCAGGGTGGCTGGACCCCAGGCCCCAGCTCTGCAGCAGGGAGGACGTGGCTGGGCTCGTGAAGCATGTGGGGGTGAGCCCAGGGGCCCCAAGGCAGGGCACCTGGCCTTCAGCCTGCCTCAGCCCTGCCTGTCTCCCAGATCACTGTCCTTCTGCCATGGCCCTGTGGATGCGCCTCCTGCCCCTGCTGGCGCTGCTGGCCCTCTGGGGACCTGACCCAGCCGCAGCCTTTGTGAACCAACACCTGTGCGGCTCACACCTGGTGGAAGCTCTCTACCTAGTGTGCGGGGAACGAGGCTTCTTCTACACACCCAAGACCCGCCGGGAGGCAGAGGACCTGCAGGGTGAGCCAACCGCCCATTGCTGCCCCTGGCCGCCCCCAGCCACCCCCTGCTCCTGGCGCTCCCACCCAGCATGGGCAGAAGGGGGCAGGAGGCTGCCACCCAGCAGGGGGTCAGGTGCACTTTTTTAAAAAGAAGTTCTCTTGGTCACGTCCTAAAAGTGACCAGCTCCCTGTGGCCCAGTCAGAATCTCAGCCTGAGGACGGTGTTGGCTTCGGCAGCCCCGAGATACATCAGAGGGTGGGCACGCTCCTCCCTCCACTCGCCCCTCAAACAAATGCCCCGCAGCCCATTTCTCCACCCTCATTTGATGACCGCAGATTCAAGTGTTTTGTTAAGTAAAGTCCTGGGTGACCTGGGGTCACAGGGTGCCCCACGCTGCCTGCCTCTGGGCGAACACCCCATCACGCCCGGAGGAGGGCGTGGCTGCCTGCCTGAGTGGGCCAGACCCCTGTCGCCAGCCTCACGGCAGCTCCATAGTCAGGAGATGGGGAAGATGCTGGGGACAGGCCCTGGGGAGAAGTACTGGGATCACCTGTTCAGGCTCCCACTGTGACGCTGCCCCGGGGCGGGGGAAGGAGGTGGGACATGTGGGCGTTGGGGCCTGTAGGTCCACACCCAGTGTGGGTGACCCTCCCTCTAACCTGGGTCCAGCCCGGCTGGAGATGGGTGGGAGTGCGACCTAGGGCTGGCGGGCAGGCGGGCACTGTGTCTCCCTGACTGTGTCCTCCTGTGTCCCTCTGCCTCGCCGCTGTTCCGGAACCTGCTCTGCGCGGCACGTCCTGGCAGTGGGGCAGGTGGAGCTGGGCGGGGGCCCTGGTGCGGCAGCCTGCAGCCCTTGGCCCTGGAGGGGTCCCTGCAGAAGCGTGGCATTGTGGAACAATGCTGTACCAGCATCTGCTCCCTCTACCAGCTGGAGAACTACTGCAACTAGACGCAGCCTGCAGGCAGCCCCACACCCGCCGCCTCCTGCACCGAGAGAGATGGAATAAAGCCCTTGAACCAGCCCTGCTGTGCCGTCTGTGTGTCTTGGGGGCCCTGGGCCAAGCCCCACTTCCCGGCACTGTTGTGAGCCCCTCCCAGCTCTCTCCACGCTCTCTGGGTGCCCACAGGTGCCAACGCCGGCCAGGCCCAGCATGCAGTGGCTCTCCCCAAAGCGGCCATGCCTGTTGGCTGCCTGCTGCCCCCACCCTGTGGCTCAGGGTCCAGTATGGGAGCTTCGGGGGTCTCTGAGGGGCCAGGATGGTGGGGCCACTGAGAAGTGACTTCTTGTTCAGTAGCTCTGGACTCTTGGAGTCCCCAGAGACCTTGTTCAGGAAAGGGAATGAGAACATTCCAGCAATTTTCCCCCCACCTAGCCCTCCCAGGTTCTATTTTTAGAGTTATTTCTGATGGAGTCCCTGTGGAGGGAGGAGGCTGGGCTGAGGGAGGGGGT 3´
Representação da fita de DNA
GTGAGGGCTTTGCTCTCCTGGAGACATTTGCCCCCAGCTGTGAGCAGGGACAGGTCTGGCCACCGGGCCCCTGGTTAAGACTCTAATGACCCGCTGGTCCTGAGGAAGAGGTGCTGACGACCAAGGAGATCTTCCCACAGACCCAGCACCAGGGAAATGGTCCGGAAATTGCAGCCTCAGCCCCCAGCCATCTGCCGACCCCCCCACCCCGCCCTAATGGGCCAGGCGGCAGGGGTTGACAGGTAGGGGAGATGGGCTCTGAGACTATAAAGCCAGCGGGGGCCCAGCAGCCCTCAGCCCTCCAGGACAGGCTGCATCAGAAGAGGCCATCAAGCAGGTCTGTTCCAAGGGCCTTTGCGTCAGGTGGGCTCAGGGTTCCAGGGTGGCTGGACCCCAGGCCCCAGCTCTGCAGCAGGGAGGACGTGGCTGGGCTCGTGAAGCATGTGGGGGTGAGCCCAGGGGCCCCAAGGCAGGGCACCTGGCCTTCAGCCTGCCTCAGCCCTGCCTGTCTCCCAGATCACTGTCCTTCTGCCATGGCCCTGTGGATGCGCCTCCTGCCCCTGCTGGCGCTGCTGGCCCTCTGGGGACCTGACCCAGCCGCAGCCTTTGTGAACCAACACCTGTGCGGCTCACACCTGGTGGAAGCTCTCTACCTAGTGTGCGGGGAACGAGGCTTCTTCTACACACCCAAGACCCGCCGGGAGGCAGAGGACCTGCAGGGTGAGCCAACCGCCCATTGCTGCCCCTGGCCGCCCCCAGCCACCCCCTGCTCCTGGCGCTCCCACCCAGCATGGGCAGAAGGGGGCAGGAGGCTGCCACCCAGCAGGGGGTCAGGTGCACTTTTTTAAAAAGAAGTTCTCTTGGTCACGTCCTAAAAGTGACCAGCTCCCTGTGGCCCAGTCAGAATCTCAGCCTGAGGACGGTGTTGGCTTCGGCAGCCCCGAGATACATCAGAGGGTGGGCACGCTCCTCCCTCCACTCGCCCCTCAAACAAATGCCCCGCAGCCCATTTCTCCACCCTCATTTGATGACCGCAGATTCAAGTGTTTTGTTAAGTAAAGTCCTGGGTGACCTGGGGTCACAGGGTGCCCCACGCTGCCTGCCTCTGGGCGAACACCCCATCACGCCCGGAGGAGGGCGTGGCTGCCTGCCTGAGTGGGCCAGACCCCTGTCGCCAGCCTCACGGCAGCTCCATAGTCAGGAGATGGGGAAGATGCTGGGGACAGGCCCTGGGGAGAAGTACTGGGATCACCTGTTCAGGCTCCCACTGTGACGCTGCCCCGGGGCGGGGGAAGGAGGTGGGACATGTGGGCGTTGGGGCCTGTAGGTCCACACCCAGTGTGGGTGACCCTCCCTCTAACCTGGGTCCAGCCCGGCTGGAGATGGGTGGGAGTGCGACCTAGGGCTGGCGGGCAGGCGGGCACTGTGTCTCCCTGACTGTGTCCTCCTGTGTCCCTCTGCCTCGCCGCTGTTCCGGAACCTGCTCTGCGCGGCACGTCCTGGCAGTGGGGCAGGTGGAGCTGGGCGGGGGCCCTGGTGCGGCAGCCTGCAGCCCTTGGCCCTGGAGGGGTCCCTGCAGAAGCGTGGCATTGTGGAACAATGCTGTACCAGCATCTGCTCCCTCTACCAGCTGGAGAACTACTGCAACTAGACGCAGCCTGCAGGCAGCCCCACACCCGCCGCCTCCTGCACCGAGAGAGATGGAATAAAGCCCTTGAACCAGCCCTGCTGTGCCGTCTGTGTGTCTTGGGGGCCCTGGGCCAAGCCCCACTTCCCGGCACTGTTGTGAGCCCCTCCCAGCTCTCTCCACGCTCTCTGGGTGCCCACAGGTGCCAACGCCGGCCAGGCCCAGCATGCAGTGGCTCTCCCCAAAGCGGCCATGCCTGTTGGCTGCCTGCTGCCCCCACCCTGTGGCTCAGGGTCCAGTATGGGAGCTTCGGGGGTCTCTGAGGGGCCAGGATGGTGGGGCCACTGAGAAGTGACTTCTTGTTCAGTAGCTCTGGACTCTTGGAGTCCCCAGAGACCTTGTTCAGGAAAGGGAATGAGAACATTCCAGCAATTTTCCCCCCACCTAGCCCTCCCAGGTTCTATTTTTAGAGTTATTTCTGATGGAGTCCCTGTGGAGGGAGGAGGCTGGGCTGAGGGAGGGGGT 
Quantos genes têm os humanos? 
50 a 100 mil genes
Genoma humano 3x109 - 108
3% do DNA humano corresponde a uma sequência gênica. E o resto? 
92% do DNA do baiacu são genes
Gene da insulina
GTGAGGGCTTTGCTCTCCTGGAGACATTTGCCCCCAGCTGTGAGCAGGGACAGGTCTGGCCACCGGGCCCCTGGTTAAGACTCTAATGACCCGCTGGTCCTGAGGAAGAGGTGCTGACGACCAAGGAGATCTTCCCACAGACCCAGCACCAGGGAAATGGTCCGGAAATTGCAGCCTCAGCCCCCAGCCATCTGCCGACCCCCCCACCCCGCCCTAATGGGCCAGGCGGCAGGGGTTGACAGGTAGGGGAGATGGGCTCTGAGACTATAAAGCCAGCGGGGGCCCAGCAGCCCTCAGCCCTCCAGGACAGGCTGCATCAGAAGAGGCCATCAAGCAGGTCTGTTCCAAGGGCCTTTGCGTCAGGTGGGCTCAGGGTTCCAGGGTGGCTGGACCCCAGGCCCCAGCTCTGCAGCAGGGAGGACGTGGCTGGGCTCGTGAAGCATGTGGGGGTGAGCCCAGGGGCCCCAAGGCAGGGCACCTGGCCTTCAGCCTGCCTCAGCCCTGCCTGTCTCCCAGATCACTGTCCTTCTGCCATGGCCCTGTGGATGCGCCTCCTGCCCCTGCTGGCGCTGCTGGCCCTCTGGGGACCTGACCCAGCCGCAGCCTTTGTGAACCAACACCTGTGCGGCTCACACCTGGTGGAAGCTCTCTACCTAGTGTGCGGGGAACGAGGCTTCTTCTACACACCCAAGACCCGCCGGGAGGCAGAGGACCTGCAGGGTGAGCCAACCGCCCATTGCTGCCCCTGGCCGCCCCCAGCCACCCCCTGCTCCTGGCGCTCCCACCCAGCATGGGCAGAAGGGGGCAGGAGGCTGCCACCCAGCAGGGGGTCAGGTGCACTTTTTTAAAAAGAAGTTCTCTTGGTCACGTCCTAAAAGTGACCAGCTCCCTGTGGCCCAGTCAGAATCTCAGCCTGAGGACGGTGTTGGCTTCGGCAGCCCCGAGATACATCAGAGGGTGGGCACGCTCCTCCCTCCACTCGCCCCTCAAACAAATGCCCCGCAGCCCATTTCTCCACCCTCATTTGATGACCGCAGATTCAAGTGTTTTGTTAAGTAAAGTCCTGGGTGACCTGGGGTCACAGGGTGCCCCACGCTGCCTGCCTCTGGGCGAACACCCCATCACGCCCGGAGGAGGGCGTGGCTGCCTGCCTGAGTGGGCCAGACCCCTGTCGCCAGCCTCACGGCAGCTCCATAGTCAGGAGATGGGGAAGATGCTGGGGACAGGCCCTGGGGAGAAGTACTGGGATCACCTGTTCAGGCTCCCACTGTGACGCTGCCCCGGGGCGGGGGAAGGAGGTGGGACATGTGGGCGTTGGGGCCTGTAGGTCCACACCCAGTGTGGGTGACCCTCCCTCTAACCTGGGTCCAGCCCGGCTGGAGATGGGTGGGAGTGCGACCTAGGGCTGGCGGGCAGGCGGGCACTGTGTCTCCCTGACTGTGTCCTCCTGTGTCCCTCTGCCTCGCCGCTGTTCCGGAACCTGCTCTGCGCGGCACGTCCTGGCAGTGGGGCAGGTGGAGCTGGGCGGGGGCCCTGGTGCGGCAGCCTGCAGCCCTTGGCCCTGGAGGGGTCCCTGCAGAAGCGTGGCATTGTGGAACAATGCTGTACCAGCATCTGCTCCCTCTACCAGCTGGAGAACTACTGCAACTAGACGCAGCCTGCAGGCAGCCCCACACCCGCCGCCTCCTGCACCGAGAGAGATGGAATAAAGCCCTTGAACCAGCCCTGCTGTGCCGTCTGTGTGTCTTGGGGGCCCTGGGCCAAGCCCCACTTCCCGGCACTGTTGTGAGCCCCTCCCAGCTCTCTCCACGCTCTCTGGGTGCCCACAGGTGCCAACGCCGGCCAGGCCCAGCATGCAGTGGCTCTCCCCAAAGCGGCCATGCCTGTTGGCTGCCTGCTGCCCCCACCCTGTGGCTCAGGGTCCAGTATGGGAGCTTCGGGGGTCTCTGAGGGGCCAGGATGGTGGGGCCACTGAGAAGTGACTTCTTGTTCAGTAGCTCTGGACTCTTGGAGTCCCCAGAGACCTTGTTCAGGAAAGGGAATGAGAACATTCCAGCAATTTTCCCCCCACCTAGCCCTCCCAGGTTCTATTTTTAGAGTTATTTCTGATGGAGTCCCTGTGGAGGGAGGAGGCTGGGCTGAGGGAGGGGGT 
Insulina
AMINOÁCIDO- PROTEÍNA
NUCLEOTÍDEO - DNA
Quem faz proteínas?
Onde estão localizados nas células? 
17
Processo de transcrição e tradução
Transcrição: transferência da informação do núcleo para o citoplasma por uma molécula de RNA. 
5’-ATGCTTGATGTAACACTG-3’
3’-TACGAACTACATTGTGAC-5’
5’-AUGCUUGAU5’-ATGCTTGATGTAACACTG-3’
 
 
3’-TACGAACTACATTGTGAC-5’
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Os transcritos são fitas de RNA (ácido ribonucléico)
O RNA, assim como o DNA, é formado por nucleotídeos. 
Adenilato (A)
Guanilato (G)
Citidilato (C)
Uridilato (U)
Nucleotídeos da molécula de RNA 
OH
OH
OH
Uracila(U)
20
Diferença entre moléculas de DNA e RNA
Ribose
Desoxiribose
21
Molécula de RNA 
Forma-se no processo de transcrição. 
A molécula de RNA é uma fita simples. 
Temporariamente é pareada (ligação pontes de hidrogênio entre as bases nitrogenadas) com uma das fitas de DNA. 
A fita que contém a informação gênica é chamada de mRNA ou RNAm (mensageiro).
Fluxo da
informação
AMINOÁCIDO- PROTEÍNA
NUCLEOTÍDEO - DNA
24
Tradução: informação de nucleotídeo para aminoácido. 
25
Há 20 aminoácidos que compõe as proteínas e 64 possibilidade de códons pela combinação dos 4 nucleotídeos em 3 posições. 
2abase
U
C
A
G
U
UUU (Phe)Fenilalanina
UUC (Phe)Fenilalanina
UUA (Leu)Leucina
UUG (Leu)Leucina
UCU (Ser)Serina
UCC (Ser)Serina
UCA (Ser)Serina
UCG (Ser)Serina
UAU (Tyr)Tirosina
UAC (Tyr)Tirosina
UAA Parada /Stop
UAG Parada /Stop
UGU (Cys)Cisteína
UGC (Cys)Cisteína
UGA Parada /Stop
UGG (Trp)Triptofano
C
CUU (Leu)Leucina
CUC (Leu)Leucina
CUA (Leu)Leucina
CUG (Leu)Leucina
CCU (Pro)Prolina
CCC (Pro)Prolina
CCA (Pro)Prolina
CCG (Pro)Prolina
CAU (His)Histidina
CAC (His)Histidina
CAA (Gln)Glutamina
CAG (Gln)Glutamina
CGU (Arg)Arginina
CGC (Arg)Arginina
CGA (Arg)Arginina
CGG (Arg)Arginina
A
AUU (Ile)Isoleucina
AUC (Ile)Isoleucina
AUA (Ile)Isoleucina
AUG (Met)MetioninaInício /Start
ACU (Thr)Treonina
ACC (Thr)Treonina
ACA (Thr)Treonina
ACG (Thr)Treonina
AAU (Asn)Asparagina
AAC (Asn)Asparagina
AAA (Lys)Lisina
AAG (Lys)Lisina
AGU (Ser)Serina
AGC (Ser)Serina
AGA (Arg)Arginina
AGG (Arg)Arginina
G
GUU (Val)Valina
GUC (Val)Valina
GUA (Val)Valina
GUG (Val)Valina
GCU (Ala)Alanina
GCC (Ala)Alanina
GCA (Ala)Alanina
GCG (Ala)Alanina
GAU (Asp)Ácido aspártico
GAC (Asp)Ácido aspártico
GAA (Glu)Ácido glutâmico
GAG (Glu)Ácido glutâmico
GGU (Gly)Glicina
GGC (Gly)Glicina
GGA (Gly)Glicina
GGG (Gly)Glicina
1a base
26
Transcrição: síntese de RNA usando DNA como molde.
Os genes possuem um início e um fim.
Ligação dos fatores de transcrição em genes eucariotos.
Fatores de transcrição:
*TATA box (caixa hogness) – Liga-se o TFIID
*CAAT box – Liga-se CTF 
*GC box – Liga-se SP1 
 
Fatores de transcrição 
29
Transcrição: Fatores de transcrição
Beta globina
SV40 
Timidina quinase
Histona H2B
TATA box
GC box
CAAT box
Motivo octâmero
 Início da 
transcrição
Amanitina: substância tóxica que impede a ligação da RNA polimerase II a região promotora dos genes. 
Amanita muscaria 
Fonte: http://morelmushroomhunting.com/amanita_muscaria.htm
Transcrição: reforçadores (enhancers)
32