RNA - PowerPoint PPT Presentation

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RNA

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RNA & Gene Expression Gene Expression Making sense of the code and doing what it says! Even though the DNA in all of the cells of one organism are the same, they all ... – PowerPoint PPT presentation

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Title: RNA


1
RNA Gene Expression
2
Gene Expression
  • Making sense of the code and doing what it says!
  • Even though the DNA in all of the cells of one
    organism are the same, they all dont perform the
    same functions
  • Certain cells only express certain genes
  • For example
  • Eye cells dont express genes that relate to
    digestion
  • Liver cells dont express genes that relate to
    reproduction
  • Genes are expressed by way of proteins

3
Making a Protein
  • Proteins are built according to instructions
    coded in DNA
  • But, DNA does not directly make proteins
  • RNA takes information from DNA to the ribosomes
    where the proteins are made
  • Why?
  • Proteins are made in two steps
  • Transcription (DNA ? RNA)
  • Translation (RNA ? Proteins)

4
DNA vs. RNA
  • DNA is composed of two strands of nucleotides
    RNA is composed of one strand
  • DNA and RNA have different types of sugars
    (deoxyribose vs. ribose)
  • DNA has the bases A,T,C,G RNA has the bases
    A,U,C,G (Thymine is replaced by Uracil)

5
Types of RNA
  • Messenger RNA (mRNA) Carries instructions from
    DNA to the ribosome
  • Transfer RNA (tRNA) Translates the instructions
    into protein building blocks (amino acids)
  • Ribosomal RNA (rRNA) What ribosomes are made up
    of

6
Transcription
  • A process where information coded on a specific
    region of DNA (a gene) is transcribed (copied)
    into mRNA
  • Occurs in nucleus
  • Steps in transcription
  • A certain segment of DNA strand unwinds and
    separates
  • Complementary nucleotides are added (Adenine
    pairs with Uracil instead of Thymine)
  • DNA strand joins back together and re-winds
  • mRNA then travels out of nucleus to ribosome

7
Transcription
NUCLEUS
mRNA leaves nucleus
8
Three-Letter Words
  • Every three nucleotide bases in mRNA is called a
    codon
  • Each codon is matched to 1 of 20 amino acids
  • The amino acids will later link up to form
    proteins

mRNA strand
9
Translation
  • Translation uses the codons on the mRNA strand to
    link amino acids together to make proteins at the
    ribosome

Amino Acid
tRNA
C
  • tRNAs anti-codon joins to mRNAs codon

A
U
anti-codon
codon
codon
codon
codon
codon
codon
A
G
U
G
G
G
C
A
A
A
A
G
C
U
C
G
G
U
10
Translation
G
U
codon
codon
codon
codon
codon
A
G
U
G
G
G
C
A
A
A
A
G
C
U
C
G
G
U
11
Translation
codon
codon
codon
U
U
C
A
G
U
G
G
G
C
A
A
A
A
G
C
U
C
G
G
U
12
Translation
codon
codon
codon
A
G
U
G
G
G
C
A
A
A
A
G
C
U
C
G
G
U
13
Translation
codon
codon
A
G
U
G
G
G
C
A
A
A
A
G
C
U
C
G
G
U
14
Translation
codon
A
G
U
G
G
G
C
A
A
A
A
G
C
U
C
G
G
U
15
Translation
Protein!
codon
A
G
U
G
G
G
C
A
A
A
A
G
C
U
C
G
G
U
16
Translation
17
  • http//www.youtube.com/watch?v4PKjF7OumYo
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